text: /*
   * Copyright 2011 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #include "GrGLGpu.h"
  #include "GrBackendSemaphore.h"
  #include "GrBackendSurface.h"
  #include "GrFixedClip.h"
  #include "GrGLBuffer.h"
  #include "GrGLGpuCommandBuffer.h"
  #include "GrGLSemaphore.h"
  #include "GrGLStencilAttachment.h"
  #include "GrGLTextureRenderTarget.h"
  #include "GrGpuResourcePriv.h"
  #include "GrMesh.h"
  #include "GrPipeline.h"
  #include "GrRenderTargetPriv.h"
  #include "GrShaderCaps.h"
  #include "GrSurfaceProxyPriv.h"
  #include "GrTexturePriv.h"
  #include "GrTypes.h"
  #include "SkAutoMalloc.h"
  #include "SkConvertPixels.h"
  #include "SkHalf.h"
  #include "SkJSONWriter.h"
  #include "SkMakeUnique.h"
  #include "SkMipMap.h"
  #include "SkPixmap.h"
  #include "SkSLCompiler.h"
  #include "SkStrokeRec.h"
  #include "SkTemplates.h"
  #include "SkTo.h"
  #include "SkTraceEvent.h"
  #include "SkTypes.h"
  #include "builders/GrGLShaderStringBuilder.h"
  
  #include <cmath>
  
  #define GL_CALL(X) GR_GL_CALL(this->glInterface(), X)
  #define GL_CALL_RET(RET, X) GR_GL_CALL_RET(this->glInterface(), RET, X)
  
  #define SKIP_CACHE_CHECK    true
  
  #if GR_GL_CHECK_ALLOC_WITH_GET_ERROR
      #define CLEAR_ERROR_BEFORE_ALLOC(iface)   GrGLClearErr(iface)
      #define GL_ALLOC_CALL(iface, call)        GR_GL_CALL_NOERRCHECK(iface, call)
      #define CHECK_ALLOC_ERROR(iface)          GR_GL_GET_ERROR(iface)
  #else
      #define CLEAR_ERROR_BEFORE_ALLOC(iface)
      #define GL_ALLOC_CALL(iface, call)        GR_GL_CALL(iface, call)
      #define CHECK_ALLOC_ERROR(iface)          GR_GL_NO_ERROR
  #endif
  
  //#define USE_NSIGHT
  
  ///////////////////////////////////////////////////////////////////////////////
  
  static const GrGLenum gXfermodeEquation2Blend[] = {
      // Basic OpenGL blend equations.
      GR_GL_FUNC_ADD,
      GR_GL_FUNC_SUBTRACT,
      GR_GL_FUNC_REVERSE_SUBTRACT,
  
      // GL_KHR_blend_equation_advanced.
      GR_GL_SCREEN,
      GR_GL_OVERLAY,
      GR_GL_DARKEN,
      GR_GL_LIGHTEN,
      GR_GL_COLORDODGE,
      GR_GL_COLORBURN,
      GR_GL_HARDLIGHT,
      GR_GL_SOFTLIGHT,
      GR_GL_DIFFERENCE,
      GR_GL_EXCLUSION,
      GR_GL_MULTIPLY,
      GR_GL_HSL_HUE,
      GR_GL_HSL_SATURATION,
      GR_GL_HSL_COLOR,
      GR_GL_HSL_LUMINOSITY
  };
  GR_STATIC_ASSERT(0 == kAdd_GrBlendEquation);
  GR_STATIC_ASSERT(1 == kSubtract_GrBlendEquation);
  GR_STATIC_ASSERT(2 == kReverseSubtract_GrBlendEquation);
  GR_STATIC_ASSERT(3 == kScreen_GrBlendEquation);
  GR_STATIC_ASSERT(4 == kOverlay_GrBlendEquation);
  GR_STATIC_ASSERT(5 == kDarken_GrBlendEquation);
  GR_STATIC_ASSERT(6 == kLighten_GrBlendEquation);
  GR_STATIC_ASSERT(7 == kColorDodge_GrBlendEquation);
  GR_STATIC_ASSERT(8 == kColorBurn_GrBlendEquation);
  GR_STATIC_ASSERT(9 == kHardLight_GrBlendEquation);
  GR_STATIC_ASSERT(10 == kSoftLight_GrBlendEquation);
  GR_STATIC_ASSERT(11 == kDifference_GrBlendEquation);
  GR_STATIC_ASSERT(12 == kExclusion_GrBlendEquation);
  GR_STATIC_ASSERT(13 == kMultiply_GrBlendEquation);
  GR_STATIC_ASSERT(14 == kHSLHue_GrBlendEquation);
  GR_STATIC_ASSERT(15 == kHSLSaturation_GrBlendEquation);
  GR_STATIC_ASSERT(16 == kHSLColor_GrBlendEquation);
  GR_STATIC_ASSERT(17 == kHSLLuminosity_GrBlendEquation);
  GR_STATIC_ASSERT(SK_ARRAY_COUNT(gXfermodeEquation2Blend) == kGrBlendEquationCnt);
  
  static const GrGLenum gXfermodeCoeff2Blend[] = {
      GR_GL_ZERO,
      GR_GL_ONE,
      GR_GL_SRC_COLOR,
      GR_GL_ONE_MINUS_SRC_COLOR,
      GR_GL_DST_COLOR,
      GR_GL_ONE_MINUS_DST_COLOR,
      GR_GL_SRC_ALPHA,
      GR_GL_ONE_MINUS_SRC_ALPHA,
      GR_GL_DST_ALPHA,
      GR_GL_ONE_MINUS_DST_ALPHA,
      GR_GL_CONSTANT_COLOR,
      GR_GL_ONE_MINUS_CONSTANT_COLOR,
      GR_GL_CONSTANT_ALPHA,
      GR_GL_ONE_MINUS_CONSTANT_ALPHA,
  
      // extended blend coeffs
      GR_GL_SRC1_COLOR,
      GR_GL_ONE_MINUS_SRC1_COLOR,
      GR_GL_SRC1_ALPHA,
      GR_GL_ONE_MINUS_SRC1_ALPHA,
  };
  
  bool GrGLGpu::BlendCoeffReferencesConstant(GrBlendCoeff coeff) {
      static const bool gCoeffReferencesBlendConst[] = {
          false,
          false,
          false,
          false,
          false,
          false,
          false,
          false,
          false,
          false,
          true,
          true,
          true,
          true,
  
          // extended blend coeffs
          false,
          false,
          false,
          false,
      };
      return gCoeffReferencesBlendConst[coeff];
      GR_STATIC_ASSERT(kGrBlendCoeffCnt == SK_ARRAY_COUNT(gCoeffReferencesBlendConst));
  
      GR_STATIC_ASSERT(0 == kZero_GrBlendCoeff);
      GR_STATIC_ASSERT(1 == kOne_GrBlendCoeff);
      GR_STATIC_ASSERT(2 == kSC_GrBlendCoeff);
      GR_STATIC_ASSERT(3 == kISC_GrBlendCoeff);
      GR_STATIC_ASSERT(4 == kDC_GrBlendCoeff);
      GR_STATIC_ASSERT(5 == kIDC_GrBlendCoeff);
      GR_STATIC_ASSERT(6 == kSA_GrBlendCoeff);
      GR_STATIC_ASSERT(7 == kISA_GrBlendCoeff);
      GR_STATIC_ASSERT(8 == kDA_GrBlendCoeff);
      GR_STATIC_ASSERT(9 == kIDA_GrBlendCoeff);
      GR_STATIC_ASSERT(10 == kConstC_GrBlendCoeff);
      GR_STATIC_ASSERT(11 == kIConstC_GrBlendCoeff);
      GR_STATIC_ASSERT(12 == kConstA_GrBlendCoeff);
      GR_STATIC_ASSERT(13 == kIConstA_GrBlendCoeff);
  
      GR_STATIC_ASSERT(14 == kS2C_GrBlendCoeff);
      GR_STATIC_ASSERT(15 == kIS2C_GrBlendCoeff);
      GR_STATIC_ASSERT(16 == kS2A_GrBlendCoeff);
      GR_STATIC_ASSERT(17 == kIS2A_GrBlendCoeff);
  
      // assertion for gXfermodeCoeff2Blend have to be in GrGpu scope
      GR_STATIC_ASSERT(kGrBlendCoeffCnt == SK_ARRAY_COUNT(gXfermodeCoeff2Blend));
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  
  sk_sp<GrGpu> GrGLGpu::Make(sk_sp<const GrGLInterface> interface, const GrContextOptions& options,
                             GrContext* context) {
      if (!interface) {
          interface = GrGLMakeNativeInterface();
          // For clients that have written their own GrGLCreateNativeInterface and haven't yet updated
          // to GrGLMakeNativeInterface.
          if (!interface) {
              interface = sk_ref_sp(GrGLCreateNativeInterface());
          }
          if (!interface) {
              return nullptr;
          }
      }
  #ifdef USE_NSIGHT
      const_cast<GrContextOptions&>(options).fSuppressPathRendering = true;
  #endif
      auto glContext = GrGLContext::Make(std::move(interface), options);
      if (!glContext) {
          return nullptr;
      }
      return sk_sp<GrGpu>(new GrGLGpu(std::move(glContext), context));
  }
  
  GrGLGpu::GrGLGpu(std::unique_ptr<GrGLContext> ctx, GrContext* context)
          : GrGpu(context)
          , fGLContext(std::move(ctx))
          , fProgramCache(new ProgramCache(this))
          , fHWProgramID(0)
          , fTempSrcFBOID(0)
          , fTempDstFBOID(0)
          , fStencilClearFBOID(0)
          , fHWMinSampleShading(0.0) {
      SkASSERT(fGLContext);
      fCaps = sk_ref_sp(fGLContext->caps());
  
      fHWBoundTextureUniqueIDs.reset(this->caps()->shaderCaps()->maxCombinedSamplers());
  
      fHWBufferState[kVertex_GrBufferType].fGLTarget = GR_GL_ARRAY_BUFFER;
      fHWBufferState[kIndex_GrBufferType].fGLTarget = GR_GL_ELEMENT_ARRAY_BUFFER;
      fHWBufferState[kTexel_GrBufferType].fGLTarget = GR_GL_TEXTURE_BUFFER;
      fHWBufferState[kDrawIndirect_GrBufferType].fGLTarget = GR_GL_DRAW_INDIRECT_BUFFER;
      if (GrGLCaps::kChromium_TransferBufferType == this->glCaps().transferBufferType()) {
          fHWBufferState[kXferCpuToGpu_GrBufferType].fGLTarget =
              GR_GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM;
          fHWBufferState[kXferGpuToCpu_GrBufferType].fGLTarget =
              GR_GL_PIXEL_PACK_TRANSFER_BUFFER_CHROMIUM;
      } else {
          fHWBufferState[kXferCpuToGpu_GrBufferType].fGLTarget = GR_GL_PIXEL_UNPACK_BUFFER;
          fHWBufferState[kXferGpuToCpu_GrBufferType].fGLTarget = GR_GL_PIXEL_PACK_BUFFER;
      }
      for (int i = 0; i < kGrBufferTypeCount; ++i) {
          fHWBufferState[i].invalidate();
      }
      GR_STATIC_ASSERT(6 == SK_ARRAY_COUNT(fHWBufferState));
  
      if (this->glCaps().shaderCaps()->pathRenderingSupport()) {
          fPathRendering.reset(new GrGLPathRendering(this));
      }
  
      GrGLClearErr(this->glInterface());
  }
  
  GrGLGpu::~GrGLGpu() {
      // Ensure any GrGpuResource objects get deleted first, since they may require a working GrGLGpu
      // to release the resources held by the objects themselves.
      fPathRendering.reset();
      fCopyProgramArrayBuffer.reset();
      fMipmapProgramArrayBuffer.reset();
      fStencilClipClearArrayBuffer.reset();
  
      fHWProgram.reset();
      if (fHWProgramID) {
          // detach the current program so there is no confusion on OpenGL's part
          // that we want it to be deleted
          GL_CALL(UseProgram(0));
      }
  
      if (fTempSrcFBOID) {
          this->deleteFramebuffer(fTempSrcFBOID);
      }
      if (fTempDstFBOID) {
          this->deleteFramebuffer(fTempDstFBOID);
      }
      if (fStencilClearFBOID) {
          this->deleteFramebuffer(fStencilClearFBOID);
      }
  
      for (size_t i = 0; i < SK_ARRAY_COUNT(fCopyPrograms); ++i) {
          if (0 != fCopyPrograms[i].fProgram) {
              GL_CALL(DeleteProgram(fCopyPrograms[i].fProgram));
          }
      }
  
      for (size_t i = 0; i < SK_ARRAY_COUNT(fMipmapPrograms); ++i) {
          if (0 != fMipmapPrograms[i].fProgram) {
              GL_CALL(DeleteProgram(fMipmapPrograms[i].fProgram));
          }
      }
  
      if (fStencilClipClearProgram) {
          GL_CALL(DeleteProgram(fStencilClipClearProgram));
      }
  
      if (fClearColorProgram.fProgram) {
          GL_CALL(DeleteProgram(fClearColorProgram.fProgram));
      }
  
      delete fProgramCache;
  }
  
  void GrGLGpu::disconnect(DisconnectType type) {
      INHERITED::disconnect(type);
      if (DisconnectType::kCleanup == type) {
          if (fHWProgramID) {
              GL_CALL(UseProgram(0));
          }
          if (fTempSrcFBOID) {
              this->deleteFramebuffer(fTempSrcFBOID);
          }
          if (fTempDstFBOID) {
              this->deleteFramebuffer(fTempDstFBOID);
          }
          if (fStencilClearFBOID) {
              this->deleteFramebuffer(fStencilClearFBOID);
          }
          for (size_t i = 0; i < SK_ARRAY_COUNT(fCopyPrograms); ++i) {
              if (fCopyPrograms[i].fProgram) {
                  GL_CALL(DeleteProgram(fCopyPrograms[i].fProgram));
              }
          }
          for (size_t i = 0; i < SK_ARRAY_COUNT(fMipmapPrograms); ++i) {
              if (fMipmapPrograms[i].fProgram) {
                  GL_CALL(DeleteProgram(fMipmapPrograms[i].fProgram));
              }
          }
          if (fStencilClipClearProgram) {
              GL_CALL(DeleteProgram(fStencilClipClearProgram));
          }
  
          if (fClearColorProgram.fProgram) {
              GL_CALL(DeleteProgram(fClearColorProgram.fProgram));
          }
      } else {
          if (fProgramCache) {
              fProgramCache->abandon();
          }
      }
  
      fHWProgram.reset();
      delete fProgramCache;
      fProgramCache = nullptr;
  
      fHWProgramID = 0;
      fTempSrcFBOID = 0;
      fTempDstFBOID = 0;
      fStencilClearFBOID = 0;
      fCopyProgramArrayBuffer.reset();
      for (size_t i = 0; i < SK_ARRAY_COUNT(fCopyPrograms); ++i) {
          fCopyPrograms[i].fProgram = 0;
      }
      fMipmapProgramArrayBuffer.reset();
      for (size_t i = 0; i < SK_ARRAY_COUNT(fMipmapPrograms); ++i) {
          fMipmapPrograms[i].fProgram = 0;
      }
      fStencilClipClearProgram = 0;
      fStencilClipClearArrayBuffer.reset();
      fClearColorProgram.fProgram = 0;
  
      if (this->glCaps().shaderCaps()->pathRenderingSupport()) {
          this->glPathRendering()->disconnect(type);
      }
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  
  void GrGLGpu::onResetContext(uint32_t resetBits) {
      if (resetBits & kMisc_GrGLBackendState) {
          // we don't use the zb at all
          GL_CALL(Disable(GR_GL_DEPTH_TEST));
          GL_CALL(DepthMask(GR_GL_FALSE));
  
          // We don't use face culling.
          GL_CALL(Disable(GR_GL_CULL_FACE));
          // We do use separate stencil. Our algorithms don't care which face is front vs. back so
          // just set this to the default for self-consistency.
          GL_CALL(FrontFace(GR_GL_CCW));
  
          fHWBufferState[kTexel_GrBufferType].invalidate();
          fHWBufferState[kDrawIndirect_GrBufferType].invalidate();
          fHWBufferState[kXferCpuToGpu_GrBufferType].invalidate();
          fHWBufferState[kXferGpuToCpu_GrBufferType].invalidate();
  
          if (kGL_GrGLStandard == this->glStandard()) {
  #ifndef USE_NSIGHT
              // Desktop-only state that we never change
              if (!this->glCaps().isCoreProfile()) {
                  GL_CALL(Disable(GR_GL_POINT_SMOOTH));
                  GL_CALL(Disable(GR_GL_LINE_SMOOTH));
                  GL_CALL(Disable(GR_GL_POLYGON_SMOOTH));
                  GL_CALL(Disable(GR_GL_POLYGON_STIPPLE));
                  GL_CALL(Disable(GR_GL_COLOR_LOGIC_OP));
                  GL_CALL(Disable(GR_GL_INDEX_LOGIC_OP));
              }
              // The windows NVIDIA driver has GL_ARB_imaging in the extension string when using a
              // core profile. This seems like a bug since the core spec removes any mention of
              // GL_ARB_imaging.
              if (this->glCaps().imagingSupport() && !this->glCaps().isCoreProfile()) {
                  GL_CALL(Disable(GR_GL_COLOR_TABLE));
              }
              GL_CALL(Disable(GR_GL_POLYGON_OFFSET_FILL));
  
              if (this->caps()->wireframeMode()) {
                  GL_CALL(PolygonMode(GR_GL_FRONT_AND_BACK, GR_GL_LINE));
              } else {
                  GL_CALL(PolygonMode(GR_GL_FRONT_AND_BACK, GR_GL_FILL));
              }
  #endif
              // Since ES doesn't support glPointSize at all we always use the VS to
              // set the point size
              GL_CALL(Enable(GR_GL_VERTEX_PROGRAM_POINT_SIZE));
  
          }
  
          if (kGLES_GrGLStandard == this->glStandard() &&
                  this->hasExtension("GL_ARM_shader_framebuffer_fetch")) {
              // The arm extension requires specifically enabling MSAA fetching per sample.
              // On some devices this may have a perf hit.  Also multiple render targets are disabled
              GL_CALL(Enable(GR_GL_FETCH_PER_SAMPLE_ARM));
          }
          fHWWriteToColor = kUnknown_TriState;
          // we only ever use lines in hairline mode
          GL_CALL(LineWidth(1));
          GL_CALL(Disable(GR_GL_DITHER));
      }
  
      if (resetBits & kMSAAEnable_GrGLBackendState) {
          fMSAAEnabled = kUnknown_TriState;
  
          if (this->caps()->usesMixedSamples()) {
              if (0 != this->caps()->maxRasterSamples()) {
                  fHWRasterMultisampleEnabled = kUnknown_TriState;
                  fHWNumRasterSamples = 0;
              }
  
              // The skia blend modes all use premultiplied alpha and therefore expect RGBA coverage
              // modulation. This state has no effect when not rendering to a mixed sampled target.
              GL_CALL(CoverageModulation(GR_GL_RGBA));
          }
      }
  
      fHWActiveTextureUnitIdx = -1; // invalid
      fLastPrimitiveType = static_cast<GrPrimitiveType>(-1);
  
      if (resetBits & kTextureBinding_GrGLBackendState) {
          for (int s = 0; s < fHWBoundTextureUniqueIDs.count(); ++s) {
              fHWBoundTextureUniqueIDs[s].makeInvalid();
          }
      }
  
      if (resetBits & kBlend_GrGLBackendState) {
          fHWBlendState.invalidate();
      }
  
      if (resetBits & kView_GrGLBackendState) {
          fHWScissorSettings.invalidate();
          fHWWindowRectsState.invalidate();
          fHWViewport.invalidate();
      }
  
      if (resetBits & kStencil_GrGLBackendState) {
          fHWStencilSettings.invalidate();
          fHWStencilTestEnabled = kUnknown_TriState;
      }
  
      // Vertex
      if (resetBits & kVertex_GrGLBackendState) {
          fHWVertexArrayState.invalidate();
          fHWBufferState[kVertex_GrBufferType].invalidate();
          fHWBufferState[kIndex_GrBufferType].invalidate();
          if (this->glCaps().requiresFlushBetweenNonAndInstancedDraws()) {
              fRequiresFlushBeforeNextInstancedDraw = true;
          }
      }
  
      if (resetBits & kRenderTarget_GrGLBackendState) {
          fHWBoundRenderTargetUniqueID.makeInvalid();
          fHWSRGBFramebuffer = kUnknown_TriState;
      }
  
      if (resetBits & kPathRendering_GrGLBackendState) {
          if (this->caps()->shaderCaps()->pathRenderingSupport()) {
              this->glPathRendering()->resetContext();
          }
      }
  
      // we assume these values
      if (resetBits & kPixelStore_GrGLBackendState) {
          if (this->glCaps().unpackRowLengthSupport()) {
              GL_CALL(PixelStorei(GR_GL_UNPACK_ROW_LENGTH, 0));
          }
          if (this->glCaps().packRowLengthSupport()) {
              GL_CALL(PixelStorei(GR_GL_PACK_ROW_LENGTH, 0));
          }
          if (this->glCaps().unpackFlipYSupport()) {
              GL_CALL(PixelStorei(GR_GL_UNPACK_FLIP_Y, GR_GL_FALSE));
          }
          if (this->glCaps().packFlipYSupport()) {
              GL_CALL(PixelStorei(GR_GL_PACK_REVERSE_ROW_ORDER, GR_GL_FALSE));
          }
      }
  
      if (resetBits & kProgram_GrGLBackendState) {
          fHWProgramID = 0;
          fHWProgram.reset();
      }
  }
  
  static bool check_backend_texture(const GrBackendTexture& backendTex, const GrGLCaps& caps,
                                    GrGLTexture::IDDesc* idDesc) {
      GrGLTextureInfo info;
      if (!backendTex.getGLTextureInfo(&info) || !info.fID) {
          return false;
      }
  
      idDesc->fInfo = info;
  
      if (GR_GL_TEXTURE_EXTERNAL == idDesc->fInfo.fTarget) {
          if (!caps.shaderCaps()->externalTextureSupport()) {
              return false;
          }
      } else if (GR_GL_TEXTURE_RECTANGLE == idDesc->fInfo.fTarget) {
          if (!caps.rectangleTextureSupport()) {
              return false;
          }
      } else if (GR_GL_TEXTURE_2D != idDesc->fInfo.fTarget) {
          return false;
      }
      return true;
  }
  
  sk_sp<GrTexture> GrGLGpu::onWrapBackendTexture(const GrBackendTexture& backendTex,
                                                 GrWrapOwnership ownership) {
      GrGLTexture::IDDesc idDesc;
      if (!check_backend_texture(backendTex, this->glCaps(), &idDesc)) {
          return nullptr;
      }
      if (!idDesc.fInfo.fFormat) {
          idDesc.fInfo.fFormat = this->glCaps().configSizedInternalFormat(backendTex.config());
      }
      if (kBorrow_GrWrapOwnership == ownership) {
          idDesc.fOwnership = GrBackendObjectOwnership::kBorrowed;
      } else {
          idDesc.fOwnership = GrBackendObjectOwnership::kOwned;
      }
  
      GrSurfaceDesc surfDesc;
      surfDesc.fFlags = kNone_GrSurfaceFlags;
      surfDesc.fWidth = backendTex.width();
      surfDesc.fHeight = backendTex.height();
      surfDesc.fConfig = backendTex.config();
      surfDesc.fSampleCnt = 1;
  
      GrMipMapsStatus mipMapsStatus = backendTex.hasMipMaps() ? GrMipMapsStatus::kValid
                                                              : GrMipMapsStatus::kNotAllocated;
  
      return GrGLTexture::MakeWrapped(this, surfDesc, mipMapsStatus, idDesc);
  }
  
  sk_sp<GrTexture> GrGLGpu::onWrapRenderableBackendTexture(const GrBackendTexture& backendTex,
                                                           int sampleCnt,
                                                           GrWrapOwnership ownership) {
      GrGLTexture::IDDesc idDesc;
      if (!check_backend_texture(backendTex, this->glCaps(), &idDesc)) {
          return nullptr;
      }
      if (!idDesc.fInfo.fFormat) {
          idDesc.fInfo.fFormat = this->glCaps().configSizedInternalFormat(backendTex.config());
      }
  
      // We don't support rendering to a EXTERNAL texture.
      if (GR_GL_TEXTURE_EXTERNAL == idDesc.fInfo.fTarget) {
          return nullptr;
      }
  
      if (kBorrow_GrWrapOwnership == ownership) {
          idDesc.fOwnership = GrBackendObjectOwnership::kBorrowed;
      } else {
          idDesc.fOwnership = GrBackendObjectOwnership::kOwned;
      }
  
      GrSurfaceDesc surfDesc;
      surfDesc.fFlags = kRenderTarget_GrSurfaceFlag;
      surfDesc.fWidth = backendTex.width();
      surfDesc.fHeight = backendTex.height();
      surfDesc.fConfig = backendTex.config();
      surfDesc.fSampleCnt = this->caps()->getRenderTargetSampleCount(sampleCnt, backendTex.config());
      if (surfDesc.fSampleCnt < 1) {
          return nullptr;
      }
  
      GrGLRenderTarget::IDDesc rtIDDesc;
      if (!this->createRenderTargetObjects(surfDesc, idDesc.fInfo, &rtIDDesc)) {
          return nullptr;
      }
  
      GrMipMapsStatus mipMapsStatus = backendTex.hasMipMaps() ? GrMipMapsStatus::kDirty
                                                              : GrMipMapsStatus::kNotAllocated;
  
      sk_sp<GrGLTextureRenderTarget> texRT(
              GrGLTextureRenderTarget::MakeWrapped(this, surfDesc, idDesc, rtIDDesc, mipMapsStatus));
      texRT->baseLevelWasBoundToFBO();
      return std::move(texRT);
  }
  
  sk_sp<GrRenderTarget> GrGLGpu::onWrapBackendRenderTarget(const GrBackendRenderTarget& backendRT) {
      GrGLFramebufferInfo info;
      if (!backendRT.getGLFramebufferInfo(&info)) {
          return nullptr;
      }
  
      GrGLRenderTarget::IDDesc idDesc;
      idDesc.fRTFBOID = info.fFBOID;
      idDesc.fMSColorRenderbufferID = 0;
      idDesc.fTexFBOID = GrGLRenderTarget::kUnresolvableFBOID;
      idDesc.fRTFBOOwnership = GrBackendObjectOwnership::kBorrowed;
      idDesc.fIsMixedSampled = false;
  
      GrSurfaceDesc desc;
      desc.fFlags = kRenderTarget_GrSurfaceFlag;
      desc.fWidth = backendRT.width();
      desc.fHeight = backendRT.height();
      desc.fConfig = backendRT.config();
      desc.fSampleCnt =
              this->caps()->getRenderTargetSampleCount(backendRT.sampleCnt(), backendRT.config());
  
      return GrGLRenderTarget::MakeWrapped(this, desc, idDesc, backendRT.stencilBits());
  }
  
  sk_sp<GrRenderTarget> GrGLGpu::onWrapBackendTextureAsRenderTarget(const GrBackendTexture& tex,
                                                                    int sampleCnt) {
      GrGLTextureInfo info;
      if (!tex.getGLTextureInfo(&info) || !info.fID) {
          return nullptr;
      }
  
      if (GR_GL_TEXTURE_RECTANGLE != info.fTarget &&
          GR_GL_TEXTURE_2D != info.fTarget) {
          // Only texture rectangle and texture 2d are supported. We do not check whether texture
          // rectangle is supported by Skia - if the caller provided us with a texture rectangle,
          // we assume the necessary support exists.
          return nullptr;
      }
  
      GrSurfaceDesc surfDesc;
      surfDesc.fFlags = kRenderTarget_GrSurfaceFlag;
      surfDesc.fWidth = tex.width();
      surfDesc.fHeight = tex.height();
      surfDesc.fConfig = tex.config();
      surfDesc.fSampleCnt = this->caps()->getRenderTargetSampleCount(sampleCnt, tex.config());
  
      GrGLRenderTarget::IDDesc rtIDDesc;
      if (!this->createRenderTargetObjects(surfDesc, info, &rtIDDesc)) {
          return nullptr;
      }
      return GrGLRenderTarget::MakeWrapped(this, surfDesc, rtIDDesc, 0);
  }
  
  static bool check_write_and_transfer_input(GrGLTexture* glTex) {
      if (!glTex) {
          return false;
      }
  
      // Write or transfer of pixels is not implemented for TEXTURE_EXTERNAL textures
      if (GR_GL_TEXTURE_EXTERNAL == glTex->target()) {
          return false;
      }
  
      return true;
  }
  
  bool GrGLGpu::onWritePixels(GrSurface* surface, int left, int top, int width, int height,
                              GrColorType srcColorType, const GrMipLevel texels[],
                              int mipLevelCount) {
      auto glTex = static_cast<GrGLTexture*>(surface->asTexture());
  
      if (!check_write_and_transfer_input(glTex)) {
          return false;
      }
  
      this->setScratchTextureUnit();
      GL_CALL(BindTexture(glTex->target(), glTex->textureID()));
  
      // No sRGB transformation occurs in uploadTexData. We choose to make the src config match the
      // srgb-ness of the surface to avoid issues in ES2 where internal/external formats must match.
      // When we're on ES2 and the dst is GL_SRGB_ALPHA by making the config be kSRGB_8888 we know
      // that our caps will choose GL_SRGB_ALPHA as the external format, too. On ES3 or regular GL our
      // caps knows to make the external format be GL_RGBA.
      auto srgbEncoded = GrPixelConfigIsSRGBEncoded(surface->config());
      auto srcAsConfig = GrColorTypeToPixelConfig(srcColorType, srgbEncoded);
      return this->uploadTexData(glTex->config(), glTex->width(), glTex->height(), glTex->target(),
                                 kWrite_UploadType, left, top, width, height, srcAsConfig, texels,
                                 mipLevelCount);
  }
  
  // For GL_[UN]PACK_ALIGNMENT. TODO: This really wants to be GrColorType.
  static inline GrGLint config_alignment(GrPixelConfig config) {
      switch (config) {
          case kAlpha_8_GrPixelConfig:
          case kAlpha_8_as_Alpha_GrPixelConfig:
          case kAlpha_8_as_Red_GrPixelConfig:
          case kGray_8_GrPixelConfig:
          case kGray_8_as_Lum_GrPixelConfig:
          case kGray_8_as_Red_GrPixelConfig:
              return 1;
          case kRGB_565_GrPixelConfig:
          case kRGBA_4444_GrPixelConfig:
          case kAlpha_half_GrPixelConfig:
          case kAlpha_half_as_Red_GrPixelConfig:
          case kRGBA_half_GrPixelConfig:
              return 2;
          case kRGBA_8888_GrPixelConfig:
          case kRGB_888_GrPixelConfig:  // We're really talking about GrColorType::kRGB_888x here.
          case kBGRA_8888_GrPixelConfig:
          case kSRGBA_8888_GrPixelConfig:
          case kSBGRA_8888_GrPixelConfig:
          case kRGBA_1010102_GrPixelConfig:
          case kRGBA_float_GrPixelConfig:
          case kRG_float_GrPixelConfig:
              return 4;
          case kUnknown_GrPixelConfig:
              return 0;
      }
      SK_ABORT("Invalid pixel config");
      return 0;
  }
  
  bool GrGLGpu::onTransferPixels(GrTexture* texture, int left, int top, int width, int height,
                                 GrColorType bufferColorType, GrBuffer* transferBuffer, size_t offset,
                                 size_t rowBytes) {
      GrGLTexture* glTex = static_cast<GrGLTexture*>(texture);
      GrPixelConfig texConfig = glTex->config();
      SkASSERT(this->caps()->isConfigTexturable(texConfig));
  
      if (!check_write_and_transfer_input(glTex)) {
          return false;
      }
  
      static_assert(sizeof(int) == sizeof(int32_t), "");
      if (width <= 0 || height <= 0) {
          return false;
      }
  
      this->setScratchTextureUnit();
      GL_CALL(BindTexture(glTex->target(), glTex->textureID()));
  
      SkASSERT(!transferBuffer->isMapped());
      SkASSERT(!transferBuffer->isCPUBacked());
      const GrGLBuffer* glBuffer = static_cast<const GrGLBuffer*>(transferBuffer);
      this->bindBuffer(kXferCpuToGpu_GrBufferType, glBuffer);
  
      SkDEBUGCODE(
          SkIRect subRect = SkIRect::MakeXYWH(left, top, width, height);
          SkIRect bounds = SkIRect::MakeWH(texture->width(), texture->height());
          SkASSERT(bounds.contains(subRect));
      )
  
      int bpp = GrColorTypeBytesPerPixel(bufferColorType);
      const size_t trimRowBytes = width * bpp;
      if (!rowBytes) {
          rowBytes = trimRowBytes;
      }
      const void* pixels = (void*)offset;
      if (width < 0 || height < 0) {
          return false;
      }
  
      bool restoreGLRowLength = false;
      if (trimRowBytes != rowBytes) {
          // we should have checked for this support already
          SkASSERT(this->glCaps().unpackRowLengthSupport());
          GL_CALL(PixelStorei(GR_GL_UNPACK_ROW_LENGTH, rowBytes / bpp));
          restoreGLRowLength = true;
      }
  
      // Internal format comes from the texture desc.
      GrGLenum internalFormat;
      // External format and type come from the upload data.
      GrGLenum externalFormat;
      GrGLenum externalType;
      auto bufferAsConfig = GrColorTypeToPixelConfig(bufferColorType, GrSRGBEncoded::kNo);
      if (!this->glCaps().getTexImageFormats(texConfig, bufferAsConfig, &internalFormat,
                                             &externalFormat, &externalType)) {
          return false;
      }
  
      GL_CALL(PixelStorei(GR_GL_UNPACK_ALIGNMENT, config_alignment(texConfig)));
      GL_CALL(TexSubImage2D(glTex->target(),
                            0,
                            left, top,
                            width,
                            height,
                            externalFormat, externalType,
                            pixels));
  
      if (restoreGLRowLength) {
          GL_CALL(PixelStorei(GR_GL_UNPACK_ROW_LENGTH, 0));
      }
  
      return true;
  }
  
  /**
   * Creates storage space for the texture and fills it with texels.
   *
   * @param config         Pixel config of the texture.
   * @param interface      The GL interface in use.
   * @param caps           The capabilities of the GL device.
   * @param internalFormat The data format used for the internal storage of the texture. May be sized.
   * @param internalFormatForTexStorage The data format used for the TexStorage API. Must be sized.
   * @param externalFormat The data format used for the external storage of the texture.
   * @param externalType   The type of the data used for the external storage of the texture.
   * @param texels         The texel data of the texture being created.
   * @param baseWidth      The width of the texture's base mipmap level
   * @param baseHeight     The height of the texture's base mipmap level
   */
  static bool allocate_and_populate_texture(GrPixelConfig config,
                                            const GrGLInterface& interface,
                                            const GrGLCaps& caps,
                                            GrGLenum target,
                                            GrGLenum internalFormat,
                                            GrGLenum internalFormatForTexStorage,
                                            GrGLenum externalFormat,
                                            GrGLenum externalType,
                                            const GrMipLevel texels[], int mipLevelCount,
                                            int baseWidth, int baseHeight) {
      CLEAR_ERROR_BEFORE_ALLOC(&interface);
  
      bool useTexStorage = caps.isConfigTexSupportEnabled(config);
      // We can only use TexStorage if we know we will not later change the storage requirements.
      // This means if we may later want to add mipmaps, we cannot use TexStorage.
      // Right now, we cannot know if we will later add mipmaps or not.
      // The only time we can use TexStorage is when we already have the
      // mipmaps.
      useTexStorage &= mipLevelCount > 1;
  
      if (useTexStorage) {
          // We never resize or change formats of textures.
          GL_ALLOC_CALL(&interface,
                        TexStorage2D(target, SkTMax(mipLevelCount, 1), internalFormatForTexStorage,
                                     baseWidth, baseHeight));
          GrGLenum error = CHECK_ALLOC_ERROR(&interface);
          if (error != GR_GL_NO_ERROR) {
              return  false;
          } else {
              for (int currentMipLevel = 0; currentMipLevel < mipLevelCount; currentMipLevel++) {
                  const void* currentMipData = texels[currentMipLevel].fPixels;
                  if (currentMipData == nullptr) {
                      continue;
                  }
                  int twoToTheMipLevel = 1 << currentMipLevel;
                  int currentWidth = SkTMax(1, baseWidth / twoToTheMipLevel);
                  int currentHeight = SkTMax(1, baseHeight / twoToTheMipLevel);
  
                  GR_GL_CALL(&interface,
                             TexSubImage2D(target,
                                           currentMipLevel,
                                           0, // left
                                           0, // top
                                           currentWidth,
                                           currentHeight,
                                           externalFormat, externalType,
                                           currentMipData));
              }
              return true;
          }
      } else {
          if (!mipLevelCount) {
              GL_ALLOC_CALL(&interface,
                            TexImage2D(target,
                                       0,
                                       internalFormat,
                                       baseWidth,
                                       baseHeight,
                                       0, // border
                                       externalFormat, externalType,
                                       nullptr));
              GrGLenum error = CHECK_ALLOC_ERROR(&interface);
              if (error != GR_GL_NO_ERROR) {
                  return false;
              }
          } else {
              for (int currentMipLevel = 0; currentMipLevel < mipLevelCount; currentMipLevel++) {
                  int twoToTheMipLevel = 1 << currentMipLevel;
                  int currentWidth = SkTMax(1, baseWidth / twoToTheMipLevel);
                  int currentHeight = SkTMax(1, baseHeight / twoToTheMipLevel);
                  const void* currentMipData = texels[currentMipLevel].fPixels;
                  // Even if curremtMipData is nullptr, continue to call TexImage2D.
                  // This will allocate texture memory which we can later populate.
                  GL_ALLOC_CALL(&interface,
                                TexImage2D(target,
                                           currentMipLevel,
                                           internalFormat,
                                           currentWidth,
                                           currentHeight,
                                           0, // border
                                           externalFormat, externalType,
                                           currentMipData));
                  GrGLenum error = CHECK_ALLOC_ERROR(&interface);
                  if (error != GR_GL_NO_ERROR) {
                      return false;
                  }
              }
          }
      }
      return true;
  }
  
  /**
   * After a texture is created, any state which was altered during its creation
   * needs to be restored.
   *
   * @param interface          The GL interface to use.
   * @param caps               The capabilities of the GL device.
   * @param restoreGLRowLength Should the row length unpacking be restored?
   * @param glFlipY            Did GL flip the texture vertically?
   */
  static void restore_pixelstore_state(const GrGLInterface& interface, const GrGLCaps& caps,
                                       bool restoreGLRowLength) {
      if (restoreGLRowLength) {
          SkASSERT(caps.unpackRowLengthSupport());
          GR_GL_CALL(&interface, PixelStorei(GR_GL_UNPACK_ROW_LENGTH, 0));
      }
  }
  
  void GrGLGpu::unbindCpuToGpuXferBuffer() {
      auto& xferBufferState = fHWBufferState[kXferCpuToGpu_GrBufferType];
      if (!xferBufferState.fBoundBufferUniqueID.isInvalid()) {
          GL_CALL(BindBuffer(xferBufferState.fGLTarget, 0));
          xferBufferState.invalidate();
      }
  
  }
  
  // TODO: Make this take a GrColorType instead of dataConfig. This requires updating GrGLCaps to
  // convert from GrColorType to externalFormat/externalType GLenum values.
  bool GrGLGpu::uploadTexData(GrPixelConfig texConfig, int texWidth, int texHeight, GrGLenum target,
                              UploadType uploadType, int left, int top, int width, int height,
                              GrPixelConfig dataConfig, const GrMipLevel texels[], int mipLevelCount,
                              GrMipMapsStatus* mipMapsStatus) {
      SkASSERT(this->caps()->isConfigTexturable(texConfig));
      SkDEBUGCODE(
          SkIRect subRect = SkIRect::MakeXYWH(left, top, width, height);
          SkIRect bounds = SkIRect::MakeWH(texWidth, texHeight);
          SkASSERT(bounds.contains(subRect));
      )
      SkASSERT(1 == mipLevelCount ||
               (0 == left && 0 == top && width == texWidth && height == texHeight));
  
      this->unbindCpuToGpuXferBuffer();
  
      // texels is const.
      // But we may need to flip the texture vertically to prepare it.
      // Rather than flip in place and alter the incoming data,
      // we allocate a new buffer to flip into.
      // This means we need to make a non-const shallow copy of texels.
      SkAutoTMalloc<GrMipLevel> texelsShallowCopy;
  
      if (mipLevelCount) {
          texelsShallowCopy.reset(mipLevelCount);
          memcpy(texelsShallowCopy.get(), texels, mipLevelCount*sizeof(GrMipLevel));
      }
  
      const GrGLInterface* interface = this->glInterface();
      const GrGLCaps& caps = this->glCaps();
  
      size_t bpp = GrBytesPerPixel(dataConfig);
  
      if (width == 0 || height == 0) {
          return false;
      }
  
      // Internal format comes from the texture desc.
      GrGLenum internalFormat;
      // External format and type come from the upload data.
      GrGLenum externalFormat;
      GrGLenum externalType;
      if (!this->glCaps().getTexImageFormats(texConfig, dataConfig, &internalFormat, &externalFormat,
                                             &externalType)) {
          return false;
      }
      // TexStorage requires a sized format, and internalFormat may or may not be
      GrGLenum internalFormatForTexStorage = this->glCaps().configSizedInternalFormat(texConfig);
  
      /*
       *  Check whether to allocate a temporary buffer for flipping y or
       *  because our srcData has extra bytes past each row. If so, we need
       *  to trim those off here, since GL ES may not let us specify
       *  GL_UNPACK_ROW_LENGTH.
       */
      bool restoreGLRowLength = false;
  
      // in case we need a temporary, trimmed copy of the src pixels
      SkAutoSMalloc<128 * 128> tempStorage;
  
      if (mipMapsStatus) {
          *mipMapsStatus = GrMipMapsStatus::kValid;
      }
  
      const bool usesMips = mipLevelCount > 1;
  
      // find the combined size of all the mip levels and the relative offset of
      // each into the collective buffer
      bool willNeedData = false;
      size_t combinedBufferSize = 0;
      SkTArray<size_t> individualMipOffsets(mipLevelCount);
      for (int currentMipLevel = 0; currentMipLevel < mipLevelCount; currentMipLevel++) {
          if (texelsShallowCopy[currentMipLevel].fPixels) {
              int twoToTheMipLevel = 1 << currentMipLevel;
              int currentWidth = SkTMax(1, width / twoToTheMipLevel);
              int currentHeight = SkTMax(1, height / twoToTheMipLevel);
              const size_t trimRowBytes = currentWidth * bpp;
              const size_t trimmedSize = trimRowBytes * currentHeight;
  
              const size_t rowBytes = texelsShallowCopy[currentMipLevel].fRowBytes
                      ? texelsShallowCopy[currentMipLevel].fRowBytes
                      : trimRowBytes;
  
              if (((!caps.unpackRowLengthSupport() || usesMips) && trimRowBytes != rowBytes)) {
                  willNeedData = true;
              }
  
              individualMipOffsets.push_back(combinedBufferSize);
              combinedBufferSize += trimmedSize;
          } else {
              if (mipMapsStatus) {
                  *mipMapsStatus = GrMipMapsStatus::kDirty;
              }
              individualMipOffsets.push_back(0);
          }
      }
      if (mipMapsStatus && mipLevelCount <= 1) {
          *mipMapsStatus = GrMipMapsStatus::kNotAllocated;
      }
      char* buffer = nullptr;
      if (willNeedData) {
          buffer = (char*)tempStorage.reset(combinedBufferSize);
      }
  
      for (int currentMipLevel = 0; currentMipLevel < mipLevelCount; currentMipLevel++) {
          if (!texelsShallowCopy[currentMipLevel].fPixels) {
              continue;
          }
          int twoToTheMipLevel = 1 << currentMipLevel;
          int currentWidth = SkTMax(1, width / twoToTheMipLevel);
          int currentHeight = SkTMax(1, height / twoToTheMipLevel);
          const size_t trimRowBytes = currentWidth * bpp;
  
          /*
           *  check whether to allocate a temporary buffer for flipping y or
           *  because our srcData has extra bytes past each row. If so, we need
           *  to trim those off here, since GL ES may not let us specify
           *  GL_UNPACK_ROW_LENGTH.
           */
          restoreGLRowLength = false;
  
          const size_t rowBytes = texelsShallowCopy[currentMipLevel].fRowBytes
                  ? texelsShallowCopy[currentMipLevel].fRowBytes
                  : trimRowBytes;
  
          // TODO: This optimization should be enabled with or without mips.
          // For use with mips, we must set GR_GL_UNPACK_ROW_LENGTH once per
          // mip level, before calling glTexImage2D.
          if (caps.unpackRowLengthSupport() && !usesMips) {
              // can't use this for flipping, only non-neg values allowed. :(
              if (rowBytes != trimRowBytes) {
                  GrGLint rowLength = static_cast<GrGLint>(rowBytes / bpp);
                  GR_GL_CALL(interface, PixelStorei(GR_GL_UNPACK_ROW_LENGTH, rowLength));
                  restoreGLRowLength = true;
              }
          } else if (trimRowBytes != rowBytes) {
              // copy data into our new storage, skipping the trailing bytes
              const char* src = (const char*)texelsShallowCopy[currentMipLevel].fPixels;
              char* dst = buffer + individualMipOffsets[currentMipLevel];
              SkRectMemcpy(dst, trimRowBytes, src, rowBytes, trimRowBytes, currentHeight);
              // now point data to our copied version
              texelsShallowCopy[currentMipLevel].fPixels = buffer +
                  individualMipOffsets[currentMipLevel];
              texelsShallowCopy[currentMipLevel].fRowBytes = trimRowBytes;
          }
      }
  
      if (mipLevelCount) {
          GR_GL_CALL(interface, PixelStorei(GR_GL_UNPACK_ALIGNMENT, config_alignment(texConfig)));
      }
  
      bool succeeded = true;
      if (kNewTexture_UploadType == uploadType) {
          if (0 == left && 0 == top && texWidth == width && texHeight == height) {
              succeeded = allocate_and_populate_texture(
                      texConfig, *interface, caps, target, internalFormat,
                      internalFormatForTexStorage, externalFormat, externalType,
                      texelsShallowCopy, mipLevelCount, width, height);
          } else {
              succeeded = false;
          }
      } else {
          for (int currentMipLevel = 0; currentMipLevel < mipLevelCount; currentMipLevel++) {
              if (!texelsShallowCopy[currentMipLevel].fPixels) {
                  continue;
              }
              int twoToTheMipLevel = 1 << currentMipLevel;
              int currentWidth = SkTMax(1, width / twoToTheMipLevel);
              int currentHeight = SkTMax(1, height / twoToTheMipLevel);
  
              GL_CALL(TexSubImage2D(target,
                                    currentMipLevel,
                                    left, top,
                                    currentWidth,
                                    currentHeight,
                                    externalFormat, externalType,
                                    texelsShallowCopy[currentMipLevel].fPixels));
          }
      }
  
      restore_pixelstore_state(*interface, caps, restoreGLRowLength);
  
      return succeeded;
  }
  
  static bool renderbuffer_storage_msaa(const GrGLContext& ctx,
                                        int sampleCount,
                                        GrGLenum format,
                                        int width, int height) {
      CLEAR_ERROR_BEFORE_ALLOC(ctx.interface());
      SkASSERT(GrGLCaps::kNone_MSFBOType != ctx.caps()->msFBOType());
      switch (ctx.caps()->msFBOType()) {
          case GrGLCaps::kStandard_MSFBOType:
          case GrGLCaps::kMixedSamples_MSFBOType:
              GL_ALLOC_CALL(ctx.interface(),
                              RenderbufferStorageMultisample(GR_GL_RENDERBUFFER,
                                                              sampleCount,
                                                              format,
                                                              width, height));
              break;
          case GrGLCaps::kES_Apple_MSFBOType:
              GL_ALLOC_CALL(ctx.interface(),
                              RenderbufferStorageMultisampleES2APPLE(GR_GL_RENDERBUFFER,
                                                                      sampleCount,
                                                                      format,
                                                                      width, height));
              break;
          case GrGLCaps::kES_EXT_MsToTexture_MSFBOType:
          case GrGLCaps::kES_IMG_MsToTexture_MSFBOType:
              GL_ALLOC_CALL(ctx.interface(),
                              RenderbufferStorageMultisampleES2EXT(GR_GL_RENDERBUFFER,
                                                                  sampleCount,
                                                                  format,
                                                                  width, height));
              break;
          case GrGLCaps::kNone_MSFBOType:
              SK_ABORT("Shouldn't be here if we don't support multisampled renderbuffers.");
              break;
      }
      return (GR_GL_NO_ERROR == CHECK_ALLOC_ERROR(ctx.interface()));
  }
  
  bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
                                          const GrGLTextureInfo& texInfo,
                                          GrGLRenderTarget::IDDesc* idDesc) {
      idDesc->fMSColorRenderbufferID = 0;
      idDesc->fRTFBOID = 0;
      idDesc->fRTFBOOwnership = GrBackendObjectOwnership::kOwned;
      idDesc->fTexFBOID = 0;
      SkASSERT((GrGLCaps::kMixedSamples_MSFBOType == this->glCaps().msFBOType()) ==
               this->caps()->usesMixedSamples());
      idDesc->fIsMixedSampled = desc.fSampleCnt > 1 && this->caps()->usesMixedSamples();
  
      GrGLenum status;
  
      GrGLenum colorRenderbufferFormat = 0; // suppress warning
  
      if (desc.fSampleCnt > 1 && GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType()) {
          goto FAILED;
      }
  
      GL_CALL(GenFramebuffers(1, &idDesc->fTexFBOID));
      if (!idDesc->fTexFBOID) {
          goto FAILED;
      }
  
      // If we are using multisampling we will create two FBOS. We render to one and then resolve to
      // the texture bound to the other. The exception is the IMG multisample extension. With this
      // extension the texture is multisampled when rendered to and then auto-resolves it when it is
      // rendered from.
      if (desc.fSampleCnt > 1 && this->glCaps().usesMSAARenderBuffers()) {
          GL_CALL(GenFramebuffers(1, &idDesc->fRTFBOID));
          GL_CALL(GenRenderbuffers(1, &idDesc->fMSColorRenderbufferID));
          if (!idDesc->fRTFBOID ||
              !idDesc->fMSColorRenderbufferID) {
              goto FAILED;
          }
          if (!this->glCaps().getRenderbufferFormat(desc.fConfig, &colorRenderbufferFormat)) {
              return false;
          }
      } else {
          idDesc->fRTFBOID = idDesc->fTexFBOID;
      }
  
      // below here we may bind the FBO
      fHWBoundRenderTargetUniqueID.makeInvalid();
      if (idDesc->fRTFBOID != idDesc->fTexFBOID) {
          SkASSERT(desc.fSampleCnt > 1);
          GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, idDesc->fMSColorRenderbufferID));
          if (!renderbuffer_storage_msaa(*fGLContext,
                                         desc.fSampleCnt,
                                         colorRenderbufferFormat,
                                         desc.fWidth, desc.fHeight)) {
              goto FAILED;
          }
          this->bindFramebuffer(GR_GL_FRAMEBUFFER, idDesc->fRTFBOID);
          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                          GR_GL_COLOR_ATTACHMENT0,
                                          GR_GL_RENDERBUFFER,
                                          idDesc->fMSColorRenderbufferID));
          if (!this->glCaps().isConfigVerifiedColorAttachment(desc.fConfig)) {
              GL_CALL_RET(status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
              if (status != GR_GL_FRAMEBUFFER_COMPLETE) {
                  goto FAILED;
              }
              fGLContext->caps()->markConfigAsValidColorAttachment(desc.fConfig);
          }
      }
      this->bindFramebuffer(GR_GL_FRAMEBUFFER, idDesc->fTexFBOID);
  
      if (this->glCaps().usesImplicitMSAAResolve() && desc.fSampleCnt > 1) {
          GL_CALL(FramebufferTexture2DMultisample(GR_GL_FRAMEBUFFER,
                                                  GR_GL_COLOR_ATTACHMENT0,
                                                  texInfo.fTarget,
                                                  texInfo.fID, 0, desc.fSampleCnt));
      } else {
          GL_CALL(FramebufferTexture2D(GR_GL_FRAMEBUFFER,
                                       GR_GL_COLOR_ATTACHMENT0,
                                       texInfo.fTarget,
                                       texInfo.fID, 0));
      }
      if (!this->glCaps().isConfigVerifiedColorAttachment(desc.fConfig)) {
          GL_CALL_RET(status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
          if (status != GR_GL_FRAMEBUFFER_COMPLETE) {
              goto FAILED;
          }
          fGLContext->caps()->markConfigAsValidColorAttachment(desc.fConfig);
      }
  
      return true;
  
  FAILED:
      if (idDesc->fMSColorRenderbufferID) {
          GL_CALL(DeleteRenderbuffers(1, &idDesc->fMSColorRenderbufferID));
      }
      if (idDesc->fRTFBOID != idDesc->fTexFBOID) {
          this->deleteFramebuffer(idDesc->fRTFBOID);
      }
      if (idDesc->fTexFBOID) {
          this->deleteFramebuffer(idDesc->fTexFBOID);
      }
      return false;
  }
  
  // good to set a break-point here to know when createTexture fails
  static sk_sp<GrTexture> return_null_texture() {
  //    SkDEBUGFAIL("null texture");
      return nullptr;
  }
  
  #if 0 && defined(SK_DEBUG)
  static size_t as_size_t(int x) {
      return x;
  }
  #endif
  
  static void set_initial_texture_params(const GrGLInterface* interface,
                                         const GrGLTextureInfo& info,
                                         GrGLTexture::TexParams* initialTexParams) {
      // Some drivers like to know filter/wrap before seeing glTexImage2D. Some
      // drivers have a bug where an FBO won't be complete if it includes a
      // texture that is not mipmap complete (considering the filter in use).
      // we only set a subset here so invalidate first
      initialTexParams->invalidate();
      initialTexParams->fMinFilter = GR_GL_NEAREST;
      initialTexParams->fMagFilter = GR_GL_NEAREST;
      initialTexParams->fWrapS = GR_GL_CLAMP_TO_EDGE;
      initialTexParams->fWrapT = GR_GL_CLAMP_TO_EDGE;
      GR_GL_CALL(interface, TexParameteri(info.fTarget,
                                          GR_GL_TEXTURE_MAG_FILTER,
                                          initialTexParams->fMagFilter));
      GR_GL_CALL(interface, TexParameteri(info.fTarget,
                                          GR_GL_TEXTURE_MIN_FILTER,
                                          initialTexParams->fMinFilter));
      GR_GL_CALL(interface, TexParameteri(info.fTarget,
                                          GR_GL_TEXTURE_WRAP_S,
                                          initialTexParams->fWrapS));
      GR_GL_CALL(interface, TexParameteri(info.fTarget,
                                          GR_GL_TEXTURE_WRAP_T,
                                          initialTexParams->fWrapT));
  }
  
  sk_sp<GrTexture> GrGLGpu::onCreateTexture(const GrSurfaceDesc& desc,
                                            SkBudgeted budgeted,
                                            const GrMipLevel texels[],
                                            int mipLevelCount) {
      // We fail if the MSAA was requested and is not available.
      if (GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType() && desc.fSampleCnt > 1) {
          //SkDebugf("MSAA RT requested but not supported on this platform.");
          return return_null_texture();
      }
  
      bool performClear = (desc.fFlags & kPerformInitialClear_GrSurfaceFlag);
  
      GrMipLevel zeroLevel;
      std::unique_ptr<uint8_t[]> zeros;
      if (performClear && !this->glCaps().clearTextureSupport() &&
          !this->glCaps().canConfigBeFBOColorAttachment(desc.fConfig)) {
          size_t rowSize = GrBytesPerPixel(desc.fConfig) * desc.fWidth;
          size_t size = rowSize * desc.fHeight;
          zeros.reset(new uint8_t[size]);
          memset(zeros.get(), 0, size);
          zeroLevel.fPixels = zeros.get();
          zeroLevel.fRowBytes = 0;
          texels = &zeroLevel;
          mipLevelCount = 1;
          performClear = false;
      }
  
      bool isRenderTarget = SkToBool(desc.fFlags & kRenderTarget_GrSurfaceFlag);
  
      GrGLTexture::IDDesc idDesc;
      idDesc.fOwnership = GrBackendObjectOwnership::kOwned;
      GrMipMapsStatus mipMapsStatus;
      GrGLTexture::TexParams initialTexParams;
      if (!this->createTextureImpl(desc, &idDesc.fInfo, isRenderTarget, &initialTexParams, texels,
                                   mipLevelCount, &mipMapsStatus)) {
          return return_null_texture();
      }
  
      sk_sp<GrGLTexture> tex;
      if (isRenderTarget) {
          // unbind the texture from the texture unit before binding it to the frame buffer
          GL_CALL(BindTexture(idDesc.fInfo.fTarget, 0));
          GrGLRenderTarget::IDDesc rtIDDesc;
  
          if (!this->createRenderTargetObjects(desc, idDesc.fInfo, &rtIDDesc)) {
              GL_CALL(DeleteTextures(1, &idDesc.fInfo.fID));
              return return_null_texture();
          }
          tex = sk_make_sp<GrGLTextureRenderTarget>(this, budgeted, desc, idDesc, rtIDDesc,
                                                    mipMapsStatus);
          tex->baseLevelWasBoundToFBO();
      } else {
          tex = sk_make_sp<GrGLTexture>(this, budgeted, desc, idDesc, mipMapsStatus);
      }
      tex->setCachedTexParams(initialTexParams, this->getResetTimestamp());
  #ifdef TRACE_TEXTURE_CREATION
      SkDebugf("--- new texture [%d] size=(%d %d) config=%d\n",
               idDesc.fInfo.fID, desc.fWidth, desc.fHeight, desc.fConfig);
  #endif
      if (tex && performClear) {
          if (this->glCaps().clearTextureSupport()) {
              static constexpr uint32_t kZero = 0;
              GL_CALL(ClearTexImage(tex->textureID(), 0, GR_GL_RGBA, GR_GL_UNSIGNED_BYTE, &kZero));
          } else {
              GrGLIRect viewport;
              this->bindSurfaceFBOForPixelOps(tex.get(), GR_GL_FRAMEBUFFER, &viewport,
                                              kDst_TempFBOTarget);
              this->disableScissor();
              this->disableWindowRectangles();
              GL_CALL(ColorMask(GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE));
              fHWWriteToColor = kYes_TriState;
              GL_CALL(ClearColor(0, 0, 0, 0));
              GL_CALL(Clear(GR_GL_COLOR_BUFFER_BIT));
              this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, tex.get());
              fHWBoundRenderTargetUniqueID.makeInvalid();
          }
      }
      return std::move(tex);
  }
  
  namespace {
  
  const GrGLuint kUnknownBitCount = GrGLStencilAttachment::kUnknownBitCount;
  
  void inline get_stencil_rb_sizes(const GrGLInterface* gl,
                                   GrGLStencilAttachment::Format* format) {
  
      // we shouldn't ever know one size and not the other
      SkASSERT((kUnknownBitCount == format->fStencilBits) ==
               (kUnknownBitCount == format->fTotalBits));
      if (kUnknownBitCount == format->fStencilBits) {
          GR_GL_GetRenderbufferParameteriv(gl, GR_GL_RENDERBUFFER,
                                           GR_GL_RENDERBUFFER_STENCIL_SIZE,
                                           (GrGLint*)&format->fStencilBits);
          if (format->fPacked) {
              GR_GL_GetRenderbufferParameteriv(gl, GR_GL_RENDERBUFFER,
                                               GR_GL_RENDERBUFFER_DEPTH_SIZE,
                                               (GrGLint*)&format->fTotalBits);
              format->fTotalBits += format->fStencilBits;
          } else {
              format->fTotalBits = format->fStencilBits;
          }
      }
  }
  }
  
  int GrGLGpu::getCompatibleStencilIndex(GrPixelConfig config) {
      static const int kSize = 16;
      SkASSERT(this->caps()->isConfigRenderable(config));
      if (!this->glCaps().hasStencilFormatBeenDeterminedForConfig(config)) {
          // Default to unsupported, set this if we find a stencil format that works.
          int firstWorkingStencilFormatIndex = -1;
  
          // Create color texture
          GrGLuint colorID = 0;
          GL_CALL(GenTextures(1, &colorID));
          this->setScratchTextureUnit();
          GL_CALL(BindTexture(GR_GL_TEXTURE_2D, colorID));
          GL_CALL(TexParameteri(GR_GL_TEXTURE_2D,
                                GR_GL_TEXTURE_MAG_FILTER,
                                GR_GL_NEAREST));
          GL_CALL(TexParameteri(GR_GL_TEXTURE_2D,
                                GR_GL_TEXTURE_MIN_FILTER,
                                GR_GL_NEAREST));
          GL_CALL(TexParameteri(GR_GL_TEXTURE_2D,
                                GR_GL_TEXTURE_WRAP_S,
                                GR_GL_CLAMP_TO_EDGE));
          GL_CALL(TexParameteri(GR_GL_TEXTURE_2D,
                                GR_GL_TEXTURE_WRAP_T,
                                GR_GL_CLAMP_TO_EDGE));
  
          GrGLenum internalFormat;
          GrGLenum externalFormat;
          GrGLenum externalType;
          if (!this->glCaps().getTexImageFormats(config, config, &internalFormat, &externalFormat,
                                                 &externalType)) {
              return false;
          }
          this->unbindCpuToGpuXferBuffer();
          CLEAR_ERROR_BEFORE_ALLOC(this->glInterface());
          GL_ALLOC_CALL(this->glInterface(), TexImage2D(GR_GL_TEXTURE_2D,
                                                        0,
                                                        internalFormat,
                                                        kSize,
                                                        kSize,
                                                        0,
                                                        externalFormat,
                                                        externalType,
                                                        nullptr));
          if (GR_GL_NO_ERROR != CHECK_ALLOC_ERROR(this->glInterface())) {
              GL_CALL(DeleteTextures(1, &colorID));
              return -1;
          }
  
          // unbind the texture from the texture unit before binding it to the frame buffer
          GL_CALL(BindTexture(GR_GL_TEXTURE_2D, 0));
  
          // Create Framebuffer
          GrGLuint fb = 0;
          GL_CALL(GenFramebuffers(1, &fb));
          this->bindFramebuffer(GR_GL_FRAMEBUFFER, fb);
          fHWBoundRenderTargetUniqueID.makeInvalid();
          GL_CALL(FramebufferTexture2D(GR_GL_FRAMEBUFFER,
                                       GR_GL_COLOR_ATTACHMENT0,
                                       GR_GL_TEXTURE_2D,
                                       colorID,
                                       0));
          GrGLuint sbRBID = 0;
          GL_CALL(GenRenderbuffers(1, &sbRBID));
  
          // look over formats till I find a compatible one
          int stencilFmtCnt = this->glCaps().stencilFormats().count();
          if (sbRBID) {
              GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, sbRBID));
              for (int i = 0; i < stencilFmtCnt && sbRBID; ++i) {
                  const GrGLCaps::StencilFormat& sFmt = this->glCaps().stencilFormats()[i];
                  CLEAR_ERROR_BEFORE_ALLOC(this->glInterface());
                  GL_ALLOC_CALL(this->glInterface(), RenderbufferStorage(GR_GL_RENDERBUFFER,
                                                                         sFmt.fInternalFormat,
                                                                         kSize, kSize));
                  if (GR_GL_NO_ERROR == CHECK_ALLOC_ERROR(this->glInterface())) {
                      GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                                      GR_GL_STENCIL_ATTACHMENT,
                                                      GR_GL_RENDERBUFFER, sbRBID));
                      if (sFmt.fPacked) {
                          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                                          GR_GL_DEPTH_ATTACHMENT,
                                                          GR_GL_RENDERBUFFER, sbRBID));
                      } else {
                          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                                          GR_GL_DEPTH_ATTACHMENT,
                                                          GR_GL_RENDERBUFFER, 0));
                      }
                      GrGLenum status;
                      GL_CALL_RET(status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
                      if (status == GR_GL_FRAMEBUFFER_COMPLETE) {
                          firstWorkingStencilFormatIndex = i;
                          break;
                      }
                      GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                                      GR_GL_STENCIL_ATTACHMENT,
                                                      GR_GL_RENDERBUFFER, 0));
                      if (sFmt.fPacked) {
                          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER,
                                                          GR_GL_DEPTH_ATTACHMENT,
                                                          GR_GL_RENDERBUFFER, 0));
                      }
                  }
              }
              GL_CALL(DeleteRenderbuffers(1, &sbRBID));
          }
          GL_CALL(DeleteTextures(1, &colorID));
          this->bindFramebuffer(GR_GL_FRAMEBUFFER, 0);
          this->deleteFramebuffer(fb);
          fGLContext->caps()->setStencilFormatIndexForConfig(config, firstWorkingStencilFormatIndex);
      }
      return this->glCaps().getStencilFormatIndexForConfig(config);
  }
  
  bool GrGLGpu::createTextureImpl(const GrSurfaceDesc& desc, GrGLTextureInfo* info, bool renderTarget,
                                  GrGLTexture::TexParams* initialTexParams, const GrMipLevel texels[],
                                  int mipLevelCount, GrMipMapsStatus* mipMapsStatus) {
      info->fID = 0;
      info->fTarget = GR_GL_TEXTURE_2D;
      GL_CALL(GenTextures(1, &(info->fID)));
  
      if (!info->fID) {
          return false;
      }
  
      this->setScratchTextureUnit();
      GL_CALL(BindTexture(info->fTarget, info->fID));
  
      if (renderTarget && this->glCaps().textureUsageSupport()) {
          // provides a hint about how this texture will be used
          GL_CALL(TexParameteri(info->fTarget,
                                GR_GL_TEXTURE_USAGE,
                                GR_GL_FRAMEBUFFER_ATTACHMENT));
      }
  
      if (info) {
          set_initial_texture_params(this->glInterface(), *info, initialTexParams);
      }
  
      if (!this->uploadTexData(desc.fConfig, desc.fWidth, desc.fHeight, info->fTarget,
                               kNewTexture_UploadType, 0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
                               texels, mipLevelCount, mipMapsStatus)) {
          GL_CALL(DeleteTextures(1, &(info->fID)));
          return false;
      }
      info->fFormat = this->glCaps().configSizedInternalFormat(desc.fConfig);
      return true;
  }
  
  GrStencilAttachment* GrGLGpu::createStencilAttachmentForRenderTarget(const GrRenderTarget* rt,
                                                                       int width, int height) {
      SkASSERT(width >= rt->width());
      SkASSERT(height >= rt->height());
  
      int samples = rt->numStencilSamples();
      GrGLStencilAttachment::IDDesc sbDesc;
  
      int sIdx = this->getCompatibleStencilIndex(rt->config());
      if (sIdx < 0) {
          return nullptr;
      }
  
      if (!sbDesc.fRenderbufferID) {
          GL_CALL(GenRenderbuffers(1, &sbDesc.fRenderbufferID));
      }
      if (!sbDesc.fRenderbufferID) {
          return nullptr;
      }
      GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, sbDesc.fRenderbufferID));
      const GrGLCaps::StencilFormat& sFmt = this->glCaps().stencilFormats()[sIdx];
      CLEAR_ERROR_BEFORE_ALLOC(this->glInterface());
      // we do this "if" so that we don't call the multisample
      // version on a GL that doesn't have an MSAA extension.
      if (samples > 1) {
          SkAssertResult(renderbuffer_storage_msaa(*fGLContext,
                                                   samples,
                                                   sFmt.fInternalFormat,
                                                   width, height));
      } else {
          GL_ALLOC_CALL(this->glInterface(), RenderbufferStorage(GR_GL_RENDERBUFFER,
                                                                 sFmt.fInternalFormat,
                                                                 width, height));
          SkASSERT(GR_GL_NO_ERROR == CHECK_ALLOC_ERROR(this->glInterface()));
      }
      fStats.incStencilAttachmentCreates();
      // After sized formats we attempt an unsized format and take
      // whatever sizes GL gives us. In that case we query for the size.
      GrGLStencilAttachment::Format format = sFmt;
      get_stencil_rb_sizes(this->glInterface(), &format);
      GrGLStencilAttachment* stencil = new GrGLStencilAttachment(this,
                                                                 sbDesc,
                                                                 width,
                                                                 height,
                                                                 samples,
                                                                 format);
      return stencil;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  
  // GL_STREAM_DRAW triggers an optimization in Chromium's GPU process where a client's vertex buffer
  // objects are implemented as client-side-arrays on tile-deferred architectures.
  #define DYNAMIC_USAGE_PARAM GR_GL_STREAM_DRAW
  
  GrBuffer* GrGLGpu::onCreateBuffer(size_t size, GrBufferType intendedType,
                                    GrAccessPattern accessPattern, const void* data) {
      return GrGLBuffer::Create(this, size, intendedType, accessPattern, data);
  }
  
  void GrGLGpu::flushScissor(const GrScissorState& scissorState,
                             const GrGLIRect& rtViewport,
                             GrSurfaceOrigin rtOrigin) {
      if (scissorState.enabled()) {
          GrGLIRect scissor;
          scissor.setRelativeTo(rtViewport, scissorState.rect(), rtOrigin);
          // if the scissor fully contains the viewport then we fall through and
          // disable the scissor test.
          if (!scissor.contains(rtViewport)) {
              if (fHWScissorSettings.fRect != scissor) {
                  scissor.pushToGLScissor(this->glInterface());
                  fHWScissorSettings.fRect = scissor;
              }
              if (kYes_TriState != fHWScissorSettings.fEnabled) {
                  GL_CALL(Enable(GR_GL_SCISSOR_TEST));
                  fHWScissorSettings.fEnabled = kYes_TriState;
              }
              return;
          }
      }
  
      // See fall through note above
      this->disableScissor();
  }
  
  void GrGLGpu::flushWindowRectangles(const GrWindowRectsState& windowState,
                                      const GrGLRenderTarget* rt, GrSurfaceOrigin origin) {
  #ifndef USE_NSIGHT
      typedef GrWindowRectsState::Mode Mode;
      SkASSERT(!windowState.enabled() || rt->renderFBOID()); // Window rects can't be used on-screen.
      SkASSERT(windowState.numWindows() <= this->caps()->maxWindowRectangles());
  
      if (!this->caps()->maxWindowRectangles() ||
          fHWWindowRectsState.knownEqualTo(origin, rt->getViewport(), windowState)) {
          return;
      }
  
      // This is purely a workaround for a spurious warning generated by gcc. Otherwise the above
      // assert would be sufficient. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=5912
      int numWindows = SkTMin(windowState.numWindows(), int(GrWindowRectangles::kMaxWindows));
      SkASSERT(windowState.numWindows() == numWindows);
  
      GrGLIRect glwindows[GrWindowRectangles::kMaxWindows];
      const SkIRect* skwindows = windowState.windows().data();
      for (int i = 0; i < numWindows; ++i) {
          glwindows[i].setRelativeTo(rt->getViewport(), skwindows[i], origin);
      }
  
      GrGLenum glmode = (Mode::kExclusive == windowState.mode()) ? GR_GL_EXCLUSIVE : GR_GL_INCLUSIVE;
      GL_CALL(WindowRectangles(glmode, numWindows, glwindows->asInts()));
  
      fHWWindowRectsState.set(origin, rt->getViewport(), windowState);
  #endif
  }
  
  void GrGLGpu::disableWindowRectangles() {
  #ifndef USE_NSIGHT
      if (!this->caps()->maxWindowRectangles() || fHWWindowRectsState.knownDisabled()) {
          return;
      }
      GL_CALL(WindowRectangles(GR_GL_EXCLUSIVE, 0, nullptr));
      fHWWindowRectsState.setDisabled();
  #endif
  }
  
  void GrGLGpu::flushMinSampleShading(float minSampleShading) {
      if (fHWMinSampleShading != minSampleShading) {
          if (minSampleShading > 0.0) {
              GL_CALL(Enable(GR_GL_SAMPLE_SHADING));
              GL_CALL(MinSampleShading(minSampleShading));
          }
          else {
              GL_CALL(Disable(GR_GL_SAMPLE_SHADING));
          }
          fHWMinSampleShading = minSampleShading;
      }
  }
  
  void GrGLGpu::resolveAndGenerateMipMapsForProcessorTextures(
          const GrPrimitiveProcessor& primProc,
          const GrPipeline& pipeline,
          const GrTextureProxy* const primProcTextures[],
          int numPrimitiveProcessorTextureSets) {
      auto genLevelsIfNeeded = [this](GrTexture* tex, const GrSamplerState& sampler) {
          SkASSERT(tex);
          if (sampler.filter() == GrSamplerState::Filter::kMipMap &&
              tex->texturePriv().mipMapped() == GrMipMapped::kYes &&
              tex->texturePriv().mipMapsAreDirty()) {
              SkASSERT(this->caps()->mipMapSupport());
              this->regenerateMipMapLevels(static_cast<GrGLTexture*>(tex));
              SkASSERT(!tex->asRenderTarget() || !tex->asRenderTarget()->needsResolve());
          } else if (auto* rt = tex->asRenderTarget()) {
              if (rt->needsResolve()) {
                  this->resolveRenderTarget(rt);
              }
          }
      };
  
      for (int set = 0, tex = 0; set < numPrimitiveProcessorTextureSets; ++set) {
          for (int sampler = 0; sampler < primProc.numTextureSamplers(); ++sampler, ++tex) {
              GrTexture* texture = primProcTextures[tex]->peekTexture();
              genLevelsIfNeeded(texture, primProc.textureSampler(sampler).samplerState());
          }
      }
  
      GrFragmentProcessor::Iter iter(pipeline);
      while (const GrFragmentProcessor* fp = iter.next()) {
          for (int i = 0; i < fp->numTextureSamplers(); ++i) {
              const auto& textureSampler = fp->textureSampler(i);
              genLevelsIfNeeded(textureSampler.peekTexture(), textureSampler.samplerState());
          }
      }
  }
  
  bool GrGLGpu::flushGLState(const GrPrimitiveProcessor& primProc,
                             const GrPipeline& pipeline,
                             const GrPipeline::FixedDynamicState* fixedDynamicState,
                             const GrPipeline::DynamicStateArrays* dynamicStateArrays,
                             int dynamicStateArraysLength,
                             bool willDrawPoints) {
      sk_sp<GrGLProgram> program(fProgramCache->refProgram(this, primProc, pipeline, willDrawPoints));
      if (!program) {
          GrCapsDebugf(this->caps(), "Failed to create program!\n");
          return false;
      }
      const GrTextureProxy* const* primProcProxiesForMipRegen = nullptr;
      const GrTextureProxy* const* primProcProxiesToBind = nullptr;
      int numPrimProcTextureSets = 1;  // number of texture per prim proc sampler.
      if (dynamicStateArrays && dynamicStateArrays->fPrimitiveProcessorTextures) {
          primProcProxiesForMipRegen = dynamicStateArrays->fPrimitiveProcessorTextures;
          numPrimProcTextureSets = dynamicStateArraysLength;
      } else if (fixedDynamicState && fixedDynamicState->fPrimitiveProcessorTextures) {
          primProcProxiesForMipRegen = fixedDynamicState->fPrimitiveProcessorTextures;
          primProcProxiesToBind = fixedDynamicState->fPrimitiveProcessorTextures;
      }
      this->resolveAndGenerateMipMapsForProcessorTextures(
              primProc, pipeline, primProcProxiesForMipRegen, numPrimProcTextureSets);
  
      GrXferProcessor::BlendInfo blendInfo;
      pipeline.getXferProcessor().getBlendInfo(&blendInfo);
  
      this->flushColorWrite(blendInfo.fWriteColor);
      this->flushMinSampleShading(primProc.getSampleShading());
  
      this->flushProgram(std::move(program));
  
      if (blendInfo.fWriteColor) {
          // Swizzle the blend to match what the shader will output.
          const GrSwizzle& swizzle = this->caps()->shaderCaps()->configOutputSwizzle(
              pipeline.proxy()->config());
          this->flushBlend(blendInfo, swizzle);
      }
  
      fHWProgram->updateUniformsAndTextureBindings(primProc, pipeline, primProcProxiesToBind);
  
      GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.renderTarget());
      GrStencilSettings stencil;
      if (pipeline.isStencilEnabled()) {
          // TODO: attach stencil and create settings during render target flush.
          SkASSERT(glRT->renderTargetPriv().getStencilAttachment());
          stencil.reset(*pipeline.getUserStencil(), pipeline.hasStencilClip(),
                        glRT->renderTargetPriv().numStencilBits());
      }
      this->flushStencil(stencil);
      if (pipeline.isScissorEnabled()) {
          static constexpr SkIRect kBogusScissor{0, 0, 1, 1};
          GrScissorState state(fixedDynamicState ? fixedDynamicState->fScissorRect : kBogusScissor);
          this->flushScissor(state, glRT->getViewport(), pipeline.proxy()->origin());
      } else {
          this->disableScissor();
      }
      this->flushWindowRectangles(pipeline.getWindowRectsState(), glRT, pipeline.proxy()->origin());
      this->flushHWAAState(glRT, pipeline.isHWAntialiasState(), !stencil.isDisabled());
  
      // This must come after textures are flushed because a texture may need
      // to be msaa-resolved (which will modify bound FBO state).
      this->flushRenderTarget(glRT);
  
      return true;
  }
  
  void GrGLGpu::flushProgram(sk_sp<GrGLProgram> program) {
      if (!program) {
          fHWProgram.reset();
          fHWProgramID = 0;
          return;
      }
      SkASSERT((program == fHWProgram) == (fHWProgramID == program->programID()));
      if (program == fHWProgram) {
          return;
      }
      auto id = program->programID();
      SkASSERT(id);
      GL_CALL(UseProgram(id));
      fHWProgram = std::move(program);
      fHWProgramID = id;
  }
  
  void GrGLGpu::flushProgram(GrGLuint id) {
      SkASSERT(id);
      if (fHWProgramID == id) {
          SkASSERT(!fHWProgram);
          return;
      }
      fHWProgram.reset();
      GL_CALL(UseProgram(id));
      fHWProgramID = id;
  }
  
  void GrGLGpu::setupGeometry(const GrBuffer* indexBuffer,
                              const GrBuffer* vertexBuffer,
                              int baseVertex,
                              const GrBuffer* instanceBuffer,
                              int baseInstance,
                              GrPrimitiveRestart enablePrimitiveRestart) {
      SkASSERT((enablePrimitiveRestart == GrPrimitiveRestart::kNo) || indexBuffer);
  
      GrGLAttribArrayState* attribState;
      if (indexBuffer) {
          SkASSERT(indexBuffer && !indexBuffer->isMapped());
          attribState = fHWVertexArrayState.bindInternalVertexArray(this, indexBuffer);
      } else {
          attribState = fHWVertexArrayState.bindInternalVertexArray(this);
      }
  
      int numAttribs = fHWProgram->numVertexAttributes() + fHWProgram->numInstanceAttributes();
      attribState->enableVertexArrays(this, numAttribs, enablePrimitiveRestart);
  
      if (int vertexStride = fHWProgram->vertexStride()) {
          SkASSERT(vertexBuffer && !vertexBuffer->isMapped());
          size_t bufferOffset = vertexBuffer->baseOffset() + baseVertex * vertexStride;
          for (int i = 0; i < fHWProgram->numVertexAttributes(); ++i) {
              const auto& attrib = fHWProgram->vertexAttribute(i);
              static constexpr int kDivisor = 0;
              attribState->set(this, attrib.fLocation, vertexBuffer, attrib.fType, vertexStride,
                               bufferOffset + attrib.fOffset, kDivisor);
          }
      }
      if (int instanceStride = fHWProgram->instanceStride()) {
          SkASSERT(instanceBuffer && !instanceBuffer->isMapped());
          size_t bufferOffset = instanceBuffer->baseOffset() + baseInstance * instanceStride;
          int attribIdx = fHWProgram->numVertexAttributes();
          for (int i = 0; i < fHWProgram->numInstanceAttributes(); ++i, ++attribIdx) {
              const auto& attrib = fHWProgram->instanceAttribute(i);
              static constexpr int kDivisor = 1;
              attribState->set(this, attrib.fLocation, instanceBuffer, attrib.fType, instanceStride,
                               bufferOffset + attrib.fOffset, kDivisor);
          }
      }
  }
  
  GrGLenum GrGLGpu::bindBuffer(GrBufferType type, const GrBuffer* buffer) {
      this->handleDirtyContext();
  
      // Index buffer state is tied to the vertex array.
      if (kIndex_GrBufferType == type) {
          this->bindVertexArray(0);
      }
  
      SkASSERT(type >= 0 && type <= kLast_GrBufferType);
      auto& bufferState = fHWBufferState[type];
  
      if (buffer->uniqueID() != bufferState.fBoundBufferUniqueID) {
          if (buffer->isCPUBacked()) {
              if (!bufferState.fBufferZeroKnownBound) {
                  GL_CALL(BindBuffer(bufferState.fGLTarget, 0));
              }
          } else {
              const GrGLBuffer* glBuffer = static_cast<const GrGLBuffer*>(buffer);
              GL_CALL(BindBuffer(bufferState.fGLTarget, glBuffer->bufferID()));
          }
          bufferState.fBufferZeroKnownBound = buffer->isCPUBacked();
          bufferState.fBoundBufferUniqueID = buffer->uniqueID();
      }
  
      return bufferState.fGLTarget;
  }
  void GrGLGpu::disableScissor() {
      if (kNo_TriState != fHWScissorSettings.fEnabled) {
          GL_CALL(Disable(GR_GL_SCISSOR_TEST));
          fHWScissorSettings.fEnabled = kNo_TriState;
          return;
      }
  }
  
  void GrGLGpu::clear(const GrFixedClip& clip, GrColor color,
                      GrRenderTarget* target, GrSurfaceOrigin origin) {
      // parent class should never let us get here with no RT
      SkASSERT(target);
  
      this->handleDirtyContext();
  
      GrGLfloat r, g, b, a;
      static const GrGLfloat scale255 = 1.f / 255.f;
      a = GrColorUnpackA(color) * scale255;
      GrGLfloat scaleRGB = scale255;
      r = GrColorUnpackR(color) * scaleRGB;
      g = GrColorUnpackG(color) * scaleRGB;
      b = GrColorUnpackB(color) * scaleRGB;
  
      if (this->glCaps().useDrawToClearColor()) {
          this->clearColorAsDraw(clip, r, g, b, a, target, origin);
          return;
      }
  
      GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(target);
  
      if (clip.scissorEnabled()) {
          this->flushRenderTarget(glRT, origin, clip.scissorRect());
      } else {
          this->flushRenderTarget(glRT);
      }
      this->flushScissor(clip.scissorState(), glRT->getViewport(), origin);
      this->flushWindowRectangles(clip.windowRectsState(), glRT, origin);
  
      GL_CALL(ColorMask(GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE));
      fHWWriteToColor = kYes_TriState;
  
      if (this->glCaps().clearToBoundaryValuesIsBroken() &&
          (1 == r || 0 == r) && (1 == g || 0 == g) && (1 == b || 0 == b) && (1 == a || 0 == a)) {
          static const GrGLfloat safeAlpha1 = nextafter(1.f, 2.f);
          static const GrGLfloat safeAlpha0 = nextafter(0.f, -1.f);
          a = (1 == a) ? safeAlpha1 : safeAlpha0;
      }
      GL_CALL(ClearColor(r, g, b, a));
      GL_CALL(Clear(GR_GL_COLOR_BUFFER_BIT));
  }
  
  void GrGLGpu::clearStencil(GrRenderTarget* target, int clearValue) {
      if (!target) {
          return;
      }
  
      GrStencilAttachment* sb = target->renderTargetPriv().getStencilAttachment();
      // this should only be called internally when we know we have a
      // stencil buffer.
      SkASSERT(sb);
  
      GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(target);
      this->flushRenderTargetNoColorWrites(glRT);
  
      this->disableScissor();
      this->disableWindowRectangles();
  
      GL_CALL(StencilMask(0xffffffff));
      GL_CALL(ClearStencil(clearValue));
      GL_CALL(Clear(GR_GL_STENCIL_BUFFER_BIT));
      fHWStencilSettings.invalidate();
      if (!clearValue) {
          sb->cleared();
      }
  }
  
  void GrGLGpu::clearStencilClip(const GrFixedClip& clip,
                                 bool insideStencilMask,
                                 GrRenderTarget* target, GrSurfaceOrigin origin) {
      SkASSERT(target);
      this->handleDirtyContext();
  
      if (this->glCaps().useDrawToClearStencilClip()) {
          this->clearStencilClipAsDraw(clip, insideStencilMask, target, origin);
          return;
      }
  
      GrStencilAttachment* sb = target->renderTargetPriv().getStencilAttachment();
      // this should only be called internally when we know we have a
      // stencil buffer.
      SkASSERT(sb);
      GrGLint stencilBitCount =  sb->bits();
  #if 0
      SkASSERT(stencilBitCount > 0);
      GrGLint clipStencilMask  = (1 << (stencilBitCount - 1));
  #else
      // we could just clear the clip bit but when we go through
      // ANGLE a partial stencil mask will cause clears to be
      // turned into draws. Our contract on GrOpList says that
      // changing the clip between stencil passes may or may not
      // zero the client's clip bits. So we just clear the whole thing.
      static const GrGLint clipStencilMask  = ~0;
  #endif
      GrGLint value;
      if (insideStencilMask) {
          value = (1 << (stencilBitCount - 1));
      } else {
          value = 0;
      }
      GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(target);
      this->flushRenderTargetNoColorWrites(glRT);
  
      this->flushScissor(clip.scissorState(), glRT->getViewport(), origin);
      this->flushWindowRectangles(clip.windowRectsState(), glRT, origin);
  
      GL_CALL(StencilMask((uint32_t) clipStencilMask));
      GL_CALL(ClearStencil(value));
      GL_CALL(Clear(GR_GL_STENCIL_BUFFER_BIT));
      fHWStencilSettings.invalidate();
  }
  
  bool GrGLGpu::readPixelsSupported(GrRenderTarget* target, GrPixelConfig readConfig) {
  #ifdef SK_BUILD_FOR_MAC
      // Chromium may ask us to read back from locked IOSurfaces. Calling the command buffer's
      // glGetIntegerv() with GL_IMPLEMENTATION_COLOR_READ_FORMAT/_TYPE causes the command buffer
      // to make a call to check the framebuffer status which can hang the driver. So in Mac Chromium
      // we always use a temporary surface to test for read pixels support.
      // https://www.crbug.com/662802
      if (this->glContext().driver() == kChromium_GrGLDriver) {
          return this->readPixelsSupported(target->config(), readConfig);
      }
  #endif
      auto bindRenderTarget = [this, target]() -> bool {
          this->flushRenderTargetNoColorWrites(static_cast<GrGLRenderTarget*>(target));
          return true;
      };
      auto unbindRenderTarget = []{};
      auto getIntegerv = [this](GrGLenum query, GrGLint* value) {
          GR_GL_GetIntegerv(this->glInterface(), query, value);
      };
      GrPixelConfig rtConfig = target->config();
      return this->glCaps().readPixelsSupported(rtConfig, readConfig, getIntegerv, bindRenderTarget,
                                                unbindRenderTarget);
  }
  
  bool GrGLGpu::readPixelsSupported(GrPixelConfig rtConfig, GrPixelConfig readConfig) {
      sk_sp<GrTexture> temp;
      auto bindRenderTarget = [this, rtConfig, &temp]() -> bool {
          GrSurfaceDesc desc;
          desc.fConfig = rtConfig;
          desc.fWidth = desc.fHeight = 16;
          if (this->glCaps().isConfigRenderable(rtConfig)) {
              desc.fFlags = kRenderTarget_GrSurfaceFlag;
              temp = this->createTexture(desc, SkBudgeted::kNo);
              if (!temp) {
                  return false;
              }
              GrGLRenderTarget* glrt = static_cast<GrGLRenderTarget*>(temp->asRenderTarget());
              this->flushRenderTargetNoColorWrites(glrt);
              return true;
          } else if (this->glCaps().canConfigBeFBOColorAttachment(rtConfig)) {
              temp = this->createTexture(desc, SkBudgeted::kNo);
              if (!temp) {
                  return false;
              }
              GrGLIRect vp;
              this->bindSurfaceFBOForPixelOps(temp.get(), GR_GL_FRAMEBUFFER, &vp, kDst_TempFBOTarget);
              fHWBoundRenderTargetUniqueID.makeInvalid();
              return true;
          }
          return false;
      };
      auto unbindRenderTarget = [this, &temp]() {
          this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, temp.get());
      };
      auto getIntegerv = [this](GrGLenum query, GrGLint* value) {
          GR_GL_GetIntegerv(this->glInterface(), query, value);
      };
      return this->glCaps().readPixelsSupported(rtConfig, readConfig, getIntegerv, bindRenderTarget,
                                                unbindRenderTarget);
  }
  
  bool GrGLGpu::readPixelsSupported(GrSurface* surfaceForConfig, GrPixelConfig readConfig) {
      if (GrRenderTarget* rt = surfaceForConfig->asRenderTarget()) {
          return this->readPixelsSupported(rt, readConfig);
      } else {
          GrPixelConfig config = surfaceForConfig->config();
          return this->readPixelsSupported(config, readConfig);
      }
  }
  
  bool GrGLGpu::onReadPixels(GrSurface* surface, int left, int top, int width, int height,
                             GrColorType dstColorType, void* buffer, size_t rowBytes) {
      SkASSERT(surface);
  
      GrGLRenderTarget* renderTarget = static_cast<GrGLRenderTarget*>(surface->asRenderTarget());
      if (!renderTarget && !this->glCaps().canConfigBeFBOColorAttachment(surface->config())) {
          return false;
      }
  
      // TODO: Avoid this conversion by making GrGLCaps work with color types.
      auto dstAsConfig = GrColorTypeToPixelConfig(dstColorType, GrSRGBEncoded::kNo);
  
      if (!this->readPixelsSupported(surface, dstAsConfig)) {
          return false;
      }
  
      GrGLenum externalFormat;
      GrGLenum externalType;
      if (!this->glCaps().getReadPixelsFormat(surface->config(), dstAsConfig, &externalFormat,
                                              &externalType)) {
          return false;
      }
  
      GrGLIRect glvp;
      if (renderTarget) {
          // resolve the render target if necessary
          switch (renderTarget->getResolveType()) {
              case GrGLRenderTarget::kCantResolve_ResolveType:
                  return false;
              case GrGLRenderTarget::kAutoResolves_ResolveType:
                  this->flushRenderTargetNoColorWrites(renderTarget);
                  break;
              case GrGLRenderTarget::kCanResolve_ResolveType:
                  this->onResolveRenderTarget(renderTarget);
                  // we don't track the state of the READ FBO ID.
                  this->bindFramebuffer(GR_GL_READ_FRAMEBUFFER, renderTarget->textureFBOID());
                  break;
              default:
                  SK_ABORT("Unknown resolve type");
          }
          glvp = renderTarget->getViewport();
      } else {
          // Use a temporary FBO.
          this->bindSurfaceFBOForPixelOps(surface, GR_GL_FRAMEBUFFER, &glvp, kSrc_TempFBOTarget);
          fHWBoundRenderTargetUniqueID.makeInvalid();
      }
  
      // the read rect is viewport-relative
      GrGLIRect readRect;
      readRect.setRelativeTo(glvp, left, top, width, height, kTopLeft_GrSurfaceOrigin);
  
      int bytesPerPixel = GrBytesPerPixel(dstAsConfig);
      size_t tightRowBytes = bytesPerPixel * width;
  
      size_t readDstRowBytes = tightRowBytes;
      void* readDst = buffer;
  
      // determine if GL can read using the passed rowBytes or if we need a scratch buffer.
      SkAutoSMalloc<32 * sizeof(GrColor)> scratch;
      if (rowBytes != tightRowBytes) {
          if (this->glCaps().packRowLengthSupport() && !(rowBytes % bytesPerPixel)) {
              GL_CALL(PixelStorei(GR_GL_PACK_ROW_LENGTH,
                                  static_cast<GrGLint>(rowBytes / bytesPerPixel)));
              readDstRowBytes = rowBytes;
          } else {
              scratch.reset(tightRowBytes * height);
              readDst = scratch.get();
          }
      }
      GL_CALL(PixelStorei(GR_GL_PACK_ALIGNMENT, config_alignment(dstAsConfig)));
  
      GL_CALL(ReadPixels(readRect.fLeft, readRect.fBottom,
                         readRect.fWidth, readRect.fHeight,
                         externalFormat, externalType, readDst));
      if (readDstRowBytes != tightRowBytes) {
          SkASSERT(this->glCaps().packRowLengthSupport());
          GL_CALL(PixelStorei(GR_GL_PACK_ROW_LENGTH, 0));
      }
  
      if (readDst != buffer) {
          SkASSERT(readDst != buffer);
          SkASSERT(rowBytes != tightRowBytes);
          const char* src = reinterpret_cast<const char*>(readDst);
          char* dst = reinterpret_cast<char*>(buffer);
          SkRectMemcpy(dst, rowBytes, src, readDstRowBytes, tightRowBytes, height);
      }
      if (!renderTarget) {
          this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, surface);
      }
      return true;
  }
  
  GrGpuRTCommandBuffer* GrGLGpu::getCommandBuffer(
          GrRenderTarget* rt, GrSurfaceOrigin origin,
          const GrGpuRTCommandBuffer::LoadAndStoreInfo& colorInfo,
          const GrGpuRTCommandBuffer::StencilLoadAndStoreInfo& stencilInfo) {
      if (!fCachedRTCommandBuffer) {
          fCachedRTCommandBuffer.reset(new GrGLGpuRTCommandBuffer(this));
      }
  
      fCachedRTCommandBuffer->set(rt, origin, colorInfo, stencilInfo);
      return fCachedRTCommandBuffer.get();
  }
  
  GrGpuTextureCommandBuffer* GrGLGpu::getCommandBuffer(GrTexture* texture, GrSurfaceOrigin origin) {
      if (!fCachedTexCommandBuffer) {
          fCachedTexCommandBuffer.reset(new GrGLGpuTextureCommandBuffer(this));
      }
  
      fCachedTexCommandBuffer->set(texture, origin);
      return fCachedTexCommandBuffer.get();
  }
  
  void GrGLGpu::flushRenderTarget(GrGLRenderTarget* target, GrSurfaceOrigin origin,
                                  const SkIRect& bounds) {
      this->flushRenderTargetNoColorWrites(target);
      this->didWriteToSurface(target, origin, &bounds);
  }
  
  void GrGLGpu::flushRenderTarget(GrGLRenderTarget* target) {
      this->flushRenderTargetNoColorWrites(target);
      this->didWriteToSurface(target, kTopLeft_GrSurfaceOrigin, nullptr);
  }
  
  void GrGLGpu::flushRenderTargetNoColorWrites(GrGLRenderTarget* target) {
      SkASSERT(target);
      GrGpuResource::UniqueID rtID = target->uniqueID();
      if (fHWBoundRenderTargetUniqueID != rtID) {
          this->bindFramebuffer(GR_GL_FRAMEBUFFER, target->renderFBOID());
  #ifdef SK_DEBUG
          // don't do this check in Chromium -- this is causing
          // lots of repeated command buffer flushes when the compositor is
          // rendering with Ganesh, which is really slow; even too slow for
          // Debug mode.
          if (kChromium_GrGLDriver != this->glContext().driver()) {
              GrGLenum status;
              GL_CALL_RET(status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
              if (status != GR_GL_FRAMEBUFFER_COMPLETE) {
                  SkDebugf("GrGLGpu::flushRenderTarget glCheckFramebufferStatus %x\n", status);
              }
          }
  #endif
          if (this->glCaps().requiresFlushBetweenNonAndInstancedDraws()) {
              fRequiresFlushBeforeNextInstancedDraw = false;
          }
          fHWBoundRenderTargetUniqueID = rtID;
          this->flushViewport(target->getViewport());
      }
  
      if (this->glCaps().srgbWriteControl()) {
          this->flushFramebufferSRGB(GrPixelConfigIsSRGB(target->config()));
      }
  }
  
  void GrGLGpu::flushFramebufferSRGB(bool enable) {
      if (enable && kYes_TriState != fHWSRGBFramebuffer) {
          GL_CALL(Enable(GR_GL_FRAMEBUFFER_SRGB));
          fHWSRGBFramebuffer = kYes_TriState;
      } else if (!enable && kNo_TriState != fHWSRGBFramebuffer) {
          GL_CALL(Disable(GR_GL_FRAMEBUFFER_SRGB));
          fHWSRGBFramebuffer = kNo_TriState;
      }
  }
  
  void GrGLGpu::flushViewport(const GrGLIRect& viewport) {
      if (fHWViewport != viewport) {
          viewport.pushToGLViewport(this->glInterface());
          fHWViewport = viewport;
      }
  }
  
  #define SWAP_PER_DRAW 0
  
  #if SWAP_PER_DRAW
      #if defined(SK_BUILD_FOR_MAC)
          #include <AGL/agl.h>
      #elif defined(SK_BUILD_FOR_WIN)
          #include <gl/GL.h>
          void SwapBuf() {
              DWORD procID = GetCurrentProcessId();
              HWND hwnd = GetTopWindow(GetDesktopWindow());
              while(hwnd) {
                  DWORD wndProcID = 0;
                  GetWindowThreadProcessId(hwnd, &wndProcID);
                  if(wndProcID == procID) {
                      SwapBuffers(GetDC(hwnd));
                  }
                  hwnd = GetNextWindow(hwnd, GW_HWNDNEXT);
              }
           }
      #endif
  #endif
  
  void GrGLGpu::draw(const GrPrimitiveProcessor& primProc,
                     const GrPipeline& pipeline,
                     const GrPipeline::FixedDynamicState* fixedDynamicState,
                     const GrPipeline::DynamicStateArrays* dynamicStateArrays,
                     const GrMesh meshes[],
                     int meshCount) {
      this->handleDirtyContext();
  
      bool hasPoints = false;
      for (int i = 0; i < meshCount; ++i) {
          if (meshes[i].primitiveType() == GrPrimitiveType::kPoints) {
              hasPoints = true;
              break;
          }
      }
      if (!this->flushGLState(primProc, pipeline, fixedDynamicState, dynamicStateArrays, meshCount,
                              hasPoints)) {
          return;
      }
  
      bool dynamicScissor = false;
      bool dynamicPrimProcTextures = false;
      if (dynamicStateArrays) {
          dynamicScissor = pipeline.isScissorEnabled() && dynamicStateArrays->fScissorRects;
          dynamicPrimProcTextures = dynamicStateArrays->fPrimitiveProcessorTextures;
      }
      for (int m = 0; m < meshCount; ++m) {
          if (GrXferBarrierType barrierType = pipeline.xferBarrierType(*this->caps())) {
              this->xferBarrier(pipeline.renderTarget(), barrierType);
          }
  
          if (dynamicScissor) {
              GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.renderTarget());
              this->flushScissor(GrScissorState(dynamicStateArrays->fScissorRects[m]),
                                 glRT->getViewport(), pipeline.proxy()->origin());
          }
          if (dynamicPrimProcTextures) {
              auto texProxyArray = dynamicStateArrays->fPrimitiveProcessorTextures +
                                   m * primProc.numTextureSamplers();
              fHWProgram->updatePrimitiveProcessorTextureBindings(primProc, texProxyArray);
          }
          if (this->glCaps().requiresCullFaceEnableDisableWhenDrawingLinesAfterNonLines() &&
              GrIsPrimTypeLines(meshes[m].primitiveType()) &&
              !GrIsPrimTypeLines(fLastPrimitiveType)) {
              GL_CALL(Enable(GR_GL_CULL_FACE));
              GL_CALL(Disable(GR_GL_CULL_FACE));
          }
          meshes[m].sendToGpu(this);
          fLastPrimitiveType = meshes[m].primitiveType();
      }
  
  #if SWAP_PER_DRAW
      glFlush();
      #if defined(SK_BUILD_FOR_MAC)
          aglSwapBuffers(aglGetCurrentContext());
          int set_a_break_pt_here = 9;
          aglSwapBuffers(aglGetCurrentContext());
      #elif defined(SK_BUILD_FOR_WIN)
          SwapBuf();
          int set_a_break_pt_here = 9;
          SwapBuf();
      #endif
  #endif
  }
  
  static GrGLenum gr_primitive_type_to_gl_mode(GrPrimitiveType primitiveType) {
      switch (primitiveType) {
          case GrPrimitiveType::kTriangles:
              return GR_GL_TRIANGLES;
          case GrPrimitiveType::kTriangleStrip:
              return GR_GL_TRIANGLE_STRIP;
          case GrPrimitiveType::kPoints:
              return GR_GL_POINTS;
          case GrPrimitiveType::kLines:
              return GR_GL_LINES;
          case GrPrimitiveType::kLineStrip:
              return GR_GL_LINE_STRIP;
          case GrPrimitiveType::kLinesAdjacency:
              return GR_GL_LINES_ADJACENCY;
      }
      SK_ABORT("invalid GrPrimitiveType");
      return GR_GL_TRIANGLES;
  }
  
  void GrGLGpu::sendMeshToGpu(GrPrimitiveType primitiveType, const GrBuffer* vertexBuffer,
                              int vertexCount, int baseVertex) {
      const GrGLenum glPrimType = gr_primitive_type_to_gl_mode(primitiveType);
      if (this->glCaps().drawArraysBaseVertexIsBroken()) {
          this->setupGeometry(nullptr, vertexBuffer, baseVertex, nullptr, 0, GrPrimitiveRestart::kNo);
          GL_CALL(DrawArrays(glPrimType, 0, vertexCount));
      } else {
          this->setupGeometry(nullptr, vertexBuffer, 0, nullptr, 0, GrPrimitiveRestart::kNo);
          GL_CALL(DrawArrays(glPrimType, baseVertex, vertexCount));
      }
      if (this->glCaps().requiresFlushBetweenNonAndInstancedDraws()) {
          fRequiresFlushBeforeNextInstancedDraw = true;
      }
      fStats.incNumDraws();
  }
  
  void GrGLGpu::sendIndexedMeshToGpu(GrPrimitiveType primitiveType, const GrBuffer* indexBuffer,
                                     int indexCount, int baseIndex, uint16_t minIndexValue,
                                     uint16_t maxIndexValue, const GrBuffer* vertexBuffer,
                                     int baseVertex, GrPrimitiveRestart enablePrimitiveRestart) {
      const GrGLenum glPrimType = gr_primitive_type_to_gl_mode(primitiveType);
      GrGLvoid* const indices = reinterpret_cast<void*>(indexBuffer->baseOffset() +
                                                        sizeof(uint16_t) * baseIndex);
  
      this->setupGeometry(indexBuffer, vertexBuffer, baseVertex, nullptr, 0, enablePrimitiveRestart);
  
      if (this->glCaps().drawRangeElementsSupport()) {
          GL_CALL(DrawRangeElements(glPrimType, minIndexValue, maxIndexValue, indexCount,
                                    GR_GL_UNSIGNED_SHORT, indices));
      } else {
          GL_CALL(DrawElements(glPrimType, indexCount, GR_GL_UNSIGNED_SHORT, indices));
      }
      if (this->glCaps().requiresFlushBetweenNonAndInstancedDraws()) {
          fRequiresFlushBeforeNextInstancedDraw = true;
      }
      fStats.incNumDraws();
  }
  
  void GrGLGpu::sendInstancedMeshToGpu(GrPrimitiveType primitiveType, const GrBuffer* vertexBuffer,
                                       int vertexCount, int baseVertex,
                                       const GrBuffer* instanceBuffer, int instanceCount,
                                       int baseInstance) {
      if (fRequiresFlushBeforeNextInstancedDraw) {
          SkASSERT(this->glCaps().requiresFlushBetweenNonAndInstancedDraws());
          GL_CALL(Flush());
          fRequiresFlushBeforeNextInstancedDraw = false;
      }
      GrGLenum glPrimType = gr_primitive_type_to_gl_mode(primitiveType);
      int maxInstances = this->glCaps().maxInstancesPerDrawArraysWithoutCrashing(instanceCount);
      for (int i = 0; i < instanceCount; i += maxInstances) {
          this->setupGeometry(nullptr, vertexBuffer, 0, instanceBuffer, baseInstance + i,
                              GrPrimitiveRestart::kNo);
          GL_CALL(DrawArraysInstanced(glPrimType, baseVertex, vertexCount,
                                      SkTMin(instanceCount - i, maxInstances)));
          fStats.incNumDraws();
      }
  }
  
  void GrGLGpu::sendIndexedInstancedMeshToGpu(GrPrimitiveType primitiveType,
                                              const GrBuffer* indexBuffer, int indexCount,
                                              int baseIndex, const GrBuffer* vertexBuffer,
                                              int baseVertex, const GrBuffer* instanceBuffer,
                                              int instanceCount, int baseInstance,
                                              GrPrimitiveRestart enablePrimitiveRestart) {
      if (fRequiresFlushBeforeNextInstancedDraw) {
          SkASSERT(this->glCaps().requiresFlushBetweenNonAndInstancedDraws());
          GL_CALL(Flush());
          fRequiresFlushBeforeNextInstancedDraw = false;
      }
      const GrGLenum glPrimType = gr_primitive_type_to_gl_mode(primitiveType);
      GrGLvoid* indices = reinterpret_cast<void*>(indexBuffer->baseOffset() +
                                                  sizeof(uint16_t) * baseIndex);
      this->setupGeometry(indexBuffer, vertexBuffer, baseVertex, instanceBuffer, baseInstance,
                          enablePrimitiveRestart);
      GL_CALL(DrawElementsInstanced(glPrimType, indexCount, GR_GL_UNSIGNED_SHORT, indices,
                                    instanceCount));
      fStats.incNumDraws();
  }
  
  void GrGLGpu::onResolveRenderTarget(GrRenderTarget* target) {
      GrGLRenderTarget* rt = static_cast<GrGLRenderTarget*>(target);
      if (rt->needsResolve()) {
          // Some extensions automatically resolves the texture when it is read.
          if (this->glCaps().usesMSAARenderBuffers()) {
              SkASSERT(rt->textureFBOID() != rt->renderFBOID());
              SkASSERT(rt->textureFBOID() != 0 && rt->renderFBOID() != 0);
              this->bindFramebuffer(GR_GL_READ_FRAMEBUFFER, rt->renderFBOID());
              this->bindFramebuffer(GR_GL_DRAW_FRAMEBUFFER, rt->textureFBOID());
  
              // make sure we go through flushRenderTarget() since we've modified
              // the bound DRAW FBO ID.
              fHWBoundRenderTargetUniqueID.makeInvalid();
              const GrGLIRect& vp = rt->getViewport();
              const SkIRect dirtyRect = rt->getResolveRect();
              // The dirty rect tracked on the RT is always stored in the native coordinates of the
              // surface. Choose kTopLeft so no adjustments are made
              static constexpr auto kDirtyRectOrigin = kTopLeft_GrSurfaceOrigin;
              if (GrGLCaps::kES_Apple_MSFBOType == this->glCaps().msFBOType()) {
                  // Apple's extension uses the scissor as the blit bounds.
                  GrScissorState scissorState;
                  scissorState.set(dirtyRect);
                  this->flushScissor(scissorState, vp, kDirtyRectOrigin);
                  this->disableWindowRectangles();
                  GL_CALL(ResolveMultisampleFramebuffer());
              } else {
                  int l, b, r, t;
                  if (GrGLCaps::kResolveMustBeFull_BlitFrambufferFlag &
                      this->glCaps().blitFramebufferSupportFlags()) {
                      l = 0;
                      b = 0;
                      r = target->width();
                      t = target->height();
                  } else {
                      GrGLIRect rect;
                      rect.setRelativeTo(vp, dirtyRect, kDirtyRectOrigin);
                      l = rect.fLeft;
                      b = rect.fBottom;
                      r = rect.fLeft + rect.fWidth;
                      t = rect.fBottom + rect.fHeight;
                  }
  
                  // BlitFrameBuffer respects the scissor, so disable it.
                  this->disableScissor();
                  this->disableWindowRectangles();
                  GL_CALL(BlitFramebuffer(l, b, r, t, l, b, r, t,
                                          GR_GL_COLOR_BUFFER_BIT, GR_GL_NEAREST));
              }
          }
          rt->flagAsResolved();
      }
  }
  
  namespace {
  
  
  GrGLenum gr_to_gl_stencil_op(GrStencilOp op) {
      static const GrGLenum gTable[kGrStencilOpCount] = {
          GR_GL_KEEP,        // kKeep
          GR_GL_ZERO,        // kZero
          GR_GL_REPLACE,     // kReplace
          GR_GL_INVERT,      // kInvert
          GR_GL_INCR_WRAP,   // kIncWrap
          GR_GL_DECR_WRAP,   // kDecWrap
          GR_GL_INCR,        // kIncClamp
          GR_GL_DECR,        // kDecClamp
      };
      GR_STATIC_ASSERT(0 == (int)GrStencilOp::kKeep);
      GR_STATIC_ASSERT(1 == (int)GrStencilOp::kZero);
      GR_STATIC_ASSERT(2 == (int)GrStencilOp::kReplace);
      GR_STATIC_ASSERT(3 == (int)GrStencilOp::kInvert);
      GR_STATIC_ASSERT(4 == (int)GrStencilOp::kIncWrap);
      GR_STATIC_ASSERT(5 == (int)GrStencilOp::kDecWrap);
      GR_STATIC_ASSERT(6 == (int)GrStencilOp::kIncClamp);
      GR_STATIC_ASSERT(7 == (int)GrStencilOp::kDecClamp);
      SkASSERT(op < (GrStencilOp)kGrStencilOpCount);
      return gTable[(int)op];
  }
  
  void set_gl_stencil(const GrGLInterface* gl,
                      const GrStencilSettings::Face& face,
                      GrGLenum glFace) {
      GrGLenum glFunc = GrToGLStencilFunc(face.fTest);
      GrGLenum glFailOp = gr_to_gl_stencil_op(face.fFailOp);
      GrGLenum glPassOp = gr_to_gl_stencil_op(face.fPassOp);
  
      GrGLint ref = face.fRef;
      GrGLint mask = face.fTestMask;
      GrGLint writeMask = face.fWriteMask;
  
      if (GR_GL_FRONT_AND_BACK == glFace) {
          // we call the combined func just in case separate stencil is not
          // supported.
          GR_GL_CALL(gl, StencilFunc(glFunc, ref, mask));
          GR_GL_CALL(gl, StencilMask(writeMask));
          GR_GL_CALL(gl, StencilOp(glFailOp, GR_GL_KEEP, glPassOp));
      } else {
          GR_GL_CALL(gl, StencilFuncSeparate(glFace, glFunc, ref, mask));
          GR_GL_CALL(gl, StencilMaskSeparate(glFace, writeMask));
          GR_GL_CALL(gl, StencilOpSeparate(glFace, glFailOp, GR_GL_KEEP, glPassOp));
      }
  }
  }
  
  void GrGLGpu::flushStencil(const GrStencilSettings& stencilSettings) {
      if (stencilSettings.isDisabled()) {
          this->disableStencil();
      } else if (fHWStencilSettings != stencilSettings) {
          if (kYes_TriState != fHWStencilTestEnabled) {
              GL_CALL(Enable(GR_GL_STENCIL_TEST));
  
              fHWStencilTestEnabled = kYes_TriState;
          }
          if (stencilSettings.isTwoSided()) {
              set_gl_stencil(this->glInterface(),
                             stencilSettings.front(),
                             GR_GL_FRONT);
              set_gl_stencil(this->glInterface(),
                             stencilSettings.back(),
                             GR_GL_BACK);
          } else {
              set_gl_stencil(this->glInterface(),
                             stencilSettings.front(),
                             GR_GL_FRONT_AND_BACK);
          }
          fHWStencilSettings = stencilSettings;
      }
  }
  
  void GrGLGpu::disableStencil() {
      if (kNo_TriState != fHWStencilTestEnabled) {
          GL_CALL(Disable(GR_GL_STENCIL_TEST));
  
          fHWStencilTestEnabled = kNo_TriState;
          fHWStencilSettings.invalidate();
      }
  }
  
  void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA, bool stencilEnabled) {
      // rt is only optional if useHWAA is false.
      SkASSERT(rt || !useHWAA);
      SkASSERT(!useHWAA || rt->isStencilBufferMultisampled());
  
      if (this->caps()->multisampleDisableSupport()) {
          if (useHWAA) {
              if (kYes_TriState != fMSAAEnabled) {
                  GL_CALL(Enable(GR_GL_MULTISAMPLE));
                  fMSAAEnabled = kYes_TriState;
              }
          } else {
              if (kNo_TriState != fMSAAEnabled) {
                  GL_CALL(Disable(GR_GL_MULTISAMPLE));
                  fMSAAEnabled = kNo_TriState;
              }
          }
      }
  
      if (0 != this->caps()->maxRasterSamples()) {
          if (useHWAA && GrFSAAType::kMixedSamples == rt->fsaaType() && !stencilEnabled) {
              // Since stencil is disabled and we want more samples than are in the color buffer, we
              // need to tell the rasterizer explicitly how many to run.
              if (kYes_TriState != fHWRasterMultisampleEnabled) {
                  GL_CALL(Enable(GR_GL_RASTER_MULTISAMPLE));
                  fHWRasterMultisampleEnabled = kYes_TriState;
              }
              int numStencilSamples = rt->numStencilSamples();
              // convert to GL's understanding of sample counts where 0 means nonMSAA.
              numStencilSamples = 1 == numStencilSamples ? 0 : numStencilSamples;
              if (numStencilSamples != fHWNumRasterSamples) {
                  SkASSERT(numStencilSamples <= this->caps()->maxRasterSamples());
                  GL_CALL(RasterSamples(numStencilSamples, GR_GL_TRUE));
                  fHWNumRasterSamples = numStencilSamples;
              }
          } else {
              if (kNo_TriState != fHWRasterMultisampleEnabled) {
                  GL_CALL(Disable(GR_GL_RASTER_MULTISAMPLE));
                  fHWRasterMultisampleEnabled = kNo_TriState;
              }
          }
      } else {
          SkASSERT(!useHWAA || GrFSAAType::kMixedSamples != rt->fsaaType() || stencilEnabled);
      }
  }
  
  void GrGLGpu::flushBlend(const GrXferProcessor::BlendInfo& blendInfo, const GrSwizzle& swizzle) {
      // Any optimization to disable blending should have already been applied and
      // tweaked the equation to "add" or "subtract", and the coeffs to (1, 0).
  
      GrBlendEquation equation = blendInfo.fEquation;
      GrBlendCoeff srcCoeff = blendInfo.fSrcBlend;
      GrBlendCoeff dstCoeff = blendInfo.fDstBlend;
      bool blendOff = (kAdd_GrBlendEquation == equation || kSubtract_GrBlendEquation == equation) &&
                      kOne_GrBlendCoeff == srcCoeff && kZero_GrBlendCoeff == dstCoeff;
      if (blendOff) {
          if (kNo_TriState != fHWBlendState.fEnabled) {
              GL_CALL(Disable(GR_GL_BLEND));
  
              // Workaround for the ARM KHR_blend_equation_advanced blacklist issue
              // https://code.google.com/p/skia/issues/detail?id=3943
              if (kARM_GrGLVendor == this->ctxInfo().vendor() &&
                  GrBlendEquationIsAdvanced(fHWBlendState.fEquation)) {
                  SkASSERT(this->caps()->advancedBlendEquationSupport());
                  // Set to any basic blending equation.
                  GrBlendEquation blend_equation = kAdd_GrBlendEquation;
                  GL_CALL(BlendEquation(gXfermodeEquation2Blend[blend_equation]));
                  fHWBlendState.fEquation = blend_equation;
              }
  
              fHWBlendState.fEnabled = kNo_TriState;
          }
          return;
      }
  
      if (kYes_TriState != fHWBlendState.fEnabled) {
          GL_CALL(Enable(GR_GL_BLEND));
  
          fHWBlendState.fEnabled = kYes_TriState;
      }
  
      if (fHWBlendState.fEquation != equation) {
          GL_CALL(BlendEquation(gXfermodeEquation2Blend[equation]));
          fHWBlendState.fEquation = equation;
      }
  
      if (GrBlendEquationIsAdvanced(equation)) {
          SkASSERT(this->caps()->advancedBlendEquationSupport());
          // Advanced equations have no other blend state.
          return;
      }
  
      if (fHWBlendState.fSrcCoeff != srcCoeff || fHWBlendState.fDstCoeff != dstCoeff) {
          GL_CALL(BlendFunc(gXfermodeCoeff2Blend[srcCoeff],
                            gXfermodeCoeff2Blend[dstCoeff]));
          fHWBlendState.fSrcCoeff = srcCoeff;
          fHWBlendState.fDstCoeff = dstCoeff;
      }
  
      if ((BlendCoeffReferencesConstant(srcCoeff) || BlendCoeffReferencesConstant(dstCoeff))) {
          GrColor blendConst = blendInfo.fBlendConstant;
          blendConst = swizzle.applyTo(blendConst);
          if (!fHWBlendState.fConstColorValid || fHWBlendState.fConstColor != blendConst) {
              GrGLfloat c[4];
              GrColorToRGBAFloat(blendConst, c);
              GL_CALL(BlendColor(c[0], c[1], c[2], c[3]));
              fHWBlendState.fConstColor = blendConst;
              fHWBlendState.fConstColorValid = true;
          }
      }
  }
  
  static inline GrGLenum wrap_mode_to_gl_wrap(GrSamplerState::WrapMode wrapMode) {
      switch (wrapMode) {
          case GrSamplerState::WrapMode::kClamp:
              return GR_GL_CLAMP_TO_EDGE;
          case GrSamplerState::WrapMode::kRepeat:
              return GR_GL_REPEAT;
          case GrSamplerState::WrapMode::kMirrorRepeat:
              return GR_GL_MIRRORED_REPEAT;
      };
      SK_ABORT("Unknown wrap mode");
      return 0;
  }
  
  static GrGLenum get_component_enum_from_char(char component) {
      switch (component) {
          case 'r':
             return GR_GL_RED;
          case 'g':
             return GR_GL_GREEN;
          case 'b':
             return GR_GL_BLUE;
          case 'a':
             return GR_GL_ALPHA;
          default:
              SK_ABORT("Unsupported component");
              return 0;
      }
  }
  
  /** If texture swizzling is available using tex parameters then it is preferred over mangling
    the generated shader code. This potentially allows greater reuse of cached shaders. */
  static void get_tex_param_swizzle(GrPixelConfig config,
                                    const GrGLCaps& caps,
                                    GrGLenum* glSwizzle) {
      const GrSwizzle& swizzle = caps.configSwizzle(config);
      for (int i = 0; i < 4; ++i) {
          glSwizzle[i] = get_component_enum_from_char(swizzle.c_str()[i]);
      }
  }
  
  static GrGLenum filter_to_gl_mag_filter(GrSamplerState::Filter filter) {
      switch (filter) {
          case GrSamplerState::Filter::kNearest:
              return GR_GL_NEAREST;
          case GrSamplerState::Filter::kBilerp:
              return GR_GL_LINEAR;
          case GrSamplerState::Filter::kMipMap:
              return GR_GL_LINEAR;
      }
      SK_ABORT("Unknown filter");
      return 0;
  }
  
  static GrGLenum filter_to_gl_min_filter(GrSamplerState::Filter filter) {
      switch (filter) {
          case GrSamplerState::Filter::kNearest:
              return GR_GL_NEAREST;
          case GrSamplerState::Filter::kBilerp:
              return GR_GL_LINEAR;
          case GrSamplerState::Filter::kMipMap:
              return GR_GL_LINEAR_MIPMAP_LINEAR;
      }
      SK_ABORT("Unknown filter");
      return 0;
  }
  
  void GrGLGpu::bindTexture(int unitIdx, const GrSamplerState& samplerState, GrGLTexture* texture) {
      SkASSERT(texture);
  
  #ifdef SK_DEBUG
      if (!this->caps()->npotTextureTileSupport()) {
          if (samplerState.isRepeated()) {
              const int w = texture->width();
              const int h = texture->height();
              SkASSERT(SkIsPow2(w) && SkIsPow2(h));
          }
      }
  #endif
  
      // If we created a rt/tex and rendered to it without using a texture and now we're texturing
      // from the rt it will still be the last bound texture, but it needs resolving. So keep this
      // out of the "last != next" check.
      GrGLRenderTarget* texRT = static_cast<GrGLRenderTarget*>(texture->asRenderTarget());
      if (texRT) {
          this->onResolveRenderTarget(texRT);
      }
  
      GrGpuResource::UniqueID textureID = texture->uniqueID();
      GrGLenum target = texture->target();
      if (fHWBoundTextureUniqueIDs[unitIdx] != textureID) {
          this->setTextureUnit(unitIdx);
          GL_CALL(BindTexture(target, texture->textureID()));
          fHWBoundTextureUniqueIDs[unitIdx] = textureID;
      }
  
      ResetTimestamp timestamp;
      const GrGLTexture::TexParams& oldTexParams = texture->getCachedTexParams(&timestamp);
      bool setAll = timestamp < this->getResetTimestamp();
      GrGLTexture::TexParams newTexParams;
  
      GrSamplerState::Filter filterMode = samplerState.filter();
  
      if (GrSamplerState::Filter::kMipMap == filterMode) {
          if (!this->caps()->mipMapSupport() ||
              texture->texturePriv().mipMapped() == GrMipMapped::kNo) {
              filterMode = GrSamplerState::Filter::kBilerp;
          }
      }
  
      newTexParams.fMinFilter = filter_to_gl_min_filter(filterMode);
      newTexParams.fMagFilter = filter_to_gl_mag_filter(filterMode);
  
  #ifdef SK_DEBUG
      // We were supposed to ensure MipMaps were up-to-date before getting here.
      if (GrSamplerState::Filter::kMipMap == filterMode) {
          SkASSERT(!texture->texturePriv().mipMapsAreDirty());
      }
  #endif
  
      newTexParams.fMaxMipMapLevel = texture->texturePriv().maxMipMapLevel();
  
      newTexParams.fWrapS = wrap_mode_to_gl_wrap(samplerState.wrapModeX());
      newTexParams.fWrapT = wrap_mode_to_gl_wrap(samplerState.wrapModeY());
      get_tex_param_swizzle(texture->config(), this->glCaps(), newTexParams.fSwizzleRGBA);
      if (setAll || newTexParams.fMagFilter != oldTexParams.fMagFilter) {
          this->setTextureUnit(unitIdx);
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_MAG_FILTER, newTexParams.fMagFilter));
      }
      if (setAll || newTexParams.fMinFilter != oldTexParams.fMinFilter) {
          this->setTextureUnit(unitIdx);
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_MIN_FILTER, newTexParams.fMinFilter));
      }
      if (setAll || newTexParams.fMaxMipMapLevel != oldTexParams.fMaxMipMapLevel) {
          // These are not supported in ES2 contexts
          if (this->glCaps().mipMapLevelAndLodControlSupport()) {
              if (newTexParams.fMaxMipMapLevel != 0) {
                  this->setTextureUnit(unitIdx);
                  GL_CALL(TexParameteri(target, GR_GL_TEXTURE_MIN_LOD, 0));
                  GL_CALL(TexParameteri(target, GR_GL_TEXTURE_BASE_LEVEL, 0));
                  GL_CALL(TexParameteri(target, GR_GL_TEXTURE_MAX_LOD,
                                        newTexParams.fMaxMipMapLevel));
                  GL_CALL(TexParameteri(target, GR_GL_TEXTURE_MAX_LEVEL,
                                        newTexParams.fMaxMipMapLevel));
              }
          }
      }
      if (setAll || newTexParams.fWrapS != oldTexParams.fWrapS) {
          this->setTextureUnit(unitIdx);
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_WRAP_S, newTexParams.fWrapS));
      }
      if (setAll || newTexParams.fWrapT != oldTexParams.fWrapT) {
          this->setTextureUnit(unitIdx);
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_WRAP_T, newTexParams.fWrapT));
      }
      if (this->glCaps().textureSwizzleSupport() &&
          (setAll || memcmp(newTexParams.fSwizzleRGBA,
                            oldTexParams.fSwizzleRGBA,
                            sizeof(newTexParams.fSwizzleRGBA)))) {
          this->setTextureSwizzle(unitIdx, target, newTexParams.fSwizzleRGBA);
      }
      texture->setCachedTexParams(newTexParams, this->getResetTimestamp());
  }
  
  void GrGLGpu::setTextureSwizzle(int unitIdx, GrGLenum target, const GrGLenum swizzle[]) {
      this->setTextureUnit(unitIdx);
      if (this->glStandard() == kGLES_GrGLStandard) {
          // ES3 added swizzle support but not GL_TEXTURE_SWIZZLE_RGBA.
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SWIZZLE_R, swizzle[0]));
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SWIZZLE_G, swizzle[1]));
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SWIZZLE_B, swizzle[2]));
          GL_CALL(TexParameteri(target, GR_GL_TEXTURE_SWIZZLE_A, swizzle[3]));
      } else {
          GR_STATIC_ASSERT(sizeof(swizzle[0]) == sizeof(GrGLint));
          GL_CALL(TexParameteriv(target, GR_GL_TEXTURE_SWIZZLE_RGBA,
                                 reinterpret_cast<const GrGLint*>(swizzle)));
      }
  }
  
  void GrGLGpu::flushColorWrite(bool writeColor) {
      if (!writeColor) {
          if (kNo_TriState != fHWWriteToColor) {
              GL_CALL(ColorMask(GR_GL_FALSE, GR_GL_FALSE,
                                GR_GL_FALSE, GR_GL_FALSE));
              fHWWriteToColor = kNo_TriState;
          }
      } else {
          if (kYes_TriState != fHWWriteToColor) {
              GL_CALL(ColorMask(GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE, GR_GL_TRUE));
              fHWWriteToColor = kYes_TriState;
          }
      }
  }
  
  void GrGLGpu::setTextureUnit(int unit) {
      SkASSERT(unit >= 0 && unit < fHWBoundTextureUniqueIDs.count());
      if (unit != fHWActiveTextureUnitIdx) {
          GL_CALL(ActiveTexture(GR_GL_TEXTURE0 + unit));
          fHWActiveTextureUnitIdx = unit;
      }
  }
  
  void GrGLGpu::setScratchTextureUnit() {
      // Bind the last texture unit since it is the least likely to be used by GrGLProgram.
      int lastUnitIdx = fHWBoundTextureUniqueIDs.count() - 1;
      if (lastUnitIdx != fHWActiveTextureUnitIdx) {
          GL_CALL(ActiveTexture(GR_GL_TEXTURE0 + lastUnitIdx));
          fHWActiveTextureUnitIdx = lastUnitIdx;
      }
      // clear out the this field so that if a program does use this unit it will rebind the correct
      // texture.
      fHWBoundTextureUniqueIDs[lastUnitIdx].makeInvalid();
  }
  
  // Determines whether glBlitFramebuffer could be used between src and dst by onCopySurface.
  static inline bool can_blit_framebuffer_for_copy_surface(
                                                  const GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                                  const GrSurface* src, GrSurfaceOrigin srcOrigin,
                                                  const SkIRect& srcRect,
                                                  const SkIPoint& dstPoint,
                                                  const GrGLCaps& caps) {
      int dstSampleCnt = 0;
      int srcSampleCnt = 0;
      if (const GrRenderTarget* rt = dst->asRenderTarget()) {
          dstSampleCnt = rt->numColorSamples();
      }
      if (const GrRenderTarget* rt = src->asRenderTarget()) {
          srcSampleCnt = rt->numColorSamples();
      }
      SkASSERT((dstSampleCnt > 0) == SkToBool(dst->asRenderTarget()));
      SkASSERT((srcSampleCnt > 0) == SkToBool(src->asRenderTarget()));
  
      const GrGLTexture* dstTex = static_cast<const GrGLTexture*>(dst->asTexture());
      const GrGLTexture* srcTex = static_cast<const GrGLTexture*>(src->asTexture());
  
      bool dstIsGLTexture2D = dstTex ? GR_GL_TEXTURE_2D == dstTex->target() : false;
      bool srcIsGLTexture2D = srcTex ? GR_GL_TEXTURE_2D == srcTex->target() : false;
  
      return caps.canCopyAsBlit(dst->config(), dstSampleCnt, SkToBool(dstTex), dstIsGLTexture2D,
                                dstOrigin, src->config(), srcSampleCnt, SkToBool(srcTex),
                                srcIsGLTexture2D, srcOrigin, src->getBoundsRect(), srcRect, dstPoint);
  }
  
  static bool rt_has_msaa_render_buffer(const GrGLRenderTarget* rt, const GrGLCaps& glCaps) {
      // A RT has a separate MSAA renderbuffer if:
      // 1) It's multisampled
      // 2) We're using an extension with separate MSAA renderbuffers
      // 3) It's not FBO 0, which is special and always auto-resolves
      return rt->numColorSamples() > 1 && glCaps.usesMSAARenderBuffers() && rt->renderFBOID() != 0;
  }
  
  static inline bool can_copy_texsubimage(const GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                          const GrSurface* src, GrSurfaceOrigin srcOrigin,
                                          const GrGLCaps& caps) {
  
      const GrGLRenderTarget* dstRT = static_cast<const GrGLRenderTarget*>(dst->asRenderTarget());
      const GrGLRenderTarget* srcRT = static_cast<const GrGLRenderTarget*>(src->asRenderTarget());
      const GrGLTexture* dstTex = static_cast<const GrGLTexture*>(dst->asTexture());
      const GrGLTexture* srcTex = static_cast<const GrGLTexture*>(src->asTexture());
  
      bool dstHasMSAARenderBuffer = dstRT ? rt_has_msaa_render_buffer(dstRT, caps) : false;
      bool srcHasMSAARenderBuffer = srcRT ? rt_has_msaa_render_buffer(srcRT, caps) : false;
  
      bool dstIsGLTexture2D = dstTex ? GR_GL_TEXTURE_2D == dstTex->target() : false;
      bool srcIsGLTexture2D = srcTex ? GR_GL_TEXTURE_2D == srcTex->target() : false;
  
      return caps.canCopyTexSubImage(dst->config(), dstHasMSAARenderBuffer, SkToBool(dstTex),
                                     dstIsGLTexture2D, dstOrigin, src->config(),
                                     srcHasMSAARenderBuffer, SkToBool(srcTex), srcIsGLTexture2D,
                                     srcOrigin);
  }
  
  // If a temporary FBO was created, its non-zero ID is returned. The viewport that the copy rect is
  // relative to is output.
  void GrGLGpu::bindSurfaceFBOForPixelOps(GrSurface* surface, GrGLenum fboTarget, GrGLIRect* viewport,
                                          TempFBOTarget tempFBOTarget) {
      GrGLRenderTarget* rt = static_cast<GrGLRenderTarget*>(surface->asRenderTarget());
      if (!rt) {
          SkASSERT(surface->asTexture());
          GrGLTexture* texture = static_cast<GrGLTexture*>(surface->asTexture());
          GrGLuint texID = texture->textureID();
          GrGLenum target = texture->target();
          GrGLuint* tempFBOID;
          tempFBOID = kSrc_TempFBOTarget == tempFBOTarget ? &fTempSrcFBOID : &fTempDstFBOID;
  
          if (0 == *tempFBOID) {
              GR_GL_CALL(this->glInterface(), GenFramebuffers(1, tempFBOID));
          }
  
          this->bindFramebuffer(fboTarget, *tempFBOID);
          GR_GL_CALL(this->glInterface(), FramebufferTexture2D(fboTarget,
                                                               GR_GL_COLOR_ATTACHMENT0,
                                                               target,
                                                               texID,
                                                               0));
          texture->baseLevelWasBoundToFBO();
          viewport->fLeft = 0;
          viewport->fBottom = 0;
          viewport->fWidth = surface->width();
          viewport->fHeight = surface->height();
      } else {
          this->bindFramebuffer(fboTarget, rt->renderFBOID());
          *viewport = rt->getViewport();
      }
  }
  
  void GrGLGpu::unbindTextureFBOForPixelOps(GrGLenum fboTarget, GrSurface* surface) {
      // bindSurfaceFBOForPixelOps temporarily binds textures that are not render targets to
      if (!surface->asRenderTarget()) {
          SkASSERT(surface->asTexture());
          GrGLenum textureTarget = static_cast<GrGLTexture*>(surface->asTexture())->target();
          GR_GL_CALL(this->glInterface(), FramebufferTexture2D(fboTarget,
                                                               GR_GL_COLOR_ATTACHMENT0,
                                                               textureTarget,
                                                               0,
                                                               0));
      }
  }
  
  void GrGLGpu::bindFramebuffer(GrGLenum target, GrGLuint fboid) {
      fStats.incRenderTargetBinds();
      GL_CALL(BindFramebuffer(target, fboid));
      if (target == GR_GL_FRAMEBUFFER || target == GR_GL_DRAW_FRAMEBUFFER) {
          fBoundDrawFramebuffer = fboid;
      }
  
      if (!this->caps()->workarounds().restore_scissor_on_fbo_change) {
          return;
      }
  
      // The driver forgets the correct scissor when modifying the FBO binding.
      if (!fHWScissorSettings.fRect.isInvalid()) {
          fHWScissorSettings.fRect.pushToGLScissor(this->glInterface());
      }
  
      // crbug.com/222018 - Also on QualComm, the flush here avoids flicker,
      // it's unclear how this bug works.
      GL_CALL(Flush());
  }
  
  void GrGLGpu::deleteFramebuffer(GrGLuint fboid) {
      if (fboid == fBoundDrawFramebuffer &&
          this->caps()->workarounds().unbind_attachments_on_bound_render_fbo_delete) {
          // This workaround only applies to deleting currently bound framebuffers
          // on Adreno 420.  Because this is a somewhat rare case, instead of
          // tracking all the attachments of every framebuffer instead just always
          // unbind all attachments.
          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_COLOR_ATTACHMENT0,
                                          GR_GL_RENDERBUFFER, 0));
          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_STENCIL_ATTACHMENT,
                                          GR_GL_RENDERBUFFER, 0));
          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_DEPTH_ATTACHMENT,
                                          GR_GL_RENDERBUFFER, 0));
      }
  
      GL_CALL(DeleteFramebuffers(1, &fboid));
  }
  
  bool GrGLGpu::onCopySurface(GrSurface* dst, GrSurfaceOrigin dstOrigin,
                              GrSurface* src, GrSurfaceOrigin srcOrigin,
                              const SkIRect& srcRect, const SkIPoint& dstPoint,
                              bool canDiscardOutsideDstRect) {
      // None of our copy methods can handle a swizzle. TODO: Make copySurfaceAsDraw handle the
      // swizzle.
      if (this->caps()->shaderCaps()->configOutputSwizzle(src->config()) !=
          this->caps()->shaderCaps()->configOutputSwizzle(dst->config())) {
          return false;
      }
      // Don't prefer copying as a draw if the dst doesn't already have a FBO object.
      // This implicitly handles this->glCaps().useDrawInsteadOfAllRenderTargetWrites().
      bool preferCopy = SkToBool(dst->asRenderTarget());
      if (preferCopy && this->glCaps().canCopyAsDraw(dst->config(), SkToBool(src->asTexture()))) {
          if (this->copySurfaceAsDraw(dst, dstOrigin, src, srcOrigin, srcRect, dstPoint)) {
              return true;
          }
      }
  
      if (can_copy_texsubimage(dst, dstOrigin, src, srcOrigin, this->glCaps())) {
          this->copySurfaceAsCopyTexSubImage(dst, dstOrigin, src, srcOrigin, srcRect, dstPoint);
          return true;
      }
  
      if (can_blit_framebuffer_for_copy_surface(dst, dstOrigin, src, srcOrigin,
                                                srcRect, dstPoint, this->glCaps())) {
          return this->copySurfaceAsBlitFramebuffer(dst, dstOrigin, src, srcOrigin,
                                                    srcRect, dstPoint);
      }
  
      if (!preferCopy && this->glCaps().canCopyAsDraw(dst->config(), SkToBool(src->asTexture()))) {
          if (this->copySurfaceAsDraw(dst, dstOrigin, src, srcOrigin, srcRect, dstPoint)) {
              return true;
          }
      }
  
      return false;
  }
  
  bool GrGLGpu::createCopyProgram(GrTexture* srcTex) {
      TRACE_EVENT0("skia", TRACE_FUNC);
  
      int progIdx = TextureToCopyProgramIdx(srcTex);
      const GrShaderCaps* shaderCaps = this->caps()->shaderCaps();
      GrSLType samplerType =
              GrSLCombinedSamplerTypeForTextureType(srcTex->texturePriv().textureType());
  
      if (!fCopyProgramArrayBuffer) {
          static const GrGLfloat vdata[] = {
              0, 0,
              0, 1,
              1, 0,
              1, 1
          };
          fCopyProgramArrayBuffer.reset(GrGLBuffer::Create(this, sizeof(vdata), kVertex_GrBufferType,
                                                           kStatic_GrAccessPattern, vdata));
      }
      if (!fCopyProgramArrayBuffer) {
          return false;
      }
  
      SkASSERT(!fCopyPrograms[progIdx].fProgram);
      GL_CALL_RET(fCopyPrograms[progIdx].fProgram, CreateProgram());
      if (!fCopyPrograms[progIdx].fProgram) {
          return false;
      }
  
      const char* version = shaderCaps->versionDeclString();
      GrShaderVar aVertex("a_vertex", kHalf2_GrSLType, GrShaderVar::kIn_TypeModifier);
      GrShaderVar uTexCoordXform("u_texCoordXform", kHalf4_GrSLType,
                                 GrShaderVar::kUniform_TypeModifier);
      GrShaderVar uPosXform("u_posXform", kHalf4_GrSLType, GrShaderVar::kUniform_TypeModifier);
      GrShaderVar uTexture("u_texture", samplerType, GrShaderVar::kUniform_TypeModifier);
      GrShaderVar vTexCoord("v_texCoord", kHalf2_GrSLType, GrShaderVar::kOut_TypeModifier);
      GrShaderVar oFragColor("o_FragColor", kHalf4_GrSLType, GrShaderVar::kOut_TypeModifier);
  
      SkString vshaderTxt(version);
      if (shaderCaps->noperspectiveInterpolationSupport()) {
          if (const char* extension = shaderCaps->noperspectiveInterpolationExtensionString()) {
              vshaderTxt.appendf("#extension %s : require\n", extension);
          }
          vTexCoord.addModifier("noperspective");
      }
  
      aVertex.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
      uTexCoordXform.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
      uPosXform.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
      vTexCoord.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
  
      vshaderTxt.append(
          "// Copy Program VS\n"
          "void main() {"
          "  v_texCoord = a_vertex.xy * u_texCoordXform.xy + u_texCoordXform.zw;"
          "  sk_Position.xy = a_vertex * u_posXform.xy + u_posXform.zw;"
          "  sk_Position.zw = half2(0, 1);"
          "}"
      );
  
      SkString fshaderTxt(version);
      if (shaderCaps->noperspectiveInterpolationSupport()) {
          if (const char* extension = shaderCaps->noperspectiveInterpolationExtensionString()) {
              fshaderTxt.appendf("#extension %s : require\n", extension);
          }
      }
      vTexCoord.setTypeModifier(GrShaderVar::kIn_TypeModifier);
      vTexCoord.appendDecl(shaderCaps, &fshaderTxt);
      fshaderTxt.append(";");
      uTexture.appendDecl(shaderCaps, &fshaderTxt);
      fshaderTxt.append(";");
      fshaderTxt.appendf(
          "// Copy Program FS\n"
          "void main() {"
          "  sk_FragColor = texture(u_texture, v_texCoord);"
          "}"
      );
  
      const char* str;
      GrGLint length;
  
      str = vshaderTxt.c_str();
      length = SkToInt(vshaderTxt.size());
      SkSL::Program::Settings settings;
      settings.fCaps = shaderCaps;
      SkSL::String glsl;
      std::unique_ptr<SkSL::Program> program = GrSkSLtoGLSL(*fGLContext, GR_GL_VERTEX_SHADER,
                                                            &str, &length, 1, settings, &glsl);
      GrGLuint vshader = GrGLCompileAndAttachShader(*fGLContext, fCopyPrograms[progIdx].fProgram,
                                                    GR_GL_VERTEX_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      str = fshaderTxt.c_str();
      length = SkToInt(fshaderTxt.size());
      program = GrSkSLtoGLSL(*fGLContext, GR_GL_FRAGMENT_SHADER, &str, &length, 1, settings, &glsl);
      GrGLuint fshader = GrGLCompileAndAttachShader(*fGLContext, fCopyPrograms[progIdx].fProgram,
                                                    GR_GL_FRAGMENT_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      GL_CALL(LinkProgram(fCopyPrograms[progIdx].fProgram));
  
      GL_CALL_RET(fCopyPrograms[progIdx].fTextureUniform,
                  GetUniformLocation(fCopyPrograms[progIdx].fProgram, "u_texture"));
      GL_CALL_RET(fCopyPrograms[progIdx].fPosXformUniform,
                  GetUniformLocation(fCopyPrograms[progIdx].fProgram, "u_posXform"));
      GL_CALL_RET(fCopyPrograms[progIdx].fTexCoordXformUniform,
                  GetUniformLocation(fCopyPrograms[progIdx].fProgram, "u_texCoordXform"));
  
      GL_CALL(BindAttribLocation(fCopyPrograms[progIdx].fProgram, 0, "a_vertex"));
  
      GL_CALL(DeleteShader(vshader));
      GL_CALL(DeleteShader(fshader));
  
      return true;
  }
  
  bool GrGLGpu::createMipmapProgram(int progIdx) {
      const bool oddWidth = SkToBool(progIdx & 0x2);
      const bool oddHeight = SkToBool(progIdx & 0x1);
      const int numTaps = (oddWidth ? 2 : 1) * (oddHeight ? 2 : 1);
  
      const GrShaderCaps* shaderCaps = this->caps()->shaderCaps();
  
      SkASSERT(!fMipmapPrograms[progIdx].fProgram);
      GL_CALL_RET(fMipmapPrograms[progIdx].fProgram, CreateProgram());
      if (!fMipmapPrograms[progIdx].fProgram) {
          return false;
      }
  
      const char* version = shaderCaps->versionDeclString();
      GrShaderVar aVertex("a_vertex", kHalf2_GrSLType, GrShaderVar::kIn_TypeModifier);
      GrShaderVar uTexCoordXform("u_texCoordXform", kHalf4_GrSLType,
                                 GrShaderVar::kUniform_TypeModifier);
      GrShaderVar uTexture("u_texture", kTexture2DSampler_GrSLType,
                           GrShaderVar::kUniform_TypeModifier);
      // We need 1, 2, or 4 texture coordinates (depending on parity of each dimension):
      GrShaderVar vTexCoords[] = {
          GrShaderVar("v_texCoord0", kHalf2_GrSLType, GrShaderVar::kOut_TypeModifier),
          GrShaderVar("v_texCoord1", kHalf2_GrSLType, GrShaderVar::kOut_TypeModifier),
          GrShaderVar("v_texCoord2", kHalf2_GrSLType, GrShaderVar::kOut_TypeModifier),
          GrShaderVar("v_texCoord3", kHalf2_GrSLType, GrShaderVar::kOut_TypeModifier),
      };
      GrShaderVar oFragColor("o_FragColor", kHalf4_GrSLType,GrShaderVar::kOut_TypeModifier);
  
      SkString vshaderTxt(version);
      if (shaderCaps->noperspectiveInterpolationSupport()) {
          if (const char* extension = shaderCaps->noperspectiveInterpolationExtensionString()) {
              vshaderTxt.appendf("#extension %s : require\n", extension);
          }
          vTexCoords[0].addModifier("noperspective");
          vTexCoords[1].addModifier("noperspective");
          vTexCoords[2].addModifier("noperspective");
          vTexCoords[3].addModifier("noperspective");
      }
  
      aVertex.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
      uTexCoordXform.appendDecl(shaderCaps, &vshaderTxt);
      vshaderTxt.append(";");
      for (int i = 0; i < numTaps; ++i) {
          vTexCoords[i].appendDecl(shaderCaps, &vshaderTxt);
          vshaderTxt.append(";");
      }
  
      vshaderTxt.append(
          "// Mipmap Program VS\n"
          "void main() {"
          "  sk_Position.xy = a_vertex * half2(2, 2) - half2(1, 1);"
          "  sk_Position.zw = half2(0, 1);"
      );
  
      // Insert texture coordinate computation:
      if (oddWidth && oddHeight) {
          vshaderTxt.append(
              "  v_texCoord0 = a_vertex.xy * u_texCoordXform.yw;"
              "  v_texCoord1 = a_vertex.xy * u_texCoordXform.yw + half2(u_texCoordXform.x, 0);"
              "  v_texCoord2 = a_vertex.xy * u_texCoordXform.yw + half2(0, u_texCoordXform.z);"
              "  v_texCoord3 = a_vertex.xy * u_texCoordXform.yw + u_texCoordXform.xz;"
          );
      } else if (oddWidth) {
          vshaderTxt.append(
              "  v_texCoord0 = a_vertex.xy * half2(u_texCoordXform.y, 1);"
              "  v_texCoord1 = a_vertex.xy * half2(u_texCoordXform.y, 1) + half2(u_texCoordXform.x, 0);"
          );
      } else if (oddHeight) {
          vshaderTxt.append(
              "  v_texCoord0 = a_vertex.xy * half2(1, u_texCoordXform.w);"
              "  v_texCoord1 = a_vertex.xy * half2(1, u_texCoordXform.w) + half2(0, u_texCoordXform.z);"
          );
      } else {
          vshaderTxt.append(
              "  v_texCoord0 = a_vertex.xy;"
          );
      }
  
      vshaderTxt.append("}");
  
      SkString fshaderTxt(version);
      if (shaderCaps->noperspectiveInterpolationSupport()) {
          if (const char* extension = shaderCaps->noperspectiveInterpolationExtensionString()) {
              fshaderTxt.appendf("#extension %s : require\n", extension);
          }
      }
      for (int i = 0; i < numTaps; ++i) {
          vTexCoords[i].setTypeModifier(GrShaderVar::kIn_TypeModifier);
          vTexCoords[i].appendDecl(shaderCaps, &fshaderTxt);
          fshaderTxt.append(";");
      }
      uTexture.appendDecl(shaderCaps, &fshaderTxt);
      fshaderTxt.append(";");
      fshaderTxt.append(
          "// Mipmap Program FS\n"
          "void main() {"
      );
  
      if (oddWidth && oddHeight) {
          fshaderTxt.append(
              "  sk_FragColor = (texture(u_texture, v_texCoord0) + "
              "                  texture(u_texture, v_texCoord1) + "
              "                  texture(u_texture, v_texCoord2) + "
              "                  texture(u_texture, v_texCoord3)) * 0.25;"
          );
      } else if (oddWidth || oddHeight) {
          fshaderTxt.append(
              "  sk_FragColor = (texture(u_texture, v_texCoord0) + "
              "                  texture(u_texture, v_texCoord1)) * 0.5;"
          );
      } else {
          fshaderTxt.append(
              "  sk_FragColor = texture(u_texture, v_texCoord0);"
          );
      }
  
      fshaderTxt.append("}");
  
      const char* str;
      GrGLint length;
  
      str = vshaderTxt.c_str();
      length = SkToInt(vshaderTxt.size());
      SkSL::Program::Settings settings;
      settings.fCaps = shaderCaps;
      SkSL::String glsl;
      std::unique_ptr<SkSL::Program> program = GrSkSLtoGLSL(*fGLContext, GR_GL_VERTEX_SHADER,
                                                            &str, &length, 1, settings, &glsl);
      GrGLuint vshader = GrGLCompileAndAttachShader(*fGLContext, fMipmapPrograms[progIdx].fProgram,
                                                    GR_GL_VERTEX_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      str = fshaderTxt.c_str();
      length = SkToInt(fshaderTxt.size());
      program = GrSkSLtoGLSL(*fGLContext, GR_GL_FRAGMENT_SHADER, &str, &length, 1, settings, &glsl);
      GrGLuint fshader = GrGLCompileAndAttachShader(*fGLContext, fMipmapPrograms[progIdx].fProgram,
                                                    GR_GL_FRAGMENT_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      GL_CALL(LinkProgram(fMipmapPrograms[progIdx].fProgram));
  
      GL_CALL_RET(fMipmapPrograms[progIdx].fTextureUniform,
                  GetUniformLocation(fMipmapPrograms[progIdx].fProgram, "u_texture"));
      GL_CALL_RET(fMipmapPrograms[progIdx].fTexCoordXformUniform,
                  GetUniformLocation(fMipmapPrograms[progIdx].fProgram, "u_texCoordXform"));
  
      GL_CALL(BindAttribLocation(fMipmapPrograms[progIdx].fProgram, 0, "a_vertex"));
  
      GL_CALL(DeleteShader(vshader));
      GL_CALL(DeleteShader(fshader));
  
      return true;
  }
  
  bool GrGLGpu::createStencilClipClearProgram() {
      TRACE_EVENT0("skia", TRACE_FUNC);
  
      if (!fStencilClipClearArrayBuffer) {
          static const GrGLfloat vdata[] = {-1, -1, 1, -1, -1, 1, 1, 1};
          fStencilClipClearArrayBuffer.reset(GrGLBuffer::Create(
                  this, sizeof(vdata), kVertex_GrBufferType, kStatic_GrAccessPattern, vdata));
          if (!fStencilClipClearArrayBuffer) {
              return false;
          }
      }
  
      SkASSERT(!fStencilClipClearProgram);
      GL_CALL_RET(fStencilClipClearProgram, CreateProgram());
      if (!fStencilClipClearProgram) {
          return false;
      }
  
      GrShaderVar aVertex("a_vertex", kHalf2_GrSLType, GrShaderVar::kIn_TypeModifier);
      const char* version = this->caps()->shaderCaps()->versionDeclString();
  
      SkString vshaderTxt(version);
      aVertex.appendDecl(this->caps()->shaderCaps(), &vshaderTxt);
      vshaderTxt.append(";");
      vshaderTxt.append(
              "// Stencil Clip Clear Program VS\n"
              "void main() {"
              "  sk_Position = float4(a_vertex.x, a_vertex.y, 0, 1);"
              "}");
  
      SkString fshaderTxt(version);
      fshaderTxt.appendf(
              "// Stencil Clip Clear Program FS\n"
              "void main() {"
              "  sk_FragColor = half4(0);"
              "}");
  
      const char* str;
      GrGLint length;
  
      str = vshaderTxt.c_str();
      length = SkToInt(vshaderTxt.size());
      SkSL::Program::Settings settings;
      settings.fCaps = this->caps()->shaderCaps();
      SkSL::String glsl;
      std::unique_ptr<SkSL::Program> program = GrSkSLtoGLSL(*fGLContext, GR_GL_VERTEX_SHADER,
                                                            &str, &length, 1, settings, &glsl);
      GrGLuint vshader = GrGLCompileAndAttachShader(*fGLContext, fStencilClipClearProgram,
                                                    GR_GL_VERTEX_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      str = fshaderTxt.c_str();
      length = SkToInt(fshaderTxt.size());
      program = GrSkSLtoGLSL(*fGLContext, GR_GL_FRAGMENT_SHADER, &str, &length, 1, settings, &glsl);
      GrGLuint fshader = GrGLCompileAndAttachShader(*fGLContext, fStencilClipClearProgram,
                                                    GR_GL_FRAGMENT_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
      SkASSERT(program->fInputs.isEmpty());
  
      GL_CALL(LinkProgram(fStencilClipClearProgram));
  
      GL_CALL(BindAttribLocation(fStencilClipClearProgram, 0, "a_vertex"));
  
      GL_CALL(DeleteShader(vshader));
      GL_CALL(DeleteShader(fshader));
  
      return true;
  }
  
  void GrGLGpu::clearStencilClipAsDraw(const GrFixedClip& clip, bool insideStencilMask,
                                       GrRenderTarget* rt, GrSurfaceOrigin origin) {
      // TODO: This should swizzle the output to match dst's config, though it is a debugging
      // visualization.
  
      this->handleDirtyContext();
      if (!fStencilClipClearProgram) {
          if (!this->createStencilClipClearProgram()) {
              SkDebugf("Failed to create stencil clip clear program.\n");
              return;
          }
      }
  
      GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(rt->asRenderTarget());
      this->flushRenderTarget(glRT);
  
      this->flushProgram(fStencilClipClearProgram);
  
      fHWVertexArrayState.setVertexArrayID(this, 0);
  
      GrGLAttribArrayState* attribs = fHWVertexArrayState.bindInternalVertexArray(this);
      attribs->enableVertexArrays(this, 1);
      attribs->set(this, 0, fStencilClipClearArrayBuffer.get(), kHalf2_GrVertexAttribType,
                   2 * sizeof(GrGLfloat), 0);
  
      GrXferProcessor::BlendInfo blendInfo;
      blendInfo.reset();
      this->flushBlend(blendInfo, GrSwizzle::RGBA());
      this->flushColorWrite(false);
      this->flushHWAAState(glRT, false, false);
      this->flushScissor(clip.scissorState(), glRT->getViewport(), origin);
      this->flushWindowRectangles(clip.windowRectsState(), glRT, origin);
      GrStencilAttachment* sb = rt->renderTargetPriv().getStencilAttachment();
      // This should only be called internally when we know we have a stencil buffer.
      SkASSERT(sb);
      GrStencilSettings settings = GrStencilSettings(
              *GrStencilSettings::SetClipBitSettings(insideStencilMask), false, sb->bits());
      this->flushStencil(settings);
      GL_CALL(DrawArrays(GR_GL_TRIANGLE_STRIP, 0, 4));
  }
  
  bool GrGLGpu::createClearColorProgram() {
      TRACE_EVENT0("skia", TRACE_FUNC);
  
      if (!fClearProgramArrayBuffer) {
          static const GrGLfloat vdata[] = {-1, -1, 1, -1, -1, 1, 1, 1};
          fClearProgramArrayBuffer.reset(GrGLBuffer::Create(this, sizeof(vdata), kVertex_GrBufferType,
                                                            kStatic_GrAccessPattern, vdata));
          if (!fClearProgramArrayBuffer) {
              return false;
          }
      }
  
      SkASSERT(!fClearColorProgram.fProgram);
      GL_CALL_RET(fClearColorProgram.fProgram, CreateProgram());
      if (!fClearColorProgram.fProgram) {
          return false;
      }
  
      GrShaderVar aVertex("a_vertex", kHalf2_GrSLType, GrShaderVar::kIn_TypeModifier);
      const char* version = this->caps()->shaderCaps()->versionDeclString();
  
      SkString vshaderTxt(version);
      aVertex.appendDecl(this->caps()->shaderCaps(), &vshaderTxt);
      vshaderTxt.append(";");
      vshaderTxt.append(R"(
              // Clear Color Program VS
              void main() {
                  sk_Position = float4(a_vertex.x, a_vertex.y, 0, 1);
              })");
  
      GrShaderVar uColor("u_color", kHalf4_GrSLType, GrShaderVar::kUniform_TypeModifier);
      SkString fshaderTxt(version);
      uColor.appendDecl(this->caps()->shaderCaps(), &fshaderTxt);
      fshaderTxt.append(";");
      fshaderTxt.appendf(R"(
              // Clear Color Program FS
              void main() {
                sk_FragColor = u_color;
              })");
  
      const char* str;
      GrGLint length;
  
      str = vshaderTxt.c_str();
      length = SkToInt(vshaderTxt.size());
      SkSL::Program::Settings settings;
      settings.fCaps = this->caps()->shaderCaps();
      SkSL::String glsl;
      GrSkSLtoGLSL(*fGLContext, GR_GL_VERTEX_SHADER, &str, &length, 1, settings, &glsl);
      GrGLuint vshader = GrGLCompileAndAttachShader(*fGLContext, fClearColorProgram.fProgram,
                                                    GR_GL_VERTEX_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
  
      str = fshaderTxt.c_str();
      length = SkToInt(fshaderTxt.size());
      GrSkSLtoGLSL(*fGLContext, GR_GL_FRAGMENT_SHADER, &str, &length, 1, settings, &glsl);
      GrGLuint fshader = GrGLCompileAndAttachShader(*fGLContext, fClearColorProgram.fProgram,
                                                    GR_GL_FRAGMENT_SHADER, glsl.c_str(), glsl.size(),
                                                    &fStats, settings);
  
      GL_CALL(LinkProgram(fClearColorProgram.fProgram));
  
      GL_CALL(BindAttribLocation(fClearColorProgram.fProgram, 0, "a_vertex"));
  
      GL_CALL_RET(fClearColorProgram.fColorUniform,
                  GetUniformLocation(fClearColorProgram.fProgram, "u_color"));
  
      GL_CALL(DeleteShader(vshader));
      GL_CALL(DeleteShader(fshader));
  
      return true;
  }
  
  void GrGLGpu::clearColorAsDraw(const GrFixedClip& clip, GrGLfloat r, GrGLfloat g, GrGLfloat b,
                                 GrGLfloat a, GrRenderTarget* dst, GrSurfaceOrigin origin) {
      if (!fClearColorProgram.fProgram) {
          if (!this->createClearColorProgram()) {
              SkDebugf("Failed to create clear color program.\n");
              return;
          }
      }
  
      GrGLIRect dstVP;
      this->bindSurfaceFBOForPixelOps(dst, GR_GL_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);
      this->flushViewport(dstVP);
      fHWBoundRenderTargetUniqueID.makeInvalid();
  
      this->flushProgram(fClearColorProgram.fProgram);
  
      fHWVertexArrayState.setVertexArrayID(this, 0);
  
      GrGLAttribArrayState* attribs = fHWVertexArrayState.bindInternalVertexArray(this);
      attribs->enableVertexArrays(this, 1);
      attribs->set(this, 0, fClearProgramArrayBuffer.get(), kHalf2_GrVertexAttribType,
                   2 * sizeof(GrGLfloat), 0);
  
      GrGLRenderTarget* glrt = static_cast<GrGLRenderTarget*>(dst);
      this->flushScissor(clip.scissorState(), glrt->getViewport(), origin);
      this->flushWindowRectangles(clip.windowRectsState(), glrt, origin);
  
      GL_CALL(Uniform4f(fClearColorProgram.fColorUniform, r, g, b, a));
  
      GrXferProcessor::BlendInfo blendInfo;
      blendInfo.reset();
      this->flushBlend(blendInfo, GrSwizzle::RGBA());
      this->flushColorWrite(true);
      this->flushHWAAState(nullptr, false, false);
      this->disableStencil();
      if (this->glCaps().srgbWriteControl()) {
          this->flushFramebufferSRGB(true);
      }
  
      GL_CALL(DrawArrays(GR_GL_TRIANGLE_STRIP, 0, 4));
      this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, dst);
      this->didWriteToSurface(dst, origin, clip.scissorEnabled() ? &clip.scissorRect() : nullptr);
  }
  
  bool GrGLGpu::copySurfaceAsDraw(GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                  GrSurface* src, GrSurfaceOrigin srcOrigin,
                                  const SkIRect& srcRect,
                                  const SkIPoint& dstPoint) {
      GrGLTexture* srcTex = static_cast<GrGLTexture*>(src->asTexture());
      int progIdx = TextureToCopyProgramIdx(srcTex);
  
      if (!this->glCaps().canConfigBeFBOColorAttachment(dst->config())) {
          return false;
      }
  
      if (!fCopyPrograms[progIdx].fProgram) {
          if (!this->createCopyProgram(srcTex)) {
              SkDebugf("Failed to create copy program.\n");
              return false;
          }
      }
  
      int w = srcRect.width();
      int h = srcRect.height();
  
      this->bindTexture(0, GrSamplerState::ClampNearest(), srcTex);
  
      GrGLIRect dstVP;
      this->bindSurfaceFBOForPixelOps(dst, GR_GL_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);
      this->flushViewport(dstVP);
      fHWBoundRenderTargetUniqueID.makeInvalid();
  
      SkIRect dstRect = SkIRect::MakeXYWH(dstPoint.fX, dstPoint.fY, w, h);
  
      this->flushProgram(fCopyPrograms[progIdx].fProgram);
  
      fHWVertexArrayState.setVertexArrayID(this, 0);
  
      GrGLAttribArrayState* attribs = fHWVertexArrayState.bindInternalVertexArray(this);
      attribs->enableVertexArrays(this, 1);
      attribs->set(this, 0, fCopyProgramArrayBuffer.get(), kHalf2_GrVertexAttribType,
                   2 * sizeof(GrGLfloat), 0);
  
      // dst rect edges in NDC (-1 to 1)
      int dw = dst->width();
      int dh = dst->height();
      GrGLfloat dx0 = 2.f * dstPoint.fX / dw - 1.f;
      GrGLfloat dx1 = 2.f * (dstPoint.fX + w) / dw - 1.f;
      GrGLfloat dy0 = 2.f * dstPoint.fY / dh - 1.f;
      GrGLfloat dy1 = 2.f * (dstPoint.fY + h) / dh - 1.f;
      if (kBottomLeft_GrSurfaceOrigin == dstOrigin) {
          dy0 = -dy0;
          dy1 = -dy1;
      }
  
      GrGLfloat sx0 = (GrGLfloat)srcRect.fLeft;
      GrGLfloat sx1 = (GrGLfloat)(srcRect.fLeft + w);
      GrGLfloat sy0 = (GrGLfloat)srcRect.fTop;
      GrGLfloat sy1 = (GrGLfloat)(srcRect.fTop + h);
      int sw = src->width();
      int sh = src->height();
      if (kBottomLeft_GrSurfaceOrigin == srcOrigin) {
          sy0 = sh - sy0;
          sy1 = sh - sy1;
      }
      // src rect edges in normalized texture space (0 to 1)
      sx0 /= sw;
      sx1 /= sw;
      sy0 /= sh;
      sy1 /= sh;
  
      GL_CALL(Uniform4f(fCopyPrograms[progIdx].fPosXformUniform, dx1 - dx0, dy1 - dy0, dx0, dy0));
      GL_CALL(Uniform4f(fCopyPrograms[progIdx].fTexCoordXformUniform,
                        sx1 - sx0, sy1 - sy0, sx0, sy0));
      GL_CALL(Uniform1i(fCopyPrograms[progIdx].fTextureUniform, 0));
  
      GrXferProcessor::BlendInfo blendInfo;
      blendInfo.reset();
      this->flushBlend(blendInfo, GrSwizzle::RGBA());
      this->flushColorWrite(true);
      this->flushHWAAState(nullptr, false, false);
      this->disableScissor();
      this->disableWindowRectangles();
      this->disableStencil();
      if (this->glCaps().srgbWriteControl()) {
          this->flushFramebufferSRGB(true);
      }
  
      GL_CALL(DrawArrays(GR_GL_TRIANGLE_STRIP, 0, 4));
      this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, dst);
      this->didWriteToSurface(dst, dstOrigin, &dstRect);
  
      return true;
  }
  
  void GrGLGpu::copySurfaceAsCopyTexSubImage(GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                             GrSurface* src, GrSurfaceOrigin srcOrigin,
                                             const SkIRect& srcRect,
                                             const SkIPoint& dstPoint) {
      SkASSERT(can_copy_texsubimage(dst, dstOrigin, src, srcOrigin, this->glCaps()));
      GrGLIRect srcVP;
      this->bindSurfaceFBOForPixelOps(src, GR_GL_FRAMEBUFFER, &srcVP, kSrc_TempFBOTarget);
      GrGLTexture* dstTex = static_cast<GrGLTexture *>(dst->asTexture());
      SkASSERT(dstTex);
      // We modified the bound FBO
      fHWBoundRenderTargetUniqueID.makeInvalid();
      GrGLIRect srcGLRect;
      srcGLRect.setRelativeTo(srcVP, srcRect, srcOrigin);
  
      this->setScratchTextureUnit();
      GL_CALL(BindTexture(dstTex->target(), dstTex->textureID()));
      GrGLint dstY;
      if (kBottomLeft_GrSurfaceOrigin == dstOrigin) {
          dstY = dst->height() - (dstPoint.fY + srcGLRect.fHeight);
      } else {
          dstY = dstPoint.fY;
      }
      GL_CALL(CopyTexSubImage2D(dstTex->target(), 0,
                                dstPoint.fX, dstY,
                                srcGLRect.fLeft, srcGLRect.fBottom,
                                srcGLRect.fWidth, srcGLRect.fHeight));
      this->unbindTextureFBOForPixelOps(GR_GL_FRAMEBUFFER, src);
      SkIRect dstRect = SkIRect::MakeXYWH(dstPoint.fX, dstPoint.fY,
                                          srcRect.width(), srcRect.height());
      this->didWriteToSurface(dst, dstOrigin, &dstRect);
  }
  
  bool GrGLGpu::copySurfaceAsBlitFramebuffer(GrSurface* dst, GrSurfaceOrigin dstOrigin,
                                             GrSurface* src, GrSurfaceOrigin srcOrigin,
                                             const SkIRect& srcRect,
                                             const SkIPoint& dstPoint) {
      SkASSERT(can_blit_framebuffer_for_copy_surface(dst, dstOrigin, src, srcOrigin,
                                                     srcRect, dstPoint, this->glCaps()));
      SkIRect dstRect = SkIRect::MakeXYWH(dstPoint.fX, dstPoint.fY,
                                          srcRect.width(), srcRect.height());
      if (dst == src) {
          if (SkIRect::IntersectsNoEmptyCheck(dstRect, srcRect)) {
              return false;
          }
      }
  
      GrGLIRect dstVP;
      GrGLIRect srcVP;
      this->bindSurfaceFBOForPixelOps(dst, GR_GL_DRAW_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);
      this->bindSurfaceFBOForPixelOps(src, GR_GL_READ_FRAMEBUFFER, &srcVP, kSrc_TempFBOTarget);
      // We modified the bound FBO
      fHWBoundRenderTargetUniqueID.makeInvalid();
      GrGLIRect srcGLRect;
      GrGLIRect dstGLRect;
      srcGLRect.setRelativeTo(srcVP, srcRect, srcOrigin);
      dstGLRect.setRelativeTo(dstVP, dstRect, dstOrigin);
  
      // BlitFrameBuffer respects the scissor, so disable it.
      this->disableScissor();
      this->disableWindowRectangles();
  
      GrGLint srcY0;
      GrGLint srcY1;
      // Does the blit need to y-mirror or not?
      if (srcOrigin == dstOrigin) {
          srcY0 = srcGLRect.fBottom;
          srcY1 = srcGLRect.fBottom + srcGLRect.fHeight;
      } else {
          srcY0 = srcGLRect.fBottom + srcGLRect.fHeight;
          srcY1 = srcGLRect.fBottom;
      }
      GL_CALL(BlitFramebuffer(srcGLRect.fLeft,
                              srcY0,
                              srcGLRect.fLeft + srcGLRect.fWidth,
                              srcY1,
                              dstGLRect.fLeft,
                              dstGLRect.fBottom,
                              dstGLRect.fLeft + dstGLRect.fWidth,
                              dstGLRect.fBottom + dstGLRect.fHeight,
                              GR_GL_COLOR_BUFFER_BIT, GR_GL_NEAREST));
      this->unbindTextureFBOForPixelOps(GR_GL_DRAW_FRAMEBUFFER, dst);
      this->unbindTextureFBOForPixelOps(GR_GL_READ_FRAMEBUFFER, src);
      this->didWriteToSurface(dst, dstOrigin, &dstRect);
      return true;
  }
  
  bool GrGLGpu::onRegenerateMipMapLevels(GrTexture* texture) {
      auto glTex = static_cast<GrGLTexture*>(texture);
      // Mipmaps are only supported on 2D textures:
      if (GR_GL_TEXTURE_2D != glTex->target()) {
          return false;
      }
  
      // Manual implementation of mipmap generation, to work around driver bugs w/sRGB.
      // Uses draw calls to do a series of downsample operations to successive mips.
  
      // The manual approach requires the ability to limit which level we're sampling and that the
      // destination can be bound to a FBO:
      if (!this->glCaps().doManualMipmapping() ||
          !this->glCaps().canConfigBeFBOColorAttachment(texture->config())) {
          GrGLenum target = glTex->target();
          this->setScratchTextureUnit();
          GL_CALL(BindTexture(target, glTex->textureID()));
          GL_CALL(GenerateMipmap(glTex->target()));
          return true;
      }
  
      int width = texture->width();
      int height = texture->height();
      int levelCount = SkMipMap::ComputeLevelCount(width, height) + 1;
      SkASSERT(levelCount == texture->texturePriv().maxMipMapLevel() + 1);
  
      // Create (if necessary), then bind temporary FBO:
      if (0 == fTempDstFBOID) {
          GL_CALL(GenFramebuffers(1, &fTempDstFBOID));
      }
      this->bindFramebuffer(GR_GL_FRAMEBUFFER, fTempDstFBOID);
      fHWBoundRenderTargetUniqueID.makeInvalid();
  
      // Bind the texture, to get things configured for filtering.
      // We'll be changing our base level further below:
      this->setTextureUnit(0);
      this->bindTexture(0, GrSamplerState::ClampBilerp(), glTex);
  
      // Vertex data:
      if (!fMipmapProgramArrayBuffer) {
          static const GrGLfloat vdata[] = {
              0, 0,
              0, 1,
              1, 0,
              1, 1
          };
          fMipmapProgramArrayBuffer.reset(GrGLBuffer::Create(this, sizeof(vdata),
                                                             kVertex_GrBufferType,
                                                             kStatic_GrAccessPattern, vdata));
      }
      if (!fMipmapProgramArrayBuffer) {
          return false;
      }
  
      fHWVertexArrayState.setVertexArrayID(this, 0);
  
      GrGLAttribArrayState* attribs = fHWVertexArrayState.bindInternalVertexArray(this);
      attribs->enableVertexArrays(this, 1);
      attribs->set(this, 0, fMipmapProgramArrayBuffer.get(), kHalf2_GrVertexAttribType,
                   2 * sizeof(GrGLfloat), 0);
  
      // Set "simple" state once:
      GrXferProcessor::BlendInfo blendInfo;
      blendInfo.reset();
      this->flushBlend(blendInfo, GrSwizzle::RGBA());
      this->flushColorWrite(true);
      this->flushHWAAState(nullptr, false, false);
      this->disableScissor();
      this->disableWindowRectangles();
      this->disableStencil();
  
      // Do all the blits:
      width = texture->width();
      height = texture->height();
      GrGLIRect viewport;
      viewport.fLeft = 0;
      viewport.fBottom = 0;
      for (GrGLint level = 1; level < levelCount; ++level) {
          // Get and bind the program for this particular downsample (filter shape can vary):
          int progIdx = TextureSizeToMipmapProgramIdx(width, height);
          if (!fMipmapPrograms[progIdx].fProgram) {
              if (!this->createMipmapProgram(progIdx)) {
                  SkDebugf("Failed to create mipmap program.\n");
                  return false;
              }
          }
          this->flushProgram(fMipmapPrograms[progIdx].fProgram);
  
          // Texcoord uniform is expected to contain (1/w, (w-1)/w, 1/h, (h-1)/h)
          const float invWidth = 1.0f / width;
          const float invHeight = 1.0f / height;
          GL_CALL(Uniform4f(fMipmapPrograms[progIdx].fTexCoordXformUniform,
                            invWidth, (width - 1) * invWidth, invHeight, (height - 1) * invHeight));
          GL_CALL(Uniform1i(fMipmapPrograms[progIdx].fTextureUniform, 0));
  
          // Only sample from previous mip
          GL_CALL(TexParameteri(GR_GL_TEXTURE_2D, GR_GL_TEXTURE_BASE_LEVEL, level - 1));
  
          GL_CALL(FramebufferTexture2D(GR_GL_FRAMEBUFFER, GR_GL_COLOR_ATTACHMENT0, GR_GL_TEXTURE_2D,
                                       glTex->textureID(), level));
  
          width = SkTMax(1, width / 2);
          height = SkTMax(1, height / 2);
          viewport.fWidth = width;
          viewport.fHeight = height;
          this->flushViewport(viewport);
  
          GL_CALL(DrawArrays(GR_GL_TRIANGLE_STRIP, 0, 4));
      }
  
      // Unbind:
      GL_CALL(FramebufferTexture2D(GR_GL_FRAMEBUFFER, GR_GL_COLOR_ATTACHMENT0,
                                   GR_GL_TEXTURE_2D, 0, 0));
  
      // We modified the base level param.
      texture->textureParamsModified();
      return true;
  }
  
  void GrGLGpu::xferBarrier(GrRenderTarget* rt, GrXferBarrierType type) {
      SkASSERT(type);
      switch (type) {
          case kTexture_GrXferBarrierType: {
              GrGLRenderTarget* glrt = static_cast<GrGLRenderTarget*>(rt);
              SkASSERT(glrt->textureFBOID() != 0 && glrt->renderFBOID() != 0);
              if (glrt->textureFBOID() != glrt->renderFBOID()) {
                  // The render target uses separate storage so no need for glTextureBarrier.
                  // FIXME: The render target will resolve automatically when its texture is bound,
                  // but we could resolve only the bounds that will be read if we do it here instead.
                  return;
              }
              SkASSERT(this->caps()->textureBarrierSupport());
              GL_CALL(TextureBarrier());
              return;
          }
          case kBlend_GrXferBarrierType:
              SkASSERT(GrCaps::kAdvanced_BlendEquationSupport ==
                       this->caps()->blendEquationSupport());
              GL_CALL(BlendBarrier());
              return;
          default: break; // placate compiler warnings that kNone not handled
      }
  }
  
  #if GR_TEST_UTILS
  GrBackendTexture GrGLGpu::createTestingOnlyBackendTexture(const void* pixels, int w, int h,
                                                            GrPixelConfig config, bool /*isRT*/,
                                                            GrMipMapped mipMapped) {
      this->handleDirtyContext();
      if (!this->caps()->isConfigTexturable(config)) {
          return GrBackendTexture();  // invalid
      }
  
      if (w > this->caps()->maxTextureSize() || h > this->caps()->maxTextureSize()) {
          return GrBackendTexture();  // invalid
      }
  
      // Currently we don't support uploading pixel data when mipped.
      if (pixels && GrMipMapped::kYes == mipMapped) {
          return GrBackendTexture();  // invalid
      }
  
      GrGLTextureInfo info;
      info.fTarget = GR_GL_TEXTURE_2D;
      info.fID = 0;
      GL_CALL(GenTextures(1, &info.fID));
      GL_CALL(ActiveTexture(GR_GL_TEXTURE0));
      GL_CALL(PixelStorei(GR_GL_UNPACK_ALIGNMENT, 1));
      GL_CALL(BindTexture(info.fTarget, info.fID));
      fHWBoundTextureUniqueIDs[0].makeInvalid();
      GL_CALL(TexParameteri(info.fTarget, GR_GL_TEXTURE_MAG_FILTER, GR_GL_NEAREST));
      GL_CALL(TexParameteri(info.fTarget, GR_GL_TEXTURE_MIN_FILTER, GR_GL_NEAREST));
      GL_CALL(TexParameteri(info.fTarget, GR_GL_TEXTURE_WRAP_S, GR_GL_CLAMP_TO_EDGE));
      GL_CALL(TexParameteri(info.fTarget, GR_GL_TEXTURE_WRAP_T, GR_GL_CLAMP_TO_EDGE));
  
      GrGLenum internalFormat;
      GrGLenum externalFormat;
      GrGLenum externalType;
  
      if (!this->glCaps().getTexImageFormats(config, config, &internalFormat, &externalFormat,
                                             &externalType)) {
          return GrBackendTexture();  // invalid
      }
  
      info.fFormat = this->glCaps().configSizedInternalFormat(config);
  
      this->unbindCpuToGpuXferBuffer();
  
      // Figure out the number of mip levels.
      int mipLevels = 1;
      if (GrMipMapped::kYes == mipMapped) {
          mipLevels = SkMipMap::ComputeLevelCount(w, h) + 1;
      }
  
      size_t bpp = GrBytesPerPixel(config);
      size_t baseLayerSize = bpp * w * h;
      SkAutoMalloc defaultStorage(baseLayerSize);
      if (!pixels) {
          // Fill in the texture with all zeros so we don't have random garbage
          pixels = defaultStorage.get();
          memset(defaultStorage.get(), 0, baseLayerSize);
      }
  
      int width = w;
      int height = h;
      for (int i = 0; i < mipLevels; ++i) {
          GL_CALL(TexImage2D(info.fTarget, i, internalFormat, width, height, 0, externalFormat,
                             externalType, pixels));
          width = SkTMax(1, width / 2);
          height = SkTMax(1, height / 2);
      }
  
      // unbind the texture from the texture unit to avoid asserts
      GL_CALL(BindTexture(info.fTarget, 0));
  
      GrBackendTexture beTex = GrBackendTexture(w, h, mipMapped, info);
      // Lots of tests don't go through Skia's public interface which will set the config so for
      // testing we make sure we set a config here.
      beTex.setPixelConfig(config);
      return beTex;
  }
  
  bool GrGLGpu::isTestingOnlyBackendTexture(const GrBackendTexture& tex) const {
      SkASSERT(kOpenGL_GrBackend == tex.backend());
  
      GrGLTextureInfo info;
      if (!tex.getGLTextureInfo(&info)) {
          return false;
      }
  
      GrGLboolean result;
      GL_CALL_RET(result, IsTexture(info.fID));
  
      return (GR_GL_TRUE == result);
  }
  
  void GrGLGpu::deleteTestingOnlyBackendTexture(const GrBackendTexture& tex) {
      SkASSERT(kOpenGL_GrBackend == tex.backend());
  
      GrGLTextureInfo info;
      if (tex.getGLTextureInfo(&info)) {
          GL_CALL(DeleteTextures(1, &info.fID));
      }
  }
  
  GrBackendRenderTarget GrGLGpu::createTestingOnlyBackendRenderTarget(int w, int h,
                                                                      GrColorType colorType) {
      if (w > this->caps()->maxRenderTargetSize() || h > this->caps()->maxRenderTargetSize()) {
          return GrBackendRenderTarget();  // invalid
      }
      this->handleDirtyContext();
      auto config = GrColorTypeToPixelConfig(colorType, GrSRGBEncoded::kNo);
      GrGLenum colorBufferFormat;
      if (!this->glCaps().getRenderbufferFormat(config, &colorBufferFormat)) {
          return {};
      }
      int sFormatIdx = this->getCompatibleStencilIndex(config);
      if (sFormatIdx < 0) {
          return {};
      }
      GrGLuint rbIDs[] = {0, 0};
      GL_CALL(GenRenderbuffers(2, rbIDs));
      if (!rbIDs[0] || !rbIDs[1]) {
          if (!rbIDs[0]) {
              GL_CALL(DeleteRenderbuffers(1, &rbIDs[0]));
          }
          if (!rbIDs[1]) {
              GL_CALL(DeleteRenderbuffers(1, &rbIDs[1]));
          }
          return {};
      }
      GrGLFramebufferInfo info;
      info.fFBOID = 0;
      GL_CALL(GenFramebuffers(1, &info.fFBOID));
      if (!info.fFBOID) {
          GL_CALL(DeleteRenderbuffers(2, rbIDs));
          return GrBackendRenderTarget();
      }
  
      this->invalidateBoundRenderTarget();
  
      this->bindFramebuffer(GR_GL_FRAMEBUFFER, info.fFBOID);
      GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, rbIDs[0]));
      GL_ALLOC_CALL(this->glInterface(),
                    RenderbufferStorage(GR_GL_RENDERBUFFER, colorBufferFormat, w, h));
      GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_COLOR_ATTACHMENT0, GR_GL_RENDERBUFFER,
                                      rbIDs[0]));
      GL_CALL(BindRenderbuffer(GR_GL_RENDERBUFFER, rbIDs[1]));
      auto stencilBufferFormat = this->glCaps().stencilFormats()[sFormatIdx].fInternalFormat;
      GL_ALLOC_CALL(this->glInterface(),
                    RenderbufferStorage(GR_GL_RENDERBUFFER, stencilBufferFormat, w, h));
      GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_STENCIL_ATTACHMENT, GR_GL_RENDERBUFFER,
                                      rbIDs[1]));
      if (this->glCaps().stencilFormats()[sFormatIdx].fPacked) {
          GL_CALL(FramebufferRenderbuffer(GR_GL_FRAMEBUFFER, GR_GL_DEPTH_ATTACHMENT,
                                          GR_GL_RENDERBUFFER, rbIDs[1]));
      }
  
      // We don't want to have to recover the renderbuffer IDs later to delete them. OpenGL has this
      // rule that if a renderbuffer is deleted and a FBO other than the current FBO has the RB
      // attached then deletion is delayed. So we unbind the FBO here and delete the renderbuffers.
      this->bindFramebuffer(GR_GL_FRAMEBUFFER, 0);
      GL_CALL(DeleteRenderbuffers(2, rbIDs));
  
      this->bindFramebuffer(GR_GL_FRAMEBUFFER, info.fFBOID);
      GrGLenum status;
      GL_CALL_RET(status, CheckFramebufferStatus(GR_GL_FRAMEBUFFER));
      if (GR_GL_FRAMEBUFFER_COMPLETE != status) {
          this->deleteFramebuffer(info.fFBOID);
          return {};
      }
      auto stencilBits = SkToInt(this->glCaps().stencilFormats()[sFormatIdx].fStencilBits);
      GrBackendRenderTarget beRT = GrBackendRenderTarget(w, h, 1, stencilBits, info);
      // Lots of tests don't go through Skia's public interface which will set the config so for
      // testing we make sure we set a config here.
      beRT.setPixelConfig(config);
      return beRT;
  }
  
  void GrGLGpu::deleteTestingOnlyBackendRenderTarget(const GrBackendRenderTarget& backendRT) {
      SkASSERT(kOpenGL_GrBackend == backendRT.backend());
      GrGLFramebufferInfo info;
      if (backendRT.getGLFramebufferInfo(&info)) {
          if (info.fFBOID) {
              this->deleteFramebuffer(info.fFBOID);
          }
      }
  }
  
  void GrGLGpu::testingOnly_flushGpuAndSync() {
      GL_CALL(Finish());
  }
  #endif
  
  ///////////////////////////////////////////////////////////////////////////////
  
  GrGLAttribArrayState* GrGLGpu::HWVertexArrayState::bindInternalVertexArray(GrGLGpu* gpu,
                                                                             const GrBuffer* ibuf) {
      GrGLAttribArrayState* attribState;
  
      if (gpu->glCaps().isCoreProfile()) {
          if (!fCoreProfileVertexArray) {
              GrGLuint arrayID;
              GR_GL_CALL(gpu->glInterface(), GenVertexArrays(1, &arrayID));
              int attrCount = gpu->glCaps().maxVertexAttributes();
              fCoreProfileVertexArray = new GrGLVertexArray(arrayID, attrCount);
          }
          if (ibuf) {
              attribState = fCoreProfileVertexArray->bindWithIndexBuffer(gpu, ibuf);
          } else {
              attribState = fCoreProfileVertexArray->bind(gpu);
          }
      } else {
          if (ibuf) {
              // bindBuffer implicitly binds VAO 0 when binding an index buffer.
              gpu->bindBuffer(kIndex_GrBufferType, ibuf);
          } else {
              this->setVertexArrayID(gpu, 0);
          }
          int attrCount = gpu->glCaps().maxVertexAttributes();
          if (fDefaultVertexArrayAttribState.count() != attrCount) {
              fDefaultVertexArrayAttribState.resize(attrCount);
          }
          attribState = &fDefaultVertexArrayAttribState;
      }
      return attribState;
  }
  
  void GrGLGpu::onFinishFlush(bool insertedSemaphore) {
      // If we inserted semaphores during the flush, we need to call GLFlush.
      if (insertedSemaphore) {
          GL_CALL(Flush());
      }
  }
  
  void GrGLGpu::submit(GrGpuCommandBuffer* buffer) {
      if (buffer->asRTCommandBuffer()) {
          SkASSERT(fCachedRTCommandBuffer.get() == buffer);
          fCachedRTCommandBuffer->reset();
      } else {
          SkASSERT(fCachedTexCommandBuffer.get() == buffer);
          fCachedTexCommandBuffer->reset();
      }
  }
  
  GrFence SK_WARN_UNUSED_RESULT GrGLGpu::insertFence() {
      SkASSERT(this->caps()->fenceSyncSupport());
      GrGLsync sync;
      GL_CALL_RET(sync, FenceSync(GR_GL_SYNC_GPU_COMMANDS_COMPLETE, 0));
      GR_STATIC_ASSERT(sizeof(GrFence) >= sizeof(GrGLsync));
      return (GrFence)sync;
  }
  
  bool GrGLGpu::waitFence(GrFence fence, uint64_t timeout) {
      GrGLenum result;
      GL_CALL_RET(result, ClientWaitSync((GrGLsync)fence, GR_GL_SYNC_FLUSH_COMMANDS_BIT, timeout));
      return (GR_GL_CONDITION_SATISFIED == result);
  }
  
  void GrGLGpu::deleteFence(GrFence fence) const {
      this->deleteSync((GrGLsync)fence);
  }
  
  sk_sp<GrSemaphore> SK_WARN_UNUSED_RESULT GrGLGpu::makeSemaphore(bool isOwned) {
      SkASSERT(this->caps()->fenceSyncSupport());
      return GrGLSemaphore::Make(this, isOwned);
  }
  
  sk_sp<GrSemaphore> GrGLGpu::wrapBackendSemaphore(const GrBackendSemaphore& semaphore,
                                                   GrResourceProvider::SemaphoreWrapType wrapType,
                                                   GrWrapOwnership ownership) {
      SkASSERT(this->caps()->fenceSyncSupport());
      return GrGLSemaphore::MakeWrapped(this, semaphore.glSync(), ownership);
  }
  
  void GrGLGpu::insertSemaphore(sk_sp<GrSemaphore> semaphore, bool flush) {
      GrGLSemaphore* glSem = static_cast<GrGLSemaphore*>(semaphore.get());
  
      GrGLsync sync;
      GL_CALL_RET(sync, FenceSync(GR_GL_SYNC_GPU_COMMANDS_COMPLETE, 0));
      glSem->setSync(sync);
  
      if (flush) {
          GL_CALL(Flush());
      }
  }
  
  void GrGLGpu::waitSemaphore(sk_sp<GrSemaphore> semaphore) {
      GrGLSemaphore* glSem = static_cast<GrGLSemaphore*>(semaphore.get());
  
      GL_CALL(WaitSync(glSem->sync(), 0, GR_GL_TIMEOUT_IGNORED));
  }
  
  void GrGLGpu::deleteSync(GrGLsync sync) const {
      GL_CALL(DeleteSync(sync));
  }
  
  void GrGLGpu::insertEventMarker(const char* msg) {
      GL_CALL(InsertEventMarker(strlen(msg), msg));
  }
  
  sk_sp<GrSemaphore> GrGLGpu::prepareTextureForCrossContextUsage(GrTexture* texture) {
      // Set up a semaphore to be signaled once the data is ready, and flush GL
      sk_sp<GrSemaphore> semaphore = this->makeSemaphore(true);
      this->insertSemaphore(semaphore, true);
  
      return semaphore;
  }
  
  int GrGLGpu::TextureToCopyProgramIdx(GrTexture* texture) {
      switch (GrSLCombinedSamplerTypeForTextureType(texture->texturePriv().textureType())) {
          case kTexture2DSampler_GrSLType:
              return 0;
          case kTexture2DRectSampler_GrSLType:
              return 1;
          case kTextureExternalSampler_GrSLType:
              return 2;
          default:
              SK_ABORT("Unexpected samper type");
              return 0;
      }
  }
  
  void GrGLGpu::onDumpJSON(SkJSONWriter* writer) const {
      // We are called by the base class, which has already called beginObject(). We choose to nest
      // all of our caps information in a named sub-object.
      writer->beginObject("GL GPU");
  
      const GrGLubyte* str;
      GL_CALL_RET(str, GetString(GR_GL_VERSION));
      writer->appendString("GL_VERSION", (const char*)(str));
      GL_CALL_RET(str, GetString(GR_GL_RENDERER));
      writer->appendString("GL_RENDERER", (const char*)(str));
      GL_CALL_RET(str, GetString(GR_GL_VENDOR));
      writer->appendString("GL_VENDOR", (const char*)(str));
      GL_CALL_RET(str, GetString(GR_GL_SHADING_LANGUAGE_VERSION));
      writer->appendString("GL_SHADING_LANGUAGE_VERSION", (const char*)(str));
  
      writer->appendName("extensions");
      glInterface()->fExtensions.dumpJSON(writer);
  
      writer->endObject();
  }
  