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.
   */
  
  #ifndef GrGpu_DEFINED
  #define GrGpu_DEFINED
  
  #include "include/core/SkPath.h"
  #include "include/core/SkSurface.h"
  #include "include/gpu/GrTypes.h"
  #include "include/private/SkTArray.h"
  #include "src/gpu/GrAllocator.h"
  #include "src/gpu/GrCaps.h"
  #include "src/gpu/GrGpuCommandBuffer.h"
  #include "src/gpu/GrProgramDesc.h"
  #include "src/gpu/GrSamplePatternDictionary.h"
  #include "src/gpu/GrSwizzle.h"
  #include "src/gpu/GrTextureProducer.h"
  #include "src/gpu/GrXferProcessor.h"
  #include <map>
  
  class GrBackendRenderTarget;
  class GrBackendSemaphore;
  class GrGpuBuffer;
  class GrContext;
  struct GrContextOptions;
  class GrGLContext;
  class GrMesh;
  class GrPath;
  class GrPathRenderer;
  class GrPathRendererChain;
  class GrPathRendering;
  class GrPipeline;
  class GrPrimitiveProcessor;
  class GrRenderTarget;
  class GrSemaphore;
  class GrStencilAttachment;
  class GrStencilSettings;
  class GrSurface;
  class GrTexture;
  class SkJSONWriter;
  
  class GrGpu : public SkRefCnt {
  public:
      GrGpu(GrContext* context);
      ~GrGpu() override;
  
      GrContext* getContext() { return fContext; }
      const GrContext* getContext() const { return fContext; }
  
      /**
       * Gets the capabilities of the draw target.
       */
      const GrCaps* caps() const { return fCaps.get(); }
      sk_sp<const GrCaps> refCaps() const { return fCaps; }
  
      GrPathRendering* pathRendering() { return fPathRendering.get();  }
  
      enum class DisconnectType {
          // No cleanup should be attempted, immediately cease making backend API calls
          kAbandon,
          // Free allocated resources (not known by GrResourceCache) before returning and
          // ensure no backend backend 3D API calls will be made after disconnect() returns.
          kCleanup,
      };
  
      // Called by GrContext when the underlying backend context is already or will be destroyed
      // before GrContext.
      virtual void disconnect(DisconnectType);
  
      /**
       * The GrGpu object normally assumes that no outsider is setting state
       * within the underlying 3D API's context/device/whatever. This call informs
       * the GrGpu that the state was modified and it shouldn't make assumptions
       * about the state.
       */
      void markContextDirty(uint32_t state = kAll_GrBackendState) { fResetBits |= state; }
  
      /**
       * Creates a texture object. If renderable is kYes then the returned texture can
       * be used as a render target by calling GrTexture::asRenderTarget(). Not all
       * pixel configs can be used as render targets. Support for configs as textures
       * or render targets can be checked using GrCaps.
       *
       * @param desc           describes the texture to be created.
       * @param format         the format for the texture (not currently used).
       * @param renderable     should the resulting texture be renderable
       * @param renderTargetSampleCnt The number of samples to use for rendering if renderable is
       *                       kYes. If renderable is kNo then this must be 1.
       * @param budgeted       does this texture count against the resource cache budget?
       * @param isProtected    should the texture be created as protected.
       * @param texels         array of mipmap levels containing texel data to load.
       *                       If level i has pixels then it is assumed that its dimensions are
       *                       max(1, floor(desc.fWidth / 2)) by max(1, floor(desc.fHeight / 2)).
       *                       If texels[i].fPixels == nullptr for all i <= mipLevelCount or
       *                       mipLevelCount is 0 then the texture's contents are uninitialized.
       *                       If a level has non-null pixels, its row bytes must be a multiple of the
       *                       config's bytes-per-pixel. The row bytes must be tight to the
       *                       level width if !caps->writePixelsRowBytesSupport().
       *                       If mipLevelCount > 1 and texels[i].fPixels != nullptr for any i > 0
       *                       then all levels must have non-null pixels. All levels must have
       *                       non-null pixels if GrCaps::createTextureMustSpecifyAllLevels() is true.
       * @param mipLevelCount  the number of levels in 'texels'. May be 0, 1, or
       *                       floor(max((log2(desc.fWidth), log2(desc.fHeight)))). It must be the
       *                       latter if GrCaps::createTextureMustSpecifyAllLevels() is true.
       * @return  The texture object if successful, otherwise nullptr.
       */
      sk_sp<GrTexture> createTexture(const GrSurfaceDesc& desc, const GrBackendFormat& format,
                                     GrRenderable renderable, int renderTargetSampleCnt, SkBudgeted,
                                     GrProtected isProtected, const GrMipLevel texels[],
                                     int mipLevelCount);
  
      /**
       * Simplified createTexture() interface for when there is no initial texel data to upload.
       */
      sk_sp<GrTexture> createTexture(const GrSurfaceDesc& desc, const GrBackendFormat& format,
                                     GrRenderable renderable, int renderTargetSampleCnt,
                                     SkBudgeted budgeted, GrProtected isProtected);
  
      sk_sp<GrTexture> createCompressedTexture(int width, int height, SkImage::CompressionType,
                                               SkBudgeted, const void* data, size_t dataSize);
  
      /**
       * Implements GrResourceProvider::wrapBackendTexture
       */
      sk_sp<GrTexture> wrapBackendTexture(const GrBackendTexture&, GrColorType,
                                          GrWrapOwnership, GrWrapCacheable, GrIOType);
  
      /**
       * Implements GrResourceProvider::wrapRenderableBackendTexture
       */
      sk_sp<GrTexture> wrapRenderableBackendTexture(const GrBackendTexture&, int sampleCnt,
                                                    GrColorType, GrWrapOwnership, GrWrapCacheable);
  
      /**
       * Implements GrResourceProvider::wrapBackendRenderTarget
       */
      sk_sp<GrRenderTarget> wrapBackendRenderTarget(const GrBackendRenderTarget&,
                                                    GrColorType colorType);
  
      /**
       * Implements GrResourceProvider::wrapBackendTextureAsRenderTarget
       */
      sk_sp<GrRenderTarget> wrapBackendTextureAsRenderTarget(const GrBackendTexture&,
                                                             int sampleCnt,
                                                             GrColorType colorType);
  
      /**
       * Implements GrResourceProvider::wrapVulkanSecondaryCBAsRenderTarget
       */
      sk_sp<GrRenderTarget> wrapVulkanSecondaryCBAsRenderTarget(const SkImageInfo&,
                                                                const GrVkDrawableInfo&);
  
      /**
       * Creates a buffer in GPU memory. For a client-side buffer use GrBuffer::CreateCPUBacked.
       *
       * @param size            size of buffer to create.
       * @param intendedType    hint to the graphics subsystem about what the buffer will be used for.
       * @param accessPattern   hint to the graphics subsystem about how the data will be accessed.
       * @param data            optional data with which to initialize the buffer.
       *
       * @return the buffer if successful, otherwise nullptr.
       */
      sk_sp<GrGpuBuffer> createBuffer(size_t size, GrGpuBufferType intendedType,
                                      GrAccessPattern accessPattern, const void* data = nullptr);
  
      /**
       * Resolves MSAA.
       */
      void resolveRenderTarget(GrRenderTarget*);
  
      /**
       * Uses the base of the texture to recompute the contents of the other levels.
       */
      bool regenerateMipMapLevels(GrTexture*);
  
      /**
       * If the backend API has stateful texture bindings, this resets them back to defaults.
       */
      void resetTextureBindings();
  
      /**
       * Reads a rectangle of pixels from a render target. No sRGB/linear conversions are performed.
       *
       * @param surface           The surface to read from
       * @param left              left edge of the rectangle to read (inclusive)
       * @param top               top edge of the rectangle to read (inclusive)
       * @param width             width of rectangle to read in pixels.
       * @param height            height of rectangle to read in pixels.
       * @param surfaceColorType  the color type for this use of the surface.
       * @param dstColorType      the color type of the destination buffer.
       * @param buffer            memory to read the rectangle into.
       * @param rowBytes          the number of bytes between consecutive rows. Must be a multiple of
       *                          dstColorType's bytes-per-pixel. Must be tight to width if
       *                          !caps->readPixelsRowBytesSupport().
       *
       * @return true if the read succeeded, false if not. The read can fail
       *              because of the surface doesn't support reading, the color type
       *              is not allowed for the format of the surface or if the rectangle
       *              read is not contained in the surface.
       */
      bool readPixels(GrSurface* surface, int left, int top, int width, int height,
                      GrColorType surfaceColorType, GrColorType dstColorType, void* buffer,
                      size_t rowBytes);
  
      /**
       * Updates the pixels in a rectangle of a surface.  No sRGB/linear conversions are performed.
       *
       * @param surface           The surface to write to.
       * @param left              left edge of the rectangle to write (inclusive)
       * @param top               top edge of the rectangle to write (inclusive)
       * @param width             width of rectangle to write in pixels.
       * @param height            height of rectangle to write in pixels.
       * @param surfaceColorType  the color type for this use of the surface.
       * @param srcColorType      the color type of the source buffer.
       * @param texels            array of mipmap levels containing texture data. Row bytes must be a
       *                          multiple of srcColorType's bytes-per-pixel. Must be tight to level
       *                          width if !caps->writePixelsRowBytesSupport().
       * @param mipLevelCount     number of levels in 'texels'
       *
       * @return true if the write succeeded, false if not. The read can fail
       *              because of the surface doesn't support writing (e.g. read only),
       *              the color type is not allowed for the format of the surface or
       *              if the rectangle written is not contained in the surface.
       */
      bool writePixels(GrSurface* surface, int left, int top, int width, int height,
                       GrColorType surfaceColorType, GrColorType srcColorType,
                       const GrMipLevel texels[], int mipLevelCount);
  
      /**
       * Helper for the case of a single level.
       */
      bool writePixels(GrSurface* surface, int left, int top, int width, int height,
                       GrColorType surfaceColorType, GrColorType srcColorType, const void* buffer,
                       size_t rowBytes) {
          GrMipLevel mipLevel = {buffer, rowBytes};
          return this->writePixels(surface, left, top, width, height, surfaceColorType, srcColorType,
                                   &mipLevel, 1);
      }
  
      /**
       * Updates the pixels in a rectangle of a texture using a buffer. If the texture is MIP mapped,
       * the base level is written to.
       *
       * @param texture          The texture to write to.
       * @param left             left edge of the rectangle to write (inclusive)
       * @param top              top edge of the rectangle to write (inclusive)
       * @param width            width of rectangle to write in pixels.
       * @param height           height of rectangle to write in pixels.
       * @param textureColorType the color type for this use of the surface.
       * @param bufferColorType  the color type of the transfer buffer's pixel data
       * @param transferBuffer   GrBuffer to read pixels from (type must be "kXferCpuToGpu")
       * @param offset           offset from the start of the buffer
       * @param rowBytes         number of bytes between consecutive rows in the buffer. Must be a
       *                         multiple of bufferColorType's bytes-per-pixel. Must be tight to width
       *                         if !caps->writePixelsRowBytesSupport().
       */
      bool transferPixelsTo(GrTexture* texture, int left, int top, int width, int height,
                            GrColorType textureColorType, GrColorType bufferColorType,
                            GrGpuBuffer* transferBuffer, size_t offset, size_t rowBytes);
  
      /**
       * Reads the pixels from a rectangle of a surface into a buffer. Use
       * GrCaps::SupportedRead::fOffsetAlignmentForTransferBuffer to determine the requirements for
       * the buffer offset alignment. If the surface is a MIP mapped texture, the base level is read.
       *
       * If successful the row bytes in the buffer is always:
       *   GrColorTypeBytesPerPixel(bufferColorType) * width
       *
       * Asserts that the caller has passed a properly aligned offset and that the buffer is
       * large enough to hold the result
       *
       * @param surface          The surface to read from.
       * @param left             left edge of the rectangle to read (inclusive)
       * @param top              top edge of the rectangle to read (inclusive)
       * @param width            width of rectangle to read in pixels.
       * @param height           height of rectangle to read in pixels.
       * @param surfaceColorType the color type for this use of the surface.
       * @param bufferColorType  the color type of the transfer buffer's pixel data
       * @param transferBuffer   GrBuffer to write pixels to (type must be "kXferGpuToCpu")
       * @param offset           offset from the start of the buffer
       */
      bool transferPixelsFrom(GrSurface* surface, int left, int top, int width, int height,
                              GrColorType surfaceColorType, GrColorType bufferColorType,
                              GrGpuBuffer* transferBuffer, size_t offset);
  
      // Called to perform a surface to surface copy. Fallbacks to issuing a draw from the src to dst
      // take place at the GrOpList level and this function implement faster copy paths. The rect
      // and point are pre-clipped. The src rect and implied dst rect are guaranteed to be within the
      // src/dst bounds and non-empty. They must also be in their exact device space coords, including
      // already being transformed for origin if need be. If canDiscardOutsideDstRect is set to true
      // then we don't need to preserve any data on the dst surface outside of the copy.
      bool copySurface(GrSurface* dst, GrSurface* src, const SkIRect& srcRect,
                       const SkIPoint& dstPoint, bool canDiscardOutsideDstRect = false);
  
      // Queries the per-pixel HW sample locations for the given render target, and then finds or
      // assigns a key that uniquely identifies the sample pattern. The actual sample locations can be
      // retrieved with retrieveSampleLocations().
      int findOrAssignSamplePatternKey(GrRenderTarget*);
  
      // Retrieves the per-pixel HW sample locations for the given sample pattern key, and, as a
      // by-product, the actual number of samples in use. (This may differ from the number of samples
      // requested by the render target.) Sample locations are returned as 0..1 offsets relative to
      // the top-left corner of the pixel.
      const SkTArray<SkPoint>& retrieveSampleLocations(int samplePatternKey) const {
          return fSamplePatternDictionary.retrieveSampleLocations(samplePatternKey);
      }
  
      // Returns a GrGpuRTCommandBuffer which GrOpLists send draw commands to instead of directly
      // to the Gpu object. The 'bounds' rect is the content rect of the destination.
      virtual GrGpuRTCommandBuffer* getCommandBuffer(
              GrRenderTarget*, GrSurfaceOrigin, const SkRect& bounds,
              const GrGpuRTCommandBuffer::LoadAndStoreInfo&,
              const GrGpuRTCommandBuffer::StencilLoadAndStoreInfo&) = 0;
  
      // Returns a GrGpuTextureCommandBuffer which GrOpLists send texture commands to instead of
      // directly to the Gpu object.
      virtual GrGpuTextureCommandBuffer* getCommandBuffer(GrTexture*, GrSurfaceOrigin) = 0;
  
      // Called by GrDrawingManager when flushing.
      // Provides a hook for post-flush actions (e.g. Vulkan command buffer submits). This will also
      // insert any numSemaphore semaphores on the gpu and set the backendSemaphores to match the
      // inserted semaphores.
      GrSemaphoresSubmitted finishFlush(GrSurfaceProxy*[], int n,
                                        SkSurface::BackendSurfaceAccess access, const GrFlushInfo&,
                                        const GrPrepareForExternalIORequests&);
  
      virtual void submit(GrGpuCommandBuffer*) = 0;
  
      virtual GrFence SK_WARN_UNUSED_RESULT insertFence() = 0;
      virtual bool waitFence(GrFence, uint64_t timeout = 1000) = 0;
      virtual void deleteFence(GrFence) const = 0;
  
      virtual sk_sp<GrSemaphore> SK_WARN_UNUSED_RESULT makeSemaphore(bool isOwned = true) = 0;
      virtual sk_sp<GrSemaphore> wrapBackendSemaphore(const GrBackendSemaphore& semaphore,
                                                      GrResourceProvider::SemaphoreWrapType wrapType,
                                                      GrWrapOwnership ownership) = 0;
      virtual void insertSemaphore(sk_sp<GrSemaphore> semaphore) = 0;
      virtual void waitSemaphore(sk_sp<GrSemaphore> semaphore) = 0;
  
      virtual void checkFinishProcs() = 0;
  
      /**
       *  Put this texture in a safe and known state for use across multiple GrContexts. Depending on
       *  the backend, this may return a GrSemaphore. If so, other contexts should wait on that
       *  semaphore before using this texture.
       */
      virtual sk_sp<GrSemaphore> prepareTextureForCrossContextUsage(GrTexture*) = 0;
  
      ///////////////////////////////////////////////////////////////////////////
      // Debugging and Stats
  
      class Stats {
      public:
  #if GR_GPU_STATS
          Stats() = default;
  
          void reset() { *this = {}; }
  
          int renderTargetBinds() const { return fRenderTargetBinds; }
          void incRenderTargetBinds() { fRenderTargetBinds++; }
  
          int shaderCompilations() const { return fShaderCompilations; }
          void incShaderCompilations() { fShaderCompilations++; }
  
          int textureCreates() const { return fTextureCreates; }
          void incTextureCreates() { fTextureCreates++; }
  
          int textureUploads() const { return fTextureUploads; }
          void incTextureUploads() { fTextureUploads++; }
  
          int transfersToTexture() const { return fTransfersToTexture; }
          void incTransfersToTexture() { fTransfersToTexture++; }
  
          int transfersFromSurface() const { return fTransfersFromSurface; }
          void incTransfersFromSurface() { fTransfersFromSurface++; }
  
          int stencilAttachmentCreates() const { return fStencilAttachmentCreates; }
          void incStencilAttachmentCreates() { fStencilAttachmentCreates++; }
  
          int numDraws() const { return fNumDraws; }
          void incNumDraws() { fNumDraws++; }
  
          int numFailedDraws() const { return fNumFailedDraws; }
          void incNumFailedDraws() { ++fNumFailedDraws; }
  
          int numFinishFlushes() const { return fNumFinishFlushes; }
          void incNumFinishFlushes() { ++fNumFinishFlushes; }
  
          int numScratchTexturesReused() const { return fNumScratchTexturesReused; }
          void incNumScratchTexturesReused() { ++fNumScratchTexturesReused; }
  
  #if GR_TEST_UTILS
          void dump(SkString*);
          void dumpKeyValuePairs(SkTArray<SkString>* keys, SkTArray<double>* values);
  #endif
      private:
          int fRenderTargetBinds = 0;
          int fShaderCompilations = 0;
          int fTextureCreates = 0;
          int fTextureUploads = 0;
          int fTransfersToTexture = 0;
          int fTransfersFromSurface = 0;
          int fStencilAttachmentCreates = 0;
          int fNumDraws = 0;
          int fNumFailedDraws = 0;
          int fNumFinishFlushes = 0;
          int fNumScratchTexturesReused = 0;
  #else
  
  #if GR_TEST_UTILS
          void dump(SkString*) {}
          void dumpKeyValuePairs(SkTArray<SkString>*, SkTArray<double>*) {}
  #endif
          void incRenderTargetBinds() {}
          void incShaderCompilations() {}
          void incTextureCreates() {}
          void incTextureUploads() {}
          void incTransfersToTexture() {}
          void incStencilAttachmentCreates() {}
          void incNumDraws() {}
          void incNumFailedDraws() {}
          void incNumFinishFlushes() {}
  #endif
      };
  
      Stats* stats() { return &fStats; }
      void dumpJSON(SkJSONWriter*) const;
  
      /**
       * Creates a texture directly in the backend API without wrapping it in a GrTexture.
       * Must be matched with a call to deleteBackendTexture().
       * Right now, the color is ignored if pixel data is provided.
       * In the future, if neither a color nor pixels are provided then the backend texture
       * will be uninitialized.
       */
      virtual GrBackendTexture createBackendTexture(int w, int h, const GrBackendFormat&,
                                                    GrMipMapped, GrRenderable,
                                                    const void* pixels, size_t rowBytes,
                                                    const SkColor4f* color,
                                                    GrProtected isProtected) = 0;
  
      /**
       * Frees a texture created by createBackendTexture(). If ownership of the backend
       * texture has been transferred to a GrContext using adopt semantics this should not be called.
       */
      virtual void deleteBackendTexture(const GrBackendTexture&) = 0;
  
  #if GR_TEST_UTILS
      /** Check a handle represents an actual texture in the backend API that has not been freed. */
      virtual bool isTestingOnlyBackendTexture(const GrBackendTexture&) const = 0;
  
      virtual GrBackendRenderTarget createTestingOnlyBackendRenderTarget(int w, int h,
                                                                         GrColorType) = 0;
  
      virtual void deleteTestingOnlyBackendRenderTarget(const GrBackendRenderTarget&) = 0;
  
      // This is only to be used in GL-specific tests.
      virtual const GrGLContext* glContextForTesting() const { return nullptr; }
  
      // This is only to be used by testing code
      virtual void resetShaderCacheForTesting() const {}
  
      /**
       * Flushes all work to the gpu and forces the GPU to wait until all the gpu work has completed.
       * This is for testing purposes only.
       */
      virtual void testingOnly_flushGpuAndSync() = 0;
  #endif
  
      // width and height may be larger than rt (if underlying API allows it).
      // Returns nullptr if compatible sb could not be created, otherwise the caller owns the ref on
      // the GrStencilAttachment.
      virtual GrStencilAttachment* createStencilAttachmentForRenderTarget(
              const GrRenderTarget*, int width, int height, int numStencilSamples) = 0;
  
      // Determines whether a texture will need to be rescaled in order to be used with the
      // GrSamplerState.
      static bool IsACopyNeededForRepeatWrapMode(const GrCaps*, GrTextureProxy* texProxy,
                                                 int width, int height,
                                                 GrSamplerState::Filter,
                                                 GrTextureProducer::CopyParams*,
                                                 SkScalar scaleAdjust[2]);
  
      // Determines whether a texture will need to be copied because the draw requires mips but the
      // texutre doesn't have any. This call should be only checked if IsACopyNeededForTextureParams
      // fails. If the previous call succeeds, then a copy should be done using those params and the
      // mip mapping requirements will be handled there.
      static bool IsACopyNeededForMips(const GrCaps* caps, const GrTextureProxy* texProxy,
                                       GrSamplerState::Filter filter,
                                       GrTextureProducer::CopyParams* copyParams);
  
      void handleDirtyContext() {
          if (fResetBits) {
              this->resetContext();
          }
      }
  
      /**
       * Returns a key that represents the sampler that will be created for the passed in parameters.
       * Currently this key is only used when we are building a vulkan pipeline with immutable
       * samplers. In that case, we need our cache key to also contain this key.
       *
       * A return value of 0 indicates that the program/pipeline we are creating is not affected by
       * the sampler.
       */
      virtual uint32_t getExtraSamplerKeyForProgram(const GrSamplerState&, const GrBackendFormat&) {
          return 0;
      }
  
      virtual void storeVkPipelineCacheData() {}
  
  protected:
      // Handles cases where a surface will be updated without a call to flushRenderTarget.
      void didWriteToSurface(GrSurface* surface, GrSurfaceOrigin origin, const SkIRect* bounds,
                             uint32_t mipLevels = 1) const;
  
      Stats                            fStats;
      std::unique_ptr<GrPathRendering> fPathRendering;
      // Subclass must initialize this in its constructor.
      sk_sp<const GrCaps>              fCaps;
  
  private:
      // called when the 3D context state is unknown. Subclass should emit any
      // assumed 3D context state and dirty any state cache.
      virtual void onResetContext(uint32_t resetBits) = 0;
  
      // Implementation of resetTextureBindings.
      virtual void onResetTextureBindings() {}
  
      // Queries the effective number of samples in use by the hardware for the given render target,
      // and queries the individual sample locations.
      virtual void querySampleLocations(GrRenderTarget*, SkTArray<SkPoint>*) = 0;
  
      // Called before certain draws in order to guarantee coherent results from dst reads.
      virtual void xferBarrier(GrRenderTarget*, GrXferBarrierType) = 0;
  
      // overridden by backend-specific derived class to create objects.
      // Texture size and sample size will have already been validated in base class before
      // onCreateTexture is called.
      virtual sk_sp<GrTexture> onCreateTexture(const GrSurfaceDesc&, GrRenderable,
                                               int renderTargetSampleCnt, SkBudgeted, GrProtected,
                                               const GrMipLevel[], int mipLevelCount) = 0;
      virtual sk_sp<GrTexture> onCreateCompressedTexture(int width, int height,
                                                         SkImage::CompressionType, SkBudgeted,
                                                         const void* data) = 0;
      virtual sk_sp<GrTexture> onWrapBackendTexture(const GrBackendTexture&, GrColorType,
                                                    GrWrapOwnership, GrWrapCacheable, GrIOType) = 0;
      virtual sk_sp<GrTexture> onWrapRenderableBackendTexture(const GrBackendTexture&, int sampleCnt,
                                                              GrColorType, GrWrapOwnership,
                                                              GrWrapCacheable) = 0;
      virtual sk_sp<GrRenderTarget> onWrapBackendRenderTarget(const GrBackendRenderTarget&,
                                                              GrColorType) = 0;
      virtual sk_sp<GrRenderTarget> onWrapBackendTextureAsRenderTarget(const GrBackendTexture&,
                                                                       int sampleCnt,
                                                                       GrColorType) = 0;
      virtual sk_sp<GrRenderTarget> onWrapVulkanSecondaryCBAsRenderTarget(const SkImageInfo&,
                                                                          const GrVkDrawableInfo&);
  
      virtual sk_sp<GrGpuBuffer> onCreateBuffer(size_t size, GrGpuBufferType intendedType,
                                                GrAccessPattern, const void* data) = 0;
  
      // overridden by backend-specific derived class to perform the surface read
      virtual bool onReadPixels(GrSurface*, int left, int top, int width, int height,
                                GrColorType surfaceColorType, GrColorType dstColorType, void* buffer,
                                size_t rowBytes) = 0;
  
      // overridden by backend-specific derived class to perform the surface write
      virtual bool onWritePixels(GrSurface*, int left, int top, int width, int height,
                                 GrColorType surfaceColorType, GrColorType srcColorType,
                                 const GrMipLevel texels[], int mipLevelCount) = 0;
  
      // overridden by backend-specific derived class to perform the texture transfer
      virtual bool onTransferPixelsTo(GrTexture*, int left, int top, int width, int height,
                                      GrColorType textiueColorType, GrColorType bufferColorType,
                                      GrGpuBuffer* transferBuffer, size_t offset,
                                      size_t rowBytes) = 0;
      // overridden by backend-specific derived class to perform the surface transfer
      virtual bool onTransferPixelsFrom(GrSurface*, int left, int top, int width, int height,
                                        GrColorType surfaceColorType, GrColorType bufferColorType,
                                        GrGpuBuffer* transferBuffer, size_t offset) = 0;
  
      // overridden by backend-specific derived class to perform the resolve
      virtual void onResolveRenderTarget(GrRenderTarget* target) = 0;
  
      // overridden by backend specific derived class to perform mip map level regeneration.
      virtual bool onRegenerateMipMapLevels(GrTexture*) = 0;
  
      // overridden by backend specific derived class to perform the copy surface
      virtual bool onCopySurface(GrSurface* dst, GrSurface* src, const SkIRect& srcRect,
                                 const SkIPoint& dstPoint, bool canDiscardOutsideDstRect) = 0;
  
      virtual void onFinishFlush(GrSurfaceProxy*[], int n, SkSurface::BackendSurfaceAccess access,
                                 const GrFlushInfo&, const GrPrepareForExternalIORequests&) = 0;
  
  #ifdef SK_ENABLE_DUMP_GPU
      virtual void onDumpJSON(SkJSONWriter*) const {}
  #endif
  
      void resetContext() {
          this->onResetContext(fResetBits);
          fResetBits = 0;
      }
  
      uint32_t fResetBits;
      // The context owns us, not vice-versa, so this ptr is not ref'ed by Gpu.
      GrContext* fContext;
      GrSamplePatternDictionary fSamplePatternDictionary;
  
      friend class GrPathRendering;
      typedef SkRefCnt INHERITED;
  };
  
  #endif
  