text: /*
   * Copyright 2006 The Android Open Source Project
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #include "SkArenaAlloc.h"
  #include "SkAtomics.h"
  #include "SkBitmapProcShader.h"
  #include "SkColorShader.h"
  #include "SkColorSpaceXformer.h"
  #include "SkEmptyShader.h"
  #include "SkMallocPixelRef.h"
  #include "SkPaint.h"
  #include "SkPicture.h"
  #include "SkPictureShader.h"
  #include "SkPM4fPriv.h"
  #include "SkRasterPipeline.h"
  #include "SkReadBuffer.h"
  #include "SkScalar.h"
  #include "SkShaderBase.h"
  #include "SkTLazy.h"
  #include "SkWriteBuffer.h"
  #include "../jumper/SkJumper.h"
  
  #if SK_SUPPORT_GPU
  #include "GrFragmentProcessor.h"
  #endif
  
  //#define SK_TRACK_SHADER_LIFETIME
  
  #ifdef SK_TRACK_SHADER_LIFETIME
      static int32_t gShaderCounter;
  #endif
  
  static inline void inc_shader_counter() {
  #ifdef SK_TRACK_SHADER_LIFETIME
      int32_t prev = sk_atomic_inc(&gShaderCounter);
      SkDebugf("+++ shader counter %d\n", prev + 1);
  #endif
  }
  static inline void dec_shader_counter() {
  #ifdef SK_TRACK_SHADER_LIFETIME
      int32_t prev = sk_atomic_dec(&gShaderCounter);
      SkDebugf("--- shader counter %d\n", prev - 1);
  #endif
  }
  
  SkShaderBase::SkShaderBase(const SkMatrix* localMatrix)
      : fLocalMatrix(localMatrix ? *localMatrix : SkMatrix::I()) {
      inc_shader_counter();
      // Pre-cache so future calls to fLocalMatrix.getType() are threadsafe.
      (void)fLocalMatrix.getType();
  }
  
  SkShaderBase::~SkShaderBase() {
      dec_shader_counter();
  }
  
  void SkShaderBase::flatten(SkWriteBuffer& buffer) const {
      this->INHERITED::flatten(buffer);
      bool hasLocalM = !fLocalMatrix.isIdentity();
      buffer.writeBool(hasLocalM);
      if (hasLocalM) {
          buffer.writeMatrix(fLocalMatrix);
      }
  }
  
  bool SkShaderBase::computeTotalInverse(const SkMatrix& ctm,
                                         const SkMatrix* outerLocalMatrix,
                                         SkMatrix* totalInverse) const {
      SkMatrix total = SkMatrix::Concat(ctm, fLocalMatrix);
      if (outerLocalMatrix) {
          total.preConcat(*outerLocalMatrix);
      }
  
      return total.invert(totalInverse);
  }
  
  bool SkShaderBase::asLuminanceColor(SkColor* colorPtr) const {
      SkColor storage;
      if (nullptr == colorPtr) {
          colorPtr = &storage;
      }
      if (this->onAsLuminanceColor(colorPtr)) {
          *colorPtr = SkColorSetA(*colorPtr, 0xFF);   // we only return opaque
          return true;
      }
      return false;
  }
  
  SkShaderBase::Context* SkShaderBase::makeContext(const ContextRec& rec, SkArenaAlloc* alloc) const {
      return this->computeTotalInverse(*rec.fMatrix, rec.fLocalMatrix, nullptr)
          ? this->onMakeContext(rec, alloc)
          : nullptr;
  }
  
  SkShaderBase::Context* SkShaderBase::makeBurstPipelineContext(const ContextRec& rec,
                                                                SkArenaAlloc* alloc) const {
  
      SkASSERT(rec.fPreferredDstType == ContextRec::kPM4f_DstType);
  
      // Always use vanilla stages for perspective.
      if (rec.fMatrix->hasPerspective() || fLocalMatrix.hasPerspective()) {
          return nullptr;
      }
  
      return this->computeTotalInverse(*rec.fMatrix, rec.fLocalMatrix, nullptr)
          ? this->onMakeBurstPipelineContext(rec, alloc)
          : nullptr;
  }
  
  SkShaderBase::Context::Context(const SkShaderBase& shader, const ContextRec& rec)
      : fShader(shader), fCTM(*rec.fMatrix)
  {
      // We should never use a context for RP-only shaders.
      SkASSERT(!shader.isRasterPipelineOnly(*rec.fMatrix));
      // ... or for perspective.
      SkASSERT(!rec.fMatrix->hasPerspective());
      SkASSERT(!rec.fLocalMatrix || !rec.fLocalMatrix->hasPerspective());
  
      // Because the context parameters must be valid at this point, we know that the matrix is
      // invertible.
      SkAssertResult(fShader.computeTotalInverse(*rec.fMatrix, rec.fLocalMatrix, &fTotalInverse));
  
      fPaintAlpha = rec.fPaint->getAlpha();
  }
  
  SkShaderBase::Context::~Context() {}
  
  void SkShaderBase::Context::shadeSpan4f(int x, int y, SkPM4f dst[], int count) {
      const int N = 128;
      SkPMColor tmp[N];
      while (count > 0) {
          int n = SkTMin(count, N);
          this->shadeSpan(x, y, tmp, n);
          for (int i = 0; i < n; ++i) {
              dst[i] = SkPM4f::FromPMColor(tmp[i]);
          }
          dst += n;
          x += n;
          count -= n;
      }
  }
  
  const SkMatrix& SkShader::getLocalMatrix() const {
      return as_SB(this)->getLocalMatrix();
  }
  
  #ifdef SK_SUPPORT_LEGACY_SHADER_ISABITMAP
  bool SkShader::isABitmap(SkBitmap* outTexture, SkMatrix* outMatrix, TileMode xy[2]) const {
      return  as_SB(this)->onIsABitmap(outTexture, outMatrix, xy);
  }
  #endif
  
  SkImage* SkShader::isAImage(SkMatrix* localMatrix, TileMode xy[2]) const {
      return as_SB(this)->onIsAImage(localMatrix, xy);
  }
  
  SkShader::GradientType SkShader::asAGradient(GradientInfo* info) const {
      return kNone_GradientType;
  }
  
  #if SK_SUPPORT_GPU
  std::unique_ptr<GrFragmentProcessor> SkShaderBase::asFragmentProcessor(const GrFPArgs&) const {
      return nullptr;
  }
  #endif
  
  sk_sp<SkShader> SkShader::makeAsALocalMatrixShader(SkMatrix*) const {
      return nullptr;
  }
  
  sk_sp<SkShader> SkShader::MakeEmptyShader() { return sk_make_sp<SkEmptyShader>(); }
  
  sk_sp<SkShader> SkShader::MakeColorShader(SkColor color) { return sk_make_sp<SkColorShader>(color); }
  
  sk_sp<SkShader> SkShader::MakeBitmapShader(const SkBitmap& src, TileMode tmx, TileMode tmy,
                                             const SkMatrix* localMatrix) {
      if (localMatrix && !localMatrix->invert(nullptr)) {
          return nullptr;
      }
      return SkMakeBitmapShader(src, tmx, tmy, localMatrix, kIfMutable_SkCopyPixelsMode);
  }
  
  sk_sp<SkShader> SkShader::MakePictureShader(sk_sp<SkPicture> src, TileMode tmx, TileMode tmy,
                                              const SkMatrix* localMatrix, const SkRect* tile) {
      if (localMatrix && !localMatrix->invert(nullptr)) {
          return nullptr;
      }
      return SkPictureShader::Make(std::move(src), tmx, tmy, localMatrix, tile);
  }
  
  #ifndef SK_IGNORE_TO_STRING
  void SkShaderBase::toString(SkString* str) const {
      if (!fLocalMatrix.isIdentity()) {
          str->append(" ");
          fLocalMatrix.toString(str);
      }
  }
  #endif
  
  bool SkShaderBase::appendStages(const StageRec& rec) const {
      return this->onAppendStages(rec);
  }
  
  bool SkShaderBase::onAppendStages(const StageRec& rec) const {
      // SkShader::Context::shadeSpan4f() handles the paint opacity internally,
      // but SkRasterPipelineBlitter applies it as a separate stage.
      // We skip the internal shadeSpan4f() step by forcing the paint opaque.
      SkTCopyOnFirstWrite<SkPaint> opaquePaint(rec.fPaint);
      if (rec.fPaint.getAlpha() != SK_AlphaOPAQUE) {
          opaquePaint.writable()->setAlpha(SK_AlphaOPAQUE);
      }
  
      ContextRec cr(*opaquePaint, rec.fCTM, rec.fLocalM, ContextRec::kPM4f_DstType, rec.fDstCS);
  
      struct CallbackCtx : SkJumper_CallbackCtx {
          sk_sp<SkShader> shader;
          Context*        ctx;
      };
      auto cb = rec.fAlloc->make<CallbackCtx>();
      cb->shader = rec.fDstCS ? SkColorSpaceXformer::Make(sk_ref_sp(rec.fDstCS))->apply(this)
                              : sk_ref_sp((SkShader*)this);
      cb->ctx = as_SB(cb->shader)->makeContext(cr, rec.fAlloc);
      cb->fn  = [](SkJumper_CallbackCtx* self, int active_pixels) {
          auto c = (CallbackCtx*)self;
          int x = (int)c->rgba[0],
          y = (int)c->rgba[1];
          c->ctx->shadeSpan4f(x,y, (SkPM4f*)c->rgba, active_pixels);
      };
  
      if (cb->ctx) {
          rec.fPipeline->append(SkRasterPipeline::seed_shader);
          rec.fPipeline->append(SkRasterPipeline::callback, cb);
          return true;
      }
      return false;
  }
  
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  
  sk_sp<SkFlattenable> SkEmptyShader::CreateProc(SkReadBuffer&) {
      return SkShader::MakeEmptyShader();
  }
  
  #ifndef SK_IGNORE_TO_STRING
  #include "SkEmptyShader.h"
  
  void SkEmptyShader::toString(SkString* str) const {
      str->append("SkEmptyShader: (");
  
      this->INHERITED::toString(str);
  
      str->append(")");
  }
  #endif
  