text: /*
   * Copyright 2017 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #include "SkPM4fPriv.h"
  #include "SkRasterPipeline.h"
  #include "SkReadBuffer.h"
  #include "SkString.h"
  #include "SkToSRGBColorFilter.h"
  #include "SkWriteBuffer.h"
  
  #if SK_SUPPORT_GPU
      #include "effects/GrNonlinearColorSpaceXformEffect.h"
  #endif
  
  void SkToSRGBColorFilter::onAppendStages(SkRasterPipeline* p,
                                           SkColorSpace* /*dst color space*/,
                                           SkArenaAlloc* alloc,
                                           bool shaderIsOpaque) const {
      // Step 1: Linearize by undoing the src transfer function.
      // Linear and sRGB will return true to isNumericalTransferFn(), so we check them first.
      SkColorSpaceTransferFn srcFn;
      if (fSrcColorSpace->gammaIsLinear()) {
          // Nothing to do.
      } else if (fSrcColorSpace->gammaCloseToSRGB()) {
          p->append(SkRasterPipeline::from_srgb);
      } else if (fSrcColorSpace->isNumericalTransferFn(&srcFn)) {
          auto copy = alloc->make<SkColorSpaceTransferFn>(srcFn);
          p->append(SkRasterPipeline::parametric_r, copy);
          p->append(SkRasterPipeline::parametric_g, copy);
          p->append(SkRasterPipeline::parametric_b, copy);
      } else {
          SkDEBUGFAIL("Looks like we got a table transfer function here, quite unexpectedly.");
          // TODO: If we really need to handle this, we can, but I don't think Ganesh does.
      }
  
      // Step 2: Transform to sRGB gamut, without clamping.
      // TODO: because...
      float* gamut_transform = alloc->makeArrayDefault<float>(12);
      (void)append_gamut_transform_noclamp(p,
                                           gamut_transform,
                                           fSrcColorSpace.get(),
                                           SkColorSpace::MakeSRGB().get());
  
      // Step 3: Back to sRGB encoding.
      p->append(SkRasterPipeline::to_srgb);
  }
  
  sk_sp<SkColorFilter> SkToSRGBColorFilter::Make(sk_sp<SkColorSpace> srcColorSpace) {
      if (!srcColorSpace || srcColorSpace->isSRGB()) {
          return nullptr;
      } else {
          return sk_sp<SkColorFilter>(new SkToSRGBColorFilter(std::move(srcColorSpace)));
      }
  }
  
  SkToSRGBColorFilter::SkToSRGBColorFilter(sk_sp<SkColorSpace> srcColorSpace)
          : fSrcColorSpace(std::move(srcColorSpace)) {
      SkASSERT(fSrcColorSpace);
  }
  
  sk_sp<SkFlattenable> SkToSRGBColorFilter::CreateProc(SkReadBuffer& buffer) {
      auto data = buffer.readByteArrayAsData();
      return data ? Make(SkColorSpace::Deserialize(data->data(), data->size())) : nullptr;
  }
  
  void SkToSRGBColorFilter::flatten(SkWriteBuffer& buffer) const {
      buffer.writeDataAsByteArray(fSrcColorSpace->serialize().get());
  }
  
  void SkToSRGBColorFilter::toString(SkString* str) const {
      // TODO
      str->append("SkToSRGBColorFilter ");
  }
  
  #if SK_SUPPORT_GPU
  std::unique_ptr<GrFragmentProcessor> SkToSRGBColorFilter::asFragmentProcessor(
          GrContext*, const GrColorSpaceInfo&) const {
      return GrNonlinearColorSpaceXformEffect::Make(fSrcColorSpace.get(),
                                                    SkColorSpace::MakeSRGB().get());
  }
  #endif
  