src/cobalt/renderer/rasterizer/skia/skia/src/effects/SkNV122RGBShader.cc

// Copyright 2016 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/renderer/rasterizer/skia/skia/src/effects/SkNV122RGBShader.h"

#include <algorithm>

#include "base/logging.h"
#include "cobalt/base/polymorphic_downcast.h"
#include "third_party/skia/include/core/SkColorPriv.h"
#include "third_party/skia/include/core/SkShader.h"
#include "third_party/skia/include/core/SkString.h"
#include "third_party/skia/src/core/SkReadBuffer.h"
#include "third_party/skia/src/core/SkWriteBuffer.h"

#if SK_SUPPORT_GPU
#include "third_party/skia/src/gpu/GrFragmentProcessor.h"
#endif

SkNV122RGBShader::SkNV122RGBShader(SkYUVColorSpace color_space,
                                   const sk_sp<SkImage>& y_image,
                                   const SkMatrix& y_matrix,
                                   const sk_sp<SkImage>& uv_image,
                                   const SkMatrix& uv_matrix)
    : color_space_(color_space),
      y_image_(y_image),
      y_matrix_(y_matrix),
      uv_image_(uv_image),
      uv_matrix_(uv_matrix) {
  DCHECK(y_image_);
  DCHECK(uv_image_);
  InitializeShaders();
}

void SkNV122RGBShader::InitializeShaders() {
  y_shader_.reset(base::polymorphic_downcast<SkImageShader*>(
      SkImageShader::Make(y_image_, SkTileMode::kClamp, SkTileMode::kClamp,
                          &y_matrix_, false)
          .get()));
  DCHECK(y_shader_);

  uv_shader_.reset(base::polymorphic_downcast<SkImageShader*>(
      SkImageShader::Make(uv_image_, SkTileMode::kClamp, SkTileMode::kClamp,
                          &uv_matrix_, false)
          .get()));
  DCHECK(uv_shader_);
}

SkNV122RGBShader::~SkNV122RGBShader() {
}

void SkNV122RGBShader::flatten(SkWriteBuffer& buffer) const {
  buffer.writeInt(color_space_);
  buffer.writeImage(y_image_.get());
  buffer.writeMatrix(y_matrix_);
  buffer.writeImage(uv_image_.get());
  buffer.writeMatrix(uv_matrix_);
}

uint32_t SkNV122RGBShader::NV122RGBShaderContext::getFlags() const { return 0; }

SkNV122RGBShader::NV122RGBShaderContext::NV122RGBShaderContext(
    SkYUVColorSpace color_space, const SkNV122RGBShader& yuv2rgb_shader,
    SkShaderBase::Context* y_shader_context,
    SkShaderBase::Context* uv_shader_context, const ContextRec& rec)
    : INHERITED(yuv2rgb_shader, rec),
      color_space_(color_space),
      y_shader_context_(y_shader_context),
      uv_shader_context_(uv_shader_context) {}

SkNV122RGBShader::NV122RGBShaderContext::~NV122RGBShaderContext() {
  y_shader_context_->~Context();
  uv_shader_context_->~Context();
}

void SkNV122RGBShader::NV122RGBShaderContext::shadeSpan(int x, int y,
                                                        SkPMColor result[],
                                                        int count) {
  static const int kPixelCountPerSpan = 64;
  SkPMColor y_values[kPixelCountPerSpan];
  SkPMColor uv_values[kPixelCountPerSpan];

  DCHECK_EQ(kRec709_SkYUVColorSpace, color_space_)
      << "Currently we only support the BT.709 YUV colorspace.";

  do {
    int count_in_chunk =
        count > kPixelCountPerSpan ? kPixelCountPerSpan : count;

    y_shader_context_->shadeSpan(x, y, y_values, count_in_chunk);
    uv_shader_context_->shadeSpan(x, y, uv_values, count_in_chunk);

    for (int i = 0; i < count_in_chunk; ++i) {
      int32_t y_value = SkColorGetA(y_values[i]) - 16;
      int32_t u_value = SkColorGetB(uv_values[i]) - 128;
      int32_t v_value = SkColorGetA(uv_values[i]) - 128;

      const float kA = 1.164f;
      const float kB = -0.213f;
      const float kC = 2.112f;
      const float kD = 1.793f;
      const float kE = -0.533f;
      int32_t r_unclamped = static_cast<int32_t>(kA * y_value + kD * v_value);
      int32_t g_unclamped =
          static_cast<int32_t>(kA * y_value + kB * u_value + kE * v_value);
      int32_t b_unclamped = static_cast<int32_t>(kA * y_value + kC * u_value);

      int32_t r_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, r_unclamped));
      int32_t g_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, g_unclamped));
      int32_t b_clamped =
          std::min<int32_t>(255, std::max<int32_t>(0, b_unclamped));

      result[i] = SkPackARGB32NoCheck(255, r_clamped, g_clamped, b_clamped);
    }
    result += count_in_chunk;
    x += count_in_chunk;
    count -= count_in_chunk;
  } while (count > 0);
}

#if SK_SUPPORT_GPU

std::unique_ptr<GrFragmentProcessor> SkNV122RGBShader::asFragmentProcessor(
    const GrFPArgs&) const {
#if 0
  // TODO SKIA_M61_EFFECTS.  Investigate if we still need this.
  // Code snippet taken from SkBitmapProcShader::asFragmentProcessor().
  SkMatrix matrix;
  matrix.setIDiv(y_image_->width(), y_image_->height());

  SkMatrix lmInverse;
  if (!y_shader_->getLocalMatrix().invert(&lmInverse)) {
    return false;
  }
  if (localMatrix) {
    SkMatrix inv;
    if (!localMatrix->invert(&inv)) {
      return false;
    }
    lmInverse.postConcat(inv);
  }
  matrix.preConcat(lmInverse);

  GrTextureParams::FilterMode filter_mode =
      paint.getFilterLevel() == SkPaint::kNone_FilterLevel
          ? GrTextureParams::kNone_FilterMode
          : GrTextureParams::kBilerp_FilterMode;
  GrTextureParams texture_params;
  texture_params.setFilterMode(filter_mode);

  *fp = GrYUVtoRGBEffect::Create(y_image_->getTexture(),
                                 uv_image_->getTexture(),
                                 NULL, matrix, texture_params,
                                 kRec709_SkYUVColorSpace, true);
  return true;
#else
  return nullptr;
#endif
}

#endif  // SK_SUPPORT_GPU