root/cc/output/render_surface_filters.cc

DEFINITIONS

1. GetBrightnessMatrix
2. GetSaturatingBrightnessMatrix
3. GetContrastMatrix
4. GetSaturateMatrix
5. GetHueRotateMatrix
6. GetInvertMatrix
7. GetOpacityMatrix
8. GetGrayscaleMatrix
9. GetSepiaMatrix
10. CreateMatrixImageFilter
11. BuildImageFilter

// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/output/render_surface_filters.h"

#include <algorithm>

#include "base/logging.h"
#include "cc/output/filter_operation.h"
#include "cc/output/filter_operations.h"
#include "skia/ext/refptr.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkFlattenableBuffers.h"
#include "third_party/skia/include/core/SkImageFilter.h"
#include "third_party/skia/include/effects/SkBlurImageFilter.h"
#include "third_party/skia/include/effects/SkColorFilterImageFilter.h"
#include "third_party/skia/include/effects/SkColorMatrixFilter.h"
#include "third_party/skia/include/effects/SkComposeImageFilter.h"
#include "third_party/skia/include/effects/SkDropShadowImageFilter.h"
#include "third_party/skia/include/effects/SkMagnifierImageFilter.h"
#include "third_party/skia/include/gpu/SkGpuDevice.h"
#include "third_party/skia/include/gpu/SkGrPixelRef.h"
#include "ui/gfx/size_f.h"

namespace cc {

namespace {

void GetBrightnessMatrix(float amount, SkScalar matrix[20]) {
  // Spec implementation
  // (http://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.html#brightnessEquivalent)
  // <feFunc[R|G|B] type="linear" slope="[amount]">
  memset(matrix, 0, 20 * sizeof(SkScalar));
  matrix[0] = matrix[6] = matrix[12] = amount;
  matrix[18] = 1.f;
}

void GetSaturatingBrightnessMatrix(float amount, SkScalar matrix[20]) {
  // Legacy implementation used by internal clients.
  // <feFunc[R|G|B] type="linear" intercept="[amount]"/>
  memset(matrix, 0, 20 * sizeof(SkScalar));
  matrix[0] = matrix[6] = matrix[12] = matrix[18] = 1.f;
  matrix[4] = matrix[9] = matrix[14] = amount * 255.f;
}

void GetContrastMatrix(float amount, SkScalar matrix[20]) {
  memset(matrix, 0, 20 * sizeof(SkScalar));
  matrix[0] = matrix[6] = matrix[12] = amount;
  matrix[4] = matrix[9] = matrix[14] = (-0.5f * amount + 0.5f) * 255.f;
  matrix[18] = 1.f;
}

void GetSaturateMatrix(float amount, SkScalar matrix[20]) {
  // Note, these values are computed to ensure MatrixNeedsClamping is false
  // for amount in [0..1]
  matrix[0] = 0.213f + 0.787f * amount;
  matrix[1] = 0.715f - 0.715f * amount;
  matrix[2] = 1.f - (matrix[0] + matrix[1]);
  matrix[3] = matrix[4] = 0.f;
  matrix[5] = 0.213f - 0.213f * amount;
  matrix[6] = 0.715f + 0.285f * amount;
  matrix[7] = 1.f - (matrix[5] + matrix[6]);
  matrix[8] = matrix[9] = 0.f;
  matrix[10] = 0.213f - 0.213f * amount;
  matrix[11] = 0.715f - 0.715f * amount;
  matrix[12] = 1.f - (matrix[10] + matrix[11]);
  matrix[13] = matrix[14] = 0.f;
  matrix[15] = matrix[16] = matrix[17] = matrix[19] = 0.f;
  matrix[18] = 1.f;
}

void GetHueRotateMatrix(float hue, SkScalar matrix[20]) {
  const float kPi = 3.1415926535897932384626433832795f;

  float cos_hue = cosf(hue * kPi / 180.f);
  float sin_hue = sinf(hue * kPi / 180.f);
  matrix[0] = 0.213f + cos_hue * 0.787f - sin_hue * 0.213f;
  matrix[1] = 0.715f - cos_hue * 0.715f - sin_hue * 0.715f;
  matrix[2] = 0.072f - cos_hue * 0.072f + sin_hue * 0.928f;
  matrix[3] = matrix[4] = 0.f;
  matrix[5] = 0.213f - cos_hue * 0.213f + sin_hue * 0.143f;
  matrix[6] = 0.715f + cos_hue * 0.285f + sin_hue * 0.140f;
  matrix[7] = 0.072f - cos_hue * 0.072f - sin_hue * 0.283f;
  matrix[8] = matrix[9] = 0.f;
  matrix[10] = 0.213f - cos_hue * 0.213f - sin_hue * 0.787f;
  matrix[11] = 0.715f - cos_hue * 0.715f + sin_hue * 0.715f;
  matrix[12] = 0.072f + cos_hue * 0.928f + sin_hue * 0.072f;
  matrix[13] = matrix[14] = 0.f;
  matrix[15] = matrix[16] = matrix[17] = 0.f;
  matrix[18] = 1.f;
  matrix[19] = 0.f;
}

void GetInvertMatrix(float amount, SkScalar matrix[20]) {
  memset(matrix, 0, 20 * sizeof(SkScalar));
  matrix[0] = matrix[6] = matrix[12] = 1.f - 2.f * amount;
  matrix[4] = matrix[9] = matrix[14] = amount * 255.f;
  matrix[18] = 1.f;
}

void GetOpacityMatrix(float amount, SkScalar matrix[20]) {
  memset(matrix, 0, 20 * sizeof(SkScalar));
  matrix[0] = matrix[6] = matrix[12] = 1.f;
  matrix[18] = amount;
}

void GetGrayscaleMatrix(float amount, SkScalar matrix[20]) {
  // Note, these values are computed to ensure MatrixNeedsClamping is false
  // for amount in [0..1]
  matrix[0] = 0.2126f + 0.7874f * amount;
  matrix[1] = 0.7152f - 0.7152f * amount;
  matrix[2] = 1.f - (matrix[0] + matrix[1]);
  matrix[3] = matrix[4] = 0.f;

  matrix[5] = 0.2126f - 0.2126f * amount;
  matrix[6] = 0.7152f + 0.2848f * amount;
  matrix[7] = 1.f - (matrix[5] + matrix[6]);
  matrix[8] = matrix[9] = 0.f;

  matrix[10] = 0.2126f - 0.2126f * amount;
  matrix[11] = 0.7152f - 0.7152f * amount;
  matrix[12] = 1.f - (matrix[10] + matrix[11]);
  matrix[13] = matrix[14] = 0.f;

  matrix[15] = matrix[16] = matrix[17] = matrix[19] = 0.f;
  matrix[18] = 1.f;
}

void GetSepiaMatrix(float amount, SkScalar matrix[20]) {
  matrix[0] = 0.393f + 0.607f * amount;
  matrix[1] = 0.769f - 0.769f * amount;
  matrix[2] = 0.189f - 0.189f * amount;
  matrix[3] = matrix[4] = 0.f;

  matrix[5] = 0.349f - 0.349f * amount;
  matrix[6] = 0.686f + 0.314f * amount;
  matrix[7] = 0.168f - 0.168f * amount;
  matrix[8] = matrix[9] = 0.f;

  matrix[10] = 0.272f - 0.272f * amount;
  matrix[11] = 0.534f - 0.534f * amount;
  matrix[12] = 0.131f + 0.869f * amount;
  matrix[13] = matrix[14] = 0.f;

  matrix[15] = matrix[16] = matrix[17] = matrix[19] = 0.f;
  matrix[18] = 1.f;
}

skia::RefPtr<SkImageFilter> CreateMatrixImageFilter(
    const SkScalar matrix[20],
    const skia::RefPtr<SkImageFilter>& input) {
  skia::RefPtr<SkColorFilter> color_filter =
      skia::AdoptRef(new SkColorMatrixFilter(matrix));
  return skia::AdoptRef(
      SkColorFilterImageFilter::Create(color_filter.get(), input.get()));
}

}  // namespace

skia::RefPtr<SkImageFilter> RenderSurfaceFilters::BuildImageFilter(
    const FilterOperations& filters,
    const gfx::SizeF& size) {
  skia::RefPtr<SkImageFilter> image_filter;
  SkScalar matrix[20];
  for (size_t i = 0; i < filters.size(); ++i) {
    const FilterOperation& op = filters.at(i);
    switch (op.type()) {
      case FilterOperation::GRAYSCALE:
        GetGrayscaleMatrix(1.f - op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::SEPIA:
        GetSepiaMatrix(1.f - op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::SATURATE:
        GetSaturateMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::HUE_ROTATE:
        GetHueRotateMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::INVERT:
        GetInvertMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::OPACITY:
        GetOpacityMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::BRIGHTNESS:
        GetBrightnessMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::CONTRAST:
        GetContrastMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::BLUR:
        image_filter = skia::AdoptRef(new SkBlurImageFilter(
            op.amount(), op.amount(), image_filter.get()));
        break;
      case FilterOperation::DROP_SHADOW:
        image_filter = skia::AdoptRef(new SkDropShadowImageFilter(
            SkIntToScalar(op.drop_shadow_offset().x()),
            SkIntToScalar(op.drop_shadow_offset().y()),
            SkIntToScalar(op.amount()),
            op.drop_shadow_color(),
            image_filter.get()));
        break;
      case FilterOperation::COLOR_MATRIX:
        image_filter = CreateMatrixImageFilter(op.matrix(), image_filter);
        break;
      case FilterOperation::ZOOM: {
        skia::RefPtr<SkImageFilter> zoom_filter = skia::AdoptRef(
            new SkMagnifierImageFilter(
                SkRect::MakeXYWH(
                    (size.width() - (size.width() / op.amount())) / 2.f,
                    (size.height() - (size.height() / op.amount())) / 2.f,
                    size.width() / op.amount(),
                    size.height() / op.amount()),
                op.zoom_inset()));
        if (image_filter.get()) {
          // TODO(ajuma): When there's a 1-input version of
          // SkMagnifierImageFilter, use that to handle the input filter
          // instead of using an SkComposeImageFilter.
          image_filter = skia::AdoptRef(new SkComposeImageFilter(
              zoom_filter.get(), image_filter.get()));
        } else {
          image_filter = zoom_filter;
        }
        break;
      }
      case FilterOperation::SATURATING_BRIGHTNESS:
        GetSaturatingBrightnessMatrix(op.amount(), matrix);
        image_filter = CreateMatrixImageFilter(matrix, image_filter);
        break;
      case FilterOperation::REFERENCE: {
        if (!op.image_filter())
          break;

        skia::RefPtr<SkColorFilter> cf;

        {
          SkColorFilter* colorfilter_rawptr = NULL;
          op.image_filter()->asColorFilter(&colorfilter_rawptr);
          cf = skia::AdoptRef(colorfilter_rawptr);
        }

        if (cf && cf->asColorMatrix(matrix) &&
            !op.image_filter()->getInput(0)) {
          image_filter = CreateMatrixImageFilter(matrix, image_filter);
        } else if (image_filter) {
          image_filter = skia::AdoptRef(new SkComposeImageFilter(
              op.image_filter().get(), image_filter.get()));
        } else {
          image_filter = op.image_filter();
        }
        break;
      }
    }
  }
  return image_filter;
}

}  // namespace cc