third_party/WebKit/Source/platform/graphics/DrawLooperBuilder.cpp

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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#include "platform/graphics/DrawLooperBuilder.h"

#include "platform/geometry/FloatSize.h"
#include "platform/graphics/Color.h"
#include "platform/graphics/skia/SkiaUtils.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkColorFilter.h"
#include "third_party/skia/include/core/SkDrawLooper.h"
#include "third_party/skia/include/core/SkPaint.h"
#include "third_party/skia/include/effects/SkBlurMaskFilter.h"
#include "wtf/PtrUtil.h"
#include "wtf/RefPtr.h"
#include <memory>

namespace blink {

DrawLooperBuilder::DrawLooperBuilder() {}

DrawLooperBuilder::~DrawLooperBuilder() {}

sk_sp<SkDrawLooper> DrawLooperBuilder::detachDrawLooper() {
  return m_skDrawLooperBuilder.detach();
}

void DrawLooperBuilder::addUnmodifiedContent() {
  SkLayerDrawLooper::LayerInfo info;
  m_skDrawLooperBuilder.addLayerOnTop(info);
}

void DrawLooperBuilder::addShadow(const FloatSize& offset,
                                  float blur,
                                  const Color& color,
                                  ShadowTransformMode shadowTransformMode,
                                  ShadowAlphaMode shadowAlphaMode) {
  ASSERT(blur >= 0);

  // Detect when there's no effective shadow.
  if (!color.alpha())
    return;

  SkColor skColor = color.rgb();

  SkLayerDrawLooper::LayerInfo info;

  switch (shadowAlphaMode) {
    case ShadowRespectsAlpha:
      info.fColorMode = SkBlendMode::kDst;
      break;
    case ShadowIgnoresAlpha:
      info.fColorMode = SkBlendMode::kSrc;
      break;
    default:
      ASSERT_NOT_REACHED();
  }

  if (blur)
    info.fPaintBits |= SkLayerDrawLooper::kMaskFilter_Bit;  // our blur
  info.fPaintBits |= SkLayerDrawLooper::kColorFilter_Bit;
  info.fOffset.set(offset.width(), offset.height());
  info.fPostTranslate = (shadowTransformMode == ShadowIgnoresTransforms);

  SkPaint* paint = m_skDrawLooperBuilder.addLayerOnTop(info);

  if (blur) {
    const SkScalar sigma = skBlurRadiusToSigma(blur);
    uint32_t mfFlags = SkBlurMaskFilter::kHighQuality_BlurFlag;
    if (shadowTransformMode == ShadowIgnoresTransforms)
      mfFlags |= SkBlurMaskFilter::kIgnoreTransform_BlurFlag;
    paint->setMaskFilter(
        SkBlurMaskFilter::Make(kNormal_SkBlurStyle, sigma, mfFlags));
  }

  paint->setColorFilter(
      SkColorFilter::MakeModeFilter(skColor, SkBlendMode::kSrcIn));
}

}  // namespace blink