Source/platform/graphics/DrawLooper.cpp

/*
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#include "config.h"
#include "platform/graphics/DrawLooper.h"

#include "platform/geometry/FloatSize.h"
#include "platform/graphics/Color.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/core/SkXfermode.h"
#include "third_party/skia/include/effects/SkBlurMaskFilter.h"
#include "third_party/skia/include/effects/SkLayerDrawLooper.h"

namespace WebCore {

DrawLooper::DrawLooper() : m_skDrawLooper(adoptRef(new SkLayerDrawLooper)) { }

DrawLooper::~DrawLooper() { }

SkDrawLooper* DrawLooper::skDrawLooper() const
{
    return m_skDrawLooper.get();
}

void DrawLooper::addUnmodifiedContent()
{
    SkLayerDrawLooper::LayerInfo info;
    m_skDrawLooper->addLayerOnTop(info);
}

void DrawLooper::addShadow(const FloatSize& offset, float blur, const Color& color,
    ShadowTransformMode shadowTransformMode, ShadowAlphaMode shadowAlphaMode)
{
    // Detect when there's no effective shadow.
    if (!color.isValid() || !color.alpha())
        return;

    SkColor skColor;
    if (color.isValid())
        skColor = color.rgb();
    else
        skColor = SkColorSetARGB(0xFF / 3, 0, 0, 0); // "std" apple shadow color.

    SkLayerDrawLooper::LayerInfo info;

    switch (shadowAlphaMode) {
    case ShadowRespectsAlpha:
        info.fColorMode = SkXfermode::kDst_Mode;
        break;
    case ShadowIgnoresAlpha:
        info.fColorMode = SkXfermode::kSrc_Mode;
        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_skDrawLooper->addLayerOnTop(info);

    if (blur) {
        uint32_t mfFlags = SkBlurMaskFilter::kHighQuality_BlurFlag;
        if (shadowTransformMode == ShadowIgnoresTransforms)
            mfFlags |= SkBlurMaskFilter::kIgnoreTransform_BlurFlag;
        RefPtr<SkMaskFilter> mf = adoptRef(SkBlurMaskFilter::Create(
            (double)blur / 2.0, SkBlurMaskFilter::kNormal_BlurStyle, mfFlags));
        paint->setMaskFilter(mf.get());
    }

    RefPtr<SkColorFilter> cf = adoptRef(SkColorFilter::CreateModeFilter(skColor, SkXfermode::kSrcIn_Mode));
    paint->setColorFilter(cf.get());
}

} // namespace WebCore