sky/engine/core/rendering/style/ShadowList.cpp

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * 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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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#include "sky/engine/core/rendering/style/ShadowList.h"

#include "sky/engine/platform/geometry/FloatRect.h"
#include "sky/engine/wtf/OwnPtr.h"

namespace blink {

static inline void calculateShadowExtent(const ShadowList* shadowList, float& shadowLeft, float& shadowRight, float& shadowTop, float& shadowBottom)
{
    ASSERT(shadowList);
    size_t shadowCount = shadowList->shadows().size();
    for (size_t i = 0; i < shadowCount; ++i) {
        const ShadowData& shadow = shadowList->shadows()[i];
        if (shadow.style() == Inset)
            continue;
        float blurAndSpread = shadow.blur() + shadow.spread();
        shadowLeft = std::min(shadow.x() - blurAndSpread, shadowLeft);
        shadowRight = std::max(shadow.x() + blurAndSpread, shadowRight);
        shadowTop = std::min(shadow.y() - blurAndSpread, shadowTop);
        shadowBottom = std::max(shadow.y() + blurAndSpread, shadowBottom);
    }
}

void ShadowList::adjustRectForShadow(LayoutRect& rect) const
{
    FloatRect floatRect(rect);
    adjustRectForShadow(floatRect);
    rect = LayoutRect(floatRect);
}

void ShadowList::adjustRectForShadow(FloatRect& rect) const
{
    float shadowLeft = 0;
    float shadowRight = 0;
    float shadowTop = 0;
    float shadowBottom = 0;
    calculateShadowExtent(this, shadowLeft, shadowRight, shadowTop, shadowBottom);

    rect.move(shadowLeft, shadowTop);
    rect.setWidth(rect.width() - shadowLeft + shadowRight);
    rect.setHeight(rect.height() - shadowTop + shadowBottom);
}

PassRefPtr<ShadowList> ShadowList::blend(const ShadowList* from, const ShadowList* to, double progress)
{
    size_t fromLength = from ? from->shadows().size() : 0;
    size_t toLength = to ? to->shadows().size() : 0;
    if (!fromLength && !toLength)
        return nullptr;

    ShadowDataVector shadows;

    DEFINE_STATIC_LOCAL(ShadowData, defaultShadowData, (FloatPoint(), 0, 0, Normal, Color::transparent));
    DEFINE_STATIC_LOCAL(ShadowData, defaultInsetShadowData, (FloatPoint(), 0, 0, Inset, Color::transparent));

    size_t maxLength = std::max(fromLength, toLength);
    for (size_t i = 0; i < maxLength; ++i) {
        const ShadowData* fromShadow = i < fromLength ? &from->shadows()[i] : 0;
        const ShadowData* toShadow = i < toLength ? &to->shadows()[i] : 0;
        if (!fromShadow)
            fromShadow = toShadow->style() == Inset ? &defaultInsetShadowData : &defaultShadowData;
        else if (!toShadow)
            toShadow = fromShadow->style() == Inset ? &defaultInsetShadowData : &defaultShadowData;
        shadows.append(toShadow->blend(*fromShadow, progress));
    }

    return ShadowList::adopt(shadows);
}

PassOwnPtr<DrawLooperBuilder> ShadowList::createDrawLooper(DrawLooperBuilder::ShadowAlphaMode alphaMode) const
{
    OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
    for (size_t i = shadows().size(); i--; ) {
        const ShadowData& shadow = shadows()[i];
        drawLooperBuilder->addShadow(FloatSize(shadow.x(), shadow.y()), shadow.blur(), shadow.color(),
            DrawLooperBuilder::ShadowRespectsTransforms, alphaMode);
    }
    drawLooperBuilder->addUnmodifiedContent();
    return drawLooperBuilder.release();
}

} // namespace blink