Source/WebCore/css/CSSImageSetValue.cpp

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#include "config.h"
#include "CSSImageSetValue.h"

#include "CSSImageSetOptionValue.h"
#include "CSSImageValue.h"
#include "CSSPrimitiveValue.h"
#include "StyleBuilderState.h"
#include "StyleImageSet.h"
#include <numeric>
#include <wtf/text/StringBuilder.h>

namespace WebCore {

Ref<CSSImageSetValue> CSSImageSetValue::create(CSSValueListBuilder builder)
{
    return adoptRef(*new CSSImageSetValue(WTF::move(builder)));
}

CSSImageSetValue::CSSImageSetValue(CSSValueListBuilder builder)
    : CSSValueContainingVector(ClassType::ImageSet, CommaSeparator, WTF::move(builder))
{
}

String CSSImageSetValue::customCSSText(const CSS::SerializationContext& context) const
{
    StringBuilder result;
    result.append("image-set("_s);
    for (size_t i = 0; i < this->length(); ++i) {
        if (i > 0)
            result.append(", "_s);
        ASSERT(is<CSSImageSetOptionValue>(item(i)));
        result.append(item(i)->cssText(context));
    }
    result.append(')');
    return result.toString();
}

RefPtr<StyleImage> CSSImageSetValue::createStyleImage(const Style::BuilderState& state) const
{
    size_t length = this->length();

    Vector<ImageWithScale> images(length, [&](size_t i) {
        RefPtr<const CSSImageSetOptionValue> option = downcast<CSSImageSetOptionValue>(item(i));
        return ImageWithScale { state.createStyleImage(option->image()), option->protectedResolution()->resolveAsResolution<float>(state.cssToLengthConversionData()), option->type() };
    });

    // Sort the images so that they are stored in order from lowest resolution to highest.
    // We want to maintain the authored order for serialization so we create a sorted indexing vector.
    Vector<size_t> sortedIndices(length);
    std::iota(sortedIndices.begin(), sortedIndices.end(), 0);

    std::stable_sort(sortedIndices.begin(), sortedIndices.end(), [&images](size_t lhs, size_t rhs) {
        return images[lhs].scaleFactor < images[rhs].scaleFactor;
    });

    return StyleImageSet::create(WTF::move(images), WTF::move(sortedIndices));
}

} // namespace WebCore