third_party/WebKit/Source/core/frame/PageScaleConstraints.cpp

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#include "core/frame/PageScaleConstraints.h"

#include <algorithm>

namespace blink {

PageScaleConstraints::PageScaleConstraints()
    : initialScale(-1), minimumScale(-1), maximumScale(-1) { }

PageScaleConstraints::PageScaleConstraints(float initial, float minimum, float maximum)
    : initialScale(initial), minimumScale(minimum), maximumScale(maximum) { }

void PageScaleConstraints::overrideWith(const PageScaleConstraints& other)
{
    if (other.initialScale != -1) {
        initialScale = other.initialScale;
        if (minimumScale != -1)
            minimumScale = std::min(minimumScale, other.initialScale);
    }
    if (other.minimumScale != -1)
        minimumScale = other.minimumScale;
    if (other.maximumScale != -1)
        maximumScale = other.maximumScale;
    if (!other.layoutSize.isZero())
        layoutSize = other.layoutSize;
    clampAll();
}

float PageScaleConstraints::clampToConstraints(float pageScaleFactor) const
{
    if (pageScaleFactor == -1)
        return pageScaleFactor;
    if (minimumScale != -1)
        pageScaleFactor = std::max(pageScaleFactor, minimumScale);
    if (maximumScale != -1)
        pageScaleFactor = std::min(pageScaleFactor, maximumScale);
    return pageScaleFactor;
}

void PageScaleConstraints::clampAll()
{
    if (minimumScale != -1 && maximumScale != -1)
        maximumScale = std::max(minimumScale, maximumScale);
    initialScale = clampToConstraints(initialScale);
}

void PageScaleConstraints::fitToContentsWidth(float contentsWidth, int viewWidthNotIncludingScrollbars)
{
    if (!contentsWidth || !viewWidthNotIncludingScrollbars)
        return;

    // Clamp the minimum scale so that the viewport can't exceed the document
    // width.
    minimumScale = std::max(minimumScale, viewWidthNotIncludingScrollbars / contentsWidth);

    clampAll();
}

void PageScaleConstraints::resolveAutoInitialScale()
{
    // If the initial scale wasn't defined, set it to minimum scale now that we
    // know the real value.
    if (initialScale == -1)
        initialScale = minimumScale;

    clampAll();
}

bool PageScaleConstraints::operator==(const PageScaleConstraints& other) const
{
    return layoutSize == other.layoutSize
        && initialScale == other.initialScale
        && minimumScale == other.minimumScale
        && maximumScale == other.maximumScale;
}

} // namespace blink