Source/core/page/PageScaleConstraintsSet.cpp

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#include "config.h"
#include "core/page/PageScaleConstraintsSet.h"

#include "wtf/Assertions.h"

namespace WebCore {

static const float defaultMinimumScale = 0.25f;
static const float defaultMaximumScale = 5.0f;

PageScaleConstraintsSet::PageScaleConstraintsSet()
    : m_lastContentsWidth(0)
    , m_needsReset(false)
    , m_constraintsDirty(false)
{
    m_finalConstraints = defaultConstraints();
}

PageScaleConstraints PageScaleConstraintsSet::defaultConstraints() const
{
    return PageScaleConstraints(-1, defaultMinimumScale, defaultMaximumScale);
}

void PageScaleConstraintsSet::updatePageDefinedConstraints(const ViewportArguments& arguments, IntSize viewSize)
{
    m_pageDefinedConstraints = arguments.resolve(viewSize);

    m_constraintsDirty = true;
}

void PageScaleConstraintsSet::setUserAgentConstraints(const PageScaleConstraints& userAgentConstraints)
{
    m_userAgentConstraints = userAgentConstraints;
    m_constraintsDirty = true;
}

void PageScaleConstraintsSet::computeFinalConstraints()
{
    m_finalConstraints = defaultConstraints();
    m_finalConstraints.overrideWith(m_pageDefinedConstraints);
    m_finalConstraints.overrideWith(m_userAgentConstraints);

    m_constraintsDirty = false;
}

void PageScaleConstraintsSet::adjustFinalConstraintsToContentsSize(IntSize viewSize, IntSize contentsSize, int nonOverlayScrollbarWidth)
{
    m_finalConstraints.fitToContentsWidth(contentsSize.width(), viewSize.width() - nonOverlayScrollbarWidth);
}

void PageScaleConstraintsSet::setNeedsReset(bool needsReset)
{
    m_needsReset = needsReset;
    if (needsReset)
        m_constraintsDirty = true;
}

void PageScaleConstraintsSet::didChangeContentsSize(IntSize contentsSize, float pageScaleFactor)
{
    // If a large fixed-width element expanded the size of the document
    // late in loading and our initial scale is not constrained, reset the
    // page scale factor to the new minimum scale.
    if (contentsSize.width() > m_lastContentsWidth
        && pageScaleFactor == finalConstraints().minimumScale
        && userAgentConstraints().initialScale == -1 && pageDefinedConstraints().initialScale == -1)
        setNeedsReset(true);

    m_constraintsDirty = true;
    m_lastContentsWidth = contentsSize.width();
}

static float computeDeprecatedTargetDensityDPIFactor(const ViewportArguments& arguments, float deviceScaleFactor)
{
    if (arguments.deprecatedTargetDensityDPI == ViewportArguments::ValueDeviceDPI)
        return 1.0f / deviceScaleFactor;

    float targetDPI = -1.0f;
    if (arguments.deprecatedTargetDensityDPI == ViewportArguments::ValueLowDPI)
        targetDPI = 120.0f;
    else if (arguments.deprecatedTargetDensityDPI == ViewportArguments::ValueMediumDPI)
        targetDPI = 160.0f;
    else if (arguments.deprecatedTargetDensityDPI == ViewportArguments::ValueHighDPI)
        targetDPI = 240.0f;
    else if (arguments.deprecatedTargetDensityDPI != ViewportArguments::ValueAuto)
        targetDPI = arguments.deprecatedTargetDensityDPI;
    return targetDPI > 0 ? 160.0f / targetDPI : 1.0f;
}

static float getLayoutWidthForNonWideViewport(const FloatSize& deviceSize, float initialScale)
{
    return initialScale == -1 ? deviceSize.width() : deviceSize.width() / initialScale;
}

void PageScaleConstraintsSet::adjustForAndroidWebViewQuirks(const ViewportArguments& arguments, IntSize viewSize, int layoutFallbackWidth, float deviceScaleFactor, bool supportTargetDensityDPI, bool wideViewportQuirkEnabled, bool useWideViewport, bool loadWithOverviewMode)
{
    if (!supportTargetDensityDPI && !wideViewportQuirkEnabled && loadWithOverviewMode)
        return;

    float initialScale = m_pageDefinedConstraints.initialScale;
    if (!loadWithOverviewMode) {
        bool resetInitialScale = false;
        if (arguments.zoom == -1) {
            if (arguments.maxWidth.isAuto())
                resetInitialScale = true;
            if (useWideViewport && arguments.maxWidth.isFixed())
                resetInitialScale = true;
        }
        if (resetInitialScale)
            m_pageDefinedConstraints.initialScale = 1.0f;
    }

    float adjustedLayoutSizeWidth = m_pageDefinedConstraints.layoutSize.width();
    float targetDensityDPIFactor = 1.0f;

    if (supportTargetDensityDPI) {
        targetDensityDPIFactor = computeDeprecatedTargetDensityDPIFactor(arguments, deviceScaleFactor);
        if (m_pageDefinedConstraints.initialScale != -1)
            m_pageDefinedConstraints.initialScale *= targetDensityDPIFactor;
        m_pageDefinedConstraints.minimumScale *= targetDensityDPIFactor;
        m_pageDefinedConstraints.maximumScale *= targetDensityDPIFactor;
        adjustedLayoutSizeWidth /= targetDensityDPIFactor;
    }

    if (wideViewportQuirkEnabled) {
        if (useWideViewport && (arguments.maxWidth.isAuto() || arguments.maxWidth.type() == ExtendToZoom) && arguments.zoom != 1.0f)
            adjustedLayoutSizeWidth = layoutFallbackWidth;
        else if (!useWideViewport)
            adjustedLayoutSizeWidth = getLayoutWidthForNonWideViewport(viewSize, initialScale) / targetDensityDPIFactor;
    }

    if (adjustedLayoutSizeWidth != m_pageDefinedConstraints.layoutSize.width()) {
        ASSERT(m_pageDefinedConstraints.layoutSize.width() > 0);
        float adjustedLayoutSizeHeight = (adjustedLayoutSizeWidth * m_pageDefinedConstraints.layoutSize.height()) / m_pageDefinedConstraints.layoutSize.width();
        m_pageDefinedConstraints.layoutSize.setWidth(adjustedLayoutSizeWidth);
        m_pageDefinedConstraints.layoutSize.setHeight(adjustedLayoutSizeHeight);
    }
}

} // namespace WebCore