source: webkit/trunk/Source/WebCore/rendering/FlexibleBoxAlgorithm.cpp

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#include "config.h"
#include "FlexibleBoxAlgorithm.h"

#include "RenderBox.h"

namespace WebCore {

FlexItem::FlexItem(RenderBox& box, LayoutUnit flexBaseContentSize, LayoutUnit mainAxisBorderAndPadding, LayoutUnit mainAxisMargin, std::pair<LayoutUnit, LayoutUnit> minMaxSizes, bool everHadLayout)
    : box(box)
    , flexBaseContentSize(flexBaseContentSize)
    , mainAxisBorderAndPadding(mainAxisBorderAndPadding)
    , mainAxisMargin(mainAxisMargin)
    , minMaxSizes(minMaxSizes)
    , hypotheticalMainContentSize(constrainSizeByMinMax(flexBaseContentSize))
    , frozen(false)
    , everHadLayout(everHadLayout)
{
    ASSERT(!box.isOutOfFlowPositioned());
}

FlexLayoutAlgorithm::FlexLayoutAlgorithm(const RenderStyle& style, LayoutUnit lineBreakLength, const Vector<FlexItem>& allItems, LayoutUnit gapBetweenItems, LayoutUnit gapBetweenLines)
    : m_style(style)
    , m_lineBreakLength(lineBreakLength)
    , m_allItems(allItems)
    , m_gapBetweenItems(gapBetweenItems)
    , m_gapBetweenLines(gapBetweenLines)
{
}

bool FlexLayoutAlgorithm::computeNextFlexLine(size_t& nextIndex, Vector<FlexItem>& lineItems, LayoutUnit& sumFlexBaseSize, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink, LayoutUnit& sumHypotheticalMainSize)
{
    lineItems.clear();
    sumFlexBaseSize = 0_lu;
    totalFlexGrow = totalFlexShrink = totalWeightedFlexShrink = 0;
    sumHypotheticalMainSize = 0_lu;

    for (; nextIndex < m_allItems.size(); ++nextIndex) {
        const auto& flexItem = m_allItems[nextIndex];
        ASSERT(!flexItem.box.isOutOfFlowPositioned());
        if (isMultiline() && sumHypotheticalMainSize + flexItem.hypotheticalMainAxisMarginBoxSize() > m_lineBreakLength && !lineItems.isEmpty())
            break;
        lineItems.append(flexItem);
        sumFlexBaseSize += flexItem.flexBaseMarginBoxSize() + m_gapBetweenItems;
        totalFlexGrow += flexItem.box.style().flexGrow();
        totalFlexShrink += flexItem.box.style().flexShrink();
        totalWeightedFlexShrink += flexItem.box.style().flexShrink() * flexItem.flexBaseContentSize;
        sumHypotheticalMainSize += flexItem.hypotheticalMainAxisMarginBoxSize() + m_gapBetweenItems;
    }

    if (!lineItems.isEmpty()) {
        // We added a gap after every item but there shouldn't be one after the last item, so subtract it here. Note that
        // sums might be negative here due to negative margins in flex items.
        sumHypotheticalMainSize -= m_gapBetweenItems;
        sumFlexBaseSize -= m_gapBetweenItems;
    }

    ASSERT(lineItems.size() > 0 || nextIndex == m_allItems.size());
    return lineItems.size() > 0;
}

LayoutUnit FlexItem::constrainSizeByMinMax(const LayoutUnit size) const
{
    return std::max(minMaxSizes.first, std::min(size, minMaxSizes.second));
}

} // namespace WebCore