InlineFormattingContextGeometry.cpp   [plain text]

/*
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#include "config.h"
#include "InlineFormattingContext.h"

#if ENABLE(LAYOUT_FORMATTING_CONTEXT)

#include "FormattingContext.h"
#include "InlineFormattingState.h"
#include "LayoutBox.h"
#include "LayoutContainer.h"
#include "LayoutState.h"
#include "TextUtil.h"

namespace WebCore {
namespace Layout {

WidthAndMargin InlineFormattingContext::Geometry::inlineBlockWidthAndMargin(LayoutState& layoutState, const Box& formattingContextRoot)
{
    ASSERT(formattingContextRoot.isInFlow());

    // 10.3.10 'Inline-block', replaced elements in normal flow

    // Exactly as inline replaced elements.
    if (formattingContextRoot.replaced())
        return inlineReplacedWidthAndMargin(layoutState, formattingContextRoot);

    // 10.3.9 'Inline-block', non-replaced elements in normal flow

    // If 'width' is 'auto', the used value is the shrink-to-fit width as for floating elements.
    // A computed value of 'auto' for 'margin-left' or 'margin-right' becomes a used value of '0'.
    auto& containingBlock = *formattingContextRoot.containingBlock();
    auto containingBlockWidth = layoutState.displayBoxForLayoutBox(containingBlock).contentBoxWidth();
    // #1
    auto width = computedValueIfNotAuto(formattingContextRoot.style().logicalWidth(), containingBlockWidth);
    if (!width)
        width = shrinkToFitWidth(layoutState, formattingContextRoot);

    // #2
    auto computedHorizontalMargin = Geometry::computedHorizontalMargin(layoutState, formattingContextRoot);

    return WidthAndMargin { *width, { computedHorizontalMargin.start.valueOr(0_lu), computedHorizontalMargin.end.valueOr(0_lu) }, computedHorizontalMargin };
}

HeightAndMargin InlineFormattingContext::Geometry::inlineBlockHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox)
{
    ASSERT(layoutBox.isInFlow());

    // 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block' replaced elements in normal flow and floating replaced elements
    if (layoutBox.replaced())
        return inlineReplacedHeightAndMargin(layoutState, layoutBox);

    // 10.6.6 Complicated cases
    // - 'Inline-block', non-replaced elements.
    return complicatedCases(layoutState, layoutBox);
}

static LayoutUnit adjustedLineLogicalLeft(TextAlignMode align, LayoutUnit lineLogicalLeft, LayoutUnit remainingWidth)
{
    switch (align) {
    case TextAlignMode::Left:
    case TextAlignMode::WebKitLeft:
    case TextAlignMode::Start:
        return lineLogicalLeft;
    case TextAlignMode::Right:
    case TextAlignMode::WebKitRight:
    case TextAlignMode::End:
        return lineLogicalLeft + std::max(remainingWidth, 0_lu);
    case TextAlignMode::Center:
    case TextAlignMode::WebKitCenter:
        return lineLogicalLeft + std::max(remainingWidth / 2, 0_lu);
    case TextAlignMode::Justify:
        ASSERT_NOT_REACHED();
        break;
    }
    ASSERT_NOT_REACHED();
    return lineLogicalLeft;
}

void InlineFormattingContext::Geometry::justifyRuns(Line& line)
{
    auto& inlineRuns = line.runs();
    auto& lastInlineRun = inlineRuns.last();

    // Adjust (forbid) trailing expansion for the last text run on line.
    auto expansionBehavior = lastInlineRun.expansionOpportunity().behavior;
    // Remove allow and add forbid.
    expansionBehavior ^= AllowTrailingExpansion;
    expansionBehavior |= ForbidTrailingExpansion;
    lastInlineRun.expansionOpportunity().behavior = expansionBehavior;

    // Collect expansion opportunities and justify the runs.
    auto widthToDistribute = line.availableWidth();
    if (widthToDistribute <= 0)
        return;

    auto expansionOpportunities = 0;
    for (auto& inlineRun : inlineRuns)
        expansionOpportunities += inlineRun.expansionOpportunity().count;

    if (!expansionOpportunities)
        return;

    float expansion = widthToDistribute.toFloat() / expansionOpportunities;
    LayoutUnit accumulatedExpansion;
    for (auto& inlineRun : inlineRuns) {
        auto expansionForRun = inlineRun.expansionOpportunity().count * expansion;

        inlineRun.expansionOpportunity().expansion = expansionForRun;
        inlineRun.setLogicalLeft(inlineRun.logicalLeft() + accumulatedExpansion);
        inlineRun.setLogicalWidth(inlineRun.logicalWidth() + expansionForRun);
        accumulatedExpansion += expansionForRun;
    }
}

void InlineFormattingContext::Geometry::computeExpansionOpportunities(Line& line, const InlineRunProvider::Run& run, InlineRunProvider::Run::Type lastRunType)
{
    auto isExpansionOpportunity = [](auto currentRunIsWhitespace, auto lastRunIsWhitespace) {
        return currentRunIsWhitespace || (!currentRunIsWhitespace && !lastRunIsWhitespace);
    };

    auto expansionBehavior = [](auto isAtExpansionOpportunity) {
        ExpansionBehavior expansionBehavior = AllowTrailingExpansion;
        expansionBehavior |= isAtExpansionOpportunity ? ForbidLeadingExpansion : AllowLeadingExpansion;
        return expansionBehavior;
    };

    auto isAtExpansionOpportunity = isExpansionOpportunity(run.isWhitespace(), lastRunType == InlineRunProvider::Run::Type::Whitespace);

    auto& currentInlineRun = line.runs().last();
    auto& expansionOpportunity = currentInlineRun.expansionOpportunity();
    if (isAtExpansionOpportunity)
        ++expansionOpportunity.count;

    expansionOpportunity.behavior = expansionBehavior(isAtExpansionOpportunity);
}

void InlineFormattingContext::Geometry::alignRuns(TextAlignMode textAlign, Line& line,  IsLastLine isLastLine)
{
    auto adjutedTextAlignment = textAlign != TextAlignMode::Justify ? textAlign : isLastLine == IsLastLine::No ? TextAlignMode::Justify : TextAlignMode::Left;
    if (adjutedTextAlignment == TextAlignMode::Justify) {
        justifyRuns(line);
        return;
    }

    auto lineLogicalLeft = line.contentLogicalLeft();
    auto adjustedLogicalLeft = adjustedLineLogicalLeft(adjutedTextAlignment, lineLogicalLeft, line.availableWidth());
    if (adjustedLogicalLeft == lineLogicalLeft)
        return;

    auto delta = adjustedLogicalLeft - lineLogicalLeft;
    for (auto& inlineRun : line.runs())
        inlineRun.setLogicalLeft(inlineRun.logicalLeft() + delta);
}

LayoutUnit InlineFormattingContext::Geometry::runWidth(const InlineContent& inlineContent, const InlineItem& inlineItem, ItemPosition from, unsigned length, LayoutUnit contentLogicalLeft) 
{
    LayoutUnit width;
    auto startPosition = from;
    auto iterator = inlineContent.find(const_cast<InlineItem*>(&inlineItem));
#if !ASSERT_DISABLED
    auto inlineItemEnd = inlineContent.end();
#endif
    while (length) {
        ASSERT(iterator != inlineItemEnd);
        auto& currentInlineItem = **iterator;
        auto endPosition = std::min<ItemPosition>(startPosition + length, currentInlineItem.textContent().length());
        auto textWidth = TextUtil::width(currentInlineItem, startPosition, endPosition, contentLogicalLeft);

        contentLogicalLeft += textWidth;
        width += textWidth;
        length -= (endPosition - startPosition);

        startPosition = 0;
        ++iterator;
    }
    return width;
}

}
}

#endif