flutter_flutter/engine/core/rendering/line/LineWidth.cpp

/*
 * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
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 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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#include "config.h"
#include "core/rendering/line/LineWidth.h"

#include "core/rendering/RenderBlock.h"
#include "core/rendering/RenderBlockFlow.h"

namespace blink {

LineWidth::LineWidth(RenderBlockFlow& block, bool isFirstLine, IndentTextOrNot shouldIndentText)
    : m_block(block)
    , m_uncommittedWidth(0)
    , m_committedWidth(0)
    , m_trailingWhitespaceWidth(0)
    , m_left(0)
    , m_right(0)
    , m_availableWidth(0)
    , m_isFirstLine(isFirstLine)
    , m_shouldIndentText(shouldIndentText)
{
    updateAvailableWidth();
}

void LineWidth::updateAvailableWidth(LayoutUnit replacedHeight)
{
    LayoutUnit height = m_block.logicalHeight();
    LayoutUnit logicalHeight = m_block.minLineHeightForReplacedRenderer(m_isFirstLine, replacedHeight);
    m_left = m_block.logicalLeftOffsetForLine(height, shouldIndentText(), logicalHeight).toFloat();
    m_right = m_block.logicalRightOffsetForLine(height, shouldIndentText(), logicalHeight).toFloat();

    computeAvailableWidthFromLeftAndRight();
}

void LineWidth::commit()
{
    m_committedWidth += m_uncommittedWidth;
    m_uncommittedWidth = 0;
}

inline static float availableWidthAtOffset(const RenderBlockFlow& block, const LayoutUnit& offset, bool shouldIndentText, float& newLineLeft, float& newLineRight)
{
    newLineLeft = block.logicalLeftOffsetForLine(offset, shouldIndentText).toFloat();
    newLineRight = block.logicalRightOffsetForLine(offset, shouldIndentText).toFloat();
    return std::max(0.0f, newLineRight - newLineLeft);
}

inline static float availableWidthAtOffset(const RenderBlockFlow& block, const LayoutUnit& offset, bool shouldIndentText)
{
    float newLineLeft = block.logicalLeftOffsetForLine(offset, shouldIndentText).toFloat();
    float newLineRight = block.logicalRightOffsetForLine(offset, shouldIndentText).toFloat();
    return std::max(0.0f, newLineRight - newLineLeft);
}

void LineWidth::updateLineDimension(LayoutUnit newLineTop, LayoutUnit newLineWidth, const float& newLineLeft, const float& newLineRight)
{
    if (newLineWidth <= m_availableWidth)
        return;

    m_block.setLogicalHeight(newLineTop);
    m_availableWidth = newLineWidth.toFloat();
    m_left = newLineLeft;
    m_right = newLineRight;
}

inline static bool isWholeLineFit(const RenderBlockFlow& block, const LayoutUnit& lineTop, LayoutUnit lineHeight, float uncommittedWidth, bool shouldIndentText)
{
    for (LayoutUnit lineBottom = lineTop; lineBottom <= lineTop + lineHeight; lineBottom++) {
        LayoutUnit availableWidthAtBottom = availableWidthAtOffset(block, lineBottom, shouldIndentText);
        if (availableWidthAtBottom < uncommittedWidth)
            return false;
    }
    return true;
}

void LineWidth::wrapNextToShapeOutside(bool isFirstLine)
{
    LayoutUnit lineHeight = m_block.lineHeight(isFirstLine, HorizontalLine, PositionOfInteriorLineBoxes);
    LayoutUnit lineLogicalTop = m_block.logicalHeight();
    LayoutUnit newLineTop = lineLogicalTop;
    LayoutUnit floatLogicalBottom = lineLogicalTop;

    float newLineWidth;
    float newLineLeft = m_left;
    float newLineRight = m_right;
    while (true) {
        newLineWidth = availableWidthAtOffset(m_block, newLineTop, shouldIndentText(), newLineLeft, newLineRight);
        if (newLineWidth >= m_uncommittedWidth && isWholeLineFit(m_block, newLineTop, lineHeight, m_uncommittedWidth, shouldIndentText()))
            break;

        if (newLineTop >= floatLogicalBottom)
            break;

        newLineTop++;
    }
    updateLineDimension(newLineTop, newLineWidth, newLineLeft, newLineRight);
}

void LineWidth::fitBelowFloats(bool isFirstLine)
{
    ASSERT(!m_committedWidth);
    ASSERT(!fitsOnLine());

    LayoutUnit floatLogicalBottom;
    LayoutUnit lastFloatLogicalBottom = m_block.logicalHeight();
    float newLineWidth = m_availableWidth;
    float newLineLeft = m_left;
    float newLineRight = m_right;

    while (true) {
        floatLogicalBottom = lastFloatLogicalBottom;
        if (floatLogicalBottom <= lastFloatLogicalBottom)
            break;

        newLineWidth = availableWidthAtOffset(m_block, floatLogicalBottom, shouldIndentText(), newLineLeft, newLineRight);
        lastFloatLogicalBottom = floatLogicalBottom;

        if (newLineWidth >= m_uncommittedWidth)
            break;
    }
    updateLineDimension(lastFloatLogicalBottom, newLineWidth, newLineLeft, newLineRight);
}

void LineWidth::computeAvailableWidthFromLeftAndRight()
{
    m_availableWidth = max(0.0f, m_right - m_left);
}

}