LineBreaker.cpp   [plain text]

/*
 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2013 ChangSeok Oh <shivamidow@gmail.com>
 * Copyright (C) 2013 Adobe Systems Inc. All right reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "LineBreaker.h"

#include "BreakingContext.h"
#include "RenderCombineText.h"

namespace WebCore {

void LineBreaker::reset()
{
    m_positionedObjects.clear();
    m_hyphenated = false;
    m_clear = Clear::None;
}

// FIXME: The entire concept of the skipTrailingWhitespace function is flawed, since we really need to be building
// line boxes even for containers that may ultimately collapse away. Otherwise we'll never get positioned
// elements quite right. In other words, we need to build this function's work into the normal line
// object iteration process.
// NB. this function will insert any floating elements that would otherwise
// be skipped but it will not position them.
void LineBreaker::skipTrailingWhitespace(InlineIterator& iterator, const LineInfo& lineInfo)
{
    while (!iterator.atEnd() && !requiresLineBox(iterator, lineInfo, TrailingWhitespace)) {
        RenderObject& object = *iterator.renderer();
        if (object.isOutOfFlowPositioned())
            setStaticPositions(m_block, downcast<RenderBox>(object), DoNotIndentText);
        else if (object.isFloating())
            m_block.insertFloatingObject(downcast<RenderBox>(object));
        iterator.increment();
    }
}

void LineBreaker::skipLeadingWhitespace(InlineBidiResolver& resolver, LineInfo& lineInfo, FloatingObject* lastFloatFromPreviousLine, LineWidth& width)
{
    while (!resolver.position().atEnd() && !requiresLineBox(resolver.position(), lineInfo, LeadingWhitespace)) {
        RenderObject& object = *resolver.position().renderer();
        if (object.isOutOfFlowPositioned()) {
            setStaticPositions(m_block, downcast<RenderBox>(object), width.shouldIndentText());
            if (object.style().isOriginalDisplayInlineType()) {
                resolver.runs().appendRun(makeUnique<BidiRun>(0, 1, object, resolver.context(), resolver.dir()));
                lineInfo.incrementRunsFromLeadingWhitespace();
            }
        } else if (object.isFloating())
            m_block.complexLineLayout()->positionNewFloatOnLine(*m_block.insertFloatingObject(downcast<RenderBox>(object)), lastFloatFromPreviousLine, lineInfo, width);
        else if (object.style().hasTextCombine() && is<RenderCombineText>(object)) {
            downcast<RenderCombineText>(object).combineTextIfNeeded();
            if (downcast<RenderCombineText>(object).isCombined())
                continue;
        }
        resolver.increment();
    }
    resolver.commitExplicitEmbedding();
}

InlineIterator LineBreaker::nextLineBreak(InlineBidiResolver& resolver, LineInfo& lineInfo, RenderTextInfo& renderTextInfo, FloatingObject* lastFloatFromPreviousLine, unsigned consecutiveHyphenatedLines, WordMeasurements& wordMeasurements)
{
    reset();

    ASSERT(resolver.position().root() == &m_block);

    bool appliedStartWidth = resolver.position().offset();

    LineWidth width(m_block, lineInfo.isFirstLine(), requiresIndent(lineInfo.isFirstLine(), lineInfo.previousLineBrokeCleanly(), m_block.style()));

    skipLeadingWhitespace(resolver, lineInfo, lastFloatFromPreviousLine, width);

    if (resolver.position().atEnd())
        return resolver.position();

    BreakingContext context(*this, resolver, lineInfo, width, renderTextInfo, lastFloatFromPreviousLine, appliedStartWidth, m_block);

    while (context.currentObject()) {
        context.initializeForCurrentObject();
        if (context.currentObject()->isBR()) {
            context.handleBR(m_clear);
        } else if (context.currentObject()->isOutOfFlowPositioned()) {
            context.handleOutOfFlowPositioned(m_positionedObjects);
        } else if (context.currentObject()->isFloating()) {
            context.handleFloat();
        } else if (context.currentObject()->isRenderInline()) {
            context.handleEmptyInline();
        } else if (context.currentObject()->isReplaced()) {
            context.handleReplaced();
        } else if (context.currentObject()->isText()) {
            if (context.handleText(wordMeasurements, m_hyphenated, consecutiveHyphenatedLines)) {
                // We've hit a hard text line break. Our line break iterator is updated, so early return.
                return context.lineBreak();
            }
        } else if (context.currentObject()->isLineBreakOpportunity())
            context.commitLineBreakAtCurrentWidth(*context.currentObject());
        else
            ASSERT_NOT_REACHED();

        if (context.atEnd())
            return context.handleEndOfLine();

        context.commitAndUpdateLineBreakIfNeeded();

        if (context.atEnd())
            return context.handleEndOfLine();

        context.increment();
    }

    context.clearLineBreakIfFitsOnLine(true);

    return context.handleEndOfLine();
}

}