bidi.cpp

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            else if (!last)
                last = curr;
        }
    }

    if (!last)
        return 0;

    RootInlineBox* prev = last->prevRootBox();
    cleanLineStart = InlineIterator(this, prev->lineBreakObj(), prev->lineBreakPos());
    cleanLineBidiStatus = prev->lineBreakBidiStatus();
    yPos = prev->blockHeight();

    for (RootInlineBox* line = last; line; line = line->nextRootBox())
        line->extractLine(); // Disconnect all line boxes from their render objects while preserving
                             // their connections to one another.

    return last;
}

bool RenderBlock::matchedEndLine(const InlineBidiResolver& resolver, const InlineIterator& endLineStart, const BidiStatus& endLineStatus, RootInlineBox*& endLine, int& endYPos, int& repaintBottom, int& repaintTop)
{
    if (resolver.position() == endLineStart) {
        if (resolver.status() != endLineStatus)
            return false;

        int delta = height() - endYPos;
        if (!delta || !m_floatingObjects)
            return true;

        // See if any floats end in the range along which we want to shift the lines vertically.
        int top = min(height(), endYPos);

        RootInlineBox* lastLine = endLine;
        while (RootInlineBox* nextLine = lastLine->nextRootBox())
            lastLine = nextLine;

        int bottom = lastLine->blockHeight() + abs(delta);

        for (FloatingObject* f = m_floatingObjects->first(); f; f = m_floatingObjects->next()) {
            if (f->m_bottom >= top && f->m_bottom < bottom)
                return false;
        }

        return true;
    }

    // The first clean line doesn't match, but we can check a handful of following lines to try
    // to match back up.
    static int numLines = 8; // The # of lines we're willing to match against.
    RootInlineBox* line = endLine;
    for (int i = 0; i < numLines && line; i++, line = line->nextRootBox()) {
        if (line->lineBreakObj() == resolver.position().obj && line->lineBreakPos() == resolver.position().pos) {
            // We have a match.
            if (line->lineBreakBidiStatus() != resolver.status())
                return false; // ...but the bidi state doesn't match.
            RootInlineBox* result = line->nextRootBox();

            // Set our yPos to be the block height of endLine.
            if (result)
                endYPos = line->blockHeight();

            int delta = height() - endYPos;
            if (delta && m_floatingObjects) {
                // See if any floats end in the range along which we want to shift the lines vertically.
                int top = min(height(), endYPos);

                RootInlineBox* lastLine = endLine;
                while (RootInlineBox* nextLine = lastLine->nextRootBox())
                    lastLine = nextLine;

                int bottom = lastLine->blockHeight() + abs(delta);

                for (FloatingObject* f = m_floatingObjects->first(); f; f = m_floatingObjects->next()) {
                    if (f->m_bottom >= top && f->m_bottom < bottom)
                        return false;
                }
            }

            // Now delete the lines that we failed to sync.
            RootInlineBox* boxToDelete = endLine;
            RenderArena* arena = renderArena();
            while (boxToDelete && boxToDelete != result) {
                repaintTop = min(repaintTop, boxToDelete->topOverflow());
                repaintBottom = max(repaintBottom, boxToDelete->bottomOverflow());
                RootInlineBox* next = boxToDelete->nextRootBox();
                boxToDelete->deleteLine(arena);
                boxToDelete = next;
            }

            endLine = result;
            return result;
        }
    }

    return false;
}

static inline bool skipNonBreakingSpace(const InlineIterator& it)
{
    if (it.obj->style()->nbspMode() != SPACE || it.current() != noBreakSpace)
        return false;

    // FIXME: This is bad.  It makes nbsp inconsistent with space and won't work correctly
    // with m_minWidth/m_maxWidth.
    // Do not skip a non-breaking space if it is the first character
    // on a line after a clean line break (or on the first line, since previousLineBrokeCleanly starts off
    // |true|).
    if (isLineEmpty && previousLineBrokeCleanly)
        return false;

    return true;
}

static inline bool shouldCollapseWhiteSpace(const RenderStyle* style)
{
    return style->collapseWhiteSpace() || (style->whiteSpace() == PRE_WRAP && (!isLineEmpty || !previousLineBrokeCleanly));
}

static inline bool shouldPreserveNewline(RenderObject* object)
{
#if ENABLE(SVG)
    if (object->isSVGText())
        return false;
#endif

    return object->style()->preserveNewline();
}

static bool inlineFlowRequiresLineBox(RenderInline* flow)
{
    // FIXME: Right now, we only allow line boxes for inlines that are truly empty.
    // We need to fix this, though, because at the very least, inlines containing only
    // ignorable whitespace should should also have line boxes. 
    return !flow->firstChild() && flow->hasHorizontalBordersPaddingOrMargin();
}

static inline bool requiresLineBox(const InlineIterator& it)
{
    if (it.obj->isFloatingOrPositioned())
        return false;

    if (it.obj->isRenderInline() && !inlineFlowRequiresLineBox(toRenderInline(it.obj)))
        return false;

    if (!shouldCollapseWhiteSpace(it.obj->style()) || it.obj->isBR())
        return true;

    UChar current = it.current();
    return current != ' ' && current != '\t' && current != softHyphen && (current != '\n' || shouldPreserveNewline(it.obj)) && !skipNonBreakingSpace(it);
}

bool RenderBlock::generatesLineBoxesForInlineChild(RenderObject* inlineObj)
{
    ASSERT(inlineObj->parent() == this);

    InlineIterator it(this, inlineObj, 0);
    while (!it.atEnd() && !requiresLineBox(it))
        it.increment();

    return !it.atEnd();
}

// 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 RenderBlock::skipTrailingWhitespace(InlineIterator& iterator)
{
    while (!iterator.atEnd() && !requiresLineBox(iterator)) {
        RenderObject* object = iterator.obj;
        if (object->isFloating()) {
            insertFloatingObject(toRenderBox(object));
        } else if (object->isPositioned()) {
            // FIXME: The math here is actually not really right.  It's a best-guess approximation that
            // will work for the common cases
            RenderObject* c = object->container();
            if (c->isRenderInline()) {
                // A relative positioned inline encloses us.  In this case, we also have to determine our
                // position as though we were an inline.  Set |staticX| and |staticY| on the relative positioned
                // inline so that we can obtain the value later.
                toRenderInline(c)->layer()->setStaticX(style()->direction() == LTR ? leftOffset(height(), false) : rightOffset(height(), false));
                toRenderInline(c)->layer()->setStaticY(height());
            }
    
            RenderBox* box = toRenderBox(object);
            if (box->style()->hasStaticX()) {
                if (box->style()->isOriginalDisplayInlineType())
                    box->layer()->setStaticX(style()->direction() == LTR ? leftOffset(height(), false) : width() - rightOffset(height(), false));
                else
                    box->layer()->setStaticX(style()->direction() == LTR ? borderLeft() + paddingLeft() : borderRight() + paddingRight());
            }
    
            if (box->style()->hasStaticY())
                box->layer()->setStaticY(height());
        }
        iterator.increment();
    }
}

int RenderBlock::skipLeadingWhitespace(InlineBidiResolver& resolver, bool firstLine)
{
    int availableWidth = lineWidth(height(), firstLine);
    while (!resolver.position().atEnd() && !requiresLineBox(resolver.position())) {
        RenderObject* object = resolver.position().obj;
        if (object->isFloating()) {
            insertFloatingObject(toRenderBox(object));
            positionNewFloats();
            availableWidth = lineWidth(height(), firstLine);
        } else if (object->isPositioned()) {
            // FIXME: The math here is actually not really right.  It's a best-guess approximation that
            // will work for the common cases
            RenderObject* c = object->container();
            if (c->isRenderInline()) {
                // A relative positioned inline encloses us.  In this case, we also have to determine our
                // position as though we were an inline.  Set |staticX| and |staticY| on the relative positioned
                // inline so that we can obtain the value later.
                toRenderInline(c)->layer()->setStaticX(style()->direction() == LTR ? leftOffset(height(), firstLine) : rightOffset(height(), firstLine));
                toRenderInline(c)->layer()->setStaticY(height());
            }
    
            RenderBox* box = toRenderBox(object);
            if (box->style()->hasStaticX()) {
                if (box->style()->isOriginalDisplayInlineType())
                    box->layer()->setStaticX(style()->direction() == LTR ? leftOffset(height(), firstLine) : width() - rightOffset(height(), firstLine));
                else
                    box->layer()->setStaticX(style()->direction() == LTR ? borderLeft() + paddingLeft() : borderRight() + paddingRight());
            }
    
            if (box->style()->hasStaticY())
                box->layer()->setStaticY(height());
        }
        resolver.increment();
    }
    resolver.commitExplicitEmbedding();
    return availableWidth;
}

// This is currently just used for list markers and inline flows that have line boxes. Neither should 
// have an effect on whitespace at the start of the line. 
static bool shouldSkipWhitespaceAfterStartObject(RenderBlock* block, RenderObject* o)
{
    RenderObject* next = bidiNext(block, o);
    if (next && !next->isBR() && next->isText() && toRenderText(next)->textLength() > 0) {
        RenderText* nextText = toRenderText(next);
        UChar nextChar = nextText->characters()[0];
        if (nextText->style()->isCollapsibleWhiteSpace(nextChar)) {
            addMidpoint(InlineIterator(0, o, 0));
            return true;
        }
    }

    return false;
}

void RenderBlock::fitBelowFloats(int widthToFit, bool firstLine, int& availableWidth)
{
    ASSERT(widthToFit > availableWidth);

    int floatBottom;
    int lastFloatBottom = height();
    int newLineWidth = availableWidth;
    while (true) {
        floatBottom = nextFloatBottomBelow(lastFloatBottom);
        if (!floatBottom)
            break;

        newLineWidth = lineWidth(floatBottom, firstLine);
        lastFloatBottom = floatBottom;
        if (newLineWidth >= widthToFit)
            break;
    }

    if (newLineWidth > availableWidth) {
        setHeight(lastFloatBottom);
        availableWidth = newLineWidth;
    }
}

static inline unsigned textWidth(RenderText* text, unsigned from, unsigned len, const Font& font, int xPos, bool isFixedPitch, bool collapseWhiteSpace)
{
    if (isFixedPitch || !from && len == text->textLength())
        return text->width(from, len, font, xPos);
    return font.width(TextRun(text->characters() + from, len, !collapseWhiteSpace, xPos));
}

InlineIterator RenderBlock::findNextLineBreak(InlineBidiResolver& resolver, bool firstLine, EClear* clear)
{
    ASSERT(resolver.position().block == this);

    bool appliedStartWidth = resolver.position().pos > 0;

    int width = skipLeadingWhitespace(resolver, firstLine);

    int w = 0;
    int tmpW = 0;

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

    // This variable is used only if whitespace isn't set to PRE, and it tells us whether
    // or not we are currently ignoring whitespace.
    bool ignoringSpaces = false;
    InlineIterator ignoreStart;
    
    // This variable tracks whether the very last character we saw was a space.  We use
    // this to detect when we encounter a second space so we know we have to terminate
    // a run.
    bool currentCharacterIsSpace = false;
    bool currentCharacterIsWS = false;
    RenderObject* trailingSpaceObject = 0;

    InlineIterator lBreak = resolver.position();

    RenderObject *o =