bidi.cpp

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                            UChar current = characters[firstSpace - 1];
                            if (!isCollapsibleSpace(current, lastText))
                                break;
                            firstSpace--;
                        }
                        if (firstSpace == trailingSpaceRun->stop())
                            trailingSpaceRun = 0;
                        else {
                            TextDirection direction = style()->direction();
                            bool shouldReorder = trailingSpaceRun != (direction == LTR ? resolver.lastRun() : resolver.firstRun());
                            if (firstSpace != trailingSpaceRun->start()) {
                                ETextAlign textAlign = style()->textAlign();
                                // If the trailing white space is at the right hand side of a left-aligned line, then computeHorizontalPositionsForLine()
                                // does not care if trailingSpaceRun includes non-spaces at the beginning. In all other cases, trailingSpaceRun has to
                                // contain only the spaces, either because we re-order them or because computeHorizontalPositionsForLine() needs to know
                                // their width.
                                bool shouldSeparateSpaces = textAlign != LEFT && textAlign != WEBKIT_LEFT && textAlign != TAAUTO || trailingSpaceRun->m_level % 2 || direction == RTL || shouldReorder;
                                if (shouldSeparateSpaces) {
                                    BidiContext* baseContext = resolver.context();
                                    while (BidiContext* parent = baseContext->parent())
                                        baseContext = parent;

                                    BidiRun* newTrailingRun = new (renderArena()) BidiRun(firstSpace, trailingSpaceRun->m_stop, trailingSpaceRun->m_object, baseContext, OtherNeutral);
                                    trailingSpaceRun->m_stop = firstSpace;
                                    if (direction == LTR)
                                        resolver.addRun(newTrailingRun);
                                    else
                                        resolver.prependRun(newTrailingRun);
                                    trailingSpaceRun = newTrailingRun;
                                    shouldReorder = false;
                                }
                            }
                            if (shouldReorder) {
                                if (direction == LTR) {
                                    resolver.moveRunToEnd(trailingSpaceRun);
                                    trailingSpaceRun->m_level = 0;
                                } else {
                                    resolver.moveRunToBeginning(trailingSpaceRun);
                                    trailingSpaceRun->m_level = 1;
                                }
                            }
                        }
                    } else
                        trailingSpaceRun = 0;
                }

                // Now that the runs have been ordered, we create the line boxes.
                // At the same time we figure out where border/padding/margin should be applied for
                // inline flow boxes.

                RootInlineBox* lineBox = 0;
                if (resolver.runCount()) {
                    lineBox = constructLine(resolver.runCount(), resolver.firstRun(), resolver.lastRun(), firstLine, !end.obj, end.obj && !end.pos ? end.obj : 0);
                    if (lineBox) {
                        lineBox->setEndsWithBreak(previousLineBrokeCleanly);

                        // Now we position all of our text runs horizontally.
                        computeHorizontalPositionsForLine(lineBox, firstLine, resolver.firstRun(), trailingSpaceRun, end.atEnd());

                        // Now position our text runs vertically.
                        computeVerticalPositionsForLine(lineBox, resolver.firstRun());

#if ENABLE(SVG)
                        // Special SVG text layout code
                        lineBox->computePerCharacterLayoutInformation();
#endif

#if PLATFORM(MAC)
                        // Highlight acts as an overflow inflation.
                        if (style()->highlight() != nullAtom)
                            lineBox->addHighlightOverflow();
#endif
                    }
                }

                resolver.deleteRuns();

                if (lineBox) {
                    lineBox->setLineBreakInfo(end.obj, end.pos, resolver.status());
                    if (useRepaintBounds) {
                        repaintTop = min(repaintTop, lineBox->topOverflow());
                        repaintBottom = max(repaintBottom, lineBox->bottomOverflow());
                    }
                }

                firstLine = false;
                newLine(clear);
            }

            if (m_floatingObjects && lastRootBox()) {
                if (lastFloat) {
                    for (FloatingObject* f = m_floatingObjects->last(); f != lastFloat; f = m_floatingObjects->prev()) {
                    }
                    m_floatingObjects->next();
                } else
                    m_floatingObjects->first();
                for (FloatingObject* f = m_floatingObjects->current(); f; f = m_floatingObjects->next()) {
                    if (f->m_bottom > lastHeight)
                        lastRootBox()->floats().append(f->m_renderer);
                    ASSERT(f->m_renderer == floats[floatIndex].object);
                    // If a float's geometry has changed, give up on syncing with clean lines.
                    if (floats[floatIndex].rect != IntRect(f->m_left, f->m_top, f->m_width, f->m_bottom - f->m_top))
                        checkForEndLineMatch = false;
                    floatIndex++;
                }
                lastFloat = m_floatingObjects->last();
            }

            lastHeight = height();
            sNumMidpoints = 0;
            sCurrMidpoint = 0;
            resolver.setPosition(end);
        }

        if (endLine) {
            if (endLineMatched) {
                // Attach all the remaining lines, and then adjust their y-positions as needed.
                int delta = height() - endLineYPos;
                for (RootInlineBox* line = endLine; line; line = line->nextRootBox()) {
                    line->attachLine();
                    if (delta) {
                        repaintTop = min(repaintTop, line->topOverflow() + min(delta, 0));
                        repaintBottom = max(repaintBottom, line->bottomOverflow() + max(delta, 0));
                        line->adjustPosition(0, delta);
                    }
                    if (Vector<RenderBox*>* cleanLineFloats = line->floatsPtr()) {
                        Vector<RenderBox*>::iterator end = cleanLineFloats->end();
                        for (Vector<RenderBox*>::iterator f = cleanLineFloats->begin(); f != end; ++f) {
                            int floatTop = (*f)->y() - (*f)->marginTop();
                            insertFloatingObject(*f);
                            setHeight(floatTop + delta);
                            positionNewFloats();
                        }
                    }
                }
                setHeight(lastRootBox()->blockHeight());
            } else {
                // Delete all the remaining lines.
                InlineRunBox* line = endLine;
                RenderArena* arena = renderArena();
                while (line) {
                    repaintTop = min(repaintTop, line->topOverflow());
                    repaintBottom = max(repaintBottom, line->bottomOverflow());
                    InlineRunBox* next = line->nextLineBox();
                    line->deleteLine(arena);
                    line = next;
                }
            }
        }
        if (m_floatingObjects && (checkForFloatsFromLastLine || positionNewFloats()) && lastRootBox()) {
            // In case we have a float on the last line, it might not be positioned up to now.
            // This has to be done before adding in the bottom border/padding, or the float will
            // include the padding incorrectly. -dwh
            if (lastFloat) {
                for (FloatingObject* f = m_floatingObjects->last(); f != lastFloat; f = m_floatingObjects->prev()) {
                }
                m_floatingObjects->next();
            } else
                m_floatingObjects->first();
            for (FloatingObject* f = m_floatingObjects->current(); f; f = m_floatingObjects->next()) {
                if (f->m_bottom > lastHeight)
                    lastRootBox()->floats().append(f->m_renderer);
            }
            lastFloat = m_floatingObjects->last();
        }
    }

    sNumMidpoints = 0;
    sCurrMidpoint = 0;

    // Now add in the bottom border/padding.
    setHeight(height() + toAdd);

    // Always make sure this is at least our height.
    m_overflowHeight = max(height(), m_overflowHeight);

    // See if any lines spill out of the block.  If so, we need to update our overflow width.
    checkLinesForOverflow();

    if (!firstLineBox() && hasLineIfEmpty())
        setHeight(height() + lineHeight(true, true));

    // See if we have any lines that spill out of our block.  If we do, then we will possibly need to
    // truncate text.
    if (hasTextOverflow)
        checkLinesForTextOverflow();
}

RootInlineBox* RenderBlock::determineStartPosition(bool& firstLine, bool& fullLayout, InlineBidiResolver& resolver, Vector<FloatWithRect>& floats, unsigned& numCleanFloats)
{
    RootInlineBox* curr = 0;
    RootInlineBox* last = 0;

    bool dirtiedByFloat = false;
    if (!fullLayout) {
        size_t floatIndex = 0;
        for (curr = firstRootBox(); curr && !curr->isDirty(); curr = curr->nextRootBox()) {
            if (Vector<RenderBox*>* cleanLineFloats = curr->floatsPtr()) {
                Vector<RenderBox*>::iterator end = cleanLineFloats->end();
                for (Vector<RenderBox*>::iterator o = cleanLineFloats->begin(); o != end; ++o) {
                    RenderBox* f = *o;
                    IntSize newSize(f->width() + f->marginLeft() +f->marginRight(), f->height() + f->marginTop() + f->marginBottom());
                    ASSERT(floatIndex < floats.size());
                    if (floats[floatIndex].object != f) {
                        // A new float has been inserted before this line or before its last known float.
                        // Just do a full layout.
                        fullLayout = true;
                        break;
                    }
                    if (floats[floatIndex].rect.size() != newSize) {
                        int floatTop = floats[floatIndex].rect.y();
                        curr->markDirty();
                        markLinesDirtyInVerticalRange(curr->blockHeight(), floatTop + max(floats[floatIndex].rect.height(), newSize.height()));
                        floats[floatIndex].rect.setSize(newSize);
                        dirtiedByFloat = true;
                    }
                    floatIndex++;
                }
            }
            if (dirtiedByFloat || fullLayout)
                break;
        }
        // Check if a new float has been inserted after the last known float.
        if (!curr && floatIndex < floats.size())
            fullLayout = true;
    }

    if (fullLayout) {
        // Nuke all our lines.
        if (firstRootBox()) {
            RenderArena* arena = renderArena();
            curr = firstRootBox(); 
            while (curr) {
                RootInlineBox* next = curr->nextRootBox();
                curr->deleteLine(arena);
                curr = next;
            }
            ASSERT(!firstLineBox() && !lastLineBox());
        }
    } else {
        if (curr) {
            // We have a dirty line.
            if (RootInlineBox* prevRootBox = curr->prevRootBox()) {
                // We have a previous line.
                if (!dirtiedByFloat && (!prevRootBox->endsWithBreak() || prevRootBox->lineBreakObj()->isText() && prevRootBox->lineBreakPos() >= toRenderText(prevRootBox->lineBreakObj())->textLength()))
                    // The previous line didn't break cleanly or broke at a newline
                    // that has been deleted, so treat it as dirty too.
                    curr = prevRootBox;
            }
        } else {
            // No dirty lines were found.
            // If the last line didn't break cleanly, treat it as dirty.
            if (lastRootBox() && !lastRootBox()->endsWithBreak())
                curr = lastRootBox();
        }

        // If we have no dirty lines, then last is just the last root box.
        last = curr ? curr->prevRootBox() : lastRootBox();
    }

    numCleanFloats = 0;
    if (!floats.isEmpty()) {
        int savedHeight = height();
        // Restore floats from clean lines.
        RootInlineBox* line = firstRootBox();
        while (line != curr) {
            if (Vector<RenderBox*>* cleanLineFloats = line->floatsPtr()) {
                Vector<RenderBox*>::iterator end = cleanLineFloats->end();
                for (Vector<RenderBox*>::iterator f = cleanLineFloats->begin(); f != end; ++f) {
                    insertFloatingObject(*f);
                    setHeight((*f)->y() - (*f)->marginTop());
                    positionNewFloats();
                    ASSERT(floats[numCleanFloats].object == *f);
                    numCleanFloats++;
                }
            }
            line = line->nextRootBox();
        }
        setHeight(savedHeight);
    }

    firstLine = !last;
    previousLineBrokeCleanly = !last || last->endsWithBreak();

    RenderObject* startObj;
    int pos = 0;
    if (last) {
        setHeight(last->blockHeight());
        startObj = last->lineBreakObj();
        pos = last->lineBreakPos();
        resolver.setStatus(last->lineBreakBidiStatus());
    } else {
        bool ltr = style()->direction() == LTR
    #if ENABLE(SVG)   
            || (style()->unicodeBidi() == UBNormal && isSVGText())
    #endif
            ;

        BidiContext* context = new BidiContext(ltr ? 0 : 1, ltr ? LeftToRight : RightToLeft, style()->unicodeBidi() == Override);

        resolver.setLastStrongDir(context->dir());
        resolver.setLastDir(context->dir());
        resolver.setEorDir(context->dir());
        resolver.setContext(context);
        startObj = bidiFirst(this, &resolver);
    }

    resolver.setPosition(InlineIterator(this, startObj, pos));

    return curr;
}

RootInlineBox* RenderBlock::determineEndPosition(RootInlineBox* startLine, InlineIterator& cleanLineStart, BidiStatus& cleanLineBidiStatus, int& yPos)
{
    RootInlineBox* last = 0;
    if (!startLine)
        last = 0;
    else {
        for (RootInlineBox* curr = startLine->nextRootBox(); curr; curr = curr->nextRootBox()) {
            if (curr->isDirty())
                last = 0;