render_layer.cpp

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    }
    if (m_negZOrderList) {
        QPtrVector<RenderLayer> mergeBuffer;
        sortByZOrder(m_negZOrderList, &mergeBuffer, 0, m_negZOrderList->count());
    }

    m_zOrderListsDirty = false;
}

void RenderLayer::collectLayers(QPtrVector<RenderLayer>*& posBuffer, QPtrVector<RenderLayer>*& negBuffer)
{
    // FIXME: A child render object or layer could override visibility.  Don't remove this
    // optimization though until RenderObject's nodeAtPoint is patched to understand what to do
    // when visibility is overridden by a child.
    if (renderer()->style()->visibility() != VISIBLE)
        return;

    // Determine which buffer the child should be in.
    QPtrVector<RenderLayer>*& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;

    // Create the buffer if it doesn't exist yet.
    if (!buffer)
        buffer = new QPtrVector<RenderLayer>();

    // Resize by a power of 2 when our buffer fills up.
    if (buffer->count() == buffer->size())
        buffer->resize(2*(buffer->size()+1));

    // Append ourselves at the end of the appropriate buffer.
    buffer->insert(buffer->count(), this);

    // Recur into our children to collect more layers, but only if we don't establish
    // a stacking context.
    if (!isStackingContext()) {
        for (RenderLayer* child = firstChild(); child; child = child->nextSibling())
            child->collectLayers(posBuffer, negBuffer);
    }
}

void RenderLayer::repaintIncludingDescendants()
{
    m_object->repaint();
    for (RenderLayer* curr = firstChild(); curr; curr = curr->nextSibling())
        curr->repaintIncludingDescendants();
}

void RenderLayer::styleChanged()
{
    if (m_object->style()->overflow() == OMARQUEE && m_object->style()->marqueeBehavior() != MNONE) {
        if (!m_marquee)
            m_marquee = new Marquee(this);
        m_marquee->updateMarqueeStyle();
    }
    else if (m_marquee) {
        delete m_marquee;
        m_marquee = 0;
    }
}

void RenderLayer::suspendMarquees()
{
    if (m_marquee)
        m_marquee->suspend();

    for (RenderLayer* curr = firstChild(); curr; curr = curr->nextSibling())
        curr->suspendMarquees();
}

// --------------------------------------------------------------------------
// Marquee implementation

Marquee::Marquee(RenderLayer* l)
:m_layer(l), m_currentLoop(0), m_timerId(0), m_start(0), m_end(0), m_speed(0), m_unfurlPos(0), m_reset(false),
 m_suspended(false), m_stopped(false), m_whiteSpace(NORMAL), m_direction(MAUTO)
{
}

int Marquee::marqueeSpeed() const
{
    int result = m_layer->renderer()->style()->marqueeSpeed();
    DOM::NodeImpl* elt = m_layer->renderer()->element();
    if (elt && elt->id() == ID_MARQUEE) {
        HTMLMarqueeElementImpl* marqueeElt = static_cast<HTMLMarqueeElementImpl*>(elt);
        result = kMax(result, marqueeElt->minimumDelay());
    }
    return result;
}

EMarqueeDirection Marquee::direction() const
{
    // FIXME: Support the CSS3 "auto" value for determining the direction of the marquee.
    // For now just map MAUTO to MBACKWARD
    EMarqueeDirection result = m_layer->renderer()->style()->marqueeDirection();
    EDirection dir =  m_layer->renderer()->style()->direction();
    if (result == MAUTO)
        result = MBACKWARD;
    if (result == MFORWARD)
        result = (dir == LTR) ? MRIGHT : MLEFT;
    if (result == MBACKWARD)
        result = (dir == LTR) ? MLEFT : MRIGHT;

    // Now we have the real direction.  Next we check to see if the increment is negative.
    // If so, then we reverse the direction.
    Length increment = m_layer->renderer()->style()->marqueeIncrement();
    if (increment.value < 0)
        result = static_cast<EMarqueeDirection>(-result);

    return result;
}

bool Marquee::isHorizontal() const
{
    return direction() == MLEFT || direction() == MRIGHT;
}

bool Marquee::isUnfurlMarquee() const
{
    EMarqueeBehavior behavior = m_layer->renderer()->style()->marqueeBehavior();
    return (behavior == MUNFURL);
}

int Marquee::computePosition(EMarqueeDirection dir, bool stopAtContentEdge)
{
    RenderObject* o = m_layer->renderer();
    RenderStyle* s = o->style();
    if (isHorizontal()) {
        bool ltr = s->direction() == LTR;
        int clientWidth = o->clientWidth();
        int contentWidth = ltr ? o->rightmostPosition(true, false) : o->leftmostPosition(true, false);
        if (ltr)
            contentWidth += (o->paddingRight() - o->borderLeft());
        else {
            contentWidth = o->width() - contentWidth;
            contentWidth += (o->paddingLeft() - o->borderRight());
        }
        if (dir == MRIGHT) {
            if (stopAtContentEdge)
                return kMax(0, ltr ? (contentWidth - clientWidth) : (clientWidth - contentWidth));
            else
                return ltr ? contentWidth : clientWidth;
        }
        else {
            if (stopAtContentEdge)
                return kMin(0, ltr ? (contentWidth - clientWidth) : (clientWidth - contentWidth));
            else
                return ltr ? -clientWidth : -contentWidth;
        }
    }
    else {
        int contentHeight = m_layer->renderer()->lowestPosition(true, false) -
                            m_layer->renderer()->borderTop() + m_layer->renderer()->paddingBottom();
        int clientHeight = m_layer->renderer()->clientHeight();
        if (dir == MUP) {
            if (stopAtContentEdge)
                 return kMin(contentHeight - clientHeight, 0);
            else
                return -clientHeight;
        }
        else {
            if (stopAtContentEdge)
                return kMax(contentHeight - clientHeight, 0);
            else
                return contentHeight;
        }
    }
}

void Marquee::start()
{
    if (m_timerId || m_layer->renderer()->style()->marqueeIncrement().value == 0)
        return;

    if (!m_suspended && !m_stopped) {
        if (isUnfurlMarquee()) {
            bool forward = direction() == MDOWN || direction() == MRIGHT;
            bool isReversed = (forward && m_currentLoop % 2) || (!forward && !(m_currentLoop % 2));
            m_unfurlPos = isReversed ? m_end : m_start;
            m_layer->renderer()->setChildNeedsLayout(true);
        }
        else {
            if (isHorizontal())
                m_layer->scrollToOffset(m_start, 0, false, false);
            else
                m_layer->scrollToOffset(0, m_start, false, false);
        }
    }
    else {
        m_suspended = false;
    m_stopped = false;
    }

    m_timerId = startTimer(speed());
}

void Marquee::suspend()
{
    if (m_timerId) {
        killTimer(m_timerId);
        m_timerId = 0;
    }

    m_suspended = true;
}

void Marquee::stop()
{
    if (m_timerId) {
        killTimer(m_timerId);
        m_timerId = 0;
    }

    m_stopped = true;
}

void Marquee::updateMarqueePosition()
{
    bool activate = (m_totalLoops <= 0 || m_currentLoop < m_totalLoops);
    if (activate) {
        if (isUnfurlMarquee()) {
            if (m_unfurlPos < m_start) {
                m_unfurlPos = m_start;
                m_layer->renderer()->setChildNeedsLayout(true);
            }
            else if (m_unfurlPos > m_end) {
                m_unfurlPos = m_end;
                m_layer->renderer()->setChildNeedsLayout(true);
            }
        }
        else {
            EMarqueeBehavior behavior = m_layer->renderer()->style()->marqueeBehavior();
            m_start = computePosition(direction(), behavior == MALTERNATE);
            m_end = computePosition(reverseDirection(), behavior == MALTERNATE || behavior == MSLIDE);
        }
        if (!m_stopped)
            start();
    }
}

void Marquee::updateMarqueeStyle()
{
    RenderStyle* s = m_layer->renderer()->style();

    if (m_direction != s->marqueeDirection() || (m_totalLoops != s->marqueeLoopCount() && m_currentLoop >= m_totalLoops))
        m_currentLoop = 0; // When direction changes or our loopCount is a smaller number than our current loop, reset our loop.

    m_totalLoops = s->marqueeLoopCount();
    m_direction = s->marqueeDirection();
    m_whiteSpace = s->whiteSpace();

    if (m_layer->renderer()->isHTMLMarquee()) {
        // Hack for WinIE.  In WinIE, a value of 0 or lower for the loop count for SLIDE means to only do
        // one loop.
        if (m_totalLoops <= 0 && (s->marqueeBehavior() == MSLIDE || s->marqueeBehavior() == MUNFURL))
            m_totalLoops = 1;

        // Hack alert: Set the white-space value to nowrap for horizontal marquees with inline children, thus ensuring
        // all the text ends up on one line by default.  Limit this hack to the <marquee> element to emulate
        // WinIE's behavior.  Someone using CSS3 can use white-space: nowrap on their own to get this effect.
        // Second hack alert: Set the text-align back to auto.  WinIE completely ignores text-align on the
        // marquee element.
        // FIXME: Bring these up with the CSS WG.
        if (isHorizontal() && m_layer->renderer()->childrenInline()) {
            s->setWhiteSpace(NOWRAP);
            s->setTextAlign(TAAUTO);
        }
    }

    if (speed() != marqueeSpeed()) {
        m_speed = marqueeSpeed();
        if (m_timerId) {
            killTimer(m_timerId);
            m_timerId = startTimer(speed());
        }
    }

    // Check the loop count to see if we should now stop.
    bool activate = (m_totalLoops <= 0 || m_currentLoop < m_totalLoops);
    if (activate && !m_timerId)
        m_layer->renderer()->setNeedsLayout(true);
    else if (!activate && m_timerId) {
        // Destroy the timer.
        killTimer(m_timerId);
        m_timerId = 0;
    }
}

void Marquee::timerEvent(QTimerEvent* evt)
{
    if (m_layer->renderer()->needsLayout())
        return;

    if (m_reset) {
        m_reset = false;
        if (isHorizontal())
            m_layer->scrollToXOffset(m_start);
        else
            m_layer->scrollToYOffset(m_start);
        return;
    }

    RenderStyle* s = m_layer->renderer()->style();

    int endPoint = m_end;
    int range = m_end - m_start;
    int newPos;
    if (range == 0)
        newPos = m_end;
    else {
        bool addIncrement = direction() == MUP || direction() == MLEFT;
        bool isReversed = s->marqueeBehavior() == MALTERNATE && m_currentLoop % 2;
        if (isUnfurlMarquee()) {
            isReversed = (!addIncrement && m_currentLoop % 2) || (addIncrement && !(m_currentLoop % 2));
            addIncrement = !isReversed;
        }
        if (isReversed) {
            // We're going in the reverse direction.
            endPoint = m_start;
            range = -range;
            if (!isUnfurlMarquee())
                addIncrement = !addIncrement;
        }
        bool positive = range > 0;
        int clientSize = isUnfurlMarquee() ? abs(range) :
            (isHorizontal() ? m_layer->renderer()->clientWidth() : m_layer->renderer()->clientHeight());
        int increment = kMax(1, abs(m_layer->renderer()->style()->marqueeIncrement().width(clientSize)));
        int currentPos = isUnfurlMarquee() ? m_unfurlPos :
            (isHorizontal() ? m_layer->scrollXOffset() : m_layer->scrollYOffset());
        newPos =  currentPos + (addIncrement ? increment : -increment);
        if (positive)
            newPos = kMin(newPos, endPoint);
        else
            newPos = kMax(newPos, endPoint);
    }

    if (newPos == endPoint) {
        m_currentLoop++;
        if (m_totalLoops > 0 && m_currentLoop >= m_totalLoops) {
            killTimer(m_timerId);
            m_timerId = 0;
        }
        else if (s->marqueeBehavior() != MALTERNATE && s->marqueeBehavior() != MUNFURL)
            m_reset = true;
    }

    if (isUnfurlMarquee()) {
        m_unfurlPos = newPos;
        m_layer->renderer()->setChildNeedsLayout(true);
    }
    else {
        if (isHorizontal())
            m_layer->scrollToXOffset(newPos);
        else
            m_layer->scrollToYOffset(newPos);
    }
}