rendermarquee.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * Portions are Copyright (C) 1998 Netscape Communications Corporation.
 *
 * Other contributors:
 *   Robert O'Callahan <[e-mail]>
 *   David Baron <[e-mail]>
 *   Christian Biesinger <[e-mail]>
 *   Randall Jesup <[e-mail]>
 *   Roland Mainz <[e-mail]>
 *   Josh Soref <[e-mail]>
 *   Boris Zbarsky <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Alternatively, the contents of this file may be used under the terms
 * of either the Mozilla Public License Version 1.1, found at
 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
 * (the "GPL"), in which case the provisions of the MPL or the GPL are
 * applicable instead of those above.  If you wish to allow use of your
 * version of this file only under the terms of one of those two
 * licenses (the MPL or the GPL) and not to allow others to use your
 * version of this file under the LGPL, indicate your decision by
 * deletingthe provisions above and replace them with the notice and
 * other provisions required by the MPL or the GPL, as the case may be.
 * If you do not delete the provisions above, a recipient may use your
 * version of this file under any of the LGPL, the MPL or the GPL.
 */

#include "config.h"

#include "RenderMarquee.h"

#include "FrameView.h"
#include "HTMLMarqueeElement.h"
#include "HTMLNames.h"
#include "RenderLayer.h"

using namespace std;

namespace WebCore {

using namespace HTMLNames;

RenderMarquee::RenderMarquee(RenderLayer* l)
    : m_layer(l), m_currentLoop(0)
    , m_totalLoops(0)
    , m_timer(this, &RenderMarquee::timerFired)
    , m_start(0), m_end(0), m_speed(0), m_reset(false)
    , m_suspended(false), m_stopped(false), m_direction(MAUTO)
{
}

int RenderMarquee::marqueeSpeed() const
{
    int result = m_layer->renderer()->style()->marqueeSpeed();
    Node* n = m_layer->renderer()->node();
    if (n && n->hasTagName(marqueeTag)) {
        HTMLMarqueeElement* marqueeElt = static_cast<HTMLMarqueeElement*>(n);
        result = max(result, marqueeElt->minimumDelay());
    }
    return result;
}

EMarqueeDirection RenderMarquee::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();
    TextDirection 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.isNegative())
        result = static_cast<EMarqueeDirection>(-result);
    
    return result;
}

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

int RenderMarquee::computePosition(EMarqueeDirection dir, bool stopAtContentEdge)
{
    RenderBox* box = m_layer->renderBox();
    ASSERT(box);
    RenderStyle* s = box->style();
    if (isHorizontal()) {
        bool ltr = s->direction() == LTR;
        int clientWidth = box->clientWidth();
        int contentWidth = ltr ? box->rightmostPosition(true, false) : box->leftmostPosition(true, false);
        if (ltr)
            contentWidth += (box->paddingRight() - box->borderLeft());
        else {
            contentWidth = box->width() - contentWidth;
            contentWidth += (box->paddingLeft() - box->borderRight());
        }
        if (dir == MRIGHT) {
            if (stopAtContentEdge)
                return max(0, ltr ? (contentWidth - clientWidth) : (clientWidth - contentWidth));
            else
                return ltr ? contentWidth : clientWidth;
        }
        else {
            if (stopAtContentEdge)
                return min(0, ltr ? (contentWidth - clientWidth) : (clientWidth - contentWidth));
            else
                return ltr ? -clientWidth : -contentWidth;
        }
    }
    else {
        int contentHeight = box->lowestPosition(true, false) - 
                            box->borderTop() + box->paddingBottom();
        int clientHeight = box->clientHeight();
        if (dir == MUP) {
            if (stopAtContentEdge)
                 return min(contentHeight - clientHeight, 0);
            else
                return -clientHeight;
        }
        else {
            if (stopAtContentEdge)
                return max(contentHeight - clientHeight, 0);
            else 
                return contentHeight;
        }
    }    
}

void RenderMarquee::start()
{
    if (m_timer.isActive() || m_layer->renderer()->style()->marqueeIncrement().isZero())
        return;

    // We may end up propagating a scroll event. It is important that we suspend events until 
    // the end of the function since they could delete the layer, including the marquee.
    FrameView* frameView = m_layer->renderer()->document()->view();
    if (frameView)
        frameView->pauseScheduledEvents();

    if (!m_suspended && !m_stopped) {
        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_timer.startRepeating(speed() * 0.001);

    if (frameView)
        frameView->resumeScheduledEvents();
}

void RenderMarquee::suspend()
{
    m_timer.stop();
    m_suspended = true;
}

void RenderMarquee::stop()
{
    m_timer.stop();
    m_stopped = true;
}

void RenderMarquee::updateMarqueePosition()
{
    bool activate = (m_totalLoops <= 0 || m_currentLoop < m_totalLoops);
    if (activate) {
        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 RenderMarquee::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();
    
    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)
            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);
        }
    }
    
    // Marquee height hack!! Make sure that, if it is a horizontal marquee, the height attribute is overridden 
    // if it is smaller than the font size. If it is a vertical marquee and height is not specified, we default
    // to a marquee of 200px.
    if (isHorizontal()) {
        if (s->height().isFixed() && s->height().value() < s->fontSize())
            s->setHeight(Length(s->fontSize(),Fixed));
    } else if (s->height().isAuto())  //vertical marquee with no specified height
        s->setHeight(Length(200, Fixed)); 
   
    if (speed() != marqueeSpeed()) {
        m_speed = marqueeSpeed();
        if (m_timer.isActive())
            m_timer.startRepeating(speed() * 0.001);
    }
    
    // Check the loop count to see if we should now stop.
    bool activate = (m_totalLoops <= 0 || m_currentLoop < m_totalLoops);
    if (activate && !m_timer.isActive())
        m_layer->renderer()->setNeedsLayout(true);
    else if (!activate && m_timer.isActive())
        m_timer.stop();
}

void RenderMarquee::timerFired(Timer<RenderMarquee>*)
{
    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 (isReversed) {
            // We're going in the reverse direction.
            endPoint = m_start;
            range = -range;
            addIncrement = !addIncrement;
        }
        bool positive = range > 0;
        int clientSize = (isHorizontal() ? m_layer->renderBox()->clientWidth() : m_layer->renderBox()->clientHeight());
        int increment = max(1, abs(m_layer->renderer()->style()->marqueeIncrement().calcValue(clientSize)));
        int currentPos = (isHorizontal() ? m_layer->scrollXOffset() : m_layer->scrollYOffset());
        newPos =  currentPos + (addIncrement ? increment : -increment);
        if (positive)
            newPos = min(newPos, endPoint);
        else
            newPos = max(newPos, endPoint);
    }

    if (newPos == endPoint) {
        m_currentLoop++;
        if (m_totalLoops > 0 && m_currentLoop >= m_totalLoops)
            m_timer.stop();
        else if (s->marqueeBehavior() != MALTERNATE)
            m_reset = true;
    }
    
    if (isHorizontal())
        m_layer->scrollToXOffset(newPos);
    else
        m_layer->scrollToYOffset(newPos);
}

} // namespace WebCore