/*
 * Copyright (c) 2010, Google Inc. All rights reserved.
 * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "platform/scroll/ScrollableArea.h"

#include "platform/graphics/GraphicsLayer.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/scroll//ScrollbarTheme.h"
#include "wtf/PassOwnPtr.h"

#include "platform/TraceEvent.h"

static const int kPixelsPerLineStep = 40;
static const float kMinFractionToStepWhenPaging = 0.875f;

namespace WebCore {

struct SameSizeAsScrollableArea {
    virtual ~SameSizeAsScrollableArea();
    void* pointer;
    unsigned bitfields : 16;
    IntPoint origin;
};

COMPILE_ASSERT(sizeof(ScrollableArea) == sizeof(SameSizeAsScrollableArea), ScrollableArea_should_stay_small);

int ScrollableArea::pixelsPerLineStep()
{
    return kPixelsPerLineStep;
}

float ScrollableArea::minFractionToStepWhenPaging()
{
    return kMinFractionToStepWhenPaging;
}

int ScrollableArea::maxOverlapBetweenPages()
{
    static int maxOverlapBetweenPages = ScrollbarTheme::theme()->maxOverlapBetweenPages();
    return maxOverlapBetweenPages;
}

ScrollableArea::ScrollableArea()
    : m_constrainsScrollingToContentEdge(true)
    , m_inLiveResize(false)
    , m_verticalScrollElasticity(ScrollElasticityNone)
    , m_horizontalScrollElasticity(ScrollElasticityNone)
    , m_scrollbarOverlayStyle(ScrollbarOverlayStyleDefault)
    , m_scrollOriginChanged(false)
{
}

ScrollableArea::~ScrollableArea()
{
}

ScrollAnimator* ScrollableArea::scrollAnimator() const
{
    if (!m_scrollAnimator)
        m_scrollAnimator = ScrollAnimator::create(const_cast<ScrollableArea*>(this));

    return m_scrollAnimator.get();
}

void ScrollableArea::setScrollOrigin(const IntPoint& origin)
{
    if (m_scrollOrigin != origin) {
        m_scrollOrigin = origin;
        m_scrollOriginChanged = true;
    }
}

bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granularity, float multiplier)
{
    ScrollbarOrientation orientation;

    if (direction == ScrollUp || direction == ScrollDown)
        orientation = VerticalScrollbar;
    else
        orientation = HorizontalScrollbar;

    if (!userInputScrollable(orientation))
        return false;

    float step = 0;
    switch (granularity) {
    case ScrollByLine:
        step = lineStep(orientation);
        break;
    case ScrollByPage:
        step = pageStep(orientation);
        break;
    case ScrollByDocument:
        step = documentStep(orientation);
        break;
    case ScrollByPixel:
    case ScrollByPrecisePixel:
        step = pixelStep(orientation);
        break;
    }

    if (direction == ScrollUp || direction == ScrollLeft)
        multiplier = -multiplier;

    return scrollAnimator()->scroll(orientation, granularity, step, multiplier);
}

void ScrollableArea::scrollToOffsetWithoutAnimation(const FloatPoint& offset)
{
    scrollAnimator()->scrollToOffsetWithoutAnimation(offset);
}

void ScrollableArea::scrollToOffsetWithoutAnimation(ScrollbarOrientation orientation, float offset)
{
    if (orientation == HorizontalScrollbar)
        scrollToOffsetWithoutAnimation(FloatPoint(offset, scrollAnimator()->currentPosition().y()));
    else
        scrollToOffsetWithoutAnimation(FloatPoint(scrollAnimator()->currentPosition().x(), offset));
}

void ScrollableArea::notifyScrollPositionChanged(const IntPoint& position)
{
    scrollPositionChanged(position);
    scrollAnimator()->setCurrentPosition(position);
}

void ScrollableArea::scrollPositionChanged(const IntPoint& position)
{
    TRACE_EVENT0("webkit", "ScrollableArea::scrollPositionChanged");

    IntPoint oldPosition = scrollPosition();
    // Tell the derived class to scroll its contents.
    setScrollOffset(position);

    Scrollbar* verticalScrollbar = this->verticalScrollbar();

    // Tell the scrollbars to update their thumb postions.
    if (Scrollbar* horizontalScrollbar = this->horizontalScrollbar()) {
        horizontalScrollbar->offsetDidChange();
        if (horizontalScrollbar->isOverlayScrollbar() && !hasLayerForHorizontalScrollbar()) {
            if (!verticalScrollbar)
                horizontalScrollbar->invalidate();
            else {
                // If there is both a horizontalScrollbar and a verticalScrollbar,
                // then we must also invalidate the corner between them.
                IntRect boundsAndCorner = horizontalScrollbar->boundsRect();
                boundsAndCorner.setWidth(boundsAndCorner.width() + verticalScrollbar->width());
                horizontalScrollbar->invalidateRect(boundsAndCorner);
            }
        }
    }
    if (verticalScrollbar) {
        verticalScrollbar->offsetDidChange();
        if (verticalScrollbar->isOverlayScrollbar() && !hasLayerForVerticalScrollbar())
            verticalScrollbar->invalidate();
    }

    if (scrollPosition() != oldPosition)
        scrollAnimator()->notifyContentAreaScrolled(scrollPosition() - oldPosition);
}

bool ScrollableArea::handleWheelEvent(const PlatformWheelEvent& wheelEvent)
{
    return scrollAnimator()->handleWheelEvent(wheelEvent);
}

// NOTE: Only called from Internals for testing.
void ScrollableArea::setScrollOffsetFromInternals(const IntPoint& offset)
{
    setScrollOffsetFromAnimation(offset);
}

void ScrollableArea::setScrollOffsetFromAnimation(const IntPoint& offset)
{
    scrollPositionChanged(offset);
}

void ScrollableArea::willStartLiveResize()
{
    if (m_inLiveResize)
        return;
    m_inLiveResize = true;
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->willStartLiveResize();
}

void ScrollableArea::willEndLiveResize()
{
    if (!m_inLiveResize)
        return;
    m_inLiveResize = false;
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->willEndLiveResize();
}

void ScrollableArea::contentAreaWillPaint() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->contentAreaWillPaint();
}

void ScrollableArea::mouseEnteredContentArea() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->mouseEnteredContentArea();
}

void ScrollableArea::mouseExitedContentArea() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->mouseEnteredContentArea();
}

void ScrollableArea::mouseMovedInContentArea() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->mouseMovedInContentArea();
}

void ScrollableArea::mouseEnteredScrollbar(Scrollbar* scrollbar) const
{
    scrollAnimator()->mouseEnteredScrollbar(scrollbar);
}

void ScrollableArea::mouseExitedScrollbar(Scrollbar* scrollbar) const
{
    scrollAnimator()->mouseExitedScrollbar(scrollbar);
}

void ScrollableArea::contentAreaDidShow() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->contentAreaDidShow();
}

void ScrollableArea::contentAreaDidHide() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->contentAreaDidHide();
}

void ScrollableArea::finishCurrentScrollAnimations() const
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->finishCurrentScrollAnimations();
}

void ScrollableArea::didAddScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
{
    if (orientation == VerticalScrollbar)
        scrollAnimator()->didAddVerticalScrollbar(scrollbar);
    else
        scrollAnimator()->didAddHorizontalScrollbar(scrollbar);

    // <rdar://problem/9797253> AppKit resets the scrollbar's style when you attach a scrollbar
    setScrollbarOverlayStyle(scrollbarOverlayStyle());
}

void ScrollableArea::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
{
    if (orientation == VerticalScrollbar)
        scrollAnimator()->willRemoveVerticalScrollbar(scrollbar);
    else
        scrollAnimator()->willRemoveHorizontalScrollbar(scrollbar);
}

void ScrollableArea::contentsResized()
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->contentsResized();
}

bool ScrollableArea::hasOverlayScrollbars() const
{
    return (verticalScrollbar() && verticalScrollbar()->isOverlayScrollbar())
        || (horizontalScrollbar() && horizontalScrollbar()->isOverlayScrollbar());
}

void ScrollableArea::setScrollbarOverlayStyle(ScrollbarOverlayStyle overlayStyle)
{
    m_scrollbarOverlayStyle = overlayStyle;

    if (horizontalScrollbar()) {
        ScrollbarTheme::theme()->updateScrollbarOverlayStyle(horizontalScrollbar());
        horizontalScrollbar()->invalidate();
    }

    if (verticalScrollbar()) {
        ScrollbarTheme::theme()->updateScrollbarOverlayStyle(verticalScrollbar());
        verticalScrollbar()->invalidate();
    }
}

void ScrollableArea::invalidateScrollbar(Scrollbar* scrollbar, const IntRect& rect)
{
    if (scrollbar == horizontalScrollbar()) {
        if (GraphicsLayer* graphicsLayer = layerForHorizontalScrollbar()) {
            graphicsLayer->setNeedsDisplay();
            graphicsLayer->setContentsNeedsDisplay();
            return;
        }
    } else if (scrollbar == verticalScrollbar()) {
        if (GraphicsLayer* graphicsLayer = layerForVerticalScrollbar()) {
            graphicsLayer->setNeedsDisplay();
            graphicsLayer->setContentsNeedsDisplay();
            return;
        }
    }
    invalidateScrollbarRect(scrollbar, rect);
}

void ScrollableArea::invalidateScrollCorner(const IntRect& rect)
{
    if (GraphicsLayer* graphicsLayer = layerForScrollCorner()) {
        graphicsLayer->setNeedsDisplay();
        return;
    }
    invalidateScrollCornerRect(rect);
}

bool ScrollableArea::hasLayerForHorizontalScrollbar() const
{
    return layerForHorizontalScrollbar();
}

bool ScrollableArea::hasLayerForVerticalScrollbar() const
{
    return layerForVerticalScrollbar();
}

bool ScrollableArea::hasLayerForScrollCorner() const
{
    return layerForScrollCorner();
}

void ScrollableArea::serviceScrollAnimations()
{
    if (ScrollAnimator* scrollAnimator = existingScrollAnimator())
        scrollAnimator->serviceScrollAnimations();
}

IntRect ScrollableArea::visibleContentRect(IncludeScrollbarsInRect scrollbarInclusion) const
{
    int verticalScrollbarWidth = 0;
    int horizontalScrollbarHeight = 0;

    if (scrollbarInclusion == IncludeScrollbars) {
        if (Scrollbar* verticalBar = verticalScrollbar())
            verticalScrollbarWidth = !verticalBar->isOverlayScrollbar() ? verticalBar->width() : 0;
        if (Scrollbar* horizontalBar = horizontalScrollbar())
            horizontalScrollbarHeight = !horizontalBar->isOverlayScrollbar() ? horizontalBar->height() : 0;
    }

    return IntRect(scrollPosition().x(),
                   scrollPosition().y(),
                   std::max(0, visibleWidth() + verticalScrollbarWidth),
                   std::max(0, visibleHeight() + horizontalScrollbarHeight));
}

IntPoint ScrollableArea::clampScrollPosition(const IntPoint& scrollPosition) const
{
    return scrollPosition.shrunkTo(maximumScrollPosition()).expandedTo(minimumScrollPosition());
}

int ScrollableArea::lineStep(ScrollbarOrientation) const
{
    return pixelsPerLineStep();
}

int ScrollableArea::documentStep(ScrollbarOrientation orientation) const
{
    return scrollSize(orientation);
}

float ScrollableArea::pixelStep(ScrollbarOrientation) const
{
    return 1;
}

} // namespace WebCore