/*

 * Copyright (C) 2006, 2007, 2008 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:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. 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.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#include "config.h"

#include "ScrollView.h"

#include "GraphicsContext.h"

#include "HostWindow.h"

#include "PlatformMouseEvent.h"

#include "PlatformWheelEvent.h"

#include "Scrollbar.h"

#include "ScrollbarTheme.h"

#include <wtf/StdLibExtras.h>

using std::max;

namespace WebCore {

ScrollView::ScrollView()

    : m_horizontalScrollbarMode(ScrollbarAuto)

    , m_verticalScrollbarMode(ScrollbarAuto)

    , m_horizontalScrollbarLock(false)

    , m_verticalScrollbarLock(false)

    , m_prohibitsScrolling(false)

    , m_canBlitOnScroll(true)

    , m_scrollbarsAvoidingResizer(0)

    , m_scrollbarsSuppressed(false)

    , m_inUpdateScrollbars(false)

    , m_updateScrollbarsPass(0)

    , m_drawPanScrollIcon(false)

    , m_useFixedLayout(false)

    , m_paintsEntireContents(false)

{

    platformInit();

}

ScrollView::~ScrollView()

{

    platformDestroy();

}

void ScrollView::addChild(PassRefPtr<Widget> prpChild) 

{

    Widget* child = prpChild.get();

    ASSERT(child != this && !child->parent());

    child->setParent(this);

    m_children.add(prpChild);

    if (child->platformWidget())

        platformAddChild(child);

}

void ScrollView::removeChild(Widget* child)

{

    ASSERT(child->parent() == this);

    child->setParent(0);

    m_children.remove(child);

    if (child->platformWidget())

        platformRemoveChild(child);

}

void ScrollView::setHasHorizontalScrollbar(bool hasBar)

{

    if (hasBar && avoidScrollbarCreation())

        return;

    if (hasBar && !m_horizontalScrollbar) {

        m_horizontalScrollbar = createScrollbar(HorizontalScrollbar);

        addChild(m_horizontalScrollbar.get());

        m_horizontalScrollbar->styleChanged();

    } else if (!hasBar && m_horizontalScrollbar) {

        removeChild(m_horizontalScrollbar.get());

        m_horizontalScrollbar = 0;

    }

}

void ScrollView::setHasVerticalScrollbar(bool hasBar)

{

    if (hasBar && avoidScrollbarCreation())

        return;

    if (hasBar && !m_verticalScrollbar) {

        m_verticalScrollbar = createScrollbar(VerticalScrollbar);

        addChild(m_verticalScrollbar.get());

        m_verticalScrollbar->styleChanged();

    } else if (!hasBar && m_verticalScrollbar) {

        removeChild(m_verticalScrollbar.get());

        m_verticalScrollbar = 0;

    }

}

#if !PLATFORM(GTK)

PassRefPtr<Scrollbar> ScrollView::createScrollbar(ScrollbarOrientation orientation)

{

    return Scrollbar::createNativeScrollbar(this, orientation, RegularScrollbar);

}

void ScrollView::setScrollbarModes(ScrollbarMode horizontalMode, ScrollbarMode verticalMode,

                                   bool horizontalLock, bool verticalLock)

{

    bool needsUpdate = false;

    if (horizontalMode != horizontalScrollbarMode() && !m_horizontalScrollbarLock) {

        m_horizontalScrollbarMode = horizontalMode;

        needsUpdate = true;

    }

    if (verticalMode != verticalScrollbarMode() && !m_verticalScrollbarLock) {

        m_verticalScrollbarMode = verticalMode;

        needsUpdate = true;

    }

    if (horizontalLock)

        setHorizontalScrollbarLock();

    if (verticalLock)

        setVerticalScrollbarLock();

    if (!needsUpdate)

        return;

    if (platformWidget())

        platformSetScrollbarModes();

    else

        updateScrollbars(scrollOffset());

}

#endif

void ScrollView::scrollbarModes(ScrollbarMode& horizontalMode, ScrollbarMode& verticalMode) const

{

    if (platformWidget()) {

        platformScrollbarModes(horizontalMode, verticalMode);

        return;

    }

    horizontalMode = m_horizontalScrollbarMode;

    verticalMode = m_verticalScrollbarMode;

}

void ScrollView::setCanHaveScrollbars(bool canScroll)

{

    ScrollbarMode newHorizontalMode;

    ScrollbarMode newVerticalMode;

    scrollbarModes(newHorizontalMode, newVerticalMode);

    if (canScroll && newVerticalMode == ScrollbarAlwaysOff)

        newVerticalMode = ScrollbarAuto;

    else if (!canScroll)

        newVerticalMode = ScrollbarAlwaysOff;

    if (canScroll && newHorizontalMode == ScrollbarAlwaysOff)

        newHorizontalMode = ScrollbarAuto;

    else if (!canScroll)

        newHorizontalMode = ScrollbarAlwaysOff;

    setScrollbarModes(newHorizontalMode, newVerticalMode);

}

void ScrollView::setCanBlitOnScroll(bool b)

{

    if (platformWidget()) {

        platformSetCanBlitOnScroll(b);

        return;

    }

    m_canBlitOnScroll = b;

}

bool ScrollView::canBlitOnScroll() const

{

    if (platformWidget())

        return platformCanBlitOnScroll();

    return m_canBlitOnScroll;

}

void ScrollView::setPaintsEntireContents(bool paintsEntireContents)

{

    m_paintsEntireContents = paintsEntireContents;

}

#if !PLATFORM(GTK)

IntRect ScrollView::visibleContentRect(bool includeScrollbars) const

{

    if (platformWidget())

        return platformVisibleContentRect(includeScrollbars);

    return IntRect(IntPoint(m_scrollOffset.width(), m_scrollOffset.height()),

                   IntSize(max(0, width() - (verticalScrollbar() && !includeScrollbars ? verticalScrollbar()->width() : 0)), 

                           max(0, height() - (horizontalScrollbar() && !includeScrollbars ? horizontalScrollbar()->height() : 0))));

}

#endif

int ScrollView::layoutWidth() const

{

    return m_fixedLayoutSize.isEmpty() || !m_useFixedLayout ? visibleWidth() : m_fixedLayoutSize.width();

}

int ScrollView::layoutHeight() const

{

    return m_fixedLayoutSize.isEmpty() || !m_useFixedLayout ? visibleHeight() : m_fixedLayoutSize.height();

}

IntSize ScrollView::fixedLayoutSize() const

{

    return m_fixedLayoutSize;

}

void ScrollView::setFixedLayoutSize(const IntSize& newSize)

{

    if (fixedLayoutSize() == newSize)

        return;

    m_fixedLayoutSize = newSize;

    updateScrollbars(scrollOffset());

}

bool ScrollView::useFixedLayout() const

{

    return m_useFixedLayout;

}

void ScrollView::setUseFixedLayout(bool enable)

{

    if (useFixedLayout() == enable)

        return;

    m_useFixedLayout = enable;

    updateScrollbars(scrollOffset());

}

IntSize ScrollView::contentsSize() const

{

    if (platformWidget())

        return platformContentsSize();

    return m_contentsSize;

}

void ScrollView::setContentsSize(const IntSize& newSize)

{

    if (contentsSize() == newSize)

        return;

    m_contentsSize = newSize;

    if (platformWidget())

        platformSetContentsSize();

    else

        updateScrollbars(scrollOffset());

}

IntPoint ScrollView::maximumScrollPosition() const

{

    IntSize maximumOffset = contentsSize() - visibleContentRect().size();

    maximumOffset.clampNegativeToZero();

    return IntPoint(maximumOffset.width(), maximumOffset.height());

}

void ScrollView::valueChanged(Scrollbar* scrollbar)

{

    // Figure out if we really moved.

    IntSize newOffset = m_scrollOffset;

    if (scrollbar) {

        if (scrollbar->orientation() == HorizontalScrollbar)

            newOffset.setWidth(scrollbar->value());

        else if (scrollbar->orientation() == VerticalScrollbar)

            newOffset.setHeight(scrollbar->value());

    }

    IntSize scrollDelta = newOffset - m_scrollOffset;

    if (scrollDelta == IntSize())

        return;

    m_scrollOffset = newOffset;

    if (scrollbarsSuppressed())

        return;

    repaintFixedElementsAfterScrolling();

    scrollContents(scrollDelta);

}

void ScrollView::setScrollPosition(const IntPoint& scrollPoint)

{

    if (prohibitsScrolling())

        return;

    if (platformWidget()) {

        platformSetScrollPosition(scrollPoint);

        return;

    }

    IntPoint newScrollPosition = scrollPoint.shrunkTo(maximumScrollPosition());

    newScrollPosition.clampNegativeToZero();

    if (newScrollPosition == scrollPosition())

        return;

    updateScrollbars(IntSize(newScrollPosition.x(), newScrollPosition.y()));

}

bool ScrollView::scroll(ScrollDirection direction, ScrollGranularity granularity)

{

    if (platformWidget())

        return platformScroll(direction, granularity);

    if (direction == ScrollUp || direction == ScrollDown) {

        if (m_verticalScrollbar)

            return m_verticalScrollbar->scroll(direction, granularity);

    } else {

        if (m_horizontalScrollbar)

            return m_horizontalScrollbar->scroll(direction, granularity);

    }

    return false;

}

static const unsigned cMaxUpdateScrollbarsPass = 2;

void ScrollView::updateScrollbars(const IntSize& desiredOffset)

{

    if (m_inUpdateScrollbars || prohibitsScrolling() || platformWidget())

        return;

    // If we came in here with the view already needing a layout, then go ahead and do that

    // first.  (This will be the common case, e.g., when the page changes due to window resizing for example).

    // This layout will not re-enter updateScrollbars and does not count towards our max layout pass total.

    if (!m_scrollbarsSuppressed) {

        m_inUpdateScrollbars = true;

        visibleContentsResized();

        m_inUpdateScrollbars = false;

    }

    bool hasHorizontalScrollbar = m_horizontalScrollbar;

    bool hasVerticalScrollbar = m_verticalScrollbar;

    bool newHasHorizontalScrollbar = hasHorizontalScrollbar;

    bool newHasVerticalScrollbar = hasVerticalScrollbar;

    ScrollbarMode hScroll = m_horizontalScrollbarMode;

    ScrollbarMode vScroll = m_verticalScrollbarMode;

    if (hScroll != ScrollbarAuto)

        newHasHorizontalScrollbar = (hScroll == ScrollbarAlwaysOn);

    if (vScroll != ScrollbarAuto)

        newHasVerticalScrollbar = (vScroll == ScrollbarAlwaysOn);

    if (m_scrollbarsSuppressed || (hScroll != ScrollbarAuto && vScroll != ScrollbarAuto)) {

        if (hasHorizontalScrollbar != newHasHorizontalScrollbar)

            setHasHorizontalScrollbar(newHasHorizontalScrollbar);

        if (hasVerticalScrollbar != newHasVerticalScrollbar)

            setHasVerticalScrollbar(newHasVerticalScrollbar);

    } else {

        bool sendContentResizedNotification = false;

        IntSize docSize = contentsSize();

        IntSize frameSize = frameRect().size();

        if (hScroll == ScrollbarAuto) {

            newHasHorizontalScrollbar = docSize.width() > visibleWidth();

            if (newHasHorizontalScrollbar && !m_updateScrollbarsPass && docSize.width() <= frameSize.width() && docSize.height() <= frameSize.height())

                newHasHorizontalScrollbar = false;

        }

        if (vScroll == ScrollbarAuto) {

            newHasVerticalScrollbar = docSize.height() > visibleHeight();

            if (newHasVerticalScrollbar && !m_updateScrollbarsPass && docSize.width() <= frameSize.width() && docSize.height() <= frameSize.height())

                newHasVerticalScrollbar = false;

        }

        // If we ever turn one scrollbar off, always turn the other one off too.  Never ever

        // try to both gain/lose a scrollbar in the same pass.

        if (!newHasHorizontalScrollbar && hasHorizontalScrollbar && vScroll != ScrollbarAlwaysOn)

            newHasVerticalScrollbar = false;

        if (!newHasVerticalScrollbar && hasVerticalScrollbar && hScroll != ScrollbarAlwaysOn)

            newHasHorizontalScrollbar = false;

        if (hasHorizontalScrollbar != newHasHorizontalScrollbar) {

            setHasHorizontalScrollbar(newHasHorizontalScrollbar);

            sendContentResizedNotification = true;

        }

        if (hasVerticalScrollbar != newHasVerticalScrollbar) {

            setHasVerticalScrollbar(newHasVerticalScrollbar);

            sendContentResizedNotification = true;

        }

        if (sendContentResizedNotification && m_updateScrollbarsPass < cMaxUpdateScrollbarsPass) {

            m_updateScrollbarsPass++;

            contentsResized();

            visibleContentsResized();

            IntSize newDocSize = contentsSize();

            if (newDocSize == docSize) {

                // The layout with the new scroll state had no impact on

                // the document's overall size, so updateScrollbars didn't get called.

                // Recur manually.

                updateScrollbars(desiredOffset);

            }

            m_updateScrollbarsPass--;

        }

    }

    // Set up the range (and page step/line step), but only do this if we're not in a nested call (to avoid

    // doing it multiple times).

    if (m_updateScrollbarsPass)

        return;

    m_inUpdateScrollbars = true;

    IntSize maxScrollPosition(contentsWidth() - visibleWidth(), contentsHeight() - visibleHeight());

    IntSize scroll = desiredOffset.shrunkTo(maxScrollPosition);

    scroll.clampNegativeToZero();

    if (m_horizontalScrollbar) {

        int clientWidth = visibleWidth();

        m_horizontalScrollbar->setEnabled(contentsWidth() > clientWidth);

        int pageStep = max(max<int>(clientWidth * Scrollbar::minFractionToStepWhenPaging(), clientWidth - Scrollbar::maxOverlapBetweenPages()), 1);

        IntRect oldRect(m_horizontalScrollbar->frameRect());

        IntRect hBarRect = IntRect(0,

                                   height() - m_horizontalScrollbar->height(),

                                   width() - (m_verticalScrollbar ? m_verticalScrollbar->width() : 0),

                                   m_horizontalScrollbar->height());

        m_horizontalScrollbar->setFrameRect(hBarRect);

        if (!m_scrollbarsSuppressed && oldRect != m_horizontalScrollbar->frameRect())

            m_horizontalScrollbar->invalidate();

        if (m_scrollbarsSuppressed)

            m_horizontalScrollbar->setSuppressInvalidation(true);

        m_horizontalScrollbar->setSteps(Scrollbar::pixelsPerLineStep(), pageStep);

        m_horizontalScrollbar->setProportion(clientWidth, contentsWidth());

        m_horizontalScrollbar->setValue(scroll.width());

        if (m_scrollbarsSuppressed)

            m_horizontalScrollbar->setSuppressInvalidation(false); 

    } 

    if (m_verticalScrollbar) {

        int clientHeight = visibleHeight();

        m_verticalScrollbar->setEnabled(contentsHeight() > clientHeight);

        int pageStep = max(max<int>(clientHeight * Scrollbar::minFractionToStepWhenPaging(), clientHeight - Scrollbar::maxOverlapBetweenPages()), 1);

        IntRect oldRect(m_verticalScrollbar->frameRect());

        IntRect vBarRect = IntRect(width() - m_verticalScrollbar->width(), 

                                   0,

                                   m_verticalScrollbar->width(),

                                   height() - (m_horizontalScrollbar ? m_horizontalScrollbar->height() : 0));

        m_verticalScrollbar->setFrameRect(vBarRect);

        if (!m_scrollbarsSuppressed && oldRect != m_verticalScrollbar->frameRect())

            m_verticalScrollbar->invalidate();

        if (m_scrollbarsSuppressed)

            m_verticalScrollbar->setSuppressInvalidation(true);

        m_verticalScrollbar->setSteps(Scrollbar::pixelsPerLineStep(), pageStep);

        m_verticalScrollbar->setProportion(clientHeight, contentsHeight());

        m_verticalScrollbar->setValue(scroll.height());

        if (m_scrollbarsSuppressed)

            m_verticalScrollbar->setSuppressInvalidation(false);

    }

    if (hasHorizontalScrollbar != (m_horizontalScrollbar != 0) || hasVerticalScrollbar != (m_verticalScrollbar != 0)) {

        frameRectsChanged();

        updateScrollCorner();

    }

    // See if our offset has changed in a situation where we might not have scrollbars.

    // This can happen when editing a body with overflow:hidden and scrolling to reveal selection.

    // It can also happen when maximizing a window that has scrollbars (but the new maximized result

    // does not).

    IntSize scrollDelta = scroll - m_scrollOffset;

    if (scrollDelta != IntSize()) {

       m_scrollOffset = scroll;

       scrollContents(scrollDelta);

    }

    m_inUpdateScrollbars = false;

}

const int panIconSizeLength = 16;

void ScrollView::scrollContents(const IntSize& scrollDelta)

{

    if (!hostWindow())

        return;

    // Since scrolling is double buffered, we will be blitting the scroll view's intersection

    // with the clip rect every time to keep it smooth.

    IntRect clipRect = windowClipRect();

    IntRect scrollViewRect = convertToContainingWindow(IntRect(0, 0, visibleWidth(), visibleHeight()));

    IntRect updateRect = clipRect;

    updateRect.intersect(scrollViewRect);

    // Invalidate the window (not the backing store).

    hostWindow()->invalidateWindow(updateRect, false /*immediate*/);

    if (m_drawPanScrollIcon) {

        int panIconDirtySquareSizeLength = 2 * (panIconSizeLength + max(abs(scrollDelta.width()), abs(scrollDelta.height()))); // We only want to repaint what's necessary

        IntPoint panIconDirtySquareLocation = IntPoint(m_panScrollIconPoint.x() - (panIconDirtySquareSizeLength / 2), m_panScrollIconPoint.y() - (panIconDirtySquareSizeLength / 2));

        IntRect panScrollIconDirtyRect = IntRect(panIconDirtySquareLocation , IntSize(panIconDirtySquareSizeLength, panIconDirtySquareSizeLength));

        panScrollIconDirtyRect.intersect(clipRect);

        hostWindow()->invalidateContentsAndWindow(panScrollIconDirtyRect, false /*immediate*/);

    }

    if (canBlitOnScroll()) { // The main frame can just blit the WebView window

        // FIXME: Find a way to scroll subframes with this faster path

        if (!scrollContentsFastPath(-scrollDelta, scrollViewRect, clipRect))

            hostWindow()->invalidateContentsForSlowScroll(updateRect, false);

    } else { 

       // We need to go ahead and repaint the entire backing store.  Do it now before moving the

       // windowed plugins.

       hostWindow()->invalidateContentsForSlowScroll(updateRect, false);

    }

    // This call will move children with native widgets (plugins) and invalidate them as well.

    frameRectsChanged();

    // Now blit the backingstore into the window which should be very fast.

    hostWindow()->invalidateWindow(IntRect(), true);