C++ PlatformWheelEvent::granularity方法代码示例

bool ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
{
#if ENABLE(CSS_SCROLL_SNAP) && PLATFORM(MAC)
    if (!m_scrollController.processWheelEventForScrollSnap(e))
        return false;
#endif
#if PLATFORM(COCOA)
    // Events in the PlatformWheelEventPhaseMayBegin phase have no deltas, and therefore never passes through the scroll handling logic below.
    // This causes us to return with an 'unhandled' return state, even though this event was successfully processed.
    //
    // We receive at least one PlatformWheelEventPhaseMayBegin when starting main-thread scrolling (see FrameView::wheelEvent), which can
    // fool the scrolling thread into attempting to handle the scroll, unless we treat the event as handled here.
    if (e.phase() == PlatformWheelEventPhaseMayBegin)
        return true;
#endif

    Scrollbar* horizontalScrollbar = m_scrollableArea.horizontalScrollbar();
    Scrollbar* verticalScrollbar = m_scrollableArea.verticalScrollbar();

    // Accept the event if we have a scrollbar in that direction and can still
    // scroll any further.
    float deltaX = horizontalScrollbar ? e.deltaX() : 0;
    float deltaY = verticalScrollbar ? e.deltaY() : 0;

    bool handled = false;

    ScrollGranularity granularity = ScrollByPixel;
    IntSize maxForwardScrollDelta = m_scrollableArea.maximumScrollPosition() - m_scrollableArea.scrollPosition();
    IntSize maxBackwardScrollDelta = m_scrollableArea.scrollPosition() - m_scrollableArea.minimumScrollPosition();
    if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
        || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
        || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
        handled = true;

        if (deltaY) {
            if (e.granularity() == ScrollByPageWheelEvent) {
                bool negative = deltaY < 0;
                deltaY = Scrollbar::pageStepDelta(m_scrollableArea.visibleHeight());
                if (negative)
                    deltaY = -deltaY;
            }
            scroll(VerticalScrollbar, granularity, verticalScrollbar->pixelStep(), -deltaY);
        }

        if (deltaX) {
            if (e.granularity() == ScrollByPageWheelEvent) {
                bool negative = deltaX < 0;
                deltaX = Scrollbar::pageStepDelta(m_scrollableArea.visibleWidth());
                if (negative)
                    deltaX = -deltaX;
            }
            scroll(HorizontalScrollbar, granularity, horizontalScrollbar->pixelStep(), -deltaX);
        }
    }
    return handled;
}

bool ScrollAnimator::handleWheelEvent(const PlatformWheelEvent& e)
{
    bool canScrollX = m_scrollableArea->userInputScrollable(HorizontalScrollbar);
    bool canScrollY = m_scrollableArea->userInputScrollable(VerticalScrollbar);

    // Accept the event if we are scrollable in that direction and can still
    // scroll any further.
    float deltaX = canScrollX ? e.deltaX() : 0;
    float deltaY = canScrollY ? e.deltaY() : 0;

    bool handled = false;

#if !OS(MACOSX)
    ScrollGranularity granularity = e.hasPreciseScrollingDeltas() ? ScrollByPrecisePixel : ScrollByPixel;
#else
    ScrollGranularity granularity = ScrollByPixel;
#endif

    IntSize maxForwardScrollDelta = m_scrollableArea->maximumScrollPosition() - m_scrollableArea->scrollPosition();
    IntSize maxBackwardScrollDelta = m_scrollableArea->scrollPosition() - m_scrollableArea->minimumScrollPosition();
    if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
        || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
        || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
        handled = true;

        if (deltaY) {
            if (e.granularity() == ScrollByPageWheelEvent) {
                bool negative = deltaY < 0;
                deltaY = m_scrollableArea->pageStep(VerticalScrollbar);
                if (negative)
                    deltaY = -deltaY;
            }

            scroll(VerticalScrollbar, granularity, m_scrollableArea->pixelStep(VerticalScrollbar), -deltaY);
        }

        if (deltaX) {
            if (e.granularity() == ScrollByPageWheelEvent) {
                bool negative = deltaX < 0;
                deltaX = m_scrollableArea->pageStep(HorizontalScrollbar);
                if (negative)
                    deltaX = -deltaX;
            }

            scroll(HorizontalScrollbar, granularity, m_scrollableArea->pixelStep(HorizontalScrollbar), -deltaX);
        }
    }
    return handled;
}

void ScrollAnimator::handleWheelEvent(PlatformWheelEvent& e)
{
    Scrollbar* horizontalScrollbar = m_scrollableArea->horizontalScrollbar();
    Scrollbar* verticalScrollbar = m_scrollableArea->verticalScrollbar();

    // Accept the event if we have a scrollbar in that direction and can still
    // scroll any further.
    float deltaX = horizontalScrollbar ? e.deltaX() : 0;
    float deltaY = verticalScrollbar ? e.deltaY() : 0;

    IntSize maxForwardScrollDelta = m_scrollableArea->maximumScrollPosition() - m_scrollableArea->scrollPosition();
    IntSize maxBackwardScrollDelta = m_scrollableArea->scrollPosition() - m_scrollableArea->minimumScrollPosition();
    if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
        || (deltaX > 0 && maxBackwardScrollDelta.width() > 0)
        || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
        e.accept();
        if (e.granularity() == ScrollByPageWheelEvent) {
            ASSERT(!e.deltaX());
            bool negative = deltaY < 0;
            deltaY = max(max(static_cast<float>(m_scrollableArea->visibleHeight()) * Scrollbar::minFractionToStepWhenPaging(), static_cast<float>(m_scrollableArea->visibleHeight() - Scrollbar::maxOverlapBetweenPages())), 1.0f);
            if (negative)
                deltaY = -deltaY;
        }

        if (deltaY)
            scroll(VerticalScrollbar, ScrollByPixel, verticalScrollbar->pixelStep(), -deltaY);
        if (deltaX)
            scroll(HorizontalScrollbar, ScrollByPixel, horizontalScrollbar->pixelStep(), -deltaX);
    }
}

void EventTargetNode::dispatchWheelEvent(PlatformWheelEvent& e)
{
    ASSERT(!eventDispatchForbidden());
    if (e.deltaX() == 0 && e.deltaY() == 0)
        return;
    
    FrameView* view = document()->view();
    if (!view)
        return;
    
    IntPoint pos = view->windowToContents(e.pos());
    
    // Convert the deltas from pixels to lines if we have a pixel scroll event.
    float deltaX = e.deltaX();
    float deltaY = e.deltaY();
    
    // FIXME: Should we do anything with a ScrollByPageWheelEvent here?
    // It will be treated like a line scroll of 1 right now.
    if (e.granularity() == ScrollByPixelWheelEvent) {
        deltaX /= cMouseWheelPixelsPerLineStep;
        deltaY /= cMouseWheelPixelsPerLineStep;
    }

    RefPtr<WheelEvent> we = WheelEvent::create(e.deltaX(), e.deltaY(),
        document()->defaultView(), e.globalX(), e.globalY(), pos.x(), pos.y(),
        e.ctrlKey(), e.altKey(), e.shiftKey(), e.metaKey());
    ExceptionCode ec = 0;
    if (!dispatchEvent(we.release(), ec))
        e.accept();
}

void ScrollView::wheelEvent(PlatformWheelEvent& e)
{
    // We don't allow mouse wheeling to happen in a ScrollView that has had its scrollbars explicitly disabled.
#if PLATFORM(WX)
    if (!canHaveScrollbars()) {
#else
    if (!canHaveScrollbars() || platformWidget()) {
#endif
        return;
    }

    // Accept the event if we have a scrollbar in that direction and can still
    // scroll any further.
    float deltaX = m_horizontalScrollbar ? e.deltaX() : 0;
    float deltaY = m_verticalScrollbar ? e.deltaY() : 0;
    IntSize maxForwardScrollDelta = maximumScrollPosition() - scrollPosition();
    IntSize maxBackwardScrollDelta = scrollPosition() - minimumScrollPosition();
    if ((deltaX < 0 && maxForwardScrollDelta.width() > 0)
        || (deltaX > 0 && maxBackwardScrollDelta.width() >0)
        || (deltaY < 0 && maxForwardScrollDelta.height() > 0)
        || (deltaY > 0 && maxBackwardScrollDelta.height() > 0)) {
        e.accept();
        if (e.granularity() == ScrollByPageWheelEvent) {
            ASSERT(!e.deltaX());
            bool negative = deltaY < 0;
            deltaY = max(max(static_cast<float>(visibleHeight()) * Scrollbar::minFractionToStepWhenPaging(), static_cast<float>(visibleHeight() - Scrollbar::maxOverlapBetweenPages())), 1.0f);
            if (negative)
                deltaY = -deltaY;
        }

        if (deltaY)
            m_verticalScrollbar->scroll(ScrollUp, ScrollByPixel, deltaY);
        if (deltaX)
            m_horizontalScrollbar->scroll(ScrollLeft, ScrollByPixel, deltaX);
    }
}

void ScrollView::setFrameRect(const IntRect& newRect)
{
    IntRect oldRect = frameRect();
    
    if (newRect == oldRect)
        return;

    Widget::setFrameRect(newRect);

    if (platformWidget())
        return;
    
    if (newRect.width() != oldRect.width() || newRect.height() != oldRect.height()) {
        updateScrollbars(m_scrollOffset);
        if (!m_useFixedLayout)
            contentsResized();
    }

    frameRectsChanged();
}

void ScrollView::wheelEvent(PlatformWheelEvent& e)
{
    // We don't allow mouse wheeling to happen in a ScrollView that has had its scrollbars explicitly disabled.
#if PLATFORM(WX)
    if (!canHaveScrollbars()) {
#else
    if (!canHaveScrollbars() || platformWidget()) {
#endif
        return;
    }

    // Determine how much we want to scroll.  If we can move at all, we will accept the event.
    IntSize maxScrollDelta = maximumScrollPosition() - scrollPosition();
    if ((e.deltaX() < 0 && maxScrollDelta.width() > 0) ||
        (e.deltaX() > 0 && scrollOffset().width() > 0) ||
        (e.deltaY() < 0 && maxScrollDelta.height() > 0) ||
        (e.deltaY() > 0 && scrollOffset().height() > 0)) {
        e.accept();
        float deltaX = e.deltaX();
        float deltaY = e.deltaY();
        if (e.granularity() == ScrollByPageWheelEvent) {
            ASSERT(deltaX == 0);
            bool negative = deltaY < 0;
            deltaY = max(max(static_cast<float>(visibleHeight()) * Scrollbar::minFractionToStepWhenPaging(), static_cast<float>(visibleHeight() - Scrollbar::maxOverlapBetweenPages())), 1.0f);
            if (negative)
                deltaY = -deltaY;
        }

        // Should we fall back on scrollBy() if there is no scrollbar for a non-zero delta?
        if (deltaY && m_verticalScrollbar)
            m_verticalScrollbar->scroll(ScrollUp, ScrollByPixel, deltaY);
        if (deltaX && m_horizontalScrollbar)
            m_horizontalScrollbar->scroll(ScrollLeft, ScrollByPixel, deltaX);
    }
}

void ScrollView::setFrameRect(const IntRect& newRect)
{
    IntRect oldRect = frameRect();
    
    if (newRect == oldRect)
        return;

    Widget::setFrameRect(newRect);

    if (platformWidget())
        return;
    
    if (newRect.width() != oldRect.width() || newRect.height() != oldRect.height()) {
        updateScrollbars(m_scrollOffset);
        if (!m_useFixedLayout)
            contentsResized();
    }

    frameRectsChanged();
}

void ScrollView::wheelEvent(PlatformWheelEvent& e)
{
    // We don't allow mouse wheeling to happen in a ScrollView that has had its scrollbars explicitly disabled.
#if PLATFORM(WX)
    if (!canHaveScrollbars()) {
#else
    if (!canHaveScrollbars() || platformWidget()) {
#endif
        return;
    }

    // Determine how much we want to scroll.  If we can move at all, we will accept the event.
    IntSize maxScrollDelta = maximumScrollPosition() - scrollPosition();
    if ((e.deltaX() < 0 && maxScrollDelta.width() > 0) ||
        (e.deltaX() > 0 && scrollOffset().width() > 0) ||
        (e.deltaY() < 0 && maxScrollDelta.height() > 0) ||
        (e.deltaY() > 0 && scrollOffset().height() > 0)) {
        e.accept();
        float deltaX = e.deltaX();
        float deltaY = e.deltaY();
        if (e.granularity() == ScrollByPageWheelEvent) {
            ASSERT(deltaX == 0);
            bool negative = deltaY < 0;
            deltaY = max(max<int>(visibleHeight() * Scrollbar::minFractionToStepWhenPaging(), visibleHeight() - Scrollbar::maxOverlapBetweenPages()), 1);
            if (negative)
                deltaY = -deltaY;
        }
        scrollBy(IntSize(-deltaX, -deltaY));
    }
}

void ScrollView::setFrameRect(const IntRect& newRect)
{
    IntRect oldRect = frameRect();
    
    if (newRect == oldRect)
        return;

    Widget::setFrameRect(newRect);

    if (platformWidget())
        return;
    

    if (newRect.width() != oldRect.width() || newRect.height() != oldRect.height()) {
        updateScrollbars(m_scrollOffset);
        contentsResized();
    }

    frameRectsChanged();
}

ScrollResult RootFrameViewport::handleWheel(const PlatformWheelEvent& event)
{
    updateScrollAnimator();

    ScrollableArea& primary = !m_invertScrollOrder ? layoutViewport() : visualViewport();
    ScrollableArea& secondary = !m_invertScrollOrder ? visualViewport() : layoutViewport();

    ScrollResult viewScrollResult = primary.handleWheel(event);

    // The visual viewport will only accept pixel scrolls.
    if (!event.canScroll() || event.granularity() == ScrollByPageWheelEvent)
        return viewScrollResult;

    // TODO(sataya.m) : The delta in PlatformWheelEvent is negative when scrolling the
    // wheel towards the user, so negate it to get the scroll delta that should be applied
    // to the page. unusedScrollDelta computed in the ScrollResult is also negative. Say
    // there is WheelEvent({0, -10} and page scroll by 2px and unusedScrollDelta computed
    // is {0, -8}. Due to which we have to negate the unusedScrollDelta to obtain the expected
    // animation.Please address http://crbug.com/504389.
    DoublePoint oldOffset = secondary.scrollPositionDouble();
    DoublePoint locationDelta;
    if (viewScrollResult.didScroll()) {
        locationDelta = -DoublePoint(viewScrollResult.unusedScrollDeltaX, viewScrollResult.unusedScrollDeltaY);
    } else {
        if (event.railsMode() != PlatformEvent::RailsModeVertical)
            locationDelta.setX(-event.deltaX());
        if (event.railsMode() != PlatformEvent::RailsModeHorizontal)
            locationDelta.setY(-event.deltaY());
    }

    DoublePoint targetPosition = secondary.clampScrollPosition(
        secondary.scrollPositionDouble() + toDoubleSize(locationDelta));
    secondary.setScrollPosition(targetPosition, UserScroll);

    DoublePoint usedLocationDelta(secondary.scrollPositionDouble() - oldOffset);

    bool didScrollX = viewScrollResult.didScrollX || usedLocationDelta.x();
    bool didScrollY = viewScrollResult.didScrollY || usedLocationDelta.y();
    return ScrollResult(didScrollX, didScrollY, -viewScrollResult.unusedScrollDeltaX - usedLocationDelta.x(), -viewScrollResult.unusedScrollDeltaY - usedLocationDelta.y());
}

inline static unsigned deltaMode(const PlatformWheelEvent& event)
{
    return event.granularity() == ScrollByPageWheelEvent ? WheelEvent::DOM_DELTA_PAGE : WheelEvent::DOM_DELTA_PIXEL;
}

inline static WheelEvent::Granularity granularity(const PlatformWheelEvent& event)
{
    return event.granularity() == ScrollByPageWheelEvent ? WheelEvent::Page : WheelEvent::Pixel;
}