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      1 /*
      2  * Copyright (c) 2010, Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef ScrollAnimator_h
     32 #define ScrollAnimator_h
     33 
     34 #include "core/platform/PlatformWheelEvent.h"
     35 #include "core/platform/ScrollTypes.h"
     36 #include "core/platform/graphics/FloatSize.h"
     37 #include "wtf/FastAllocBase.h"
     38 #include "wtf/Forward.h"
     39 #include "wtf/UnusedParam.h"
     40 
     41 namespace WebCore {
     42 
     43 class FloatPoint;
     44 class ScrollableArea;
     45 class Scrollbar;
     46 
     47 class ScrollAnimator {
     48     WTF_MAKE_FAST_ALLOCATED;
     49 public:
     50     static PassOwnPtr<ScrollAnimator> create(ScrollableArea*);
     51 
     52     virtual ~ScrollAnimator();
     53 
     54     // Computes a scroll destination for the given parameters.  Returns false if
     55     // already at the destination.  Otherwise, starts scrolling towards the
     56     // destination and returns true.  Scrolling may be immediate or animated.
     57     // The base class implementation always scrolls immediately, never animates.
     58     virtual bool scroll(ScrollbarOrientation, ScrollGranularity, float step, float multiplier);
     59 
     60     virtual void scrollToOffsetWithoutAnimation(const FloatPoint&);
     61 
     62     ScrollableArea* scrollableArea() const { return m_scrollableArea; }
     63 
     64     virtual void setIsActive() { }
     65 
     66     virtual bool handleWheelEvent(const PlatformWheelEvent&);
     67 
     68 #if OS(DARWIN)
     69     virtual void handleWheelEventPhase(PlatformWheelEventPhase) { }
     70 #endif
     71 
     72     void setCurrentPosition(const FloatPoint&);
     73     FloatPoint currentPosition() const;
     74 
     75     virtual void cancelAnimations() { }
     76     virtual void serviceScrollAnimations() { }
     77 
     78     virtual void contentAreaWillPaint() const { }
     79     virtual void mouseEnteredContentArea() const { }
     80     virtual void mouseExitedContentArea() const { }
     81     virtual void mouseMovedInContentArea() const { }
     82     virtual void mouseEnteredScrollbar(Scrollbar*) const { }
     83     virtual void mouseExitedScrollbar(Scrollbar*) const { }
     84     virtual void willStartLiveResize() { }
     85     virtual void contentsResized() const { }
     86     virtual void willEndLiveResize() { }
     87     virtual void contentAreaDidShow() const { }
     88     virtual void contentAreaDidHide() const { }
     89 
     90     virtual void finishCurrentScrollAnimations() { }
     91 
     92     virtual void didAddVerticalScrollbar(Scrollbar*) { }
     93     virtual void willRemoveVerticalScrollbar(Scrollbar*) { }
     94     virtual void didAddHorizontalScrollbar(Scrollbar*) { }
     95     virtual void willRemoveHorizontalScrollbar(Scrollbar*) { }
     96 
     97     virtual bool shouldScrollbarParticipateInHitTesting(Scrollbar*) { return true; }
     98 
     99     virtual void notifyContentAreaScrolled(const FloatSize& delta) { UNUSED_PARAM(delta); }
    100 
    101     virtual bool isRubberBandInProgress() const { return false; }
    102 
    103 protected:
    104     explicit ScrollAnimator(ScrollableArea*);
    105 
    106     virtual void notifyPositionChanged(const FloatSize& delta);
    107 
    108     ScrollableArea* m_scrollableArea;
    109     float m_currentPosX; // We avoid using a FloatPoint in order to reduce
    110     float m_currentPosY; // subclass code complexity.
    111 
    112 private:
    113     float clampScrollPosition(ScrollbarOrientation, float);
    114 };
    115 
    116 } // namespace WebCore
    117 
    118 #endif // ScrollAnimator_h
    119