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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 "platform/PlatformExport.h"
     35 #include "platform/PlatformWheelEvent.h"
     36 #include "platform/geometry/FloatSize.h"
     37 #include "platform/scroll/ScrollTypes.h"
     38 #include "wtf/FastAllocBase.h"
     39 #include "wtf/Forward.h"
     40 #include "wtf/Noncopyable.h"
     41 
     42 namespace blink {
     43 
     44 class FloatPoint;
     45 class ScrollableArea;
     46 class Scrollbar;
     47 
     48 class PLATFORM_EXPORT ScrollAnimator {
     49     WTF_MAKE_FAST_ALLOCATED; WTF_MAKE_NONCOPYABLE(ScrollAnimator);
     50 public:
     51     static PassOwnPtr<ScrollAnimator> create(ScrollableArea*);
     52 
     53     virtual ~ScrollAnimator();
     54 
     55     // Computes a scroll destination for the given parameters.  Returns false if
     56     // already at the destination.  Otherwise, starts scrolling towards the
     57     // destination and returns true.  Scrolling may be immediate or animated.
     58     // The base class implementation always scrolls immediately, never animates.
     59     virtual bool scroll(ScrollbarOrientation, ScrollGranularity, float step, float delta);
     60 
     61     virtual void scrollToOffsetWithoutAnimation(const FloatPoint&);
     62 
     63     ScrollableArea* scrollableArea() const { return m_scrollableArea; }
     64 
     65     virtual void setIsActive() { }
     66 
     67     virtual bool handleWheelEvent(const PlatformWheelEvent&);
     68 
     69 #if OS(MACOSX)
     70     virtual void handleWheelEventPhase(PlatformWheelEventPhase) { }
     71 #endif
     72 
     73     void setCurrentPosition(const FloatPoint&);
     74     FloatPoint currentPosition() const;
     75 
     76     virtual void cancelAnimations() { }
     77     virtual void serviceScrollAnimations() { }
     78 
     79     virtual void contentAreaWillPaint() const { }
     80     virtual void mouseEnteredContentArea() const { }
     81     virtual void mouseExitedContentArea() const { }
     82     virtual void mouseMovedInContentArea() const { }
     83     virtual void mouseEnteredScrollbar(Scrollbar*) const { }
     84     virtual void mouseExitedScrollbar(Scrollbar*) const { }
     85     virtual void willStartLiveResize() { }
     86     virtual void contentsResized() const { }
     87     virtual void willEndLiveResize() { }
     88     virtual void contentAreaDidShow() const { }
     89     virtual void contentAreaDidHide() const { }
     90 
     91     virtual void finishCurrentScrollAnimations() { }
     92 
     93     virtual void didAddVerticalScrollbar(Scrollbar*) { }
     94     virtual void willRemoveVerticalScrollbar(Scrollbar*) { }
     95     virtual void didAddHorizontalScrollbar(Scrollbar*) { }
     96     virtual void willRemoveHorizontalScrollbar(Scrollbar*) { }
     97 
     98     virtual bool shouldScrollbarParticipateInHitTesting(Scrollbar*) { return true; }
     99 
    100     virtual void notifyContentAreaScrolled(const FloatSize&) { }
    101 
    102     virtual bool isRubberBandInProgress() const { return false; }
    103 
    104 protected:
    105     explicit ScrollAnimator(ScrollableArea*);
    106 
    107     virtual void notifyPositionChanged();
    108 
    109     ScrollableArea* m_scrollableArea;
    110     float m_currentPosX; // We avoid using a FloatPoint in order to reduce
    111     float m_currentPosY; // subclass code complexity.
    112 
    113 private:
    114     float clampScrollPosition(ScrollbarOrientation, float);
    115 };
    116 
    117 } // namespace blink
    118 
    119 #endif // ScrollAnimator_h
    120