Mac: Delete now-dead elastic overscroll code

Source/platform/mac/ScrollElasticityController.h

-/*
- * Copyright (C) 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:
- * 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 INC. AND ITS CONTRIBUTORS ``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 INC. OR ITS 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.
- */
-
-#ifndef ScrollElasticityController_h
-#define ScrollElasticityController_h
-
-#if USE(RUBBER_BANDING)
-
-#include "platform/PlatformExport.h"
-#include "platform/geometry/FloatPoint.h"
-#include "platform/geometry/FloatSize.h"
-#include "platform/scroll/ScrollTypes.h"
-#include "wtf/Noncopyable.h"
-
-namespace blink {
-
-class PlatformWheelEvent;
-
-class ScrollElasticityControllerClient {
-protected:
-    virtual ~ScrollElasticityControllerClient() { }
-
-public:
-    virtual bool allowsHorizontalStretching() = 0;
-    virtual bool allowsVerticalStretching() = 0;
-    // The amount that the view is stretched past the normal allowable bounds.
-    // The "overhang" amount.
-    virtual IntSize stretchAmount() = 0;
-    virtual bool pinnedInDirection(const FloatSize&) = 0;
-    virtual bool canScrollHorizontally() = 0;
-    virtual bool canScrollVertically() = 0;
-
-    // Return the absolute scroll position, not relative to the scroll origin.
-    virtual IntPoint absoluteScrollPosition() = 0;
-
-    virtual void immediateScrollBy(const FloatSize&) = 0;
-    virtual void immediateScrollByWithoutContentEdgeConstraints(const FloatSize&) = 0;
-    virtual void startSnapRubberbandTimer() = 0;
-    virtual void stopSnapRubberbandTimer() = 0;
-
-    // If the current scroll position is within the overhang area, this function will cause
-    // the page to scroll to the nearest boundary point.
-    virtual void adjustScrollPositionToBoundsIfNecessary() = 0;
-};
-
-class PLATFORM_EXPORT ScrollElasticityController {
-    WTF_MAKE_NONCOPYABLE(ScrollElasticityController);
-
-public:
-    explicit ScrollElasticityController(ScrollElasticityControllerClient*);
-
-    // This method is responsible for both scrolling and rubber-banding.
-    //
-    // Events are passed by IPC from the embedder. Events on Mac are grouped
-    // into "gestures". If this method returns 'true', then this object has
-    // handled the event. It expects the embedder to continue to forward events
-    // from the gesture.
-    //
-    // This method makes the assumption that there is only 1 input device being
-    // used at a time. If the user simultaneously uses multiple input devices,
-    // Cocoa does not correctly pass all the gestureBegin/End events. The state
-    // of this class is guaranteed to become eventually consistent, once the
-    // user stops using multiple input devices.
-    bool handleWheelEvent(const PlatformWheelEvent&);
-    void snapRubberBandTimerFired();
-
-    bool isRubberBandInProgress() const;
-
-private:
-    void stopSnapRubberbandTimer();
-    void snapRubberBand();
-
-    // This method determines whether a given event should be handled. The
-    // logic for control events of gestures (PhaseBegan, PhaseEnded) is handled
-    // elsewhere.
-    //
-    // This class handles almost all wheel events. All of the following
-    // conditions must be met for this class to ignore an event:
-    // + No previous events in this gesture have caused any scrolling or rubber
-    // banding.
-    // + The event contains a horizontal component.
-    // + The client's view is pinned in the horizontal direction of the event.
-    // + The wheel event disallows rubber banding in the horizontal direction
-    // of the event.
-    bool shouldHandleEvent(const PlatformWheelEvent&);
-
-    ScrollElasticityControllerClient* m_client;
-
-    // There is an active scroll gesture event. This parameter only gets set to
-    // false after the rubber band has been snapped, and before a new gesture
-    // has begun. A careful audit of the code may deprecate the need for this
-    // parameter.
-    bool m_inScrollGesture;
-    // At least one event in the current gesture has been consumed and has
-    // caused the view to scroll or rubber band. All future events in this
-    // gesture will be consumed and overscrolls will cause rubberbanding.
-    bool m_hasScrolled;
-    bool m_momentumScrollInProgress;
-    bool m_ignoreMomentumScrolls;
-
-    CFTimeInterval m_lastMomentumScrollTimestamp;
-    FloatSize m_overflowScrollDelta;
-    FloatSize m_stretchScrollForce;
-    FloatSize m_momentumVelocity;
-
-    // Rubber band state.
-    CFTimeInterval m_startTime;
-    FloatSize m_startStretch;
-    FloatPoint m_origOrigin;
-    FloatSize m_origVelocity;
-
-    bool m_snapRubberbandTimerIsActive;
-};
-
-} // namespace blink
-
-#endif // USE(RUBBER_BANDING)
-
-#endif // ScrollElasticityController_h