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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_RENDERER_INPUT_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_
#define CONTENT_RENDERER_INPUT_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_
#include "base/macros.h"
#include "base/time/time.h"
#include "third_party/WebKit/public/web/WebInputEvent.h"
#include "ui/gfx/geometry/vector2d_f.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.
*/
namespace content {
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 gfx::Vector2dF StretchAmount() = 0;
virtual bool PinnedInDirection(const gfx::Vector2dF& direction) = 0;
virtual bool CanScrollHorizontally() = 0;
virtual bool CanScrollVertically() = 0;
// Return the absolute scroll position, not relative to the scroll origin.
virtual gfx::Vector2dF AbsoluteScrollPosition() = 0;
virtual void ImmediateScrollBy(const gfx::Vector2dF& scroll) = 0;
virtual void ImmediateScrollByWithoutContentEdgeConstraints(const gfx::Vector2dF& scroll) = 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 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 blink::WebMouseWheelEvent& wheel_event);
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 blink::WebMouseWheelEvent& wheel_event);
ScrollElasticityControllerClient* 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 in_scroll_gesture_;
// 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 has_scrolled_;
bool momentum_scroll_in_progress_;
bool ignore_momentum_scrolls_;
// Used with blink::WebInputEvent::timeStampSeconds, in seconds since epoch.
double last_momentum_scroll_timestamp_;
gfx::Vector2dF overflow_scroll_delta_;
gfx::Vector2dF stretch_scroll_force_;
gfx::Vector2dF momentum_velocity_;
// Rubber band state.
base::Time start_time_;
gfx::Vector2dF start_stretch_;
gfx::Vector2dF orig_origin_;
gfx::Vector2dF orig_velocity_;
bool snap_rubberband_timer_is_active_;
DISALLOW_COPY_AND_ASSIGN(ScrollElasticityController);
};
} // namespace content
#endif // CONTENT_RENDERER_INPUT_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_
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