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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_CHILD_TOUCH_FLING_GESTURE_CURVE_H_
      6 #define CONTENT_CHILD_TOUCH_FLING_GESTURE_CURVE_H_
      7 
      8 #include "content/common/content_export.h"
      9 #include "third_party/WebKit/public/platform/WebFloatPoint.h"
     10 #include "third_party/WebKit/public/platform/WebFloatSize.h"
     11 #include "third_party/WebKit/public/platform/WebGestureCurve.h"
     12 #include "third_party/WebKit/public/platform/WebSize.h"
     13 
     14 namespace blink {
     15 class WebGestureCurveTarget;
     16 }
     17 
     18 namespace content {
     19 
     20 // Implementation of WebGestureCurve suitable for touch pad/screen-based
     21 // fling scroll. Starts with a flat velocity profile based on 'velocity', which
     22 // tails off to zero. Time is scaled to that duration of the fling is
     23 // proportional to the initial velocity.
     24 class TouchFlingGestureCurve : public blink::WebGestureCurve {
     25  public:
     26 
     27   static CONTENT_EXPORT WebGestureCurve* Create(
     28       const blink::WebFloatPoint& initial_velocity,
     29       const blink::WebSize& cumulativeScroll);
     30 
     31  virtual bool apply(double monotonicTime,
     32                     blink::WebGestureCurveTarget*) OVERRIDE;
     33 
     34  private:
     35   TouchFlingGestureCurve(const blink::WebFloatPoint& initial_velocity,
     36                          const blink::WebSize& cumulativeScroll);
     37   virtual ~TouchFlingGestureCurve();
     38 
     39   blink::WebFloatPoint displacement_ratio_;
     40   blink::WebFloatSize cumulative_scroll_;
     41   float time_offset_;
     42   float curve_duration_;
     43   float position_offset_;
     44 
     45   DISALLOW_COPY_AND_ASSIGN(TouchFlingGestureCurve);
     46 };
     47 
     48 } // namespace content
     49 
     50 #endif // CONTENT_CHILD_TOUCH_FLING_GESTURE_CURVE_H_
     51