ui/events/gesture_curve.h

   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 UI_EVENTS_GESTURE_CURVE_H_
   6 #define UI_EVENTS_GESTURE_CURVE_H_
   7
   8 #include "base/time/time.h"
   9 #include "ui/gfx/geometry/vector2d_f.h"
  10
  11 namespace ui {
  12
  13 // An abstraction of curve-based gesture motion, allowing platform-specific
  14 // motion tailoring.
  15 class EVENTS_BASE_EXPORT GestureCurve {
  16  public:
  17   virtual ~GestureCurve() {}
  18
  19   // The output |offset| represents the total movement of the curve from its
  20   // start until |time|.
  21   // The output |velocity| represents the instantenous velocity at |time|.
  22   // Returns false if |time| exceeds the fling duration, in which case
  23   // the terminal offset will be reported.
  24   virtual bool ComputeScrollOffset(base::TimeTicks time,
  25                                    gfx::Vector2dF* offset,
  26                                    gfx::Vector2dF* velocity) = 0;
  27 };
  28
  29 }  // namespace ui
  30
  31 #endif  // UI_EVENTS_GESTURE_CURVE_H_