ui/events/android/scroller.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_ANDROID_SCROLLER_H_
   6 #define UI_EVENTS_ANDROID_SCROLLER_H_
   7
   8 #include "base/time/time.h"
   9 #include "ui/events/events_base_export.h"
  10 #include "ui/events/gesture_curve.h"
  11 #include "ui/gfx/geometry/vector2d_f.h"
  12
  13 namespace ui {
  14
  15 // Native port of android.widget.Scroller.
  16 // * Change-Id: I4365946f890a76fcfa78ca9d69f2a8e0848095a9
  17 // * Please update the Change-Id as upstream Android changes are pulled.
  18 class EVENTS_BASE_EXPORT Scroller : public GestureCurve {
  19  public:
  20   struct Config {
  21     Config();
  22
  23     // Controls fling deceleration. Defaults to 0.015f.
  24     float fling_friction;
  25
  26     // Controls fling accumulation. Defaults to disabled.
  27     bool flywheel_enabled;
  28   };
  29
  30   explicit Scroller(const Config& config);
  31   ~Scroller() override;
  32
  33   // GestureCurve implementation.
  34   bool ComputeScrollOffset(base::TimeTicks time,
  35                            gfx::Vector2dF* offset,
  36                            gfx::Vector2dF* velocity) override;
  37
  38   // Start scrolling by providing a starting point and the distance to travel.
  39   // The default value of 250 milliseconds will be used for the duration.
  40   void StartScroll(float start_x,
  41                    float start_y,
  42                    float dx,
  43                    float dy,
  44                    base::TimeTicks start_time);
  45
  46   // Start scrolling by providing a starting point, the distance to travel,
  47   // and the duration of the scroll.
  48   void StartScroll(float start_x,
  49                    float start_y,
  50                    float dx,
  51                    float dy,
  52                    base::TimeTicks start_time,
  53                    base::TimeDelta duration);
  54
  55   // Start scrolling based on a fling gesture. The distance travelled will
  56   // depend on the initial velocity of the fling.
  57   void Fling(float start_x,
  58              float start_y,
  59              float velocity_x,
  60              float velocity_y,
  61              float min_x,
  62              float max_x,
  63              float min_y,
  64              float max_y,
  65              base::TimeTicks start_time);
  66
  67   // Extend the scroll animation by |extend|. This allows a running animation
  68   // to scroll further and longer when used with |SetFinalX()| or |SetFinalY()|.
  69   void ExtendDuration(base::TimeDelta extend);
  70   void SetFinalX(float new_x);
  71   void SetFinalY(float new_y);
  72
  73   // Stops the animation. Contrary to |ForceFinished()|, aborting the animation
  74   // causes the scroller to move to the final x and y position.
  75   void AbortAnimation();
  76
  77   // Terminate the scroll without affecting the current x and y positions.
  78   void ForceFinished(bool finished);
  79
  80   // Returns whether the scroller has finished scrolling.
  81   bool IsFinished() const;
  82
  83   // Returns the time elapsed since the beginning of the scrolling.
  84   base::TimeDelta GetTimePassed() const;
  85
  86   // Returns how long the scroll event will take.
  87   base::TimeDelta GetDuration() const;
  88
  89   float GetStartX() const;
  90   float GetStartY() const;
  91   float GetCurrX() const;
  92   float GetCurrY() const;
  93   float GetCurrVelocity() const;
  94   float GetCurrVelocityX() const;
  95   float GetCurrVelocityY() const;
  96   float GetFinalX() const;
  97   float GetFinalY() const;
  98
  99   bool IsScrollingInDirection(float xvel, float yvel) const;
 100
 101  private:
 102   enum Mode {
 103     UNDEFINED,
 104     SCROLL_MODE,
 105     FLING_MODE,
 106   };
 107
 108   bool ComputeScrollOffsetInternal(base::TimeTicks time);
 109   void RecomputeDeltas();
 110
 111   double GetSplineDeceleration(float velocity) const;
 112   base::TimeDelta GetSplineFlingDuration(float velocity) const;
 113   double GetSplineFlingDistance(float velocity) const;
 114
 115   Mode mode_;
 116
 117   float start_x_;
 118   float start_y_;
 119   float final_x_;
 120   float final_y_;
 121
 122   float min_x_;
 123   float max_x_;
 124   float min_y_;
 125   float max_y_;
 126
 127   float curr_x_;
 128   float curr_y_;
 129   base::TimeTicks start_time_;
 130   base::TimeTicks curr_time_;
 131   base::TimeDelta duration_;
 132   double duration_seconds_reciprocal_;
 133   float delta_x_;
 134   float delta_x_norm_;
 135   float delta_y_;
 136   float delta_y_norm_;
 137   bool finished_;
 138   bool flywheel_enabled_;
 139
 140   float velocity_;
 141   float curr_velocity_;
 142   float distance_;
 143
 144   float fling_friction_;
 145   float deceleration_;
 146   float tuning_coeff_;
 147 };
 148
 149 }  // namespace ui
 150
 151 #endif  // UI_EVENTS_ANDROID_SCROLLER_H_