ui/gfx/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_GFX_ANDROID_SCROLLER_H_
   6 #define UI_GFX_ANDROID_SCROLLER_H_
   7
   8 #include "base/time/time.h"
   9 #include "ui/gfx/gfx_export.h"
  10
  11 namespace gfx {
  12
  13 // Native port of android.widget.Scroller.
  14 // * Change-Id: I4365946f890a76fcfa78ca9d69f2a8e0848095a9
  15 // * Please update the Change-Id as upstream Android changes are pulled.
  16 class GFX_EXPORT Scroller {
  17  public:
  18   struct Config {
  19     Config();
  20
  21     // Controls fling deceleration. Defaults to 0.015f.
  22     float fling_friction;
  23
  24     // Controls fling accumulation. Defaults to disabled.
  25     bool flywheel_enabled;
  26   };
  27
  28   explicit Scroller(const Config& config);
  29   ~Scroller();
  30
  31   // Start scrolling by providing a starting point and the distance to travel.
  32   // The default value of 250 milliseconds will be used for the duration.
  33   void StartScroll(float start_x,
  34                    float start_y,
  35                    float dx,
  36                    float dy,
  37                    base::TimeTicks start_time);
  38
  39   // Start scrolling by providing a starting point, the distance to travel,
  40   // and the duration of the scroll.
  41   void StartScroll(float start_x,
  42                    float start_y,
  43                    float dx,
  44                    float dy,
  45                    base::TimeTicks start_time,
  46                    base::TimeDelta duration);
  47
  48   // Start scrolling based on a fling gesture. The distance travelled will
  49   // depend on the initial velocity of the fling.
  50   void Fling(float start_x,
  51              float start_y,
  52              float velocity_x,
  53              float velocity_y,
  54              float min_x,
  55              float max_x,
  56              float min_y,
  57              float max_y,
  58              base::TimeTicks start_time);
  59
  60   // Call this when you want to know the new location.  If it returns true,
  61   // the animation is not yet finished.
  62   bool ComputeScrollOffset(base::TimeTicks time);
  63
  64   // Extend the scroll animation by |extend|. This allows a running animation
  65   // to scroll further and longer when used with |SetFinalX()| or |SetFinalY()|.
  66   void ExtendDuration(base::TimeDelta extend);
  67   void SetFinalX(float new_x);
  68   void SetFinalY(float new_y);
  69
  70   // Stops the animation. Contrary to |ForceFinished()|, aborting the animation
  71   // causes the scroller to move to the final x and y position.
  72   void AbortAnimation();
  73
  74   // Terminate the scroll without affecting the current x and y positions.
  75   void ForceFinished(bool finished);
  76
  77   // Returns whether the scroller has finished scrolling.
  78   bool IsFinished() const;
  79
  80   // Returns the time elapsed since the beginning of the scrolling.
  81   base::TimeDelta GetTimePassed() const;
  82
  83   // Returns how long the scroll event will take.
  84   base::TimeDelta GetDuration() const;
  85
  86   float GetStartX() const;
  87   float GetStartY() const;
  88   float GetCurrX() const;
  89   float GetCurrY() const;
  90   float GetCurrVelocity() const;
  91   float GetCurrVelocityX() const;
  92   float GetCurrVelocityY() const;
  93   float GetFinalX() const;
  94   float GetFinalY() const;
  95
  96   bool IsScrollingInDirection(float xvel, float yvel) const;
  97
  98  private:
  99   enum Mode {
 100     UNDEFINED,
 101     SCROLL_MODE,
 102     FLING_MODE,
 103   };
 104
 105   void OnDurationChanged();
 106   void RecomputeDeltas();
 107
 108   double GetSplineDeceleration(float velocity) const;
 109   base::TimeDelta GetSplineFlingDuration(float velocity) const;
 110   double GetSplineFlingDistance(float velocity) const;
 111
 112   Mode mode_;
 113
 114   float start_x_;
 115   float start_y_;
 116   float final_x_;
 117   float final_y_;
 118
 119   float min_x_;
 120   float max_x_;
 121   float min_y_;
 122   float max_y_;
 123
 124   float curr_x_;
 125   float curr_y_;
 126   base::TimeTicks start_time_;
 127   base::TimeTicks curr_time_;
 128   base::TimeDelta duration_;
 129   double duration_seconds_reciprocal_;
 130   float delta_x_;
 131   float delta_x_norm_;
 132   float delta_y_;
 133   float delta_y_norm_;
 134   bool finished_;
 135   bool flywheel_enabled_;
 136
 137   float velocity_;
 138   float curr_velocity_;
 139   float distance_;
 140
 141   float fling_friction_;
 142   float deceleration_;
 143   float tuning_coeff_;
 144 };
 145
 146 }  // namespace gfx
 147
 148 #endif  // UI_GFX_ANDROID_SCROLLER_H_