athena/wm/bezel_controller.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 ATHENA_WM_BEZEL_CONTROLLER_H_
   6 #define ATHENA_WM_BEZEL_CONTROLLER_H_
   7
   8 #include "ui/events/event_handler.h"
   9
  10 namespace aura {
  11 class Window;
  12 }
  13
  14 namespace gfx {
  15 class PointF;
  16 }
  17
  18 namespace ui {
  19 class EventTarget;
  20 }
  21
  22 namespace athena {
  23
  24 // Responsible for detecting bezel gestures and notifying the delegate(s)
  25 // subscribed to them.
  26 class BezelController : public ui::EventHandler {
  27  public:
  28   enum Bezel { BEZEL_NONE, BEZEL_LEFT, BEZEL_RIGHT, BEZEL_TOP, BEZEL_BOTTOM };
  29
  30   // Responsible for handling scroll gestures initiated from the bezel.
  31   // Two touch points are need to perform the bezel scroll gesture from
  32   // the left and right bezel.
  33   class ScrollDelegate {
  34    public:
  35     virtual ~ScrollDelegate() {}
  36
  37     // Beginning of a bezel scroll gesture started from the |bezel|.
  38     // |delta| is the difference between the x-coordinate of the current scroll
  39     // position and the bezel. It will be zero or negative for the right bezel.
  40     virtual void ScrollBegin(Bezel bezel, float delta) = 0;
  41
  42     // End of the current bezel scroll
  43     virtual void ScrollEnd() = 0;
  44
  45     // Update of the scroll position for the currently active bezel scroll.
  46     // |delta| has the same meaning as in ScrollBegin().
  47     virtual void ScrollUpdate(float delta) = 0;
  48
  49     // Should return false if the delegate isn't going to react to the scroll
  50     // events.
  51     virtual bool CanScroll() = 0;
  52   };
  53
  54   explicit BezelController(aura::Window* container);
  55   virtual ~BezelController() {}
  56
  57   // Set the delegate to handle the gestures from left and right bezels.
  58   // Two touch points are need to perform the bezel scroll gesture from
  59   // the left and right bezel.
  60   void set_left_right_delegate(ScrollDelegate* delegate) {
  61     left_right_delegate_ = delegate;
  62   }
  63
  64  private:
  65   enum State {
  66     NONE,
  67     IGNORE_CURRENT_SCROLL,
  68     BEZEL_GESTURE_STARTED,
  69     BEZEL_SCROLLING_ONE_FINGER,
  70     BEZEL_SCROLLING_TWO_FINGERS,
  71   };
  72
  73   void SetState(State state);
  74   // |scroll_delta| only needs to be passed when |state| is one of the
  75   // BEZEL_SROLLING states.
  76   void SetState(State state, float scroll_delta);
  77
  78   // Returns the bezel corresponding to the |location| or BEZEL_NONE if the
  79   // location is outside of the bezel area.
  80   Bezel GetBezel(const gfx::PointF& location);
  81
  82   // ui::EventHandler overrides
  83   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
  84
  85   aura::Window* container_;
  86
  87   State state_;
  88
  89   // The bezel where the currently active scroll was started.
  90   Bezel scroll_bezel_;
  91
  92   // The target of the bezel scroll gesture. Used to filter out other gestures
  93   // when the bezel scroll is in progress.
  94   ui::EventTarget* scroll_target_;
  95
  96   // Responsible for handling gestures started from the left and right bezels.
  97   // Not owned.
  98   ScrollDelegate* left_right_delegate_;
  99
 100   DISALLOW_COPY_AND_ASSIGN(BezelController);
 101 };
 102
 103 }  // namespace athena
 104
 105 #endif  // ATHENA_WM_BEZEL_CONTROLLER_H_