athena/home/home_card_gesture_manager.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_HOME_HOME_CARD_GESTURE_MANAGER_H_
   6 #define ATHENA_HOME_HOME_CARD_GESTURE_MANAGER_H_
   7
   8 #include "athena/home/public/home_card.h"
   9 #include "athena/athena_export.h"
  10 #include "ui/gfx/geometry/rect.h"
  11
  12 namespace ui {
  13 class GestureEvent;
  14 }
  15
  16 namespace athena {
  17
  18 // Handles the touch gestures over the home card.
  19 class ATHENA_EXPORT HomeCardGestureManager {
  20  public:
  21   class Delegate {
  22    public:
  23     // Called when the gesture has ended. The state of the home card will
  24     // end up with |final_state|. |is_fling| is true only when the gesture has
  25     // ended with a fling action.
  26     virtual void OnGestureEnded(HomeCard::State final_state,
  27                                 bool is_fling) = 0;
  28
  29     // Called when the gesture position is updated so that |delegate| updates
  30     // the visual. The arguments indicate that the gesture is switching between
  31     // |from_state| and |to_state|, and that the level of progress is at
  32     // |progress|, which is in the range (0, 1]. The home card was previously
  33     // at either |from_state| or |to_state|. In particular, the home card may
  34     // never have been at |from_state|. |from_state| is never equal to
  35     // |to_state|.
  36     virtual void OnGestureProgressed(
  37         HomeCard::State from_state,
  38         HomeCard::State to_state,
  39         float progress) = 0;
  40   };
  41
  42   HomeCardGestureManager(Delegate* delegate,
  43                          const gfx::Rect& screen_bounds);
  44   ~HomeCardGestureManager();
  45
  46   void ProcessGestureEvent(ui::GestureEvent* event);
  47
  48  private:
  49   // Get the final state from the last position.
  50   HomeCard::State GetFinalState() const;
  51
  52   // Update the current position and emits OnGestureProgressed().
  53   void UpdateScrollState(const ui::GestureEvent& event);
  54
  55   Delegate* delegate_;  // Not owned.
  56
  57   // The state when the gesture starts.
  58   HomeCard::State original_state_;
  59
  60   // The offset from the top edge of the home card and the initial position of
  61   // gesture.
  62   int y_offset_;
  63
  64   // The estimated height of the home card after the last touch event.
  65   int last_estimated_height_;
  66
  67   // The bounds of the screen to compute the home card bounds.
  68   gfx::Rect screen_bounds_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(HomeCardGestureManager);
  71 };
  72
  73 }  // namespace athena
  74
  75 #endif  // ATHENA_HOME_HOME_CARD_GESTURE_MANAGER_H_