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      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_
     76