Add multi-finger swipe detection to GestureDetector

ui/events/gesture_detection/gesture_detector.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_
 #define UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
@@ skipping 22 matching lines @@
 
     // Distance the first touch can wander before it is no longer considered a
     // double tap (in dips).
     float double_tap_slop;
 
     // Minimum velocity to initiate a fling (in dips/second).
     float minimum_fling_velocity;
 
     // Maximum velocity of an initiated fling (in dips/second).
     float maximum_fling_velocity;
+
+    // Whether |OnSwipe| should be called after a secondary touch is released
+    // while a logical swipe gesture is active. Defaults to false.
+    bool swipe_enabled;
+
+    // Minimum velocity to initiate a swipe (in dips/second).
+    float minimum_swipe_velocity;
+
+    // Maximum angle of the swipe from it's dominant component axis, between

[tdresser, 2014/04/24 12:42:40]

Extremely nitful nit.
it's -> its

[jdduke (slow), 2014/04/24 15:13:55]

Done.

+    // (0, 45] degrees. The closer this is to 0, the closer the dominant
+    // direction of the swipe must be to up, down left or right.
+    float maximum_swipe_deviation_angle;
   };
 
   class GestureListener {
    public:
     virtual ~GestureListener() {}
     virtual bool OnDown(const MotionEvent& e) = 0;
     virtual void OnShowPress(const MotionEvent& e) = 0;
     virtual bool OnSingleTapUp(const MotionEvent& e) = 0;
     virtual bool OnLongPress(const MotionEvent& e) = 0;
-    virtual bool OnScroll(const MotionEvent& e1, const MotionEvent& e2,
-                          float distance_x, float distance_y) = 0;
-    virtual bool OnFling(const MotionEvent& e1, const MotionEvent& e2,
-                         float velocity_x, float velocity_y) = 0;
+    virtual bool OnScroll(const MotionEvent& e1,
+                          const MotionEvent& e2,
+                          float distance_x,
+                          float distance_y) = 0;
+    virtual bool OnFling(const MotionEvent& e1,
+                         const MotionEvent& e2,
+                         float velocity_x,
+                         float velocity_y) = 0;
+    // Added for Chromium (Aura).
+    virtual bool OnSwipe(const MotionEvent& e1,
+                         const MotionEvent& e2,
+                         float velocity_x,
+                         float velocity_y) = 0;
   };
 
   class DoubleTapListener {
    public:
     virtual ~DoubleTapListener() {}
     virtual bool OnSingleTapConfirmed(const MotionEvent& e) = 0;
     virtual bool OnDoubleTap(const MotionEvent& e) = 0;
     virtual bool OnDoubleTapEvent(const MotionEvent& e) = 0;
   };
 
   // A convenience class to extend when you only want to listen for a subset
   // of all the gestures. This implements all methods in the
   // |GestureListener| and |DoubleTapListener| but does
   // nothing and returns false for all applicable methods.
   class SimpleGestureListener : public GestureListener,
                                 public DoubleTapListener {
    public:
     // GestureListener implementation.
     virtual bool OnDown(const MotionEvent& e) OVERRIDE;
     virtual void OnShowPress(const MotionEvent& e) OVERRIDE;
     virtual bool OnSingleTapUp(const MotionEvent& e) OVERRIDE;
     virtual bool OnLongPress(const MotionEvent& e) OVERRIDE;
-    virtual bool OnScroll(const MotionEvent& e1, const MotionEvent& e2,
-                          float distance_x, float distance_y) OVERRIDE;
-    virtual bool OnFling(const MotionEvent& e1, const MotionEvent& e2,
-                         float velocity_x, float velocity_y) OVERRIDE;
+    virtual bool OnScroll(const MotionEvent& e1,
+                          const MotionEvent& e2,
+                          float distance_x,
+                          float distance_y) OVERRIDE;
+    virtual bool OnFling(const MotionEvent& e1,
+                         const MotionEvent& e2,
+                         float velocity_x,
+                         float velocity_y) OVERRIDE;
+    virtual bool OnSwipe(const MotionEvent& e1,
+                         const MotionEvent& e2,
+                         float velocity_x,
+                         float velocity_y) OVERRIDE;
 
     // DoubleTapListener implementation.
     virtual bool OnSingleTapConfirmed(const MotionEvent& e) OVERRIDE;
     virtual bool OnDoubleTap(const MotionEvent& e) OVERRIDE;
     virtual bool OnDoubleTapEvent(const MotionEvent& e) OVERRIDE;
   };
 
   GestureDetector(const Config& config,
                   GestureListener* listener,
                   DoubleTapListener* optional_double_tap_listener);
   ~GestureDetector();
 
   bool OnTouchEvent(const MotionEvent& ev);
 
   // Setting a valid |double_tap_listener| will enable double-tap detection,
   // wherein calls to |OnSimpleTapConfirmed| are delayed by the tap timeout.
   // Note: The listener must never be changed while |is_double_tapping| is true.
   void SetDoubleTapListener(DoubleTapListener* double_tap_listener);
 
   bool has_doubletap_listener() const { return double_tap_listener_ != NULL; }
 
   bool is_double_tapping() const { return is_double_tapping_; }
 
-  void set_is_longpress_enabled(bool is_longpress_enabled) {
-    is_longpress_enabled_ = is_longpress_enabled;
-  }
-
-  bool is_longpress_enabled() const { return is_longpress_enabled_; }
+  void set_longpress_enabled(bool enabled) { longpress_enabled_ = enabled; }
 
  private:
   void Init(const Config& config);
   void OnShowPressTimeout();
   void OnLongPressTimeout();
   void OnTapTimeout();
   void Cancel();
   void CancelTaps();
   bool IsConsideredDoubleTap(const MotionEvent& first_down,
                              const MotionEvent& first_up,
                              const MotionEvent& second_down) const;
 
   class TimeoutGestureHandler;
   scoped_ptr<TimeoutGestureHandler> timeout_handler_;
   GestureListener* const listener_;
   DoubleTapListener* double_tap_listener_;
 
   float touch_slop_square_;
   float double_tap_touch_slop_square_;
   float double_tap_slop_square_;
   float min_fling_velocity_;
   float max_fling_velocity_;
+  float min_swipe_velocity_;
+  float min_swipe_direction_component_ratio_;
   base::TimeDelta double_tap_timeout_;
 
   bool still_down_;
   bool defer_confirm_single_tap_;
   bool in_longpress_;
   bool always_in_tap_region_;
   bool always_in_bigger_tap_region_;
 
   scoped_ptr<MotionEvent> current_down_event_;
   scoped_ptr<MotionEvent> previous_up_event_;
 
   // True when the user is still touching for the second tap (down, move, and
   // up events). Can only be true if there is a double tap listener attached.
   bool is_double_tapping_;
 
   float last_focus_x_;
   float last_focus_y_;
   float down_focus_x_;
   float down_focus_y_;
 
-  bool is_longpress_enabled_;
+  bool longpress_enabled_;
+  bool swipe_enabled_;
 
   // Determines speed during touch scrolling.
   VelocityTrackerState velocity_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureDetector);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_