Changing the bounding box for show press and tap gesture

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 54 matching lines @@
     float two_finger_tap_max_separation;
 
     // Maximum time the second pointer can be active for a two finger tap.
     base::TimeDelta two_finger_tap_timeout;
   };
 
   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 void OnShowPress(const MotionEvent& e, float max_radius) = 0;
+    virtual bool OnSingleTapUp(const MotionEvent& e,

[jdduke (slow), 2014/09/04 15:01:25]

These callbacks variations are rather unfortunate, and I'm not sure we need to
couple the GestureDetector to our specific interpretation of how a press/tap
should be positioned. What if we instead do the necessary bookkeeping in the
GestureListenerImpl? 

+                               float x,
+                               float y,
+                               float max_radius) = 0;
     virtual void 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;
     // Added for Chromium (Aura).
     virtual bool OnSwipe(const MotionEvent& e1,
                          const MotionEvent& e2,
                          float velocity_x,
                          float velocity_y) = 0;
     virtual bool OnTwoFingerTap(const MotionEvent& e1,
                                 const MotionEvent& e2) = 0;
   };
 
   class DoubleTapListener {
    public:
     virtual ~DoubleTapListener() {}
-    virtual bool OnSingleTapConfirmed(const MotionEvent& e) = 0;
+    virtual bool OnSingleTapConfirmed(const MotionEvent& e,
+                                      float x,
+                                      float y,
+                                      float max_radius) = 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 void OnShowPress(const MotionEvent& e, float max_radius) OVERRIDE;
+    virtual bool OnSingleTapUp(const MotionEvent& e,
+                               float x,
+                               float y,
+                               float max_radius) OVERRIDE;
     virtual void 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 OnSwipe(const MotionEvent& e1,
                          const MotionEvent& e2,
                          float velocity_x,
                          float velocity_y) OVERRIDE;
     virtual bool OnTwoFingerTap(const MotionEvent& e1,
                                 const MotionEvent& e2) OVERRIDE;
 
     // DoubleTapListener implementation.
-    virtual bool OnSingleTapConfirmed(const MotionEvent& e) OVERRIDE;
+    virtual bool OnSingleTapConfirmed(const MotionEvent& e,
+                                      float x,
+                                      float y,
+                                      float max_radius) 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);
@@ skipping 41 matching lines @@
   bool still_down_;
   bool defer_confirm_single_tap_;
   bool always_in_tap_region_;
   bool always_in_bigger_tap_region_;
   bool two_finger_tap_allowed_for_gesture_;
 
   scoped_ptr<MotionEvent> current_down_event_;
   scoped_ptr<MotionEvent> previous_up_event_;
   scoped_ptr<MotionEvent> secondary_pointer_down_event_;
 
+  // The maximum diameter of the finger touches before show press gesture is
+  // sent.

[tdresser, 2014/09/04 13:54:00]

Perhaps:
// The maximum touch diameter before the show press gesture is sent.

[lanwei, 2014/09/05 20:40:36]

Done.

+  float max_touch_diameter_;

[tdresser, 2014/09/04 13:54:00]

Perhaps |max_diameter_before_show_press_|.

It's a little long, but I think it's better to be explicit here.

[lanwei, 2014/09/05 20:40:36]

Done.

+
   // 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 longpress_enabled_;
   bool swipe_enabled_;
   bool two_finger_tap_enabled_;
 
   // Determines speed during touch scrolling.
   VelocityTrackerState velocity_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureDetector);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_