Extend MotionEvent to have tool type and button state

ui/events/gesture_detection/motion_event.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_MOTION_EVENT_H_
 #define UI_EVENTS_GESTURE_DETECTION_MOTION_EVENT_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
 
 namespace ui {
 
 // Abstract class for a generic motion-related event, patterned after that
 // subset of Android's MotionEvent API used in gesture detection.
 class GESTURE_DETECTION_EXPORT MotionEvent {
  public:
   enum Action {
-    ACTION_DOWN,
+    ACTION_DOWN = 100,

[jdduke (slow), 2014/06/20 15:33:25]

Any reason for the 100/200?

[Changwan Ryu, 2014/06/20 21:00:34]

No specific reason. I just wanted to assign SOME distinct values so that when we
debug we can tell which enum value was used from debug message and log (such as
in ToAndroid... functions).

[jdduke (slow), 2014/06/20 21:19:41]

I see, let's stick with not assigning them specific non-zero values for now, as
the user would have to look at the header anyway to figure out the corresponding
value, and by then they'd know the context (whether it's action or tool type).

[Changwan Ryu, 2014/06/20 21:32:01]

Done.

     ACTION_UP,
     ACTION_MOVE,
     ACTION_CANCEL,
     ACTION_POINTER_DOWN,
     ACTION_POINTER_UP,
   };
 
+  enum ToolType {
+    TOOL_TYPE_UNKNOWN = 200,
+    TOOL_TYPE_FINGER,
+    TOOL_TYPE_STYLUS,
+    TOOL_TYPE_MOUSE,
+  };
+
+  const static int BUTTON_NONE = 0;

[jdduke (slow), 2014/06/20 15:33:25]

I would go ahead and use an enum bit mask here, e.g., 

enum ButtonType {
  BUTTON_PRIMARY = 1 << 0,
  BUTTON_SECONDARY = 1 << 1,
  ...
}

[Changwan Ryu, 2014/06/20 21:00:34]

Done.

+  const static int BUTTON_PRIMARY = 1;
+  const static int BUTTON_SECONDARY = 2;
+  const static int BUTTON_TERTIARY = 4;
+  const static int BUTTON_BACK = 8;
+  const static int BUTTON_FORWARD = 16;
+
   // The implementer promises that |GetPointerId()| will never exceed this.
   enum { MAX_POINTER_ID = 31 };
 
   virtual ~MotionEvent() {}
 
   virtual int GetId() const = 0;
   virtual Action GetAction() const = 0;
   // Only valid if |GetAction()| returns ACTION_POINTER_UP or
   // ACTION_POINTER_DOWN.
   virtual int GetActionIndex() const = 0;
   virtual size_t GetPointerCount() const = 0;
   virtual int GetPointerId(size_t pointer_index) const = 0;
   virtual float GetX(size_t pointer_index) const = 0;
   virtual float GetY(size_t pointer_index) const = 0;
   virtual float GetRawX(size_t pointer_index) const = 0;
   virtual float GetRawY(size_t pointer_index) const = 0;
   virtual float GetTouchMajor(size_t pointer_index) const = 0;
   virtual float GetPressure(size_t pointer_index) const = 0;
   virtual base::TimeTicks GetEventTime() const = 0;
 
   virtual size_t GetHistorySize() const = 0;
   virtual base::TimeTicks GetHistoricalEventTime(
       size_t historical_index) const = 0;
   virtual float GetHistoricalTouchMajor(size_t pointer_index,
                                         size_t historical_index) const = 0;
   virtual float GetHistoricalX(size_t pointer_index,
                                size_t historical_index) const = 0;
   virtual float GetHistoricalY(size_t pointer_index,
                                size_t historical_index) const = 0;
+  virtual ToolType GetToolType(size_t pointer_index) const = 0;
+  virtual int GetButtonState() const = 0;
 
   virtual scoped_ptr<MotionEvent> Clone() const = 0;
   virtual scoped_ptr<MotionEvent> Cancel() const = 0;
 
   // Utility accessor methods for convenience.
   float GetX() const { return GetX(0); }
   float GetY() const { return GetY(0); }
   float GetRawX() const { return GetRawX(0); }
   float GetRawY() const { return GetRawY(0); }
   float GetTouchMajor() const { return GetTouchMajor(0); }
   float GetPressure() const { return GetPressure(0); }
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_MOTION_EVENT_H_