Gestures are now possible using touch events with any ids

ui/aura/gestures/gesture_point.h

 // Copyright (c) 2012 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_AURA_GESTURES_GESTURE_POINT_H_
 #define UI_AURA_GESTURES_GESTURE_POINT_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "ui/aura/gestures/velocity_calculator.h"
@@ skipping 35 matching lines @@
   bool BreaksVerticalRail();
   bool DidScroll(const TouchEvent& event, int distance) const;
 
   const gfx::Point& first_touch_position() const {
     return first_touch_position_;
   }
 
   double last_touch_time() const { return last_touch_time_; }
   const gfx::Point& last_touch_position() const { return last_touch_position_; }
 
-  void set_touch_id(unsigned int touch_id) { touch_id_ = touch_id; }
-  const unsigned int touch_id() const { return touch_id_; }
+  // point_id_ is used to drive GestureSequence::ProcessTouchEventForGesture.
+  // point_ids are maintained such that the set of point_ids is always
+  // contiguous, from 0 to the number of current touches.
+  // A lower point_id indicates that a touch occurred first.
+  // A negative point_id indicates that the GesturePoint is not currently
+  // associated with a touch.
+  void set_point_id(int point_id) { point_id_ = point_id; }
+  const int point_id() const { return point_id_; }
+
+  const bool in_use() const { return point_id_ >= 0; }
 
   double x_delta() const {
     return last_touch_position_.x() - first_touch_position_.x();
   }
 
   double y_delta() const {
     return last_touch_position_.y() - first_touch_position_.y();
   }
 
   float XVelocity() { return velocity_calculator_.XVelocity(); }
@@ skipping 12 matching lines @@
   gfx::Point first_touch_position_;
   double first_touch_time_;
   gfx::Point last_touch_position_;
   double last_touch_time_;
 
   double last_tap_time_;
   gfx::Point last_tap_position_;
 
   VelocityCalculator velocity_calculator_;
 
-  unsigned int touch_id_;
+  bool in_use_;

[sadrul, 2012/02/23 21:44:14]

Remove

[tdresser, 2012/02/23 22:16:55]

Done.

+  int point_id_;
   DISALLOW_COPY_AND_ASSIGN(GesturePoint);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_GESTURES_GESTURE_POINT_H_