aura: Update GestureRecognizer to be able to process multi-point gestures.

ui/aura/gestures/gesture_point.h

Index: ui/aura/gestures/gesture_point.h
diff --git a/ui/aura/gestures/gesture_point.h b/ui/aura/gestures/gesture_point.h
new file mode 100644
index 0000000000000000000000000000000000000000..da7d17703823a20d24b88c5ec43c99cafb9ec83c
--- /dev/null
+++ b/ui/aura/gestures/gesture_point.h
@@ -0,0 +1,91 @@
+// 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/gfx/point.h"
+
+namespace aura {
+class TouchEvent;
+
+// Gesture state.
+enum GestureState {
+  GS_NO_GESTURE,
+  GS_PENDING_SYNTHETIC_CLICK,
+  GS_SCROLL,
+};
+
+// A GesturePoint represents a single touch-point/finger during a gesture
+// recognition process.
+class GesturePoint {
+ public:
+  GesturePoint();
+  virtual ~GesturePoint() {}
+
+  // Resets various states.
+  void Reset();
+
+  // Updates some states when a Tap gesture has been recognized for this point.
+  void UpdateForTap();
+
+  // Updates some states when a Scroll gesture has been recognized for this
+  // point.
+  void UpdateForScroll();
+
+  // Updates states depending on the event and the gesture-state.
+  void UpdateValues(const TouchEvent& event, GestureState state);
+
+  // Responds according to the state of the gesture point (i.e. the point can
+  // represent a click or scroll etc.)
+  bool IsInClickWindow(const TouchEvent& event) const;
+  bool IsInDoubleClickWindow(const TouchEvent& event) const;
+  bool IsInScrollWindow(const TouchEvent& event) const;
+  bool IsInFlickWindow(const TouchEvent& event) 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_; }
+
+  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 x_velocity() const { return x_velocity_; }
+  float y_velocity() const { return y_velocity_; }
+
+ private:
+  // Various statistical functions to manipulate gestures.
+  bool IsInClickTimeWindow() const;
+  bool IsInSecondClickTimeWindow() const;
+  bool IsInsideManhattanSquare(const TouchEvent& event) const;
+  bool IsSecondClickInsideManhattanSquare(const TouchEvent& event) const;
+  bool IsOverMinFlickSpeed() const;
+
+  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_;
+
+  float x_velocity_;
+  float y_velocity_;
+
+  DISALLOW_COPY_AND_ASSIGN(GesturePoint);
+};
+
+}  // namespace aura
+
+#endif  // UI_AURA_GESTURES_GESTURE_POINT_H_