This patch implements Chromium's Aura gesture recognizer in terms of utouch-grail and utouch-frame …

ui/aura/event.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_EVENT_H_
 #define UI_AURA_EVENT_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/event_types.h"
@@ skipping 276 matching lines @@
 class AURA_EXPORT ScrollEvent : public MouseEvent {
  public:
   explicit ScrollEvent(const base::NativeEvent& native_event);
   ScrollEvent(const ScrollEvent& model,
               Window* source,
               Window* target,
               ui::EventType type,
               int flags)
       : MouseEvent(model, source, target, type, flags),
         x_offset_(model.x_offset_),
-        y_offset_(model.y_offset_) {
-  }
+        y_offset_(model.y_offset_) {}
 
   float x_offset() const { return x_offset_; }
   float y_offset() const { return y_offset_; }
 
  private:
   float x_offset_;
   float y_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollEvent);
 };
 
 class AURA_EXPORT GestureEvent : public LocatedEvent {
  public:
+  // Bundles properties of a gesture event and allows
+  // for a uniform c'tor signature for GestureEvent.
+  // REMARK(tvoss): Instead of modelling "isolated" fields
+  // in this property, a 3x3 transformation matrix might be
+  // more appropriate.
+  struct Properties {
+    Properties()
+        : point_id(-1),
+          delta_x(0.f),
+          delta_y(0.f),
+          scale_x(1.f),
+          scale_y(1.f) {
+    }
+
+    // Point or touch-id in case of long-press gestures.
+    int point_id;
+
+    // For drag gestures
+    float delta_x;
+    float delta_y;
+
+    // For pinch gestures
+    float scale_x;
+    float scale_y;
+  };
+
   GestureEvent(ui::EventType type,
                int x,
                int y,
                int flags,
                base::Time time_stamp,
-               float delta_x,
-               float delta_y);
+               const Properties& properties);
 
   // Create a new TouchEvent which is identical to the provided model.
   // If source / target windows are provided, the model location will be
   // converted from |source| coordinate system to |target| coordinate system.
   GestureEvent(const GestureEvent& model, Window* source, Window* target);
 
-  float delta_x() const { return delta_x_; }
-  float delta_y() const { return delta_y_; }
+  int point_id() const { return properties_.point_id; }
+
+  float delta_x() const { return properties_.delta_x; }
+  float delta_y() const { return properties_.delta_y; }
+
+  float scale_x() const { return properties_.scale_x; }
+  float scale_y() const { return properties_.scale_y; }
+
+  const Properties& properties() const { return properties_; }
 
  private:
-  float delta_x_;
-  float delta_y_;
+  Properties properties_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureEvent);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_EVENT_H_