Initial views touchui GestureRecognizer support

views/touchui/gesture_recognizer.h

+// Copyright (c) 2011 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 VIEWS_TOUCHUI_GESTURE_RECOGNIZER_H_
+#define VIEWS_TOUCHUI_GESTURE_RECOGNIZER_H_
+#pragma once
+
+#include <map>
+#include <vector>
+
+#include "base/memory/linked_ptr.h"
+#include "base/memory/singleton.h"
+#include "ui/base/events.h"
+#include "ui/gfx/point.h"
+#include "views/views_export.h"
+
+namespace views {
+class GestureManager;
+class TouchEvent;
+class GestureEvent;
+
+// A GestureRecognizer recognizes gestures from touch sequences.
+class VIEWS_EXPORT GestureRecognizer {
+ public:
+  // Gesture state.
+  enum GestureState {
+    GS_NO_GESTURE,
+    GS_PENDING_SYNTHETIC_CLICK,
+    GS_SCROLL,
+  };
+
+  // Touch state.
+  enum TouchState {

[sadrul, 2011/11/18 19:01:50]

Let's move the comment from line 68 to here to explain that the ui::EventType is
mapped to GestureRecognizer::TouchState so it can fit into 3 bits of Signature.

[Gajen, 2011/11/21 15:56:50]

Done.

+    TS_RELEASED,
+    TS_PRESSED,
+    TS_MOVED,
+    TS_STATIONARY,
+    TS_CANCELLED,
+    TS_UNKNOWN,
+  };
+
+  // List of GestureEvent*.
+  typedef std::vector<linked_ptr<GestureEvent> > Gestures;
+
+  GestureRecognizer();
+  virtual ~GestureRecognizer();
+
+  static GestureRecognizer* GetInstance();
+
+  // Invoked for each touch event that could contribute to the current gesture.
+  // Returns list of  zero or more GestureEvents identified after processing
+  // TouchEvent.
+  // Caller would be responsible for freeing up Gestures.
+  virtual Gestures* ProcessTouchEventForGesture(const TouchEvent& event,
+                                                ui::TouchStatus status);
+
+  // Clears the GestureRecognizer to its initial state.
+  virtual void Reset();
+
+  // Accessor function.
+  GestureState GetState() { return state_; }

[sadrul, 2011/11/18 19:01:50]

Simple accessors are usually like this:

GestureState state() const { return state_; }

[Gajen, 2011/11/21 15:56:50]

Done.

+
+ private:
+  friend struct DefaultSingletonTraits<GestureRecognizer>;
+
+  // Get equivalent TouchState from EventType |type|
+  // This is required in order to fit TouchState in 3 bits of Signature.
+  static TouchState TouchEventTypeToTouchState(ui::EventType type);
+
+  // Create a 32 bit signature to identify GestureTransitionFunction.
+  static unsigned int Signature(GestureState state,
+                                unsigned int touch_id, ui::EventType type,
+                                bool touch_handled);
+
+  // Various statistical functions to manipulate gestures.
+  bool IsInClickTimeWindow();
+  bool IsInSecondClickTimeWindow();
+  bool IsInsideManhattanSquare(const TouchEvent& event);
+  bool IsSecondClickInsideManhattanSquare(const TouchEvent& event);
+  bool IsOverMinFlickSpeed();
+
+  // Functions to be called to add GestureEvents, after succesful recognition.
+  void AppendTapDownGestureEvent(const TouchEvent& event, Gestures* gestures);
+  void AppendClickGestureEvent(const TouchEvent& event, Gestures* gestures);
+  void AppendDoubleClickGestureEvent(const TouchEvent& event,
+                                     Gestures* gestures);
+  void AppendScrollGestureBegin(const TouchEvent& event, Gestures* gestures);
+  void AppendScrollGestureEnd(const TouchEvent& event,
+                               Gestures* gestures,
+                               float x_velocity, float y_velocity);
+  void AppendScrollGestureUpdate(const TouchEvent& event, Gestures* gestures);
+
+  void UpdateValues(const TouchEvent& event);
+  void SetState(const GestureState state ) { state_ = state; }
+
+  // Various GestureTransitionFunctions for a signature.
+  // There is, 1:many mapping from GestureTransitionFunction to Signature
+  // But a Signature have only one GestureTransitionFunction.
+  bool Click(const TouchEvent& event, Gestures* gestures);
+  bool InClickOrScroll(const TouchEvent& event, Gestures* gestures);
+  bool InScroll(const TouchEvent& event, Gestures* gestures);
+  bool NoGesture(const TouchEvent& event, Gestures* gestures);
+  bool TouchDown(const TouchEvent& event, Gestures* gestures);
+  bool ScrollEnd(const TouchEvent& event, Gestures* gestures);
+
+  // Location of first touch event in a touch sequence.
+  gfx::Point first_touch_position_;
+
+  // Time of first touch event in a touch sequence.
+  double first_touch_time_;
+
+  // Current state of gesture recognizer.
+  GestureState state_;
+
+  // Time of current touch event in a touch sequence.
+  double last_touch_time_;
+
+  // Time of click gesture.
+  double last_click_time_;
+
+  // Location of click gesture.
+  gfx::Point last_click_position_;
+
+  // Location of current touch event in a touch sequence.
+  gfx::Point last_touch_position_;
+
+  // Velocity in x and y direction.
+  float x_velocity_;
+  float y_velocity_;
+
+  // Event flags.
+  int flags_;

[sadrul, 2011/11/18 19:01:50]

Are these ui::EventFlags?

[Gajen, 2011/11/21 15:56:50]

Yes, and updated comments too.

+
+  DISALLOW_COPY_AND_ASSIGN(GestureRecognizer);
+};
+
+}  // namespace views
+
+#endif  // VIEWS_TOUCHUI_GESTURE_RECOGNIZER_H_