Forward touch events to a RenderWidget's associated WebWidget

chrome/renderer/gesture_manager.h

+// Copyright (c) 2010 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 CHROME_RENDERER_GESTURE_MANAGER_H_
+#define CHROME_RENDERER_GESTURE_MANAGER_H_
+#pragma once
+
+#include "base/singleton.h"
+
+#include "third_party/WebKit/WebKit/chromium/public/WebPoint.h"
+
+class RenderWidget;
+
+namespace WebKit {
+class WebTouchEvent;
+class WebTouchPoint;
+}
+
+// A GestureManager singleton detects gestures occurring in the
+// incoming feed of touch events in the Renderer. In response to
+// a given touch event, the GestureManager, updates its internal state
+// and optionally dispatches synthetic events to the invoking
+// RenderWidget.
+// 
+// This GestureManager is a singleton in the renderer process and differs
+// from the GestureManager found in the browser process. 
+// A subsequent CL will unify these and provide more complete
+// functionality.
+class GestureManager /* : public AbstractGestureManager */ {
+ public:
+  // The states of the gesture manager state machine.
+  enum SyntheticCandidateGesture {
+    NO_GESTURE,
+    PENDING_SYNTHETIC_CLICK,
+    SCROLL,
+  };
+  
+  virtual ~GestureManager();
+  static GestureManager* Get();
+
+  // Invoked for each touch event that could contribute to the current gesture.
+  // Takes the event and the RenderWidget that originated it and which will also
+  // be the target of any generated synthetic event. Finally, previously_handled
+  // specifies if the event was actually handled explicitly by a WebWidget.
+  // Returns true if the event resulted in firing a synthetic event.
+  virtual bool ProcessTouchEventForGesture(const WebKit::WebTouchEvent& event,
+                                           RenderWidget* source,
+                                           bool previously_handled);
+
+ protected:
+  GestureManager();
+
+ private:
+  // Dispatch a mouseDown/mouseUp/Click sequence.
+  void DispatchSyntheticClick(RenderWidget* w,
+                              const WebKit::WebTouchEvent& event,
+                              const WebKit::WebTouchPoint& p);
+
+  // True for a time within the click interval.
+  bool IsInClickTimeWindow(double ts);
+  
+  // True for a point p still inside the thresholded square.
+  bool IsInsideManhattanSquare(const WebKit::WebTouchPoint& p);
+  
+  // Scroll the screen.
+  void ScrollViaTouchMotion(const WebKit::WebTouchPoint& p, RenderWidget* w);
+
+  friend struct DefaultSingletonTraits<GestureManager>;
+
+  // The synthetic candidate gesture to fire at the end of a touch event
+  // sequence.
+  SyntheticCandidateGesture candidate_gesture_;
+
+  // Location of first touch.
+  WebKit::WebPoint first_touch_position_;
+
+  // Time of first touch.
+  double first_touch_time_;
+
+  DISALLOW_COPY_AND_ASSIGN(GestureManager);
+};
+
+#endif  // CHROME_RENDERER_GESTURE_MANAGER_H_