[Tracking Patch] Unified gesture detection

content/browser/renderer_host/input/gestures/zoom_manager.h

+// Copyright 2014 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 CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURES_ZOOM_MANAGER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURES_ZOOM_MANAGER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/renderer_host/input/gestures/scale_gesture_detector.h"
+
+namespace content {
+
+// Port of ZoomManager.java from Chromium
+// * Changes to this class should be cosmetic only, easing fork maintenance.

[tdresser, 2014/01/08 19:18:21]

Will we still need the java version of ZoomManager once this has landed?

+// Responsible for maintaining zoom state and processing scale-related gestures.
+class ZoomManager : public ScaleGestureDetector::OnScaleGestureListener {
+ public:
+  ZoomManager(ScaleGestureDetector::Config config,
+              ScaleGestureDetector::OnScaleGestureListener* listener);
+  virtual ~ZoomManager();
+
+  // Passes the touch event to ScaleGestureDetector so that its internal
+  // state won't go wrong, but instructs the listener to ignore the result
+  // of processing, if any.
+  void PassTouchEventThrough(const MotionEvent& event);
+
+  // Passes the touch event to ScaleGestureDetector so that its internal state
+  // won't go wrong. ScaleGestureDetector needs two pointers in a MotionEvent
+  // to recognize a zoom gesture.
+  bool ProcessTouchEvent(const MotionEvent& event);
+
+  void UpdateMultiTouchSupport(bool supports_multi_touch_zoom);
+
+  bool IsScaleGestureDetectionInProgress() const;
+
+ private:
+  // OnScaleGestureListener
+  virtual bool OnScaleBegin(const ScaleGestureDetector& detector) OVERRIDE;
+  virtual void OnScaleEnd(const ScaleGestureDetector& detector) OVERRIDE;
+  virtual bool OnScale(const ScaleGestureDetector& detector) OVERRIDE;
+
+  bool IgnoreDetectorEvents() const;
+
+  scoped_ptr<ScaleGestureDetector> multi_touch_detector_;
+
+  ScaleGestureDetector::OnScaleGestureListener* const listener_;
+
+  // Completely silence scaling events. Used in WebView when zoom support
+  // is turned off.
+  bool permanently_ignore_detector_events_;
+
+  // Bypass events through the detector to maintain its state. Used when
+  // renderes already handles the touch event.
+  bool temporarily_ignore_detector_events_;
+
+  // Whether any pinch zoom event has been sent to native.
+  bool pinch_event_sent_;
+
+  DISALLOW_COPY_AND_ASSIGN(ZoomManager);
+};
+
+}  //  namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURES_ZOOM_MANAGER_H_