Port of Android platform gesture detection code to C++

ui/events/gesture_detection/gesture_provider.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 UI_EVENTS_GESTURE_DETECTION_GESTURE_PROVIDER_H_
+#define UI_EVENTS_GESTURE_DETECTION_GESTURE_PROVIDER_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/events/gesture_detection/gesture_detection_export.h"
+#include "ui/events/gesture_detection/gesture_detector.h"
+#include "ui/events/gesture_detection/scale_gesture_detector.h"
+#include "ui/events/gesture_detection/snap_scroll_controller.h"
+
+namespace ui {
+
+struct GestureEventParams;
+
+class GESTURE_DETECTION_EXPORT GestureProviderClient {
+ public:
+  virtual ~GestureProviderClient() {}
+  virtual void OnGestureEvent(const GestureEventParams& gesture) = 0;
+};
+
+// Given a stream of |MotionEvent|'s, provides gesture detection and gesture
+// event dispatch.
+class GESTURE_DETECTION_EXPORT GestureProvider {
+ public:
+  struct GESTURE_DETECTION_EXPORT Config {
+    Config();
+    ~Config();
+    GestureDetector::Config gesture_detector_config;
+    ScaleGestureDetector::Config scale_gesture_detector_config;
+    SnapScrollController::Config snap_scroll_controller_config;
+    bool disable_click_delay;
+  };
+
+  GestureProvider(const Config& config, GestureProviderClient* client);
+  ~GestureProvider();
+
+  // Handle the incoming MotionEvent, returning false if the event could not
+  // be handled.
+  bool OnTouchEvent(const MotionEvent& event);
+
+  // Resets all gesture detectors; called on DidStartLoading().
+  void ResetGestureDetectors();
+
+  // Cancel the current touch event sequence by sending ACTION_CANCEL, and
+  // ignore all the subsequent events until the next ACTION_DOWN.
+  // One example usecase is to stop processing the touch events when showing
+  // a context popup menu.
+  void CancelActiveTouchSequence();
+
+  // Update whether multi-touch gestures are supported.
+  void UpdateMultiTouchSupport(bool support_multi_touch_zoom);
+
+  // Update whether double-tap gestures are supported. This allows
+  // double-tap gesture suppression independent of whether or not the page's
+  // viewport and scale would normally prevent double-tap.
+  // Note: This should not be called while a double-tap gesture is in progress.
+  void UpdateDoubleTapSupportForPlatform(bool support_double_tap);
+
+  // Update whether double-tap gesture detection should be suppressed due to
+  // the viewport or scale of the current page. Suppressing double-tap gesture
+  // detection allows for rapid and responsive single-tap gestures.
+  void UpdateDoubleTapSupportForPage(bool support_double_tap);
+
+  // Whether a scroll gesture is in-progress.
+  bool IsScrollInProgress() const;
+
+  // Whether a pinch gesture is in-progress (i.e. a pinch update has been
+  // forwarded and detection is still active).
+  bool IsPinchInProgress() const;
+
+  // Whether a double tap-gesture is in-progress.
+  bool IsDoubleTapInProgress() const;
+
+ private:
+  void InitGestureDetectors(const Config& config);
+
+  bool CanHandle(const MotionEvent& event) const;
+
+  void Fling(base::TimeTicks time,
+             float x,
+             float y,
+             float velocity_x,
+             float velocity_y);
+  void Send(const GestureEventParams& gesture);
+  void SendTapCancelIfNecessary(const MotionEvent& event);
+  bool SendLongTapIfNecessary(const MotionEvent& event);
+  void EndTouchScrollIfNecessary(base::TimeTicks time,
+                                 bool send_scroll_end_event);
+
+  GestureProviderClient* const client_;
+
+  class GestureListenerImpl;
+  friend class GestureListenerImpl;
+  scoped_ptr<GestureListenerImpl> gesture_listener_;
+
+  class ScaleGestureListenerImpl;
+  friend class ScaleGestureListenerImpl;
+  scoped_ptr<ScaleGestureListenerImpl> scale_gesture_listener_;
+
+  scoped_ptr<MotionEvent> current_down_event_;
+
+  // Whether a GESTURE_SHOW_PRESS was sent for the current touch sequence.
+  // Sending a GESTURE_SINGLE_TAP* event will forward a GESTURE_SHOW_PRESS if
+  // one has not yet been sent.
+  bool needs_show_press_event_;
+
+  // Whether a sent GESTURE_TAP_DOWN event has yet to be accompanied by a
+  // corresponding GESTURE_SINGLE_TAP_CONFIRMED, GESTURE_TAP_CANCEL or
+  // GESTURE_DOUBLE_TAP.
+  bool needs_tap_ending_event_;
+
+  // Whether the respective {SCROLL,PINCH}_BEGIN gestures have been terminated
+  // with a {SCROLL,PINCH}_END.
+  bool touch_scroll_in_progress_;
+  bool pinch_in_progress_;
+
+  // Keeps track of the current GESTURE_LONG_PRESS event. If a context menu is
+  // opened after a GESTURE_LONG_PRESS, this is used to insert a
+  // GESTURE_TAP_CANCEL for removing any ::active styling.
+  base::TimeTicks current_longpress_time_;
+};
+
+}  //  namespace ui
+
+#endif  // UI_EVENTS_GESTURE_DETECTION_GESTURE_PROVIDER_H_