Port of Android platform gesture detection code to C++

ui/events/gesture_detection/gesture_detector.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_DETECTOR_H_
+#define UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "ui/events/gesture_detection/gesture_detection_export.h"
+#include "ui/events/gesture_detection/velocity_tracker_state.h"
+
+namespace ui {
+
+class MotionEvent;
+
+// Port of GestureDetector.java from Android
+// * platform/frameworks/base/core/java/android/view/GestureDetector.java
+// * Change-Id: Ib470735ec929b0b358fca4597e92dc81084e675f
+// * Please update the Change-Id as upstream Android changes are pulled.
+class GestureDetector {
+ public:
+  struct GESTURE_DETECTION_EXPORT Config {
+    Config();
+    ~Config();
+    base::TimeDelta longpress_timeout;
+    base::TimeDelta tap_timeout;
+    base::TimeDelta double_tap_timeout;
+    int scaled_touch_slop;
+    int scaled_double_tap_slop;
+    int scaled_minimum_fling_velocity;
+    int scaled_maximum_fling_velocity;
+  };
+
+  class GestureListener {
+   public:
+    virtual ~GestureListener() {}
+    virtual bool OnDown(const MotionEvent& e) = 0;
+    virtual void OnShowPress(const MotionEvent& e) = 0;
+    virtual bool OnSingleTapUp(const MotionEvent& e) = 0;
+    virtual bool OnLongPress(const MotionEvent& e) = 0;
+    virtual bool OnScroll(const MotionEvent& e1, const MotionEvent& e2,
+                          float distance_x, float distance_y) = 0;
+    virtual bool OnFling(const MotionEvent& e1, const MotionEvent& e2,
+                         float velocity_x, float velocity_y) = 0;
+  };
+
+  class DoubleTapListener {
+   public:
+    virtual ~DoubleTapListener() {}
+    virtual bool OnSingleTapConfirmed(const MotionEvent& e) = 0;
+    virtual bool OnDoubleTap(const MotionEvent& e) = 0;
+    virtual bool OnDoubleTapEvent(const MotionEvent& e) = 0;
+  };
+
+  // A convenience class to extend when you only want to listen for a subset
+  // of all the gestures. This implements all methods in the
+  // |GestureListener| and |DoubleTapListener| but does
+  // nothing and returns false for all applicable methods.
+  class SimpleGestureListener : public GestureListener,
+                                public DoubleTapListener {
+   public:
+    // GestureListener implementation.
+    virtual bool OnDown(const MotionEvent& e) OVERRIDE;
+    virtual void OnShowPress(const MotionEvent& e) OVERRIDE;
+    virtual bool OnSingleTapUp(const MotionEvent& e) OVERRIDE;
+    virtual bool OnLongPress(const MotionEvent& e) OVERRIDE;
+    virtual bool OnScroll(const MotionEvent& e1, const MotionEvent& e2,
+                          float distance_x, float distance_y) OVERRIDE;
+    virtual bool OnFling(const MotionEvent& e1, const MotionEvent& e2,
+                         float velocity_x, float velocity_y) OVERRIDE;
+
+    // DoubleTapListener implementation.
+    virtual bool OnSingleTapConfirmed(const MotionEvent& e) OVERRIDE;
+    virtual bool OnDoubleTap(const MotionEvent& e) OVERRIDE;
+    virtual bool OnDoubleTapEvent(const MotionEvent& e) OVERRIDE;
+  };
+
+  GestureDetector(const Config& config,
+                  GestureListener* listener,
+                  DoubleTapListener* optional_double_tap_listener);
+  ~GestureDetector();
+
+  bool OnTouchEvent(const MotionEvent& ev);
+
+  void set_doubletap_listener(DoubleTapListener* double_tap_listener) {
+    double_tap_listener_ = double_tap_listener;
+  }
+
+  void set_is_longpress_enabled(bool is_longpress_enabled) {
+    is_longpress_enabled_ = is_longpress_enabled;
+  }
+
+  bool is_longpress_enabled() const { return is_longpress_enabled_; }
+
+ private:
+  void Init(const Config& config);
+  void OnShowPressTimeout();
+  void OnLongPressTimeout();
+  void OnTapTimeout();
+  void Cancel();
+  void CancelTaps();
+  bool IsConsideredDoubleTap(const MotionEvent& first_down,
+                             const MotionEvent& first_up,
+                             const MotionEvent& second_down) const;
+
+  class TimeoutGestureHandler;
+  scoped_ptr<TimeoutGestureHandler> timeout_handler_;
+  GestureListener* const listener_;
+  DoubleTapListener* double_tap_listener_;
+
+  int touch_slop_square_;
+  int double_tap_touch_slop_square_;
+  int double_tap_slop_square_;
+  int min_fling_velocity_;
+  int max_fling_velocity_;
+  base::TimeDelta double_tap_timeout_;
+
+  bool still_down_;
+  bool defer_confirm_single_tap_;
+  bool in_longpress_;
+  bool always_in_tap_region_;
+  bool always_in_bigger_tap_region_;
+
+  scoped_ptr<MotionEvent> current_down_event_;
+  scoped_ptr<MotionEvent> previous_up_event_;
+
+  // True when the user is still touching for the second tap (down, move, and
+  // up events). Can only be true if there is a double tap listener attached.
+  bool is_double_tapping_;
+
+  float last_focus_x_;
+  float last_focus_y_;
+  float down_focus_x_;
+  float down_focus_y_;
+
+  bool is_longpress_enabled_;
+
+  // Determines speed during touch scrolling.
+  VelocityTrackerState velocity_tracker_;
+
+  DISALLOW_COPY_AND_ASSIGN(GestureDetector);
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_GESTURE_DETECTION_GESTURE_DETECTOR_H_