1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef UI_EVENTS_GESTURE_DETECTION_SCALE_GESTURE_DETECTOR_H_ 6 #define UI_EVENTS_GESTURE_DETECTION_SCALE_GESTURE_DETECTOR_H_ 7 8 #include "base/memory/scoped_ptr.h" 9 #include "base/time/time.h" 10 #include "ui/events/gesture_detection/gesture_detection_export.h" 11 #include "ui/events/gesture_detection/gesture_detector.h" 12 13 namespace ui { 14 15 class MotionEvent; 16 17 // Port of ScaleGestureDetector.java from Android 18 // * platform/frameworks/base/core/java/android/view/ScaleGestureDetector.java 19 // * Change-Id: I3e7926a4f6f9ab4951f380bd004499c78b3bda69 20 // * Please update the Change-Id as upstream Android changes are pulled. 21 class ScaleGestureDetector : public GestureDetector::SimpleGestureListener { 22 public: 23 struct GESTURE_DETECTION_EXPORT Config { 24 Config(); 25 ~Config(); 26 GestureDetector::Config gesture_detector_config; 27 28 // Minimum accepted value for TouchMajor while scaling (in dips). 29 float min_scaling_touch_major; 30 31 // Minimum span needed to initiate a scaling gesture (in dips). 32 float min_scaling_span; 33 34 // Whether double-tap drag scaling is enabled. 35 bool quick_scale_enabled; 36 37 // Minimum pinch span change before pinch occurs (in dips). See 38 // crbug.com/373318. 39 float min_pinch_update_span_delta; 40 }; 41 42 class ScaleGestureListener { 43 public: ~ScaleGestureListener()44 virtual ~ScaleGestureListener() {} 45 virtual bool OnScale(const ScaleGestureDetector& detector, 46 const MotionEvent& e) = 0; 47 virtual bool OnScaleBegin(const ScaleGestureDetector& detector, 48 const MotionEvent& e) = 0; 49 virtual void OnScaleEnd(const ScaleGestureDetector& detector, 50 const MotionEvent& e) = 0; 51 }; 52 53 // A convenience class to extend when you only want to listen for a subset of 54 // scaling-related events. This implements all methods in 55 // |ScaleGestureListener| but does nothing. 56 // |OnScale()| returns false so that a subclass can retrieve the accumulated 57 // scale factor in an overridden |OnScaleEnd()|. 58 // |OnScaleBegin() returns true. 59 class SimpleScaleGestureListener : public ScaleGestureListener { 60 public: 61 // ScaleGestureListener implementation. 62 virtual bool OnScale(const ScaleGestureDetector&, 63 const MotionEvent&) OVERRIDE; 64 virtual bool OnScaleBegin(const ScaleGestureDetector&, 65 const MotionEvent&) OVERRIDE; 66 virtual void OnScaleEnd(const ScaleGestureDetector&, 67 const MotionEvent&) OVERRIDE; 68 }; 69 70 ScaleGestureDetector(const Config& config, ScaleGestureListener* listener); 71 virtual ~ScaleGestureDetector(); 72 73 // Accepts MotionEvents and dispatches events to a |ScaleGestureListener| 74 // when appropriate. 75 // 76 // Note: Applications should pass a complete and consistent event stream to 77 // this method. A complete and consistent event stream involves all 78 // MotionEvents from the initial ACTION_DOWN to the final ACTION_UP or 79 // ACTION_CANCEL. 80 // 81 // Returns true if the event was processed and the detector wants to receive 82 // the rest of the MotionEvents in this event stream. 83 bool OnTouchEvent(const MotionEvent& event); 84 85 // Set whether the associated |ScaleGestureListener| should receive 86 // OnScale callbacks when the user performs a doubletap followed by a swipe. 87 void SetQuickScaleEnabled(bool scales); 88 bool IsQuickScaleEnabled() const; 89 bool IsInProgress() const; 90 bool InDoubleTapMode() const; 91 float GetFocusX() const; 92 float GetFocusY() const; 93 float GetCurrentSpan() const; 94 float GetCurrentSpanX() const; 95 float GetCurrentSpanY() const; 96 float GetPreviousSpan() const; 97 float GetPreviousSpanX() const; 98 float GetPreviousSpanY() const; 99 float GetScaleFactor() const; 100 base::TimeDelta GetTimeDelta() const; 101 base::TimeTicks GetEventTime() const; 102 103 private: 104 enum DoubleTapMode { DOUBLE_TAP_MODE_NONE, DOUBLE_TAP_MODE_IN_PROGRESS }; 105 106 // DoubleTapListener implementation. 107 virtual bool OnDoubleTap(const MotionEvent& ev) OVERRIDE; 108 109 // The TouchMajor/TouchMinor elements of a MotionEvent can flutter/jitter on 110 // some hardware/driver combos. Smooth out to get kinder, gentler behavior. 111 void AddTouchHistory(const MotionEvent& ev); 112 void ResetTouchHistory(); 113 114 void ResetScaleWithSpan(float span); 115 116 ScaleGestureListener* const listener_; 117 118 Config config_; 119 120 float focus_x_; 121 float focus_y_; 122 123 bool quick_scale_enabled_; 124 125 float curr_span_; 126 float prev_span_; 127 float initial_span_; 128 float curr_span_x_; 129 float curr_span_y_; 130 float prev_span_x_; 131 float prev_span_y_; 132 base::TimeTicks curr_time_; 133 base::TimeTicks prev_time_; 134 bool in_progress_; 135 float span_slop_; 136 float min_span_; 137 138 // Bounds for recently seen values. 139 float touch_upper_; 140 float touch_lower_; 141 float touch_history_last_accepted_; 142 int touch_history_direction_; 143 base::TimeTicks touch_history_last_accepted_time_; 144 float touch_min_major_; 145 float double_tap_focus_x_; 146 float double_tap_focus_y_; 147 DoubleTapMode double_tap_mode_; 148 149 bool event_before_or_above_starting_gesture_event_; 150 151 scoped_ptr<GestureDetector> gesture_detector_; 152 153 DISALLOW_COPY_AND_ASSIGN(ScaleGestureDetector); 154 }; 155 156 } // namespace ui 157 158 #endif // UI_EVENTS_GESTURE_DETECTION_SCALE_GESTURE_DETECTOR_H_ 159