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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 'use strict'; | 5 'use strict'; |
6 | 6 |
7 /** | 7 /** |
8 * A class that listens for touch events and produces events when these | 8 * A class that listens for touch events and produces events when these |
9 * touches form gestures (e.g. pinching). | 9 * touches form gestures (e.g. pinching). |
10 */ | 10 */ |
11 class GestureDetector { | 11 class GestureDetector { |
12 /** | 12 /** |
13 * Constructs a GestureDetector. | 13 * Constructs a GestureDetector. |
14 * @param {!Element} element The element to monitor for touch gestures. | 14 * @param {!Element} element The element to monitor for touch gestures. |
15 */ | 15 */ |
16 constructor(element) { | 16 constructor(element) { |
17 /** @private {!Element} */ | |
17 this.element_ = element; | 18 this.element_ = element; |
18 | 19 |
19 this.element_.addEventListener( | 20 this.element_.addEventListener( |
20 'touchstart', this.onTouchStart_.bind(this), { passive: true }); | 21 'touchstart', |
22 /** @type {function(!Event)} */ (this.onTouchStart_.bind(this)), | |
dpapad
2017/05/23 18:38:38
Changed the code to use a different function refer
| |
23 { passive: true }); | |
24 | |
21 this.element_.addEventListener( | 25 this.element_.addEventListener( |
22 'touchmove', this.onTouch_.bind(this), { passive: false }); | 26 'touchmove', |
27 /** @type {function(!Event)} */ (this.onTouch_.bind(this)), | |
28 { passive: false }); | |
23 this.element_.addEventListener( | 29 this.element_.addEventListener( |
24 'touchend', this.onTouch_.bind(this), { passive: true }); | 30 'touchend', |
31 /** @type {function(!Event)} */ (this.onTouch_.bind(this)), | |
32 { passive: true }); | |
25 this.element_.addEventListener( | 33 this.element_.addEventListener( |
26 'touchcancel', this.onTouch_.bind(this), { passive: true }); | 34 'touchcancel', |
35 /** @type {function(!Event)} */ (this.onTouch_.bind(this)), | |
36 { passive: true }); | |
27 | 37 |
28 this.pinchStartEvent_ = null; | 38 this.pinchStartEvent_ = null; |
29 this.lastTouchTouchesCount_ = 0; | 39 this.lastTouchTouchesCount_ = 0; |
40 | |
41 /** @private {?TouchEvent} */ | |
30 this.lastEvent_ = null; | 42 this.lastEvent_ = null; |
31 | 43 |
44 /** @private {!Map<string, !Array<!Function>>} */ | |
32 this.listeners_ = new Map([ | 45 this.listeners_ = new Map([ |
33 ['pinchstart', []], | 46 ['pinchstart', []], |
34 ['pinchupdate', []], | 47 ['pinchupdate', []], |
35 ['pinchend', []] | 48 ['pinchend', []] |
36 ]); | 49 ]); |
37 } | 50 } |
38 | 51 |
39 /** | 52 /** |
40 * Add a |listener| to be notified of |type| events. | 53 * Add a |listener| to be notified of |type| events. |
41 * @param {string} type The event type to be notified for. | 54 * @param {string} type The event type to be notified for. |
42 * @param {Function} listener The callback. | 55 * @param {!Function} listener The callback. |
43 */ | 56 */ |
44 addEventListener(type, listener) { | 57 addEventListener(type, listener) { |
45 if (this.listeners_.has(type)) { | 58 if (this.listeners_.has(type)) { |
46 this.listeners_.get(type).push(listener); | 59 this.listeners_.get(type).push(listener); |
47 } | 60 } |
48 } | 61 } |
49 | 62 |
50 /** | 63 /** |
51 * Returns true if the last touch start was a two finger touch. | 64 * Returns true if the last touch start was a two finger touch. |
52 * @return {boolean} True if the last touch start was a two finger touch. | 65 * @return {boolean} True if the last touch start was a two finger touch. |
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87 | 100 |
88 /** | 101 /** |
89 * The callback for touch move, end, and cancel events on the element. | 102 * The callback for touch move, end, and cancel events on the element. |
90 * @private | 103 * @private |
91 * @param {!TouchEvent} event Touch event on the element. | 104 * @param {!TouchEvent} event Touch event on the element. |
92 */ | 105 */ |
93 onTouch_(event) { | 106 onTouch_(event) { |
94 if (!this.pinchStartEvent_) | 107 if (!this.pinchStartEvent_) |
95 return; | 108 return; |
96 | 109 |
110 let lastEvent = /** @type {!TouchEvent} */ (this.lastEvent_); | |
111 | |
97 // Check if the pinch ends with the current event. | 112 // Check if the pinch ends with the current event. |
98 if (event.touches.length < 2 || | 113 if (event.touches.length < 2 || |
99 this.lastEvent_.touches.length !== event.touches.length) { | 114 lastEvent.touches.length !== event.touches.length) { |
100 let startScaleRatio = GestureDetector.pinchScaleRatio_( | 115 let startScaleRatio = GestureDetector.pinchScaleRatio_( |
101 this.lastEvent_, this.pinchStartEvent_); | 116 lastEvent, this.pinchStartEvent_); |
102 let center = GestureDetector.center_(this.lastEvent_); | 117 let center = GestureDetector.center_(lastEvent); |
103 let endEvent = { | 118 let endEvent = { |
104 type: 'pinchend', | 119 type: 'pinchend', |
105 startScaleRatio: startScaleRatio, | 120 startScaleRatio: startScaleRatio, |
106 center: center | 121 center: center |
107 }; | 122 }; |
108 this.pinchStartEvent_ = null; | 123 this.pinchStartEvent_ = null; |
109 this.lastEvent_ = null; | 124 this.lastEvent_ = null; |
110 this.notify_(endEvent); | 125 this.notify_(endEvent); |
111 return; | 126 return; |
112 } | 127 } |
113 | 128 |
114 // We must preventDefault two finger touchmoves. By doing so native | 129 // We must preventDefault two finger touchmoves. By doing so native |
115 // pinch-zoom does not interfere with our way of handling the event. | 130 // pinch-zoom does not interfere with our way of handling the event. |
116 event.preventDefault(); | 131 event.preventDefault(); |
117 | 132 |
118 let scaleRatio = GestureDetector.pinchScaleRatio_(event, this.lastEvent_); | 133 let scaleRatio = GestureDetector.pinchScaleRatio_(event, lastEvent); |
119 let startScaleRatio = GestureDetector.pinchScaleRatio_( | 134 let startScaleRatio = GestureDetector.pinchScaleRatio_( |
120 event, this.pinchStartEvent_); | 135 event, this.pinchStartEvent_); |
121 let center = GestureDetector.center_(event); | 136 let center = GestureDetector.center_(event); |
122 this.notify_({ | 137 this.notify_({ |
123 type: 'pinchupdate', | 138 type: 'pinchupdate', |
124 scaleRatio: scaleRatio, | 139 scaleRatio: scaleRatio, |
125 direction: scaleRatio > 1.0 ? 'in' : 'out', | 140 direction: scaleRatio > 1.0 ? 'in' : 'out', |
126 startScaleRatio: startScaleRatio, | 141 startScaleRatio: startScaleRatio, |
127 center: center | 142 center: center |
128 }); | 143 }); |
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167 */ | 182 */ |
168 static center_(event) { | 183 static center_(event) { |
169 let touch1 = event.touches[0]; | 184 let touch1 = event.touches[0]; |
170 let touch2 = event.touches[1]; | 185 let touch2 = event.touches[1]; |
171 return { | 186 return { |
172 x: (touch1.clientX + touch2.clientX) / 2, | 187 x: (touch1.clientX + touch2.clientX) / 2, |
173 y: (touch1.clientY + touch2.clientY) / 2 | 188 y: (touch1.clientY + touch2.clientY) / 2 |
174 }; | 189 }; |
175 } | 190 } |
176 }; | 191 }; |
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