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1 // Copyright 2015 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 'use strict'; | |
6 | |
7 /** | |
8 * @private | |
9 * The period of time in milliseconds to wait between updating the viewport | |
10 * position by the scroll velocity. | |
11 */ | |
12 ViewportScroller.DRAG_TIMER_INTERVAL_MS_ = 100; | |
13 | |
14 /** | |
15 * @private | |
16 * The maximum drag scroll distance per DRAG_TIMER_INTERVAL in pixels. | |
17 */ | |
18 ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_ = 100; | |
19 | |
20 /** | |
21 * Creates a new ViewportScroller. | |
22 * A ViewportScroller scrolls the page in response to drag selection with the | |
23 * mouse. | |
24 * @param {Object} viewport The viewport info of the page. | |
25 * @param {Object} plugin The PDF plugin element. | |
26 * @param {Object} window The window containing the viewer. | |
27 */ | |
28 function ViewportScroller(viewport, plugin, window) { | |
29 this.viewport_ = viewport; | |
30 this.plugin_ = plugin; | |
31 this.window_ = window; | |
32 this.mousemoveCallback_ = null; | |
33 this.timerId_ = null; | |
34 this.scrollVelocity_ = null; | |
35 this.lastFrameTime_ = 0; | |
36 } | |
37 | |
38 ViewportScroller.prototype = { | |
39 /** | |
40 * @private | |
41 * Start scrolling the page by |scrollVelocity_| every | |
42 * |DRAG_TIMER_INTERVAL_MS_|. | |
43 */ | |
44 startDragScrollTimer_: function() { | |
45 if (this.timerId_ === null) { | |
46 this.timerId_ = | |
47 this.window_.setInterval(this.dragScrollPage_.bind(this), | |
48 ViewportScroller.DRAG_TIMER_INTERVAL_MS_); | |
49 this.lastFrameTime_ = Date.now(); | |
50 } | |
51 }, | |
52 | |
53 /** | |
54 * @private | |
55 * Stops the drag scroll timer if it is active. | |
56 */ | |
57 stopDragScrollTimer_: function() { | |
58 if (this.timerId_ !== null) { | |
59 this.window_.clearInterval(this.timerId_); | |
60 this.timerId_ = null; | |
61 this.lastFrameTime_ = 0; | |
62 } | |
63 }, | |
64 | |
65 /** | |
66 * @private | |
67 * Scrolls the viewport by the current scroll velocity. | |
68 */ | |
69 dragScrollPage_: function() { | |
70 var position = this.viewport_.position; | |
71 var currentFrameTime_ = Date.now(); | |
Bernhard Bauer
2015/02/13 10:06:22
And local variables don't end with underscores.
Deepak
2015/02/13 11:11:09
Done.
| |
72 var timeAdjustment = (currentFrameTime_ - this.lastFrameTime_) / | |
73 ViewportScroller.DRAG_TIMER_INTERVAL_MS_; | |
74 position.y += (this.scrollVelocity_.y * timeAdjustment); | |
75 position.x += (this.scrollVelocity_.x * timeAdjustment); | |
76 this.viewport_.position = position; | |
77 this.lastFrameTime_ = currentFrameTime_; | |
78 }, | |
79 | |
80 /** | |
81 * @private | |
82 * Calculate the velocity to scroll while dragging using the distance of the | |
83 * cursor outside the viewport. | |
84 * @param {Object} event The mousemove event. | |
85 * @return {Object} Object with x and y direction scroll velocity. | |
86 */ | |
87 calculateVelocity_: function(event) { | |
88 var x = Math.min(Math.max(-event.offsetX, | |
89 event.offsetX - this.plugin_.offsetWidth, 0), | |
90 ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_) * | |
91 Math.sign(event.offsetX); | |
92 var y = Math.min(Math.max(-event.offsetY, | |
93 event.offsetY - this.plugin_.offsetHeight, 0), | |
94 ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_) * | |
95 Math.sign(event.offsetY); | |
96 return { | |
97 x: x, | |
98 y: y | |
99 }; | |
100 }, | |
101 | |
102 /** | |
103 * @private | |
104 * Handles mousemove events. It updates the scroll velocity and starts and | |
105 * stops timer based on scroll velocity. | |
106 * @param {Object} event The mousemove event. | |
107 */ | |
108 onMousemove_: function(event) { | |
109 this.scrollVelocity_ = this.calculateVelocity_(event); | |
110 if (!this.scrollVelocity_.x && !this.scrollVelocity_.y) | |
111 this.stopDragScrollTimer_(); | |
112 else if (!this.timerId_) | |
113 this.startDragScrollTimer_(); | |
114 }, | |
115 | |
116 /** | |
117 * Sets whether to scroll the viewport when the mouse is outside the | |
118 * viewport. | |
119 * @param {boolean} isSelecting Represents selection status. | |
120 */ | |
121 setEnableScrolling: function(isSelecting) { | |
122 if (isSelecting) { | |
123 if (!this.mousemoveCallback_) | |
124 this.mousemoveCallback_ = this.onMousemove_.bind(this); | |
125 this.plugin_.addEventListener('mousemove', this.mousemoveCallback_, | |
126 false); | |
127 } else { | |
128 this.stopDragScrollTimer_(); | |
129 if (this.mousemoveCallback_) { | |
130 this.plugin_.removeEventListener('mousemove', this.mousemoveCallback_, | |
131 false); | |
132 } | |
133 } | |
134 } | |
135 }; | |
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