1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
// Copyright 2012 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.
// This file provides the ScrollAction object, which scrolls a page
// to the bottom or for a specified distance:
// 1. var action = new __ScrollAction(callback, opt_distance_func)
// 2. action.start(scroll_options)
'use strict';
(function() {
var MAX_SCROLL_LENGTH_TIME_MS = 6250;
function ScrollGestureOptions(opt_options) {
if (opt_options) {
this.element_ = opt_options.element;
this.leftStartRatio_ = opt_options.left_start_ratio;
this.topStartRatio_ = opt_options.top_start_ratio;
this.direction_ = opt_options.direction;
this.speed_ = opt_options.speed;
this.gesture_source_type_ = opt_options.gesture_source_type;
} else {
this.element_ = document.scrollingElement || document.body;
this.leftStartRatio_ = 0.5;
this.topStartRatio_ = 0.5;
this.direction_ = 'down';
this.speed_ = 800;
this.gesture_source_type_ = chrome.gpuBenchmarking.DEFAULT_INPUT;
}
}
function supportedByBrowser() {
return !!(window.chrome &&
chrome.gpuBenchmarking &&
chrome.gpuBenchmarking.smoothScrollBy &&
chrome.gpuBenchmarking.visualViewportHeight &&
chrome.gpuBenchmarking.visualViewportWidth);
}
// This class scrolls a page from the top to the bottom once.
//
// The page is scrolled down by a single scroll gesture.
function ScrollAction(opt_callback, opt_distanceFunc) {
var self = this;
this.beginMeasuringHook = function() {};
this.endMeasuringHook = function() {};
this.callback_ = opt_callback;
this.distance_func_ = opt_distanceFunc;
}
ScrollAction.prototype.getScrollDistanceDown_ = function() {
var clientHeight;
// clientHeight is "special" for the body element.
if (this.element_ === document.body)
clientHeight = __GestureCommon_GetWindowHeight();
else
clientHeight = this.element_.clientHeight;
return this.element_.scrollHeight -
this.element_.scrollTop -
clientHeight;
};
ScrollAction.prototype.getScrollDistanceUp_ = function() {
return this.element_.scrollTop;
};
ScrollAction.prototype.getScrollDistanceRight_ = function() {
var clientWidth;
// clientWidth is "special" for the body element.
if (this.element_ === document.body)
clientWidth = __GestureCommon_GetWindowWidth();
else
clientWidth = this.element_.clientWidth;
return this.element_.scrollWidth - this.element_.scrollLeft - clientWidth;
};
ScrollAction.prototype.getScrollDistanceLeft_ = function() {
return this.element_.scrollLeft;
};
ScrollAction.prototype.getScrollDistance_ = function() {
if (this.distance_func_)
return this.distance_func_();
if (this.options_.direction_ === 'down') {
return this.getScrollDistanceDown_();
} else if (this.options_.direction_ === 'up') {
return this.getScrollDistanceUp_();
} else if (this.options_.direction_ === 'right') {
return this.getScrollDistanceRight_();
} else if (this.options_.direction_ === 'left') {
return this.getScrollDistanceLeft_();
} else if (this.options_.direction_ === 'upleft') {
return Math.min(this.getScrollDistanceUp_(),
this.getScrollDistanceLeft_());
} else if (this.options_.direction_ === 'upright') {
return Math.min(this.getScrollDistanceUp_(),
this.getScrollDistanceRight_());
} else if (this.options_.direction_ === 'downleft') {
return Math.min(this.getScrollDistanceDown_(),
this.getScrollDistanceLeft_());
} else if (this.options_.direction_ === 'downright') {
return Math.min(this.getScrollDistanceDown_(),
this.getScrollDistanceRight_());
}
};
ScrollAction.prototype.start = function(opt_options) {
this.options_ = new ScrollGestureOptions(opt_options);
// Assign this.element_ here instead of constructor, because the constructor
// ensures this method will be called after the document is loaded.
this.element_ = this.options_.element_;
// Calculate scroll point.
var rect = __GestureCommon_GetBoundingVisibleRect(this.options_.element_);
this.startLeft = rect.left + rect.width * this.options_.leftStartRatio_;
this.startTop = rect.top + rect.height * this.options_.topStartRatio_;
if (rect.width === 0 || rect.height === 0) {
throw new Error('Scroll element has zero height and/or width.');
}
requestAnimationFrame(this.startGesture_.bind(this));
};
ScrollAction.prototype.startGesture_ = function() {
this.beginMeasuringHook();
var maxScrollLengthPixels = (MAX_SCROLL_LENGTH_TIME_MS / 1000) *
this.options_.speed_;
var distance = Math.min(maxScrollLengthPixels, this.getScrollDistance_());
chrome.gpuBenchmarking.smoothScrollBy(
distance, this.onGestureComplete_.bind(this),
this.startLeft, this.startTop, this.options_.gesture_source_type_,
this.options_.direction_, this.options_.speed_);
};
ScrollAction.prototype.onGestureComplete_ = function() {
this.endMeasuringHook();
// We're done.
if (this.callback_)
this.callback_();
};
window.__ScrollAction = ScrollAction;
window.__ScrollAction_SupportedByBrowser = supportedByBrowser;
})();
|
