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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
ash / webui / common / resources / cr_scrollable_behavior.js [blame]
// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview Behavior for scrollable containers with <iron-list>.
*
* Any containers with the 'scrollable' attribute set will have the following
* classes toggled appropriately: can-scroll, is-scrolled, scrolled-to-bottom.
* These classes are used to style the container div and list elements
* appropriately, see cr_shared_style.css.
*
* The associated HTML should look something like:
* <div id="container" scrollable>
* <iron-list items="[[items]]" scroll-target="container">
* <template>
* <my-element item="[[item]] tabindex$="[[tabIndex]]"></my-element>
* </template>
* </iron-list>
* </div>
*
* In order to get correct keyboard focus (tab) behavior within the list,
* any elements with tabbable sub-elements also need to set tabindex, e.g:
*
* <dom-module id="my-element>
* <template>
* ...
* <paper-icon-button toggles active="{{opened}}" tabindex$="[[tabindex]]">
* </template>
* </dom-module>
*
* NOTE: If 'container' is not fixed size, it is important to call
* updateScrollableContents() when [[items]] changes, otherwise the container
* will not be sized correctly.
*
* NOTE: This file is deprecated in favor of cr_scrollable_mixin.ts. Don't use
* it in new code.
*/
// clang-format off
import {beforeNextRender, Polymer} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
import 'chrome://resources/polymer/v3_0/iron-list/iron-list.js';
// clang-format on
/** @polymerBehavior */
export const CrScrollableBehavior = {
/** @private {number|null} */
intervalId_: null,
ready() {
beforeNextRender(this, () => {
this.requestUpdateScroll();
// Listen to the 'scroll' event for each scrollable container.
const scrollableElements =
this.shadowRoot.querySelectorAll('[scrollable]');
for (let i = 0; i < scrollableElements.length; i++) {
scrollableElements[i].addEventListener(
'scroll', this.updateScrollEvent_.bind(this));
}
});
},
detached() {
if (this.intervalId_ !== null) {
clearInterval(this.intervalId_);
}
},
/**
* Called any time the contents of a scrollable container may have changed.
* This ensures that the <iron-list> contents of dynamically sized
* containers are resized correctly.
*/
updateScrollableContents() {
if (this.intervalId_ !== null) {
return;
} // notifyResize is already in progress.
this.requestUpdateScroll();
const nodeList = this.shadowRoot.querySelectorAll('[scrollable] iron-list');
if (!nodeList.length) {
return;
}
let nodesToResize = Array.from(nodeList).map(node => ({
node: node,
lastScrollHeight: 0,
}));
// Use setInterval to avoid initial render / sizing issues.
this.intervalId_ = window.setInterval(() => {
const checkAgain = [];
nodesToResize.forEach(({node, lastScrollHeight}) => {
const scrollHeight = node.parentNode.scrollHeight;
// A hidden scroll-container has a height of 0. When not hidden, it has
// a min-height of 1px and the iron-list needs a resize to show the
// initial items and update the |scrollHeight|. The initial item count
// is determined by the |scrollHeight|. A scrollHeight of 1px will
// result in the minimum default item count (currently 3). After the
// |scrollHeight| is updated to be greater than 1px, another resize is
// needed to correctly calculate the number of physical iron-list items
// to render.
if (scrollHeight !== lastScrollHeight) {
const ironList = /** @type {!IronListElement} */ (node);
ironList.notifyResize();
}
// TODO(crbug.com/40146300): Add UI Test for this behavior.
if (scrollHeight <= 1 &&
window.getComputedStyle(node.parentNode).display !== 'none') {
checkAgain.push({
node: node,
lastScrollHeight: scrollHeight,
});
}
});
if (checkAgain.length === 0) {
window.clearInterval(this.intervalId_);
this.intervalId_ = null;
} else {
nodesToResize = checkAgain;
}
}, 10);
},
/**
* Setup the initial scrolling related classes for each scrollable container.
* Called from ready() and updateScrollableContents(). May also be called
* directly when the contents change (e.g. when not using iron-list).
*/
requestUpdateScroll() {
requestAnimationFrame(function() {
const scrollableElements =
this.shadowRoot.querySelectorAll('[scrollable]');
for (let i = 0; i < scrollableElements.length; i++) {
this.updateScroll_(/** @type {!HTMLElement} */ (scrollableElements[i]));
}
}.bind(this));
},
/** @param {!IronListElement} list */
saveScroll(list) {
// Store a FIFO of saved scroll positions so that multiple updates in a
// frame are applied correctly. Specifically we need to track when '0' is
// saved (but not apply it), and still handle patterns like [30, 0, 32].
list.savedScrollTops = list.savedScrollTops || [];
list.savedScrollTops.push(list.scrollTarget.scrollTop);
},
/** @param {!IronListElement} list */
restoreScroll(list) {
this.async(function() {
const scrollTop = list.savedScrollTops.shift();
// Ignore scrollTop of 0 in case it was intermittent (we do not need to
// explicitly scroll to 0).
if (scrollTop !== 0) {
list.scroll(0, scrollTop);
}
});
},
/**
* Event wrapper for updateScroll_.
* @param {!Event} event
* @private
*/
updateScrollEvent_(event) {
const scrollable = /** @type {!HTMLElement} */ (event.target);
this.updateScroll_(scrollable);
},
/**
* This gets called once initially and any time a scrollable container
* scrolls.
* @param {!HTMLElement} scrollable
* @private
*/
updateScroll_(scrollable) {
scrollable.classList.toggle(
'can-scroll', scrollable.clientHeight < scrollable.scrollHeight);
scrollable.classList.toggle('is-scrolled', scrollable.scrollTop > 0);
scrollable.classList.toggle(
'scrolled-to-bottom',
scrollable.scrollTop + scrollable.clientHeight >=
scrollable.scrollHeight);
},
};
export class CrScrollableBehaviorInterface {
updateScrollableContents() {}
requestUpdateScroll() {}
}