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
|
// Copyright 2012 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Bidi utility functions.
*
*/
goog.provide('goog.style.bidi');
goog.require('goog.dom');
goog.require('goog.style');
goog.require('goog.userAgent');
/**
* Returns the normalized scrollLeft position for a scrolled element.
* @param {Element} element The scrolled element.
* @return {number} The number of pixels the element is scrolled. 0 indicates
* that the element is not scrolled at all (which, in general, is the
* left-most position in ltr and the right-most position in rtl).
*/
goog.style.bidi.getScrollLeft = function(element) {
var isRtl = goog.style.isRightToLeft(element);
if (isRtl && goog.userAgent.GECKO) {
// ScrollLeft starts at 0 and then goes negative as the element is scrolled
// towards the left.
return -element.scrollLeft;
} else if (isRtl && !(goog.userAgent.IE && goog.userAgent.isVersion('8'))) {
// ScrollLeft starts at the maximum positive value and decreases towards
// 0 as the element is scrolled towards the left.
return element.scrollWidth - element.clientWidth - element.scrollLeft;
}
// ScrollLeft behavior is identical in rtl and ltr, it starts at 0 and
// increases as the element is scrolled away from the start.
return element.scrollLeft;
};
/**
* Returns the "offsetStart" of an element, analagous to offsetLeft but
* normalized for right-to-left environments and various browser
* inconsistencies. This value returned can always be passed to setScrollOffset
* to scroll to an element's left edge in a left-to-right offsetParent or
* right edge in a right-to-left offsetParent.
*
* For example, here offsetStart is 10px in an LTR environment and 5px in RTL:
*
* <pre>
* | xxxxxxxxxx |
* ^^^^^^^^^^ ^^^^ ^^^^^
* 10px elem 5px
* </pre>
*
* If an element is positioned before the start of its offsetParent, the
* startOffset may be negative. This can be used with setScrollOffset to
* reliably scroll to an element:
*
* <pre>
* var scrollOffset = goog.style.bidi.getOffsetStart(element);
* goog.style.bidi.setScrollOffset(element.offsetParent, scrollOffset);
* </pre>
*
* @see setScrollOffset
*
* @param {Element} element The element for which we need to determine the
* offsetStart position.
* @return {number} The offsetStart for that element.
*/
goog.style.bidi.getOffsetStart = function(element) {
var offsetLeftForReal = element.offsetLeft;
// The element might not have an offsetParent.
// For example, the node might not be attached to the DOM tree,
// and position:fixed children do not have an offset parent.
// Just try to do the best we can with what we have.
var bestParent = element.offsetParent;
if (!bestParent && goog.style.getComputedPosition(element) == 'fixed') {
bestParent = goog.dom.getOwnerDocument(element).documentElement;
}
// Just give up in this case.
if (!bestParent) {
return offsetLeftForReal;
}
if (goog.userAgent.GECKO) {
// When calculating an element's offsetLeft, Firefox erroneously subtracts
// the border width from the actual distance. So we need to add it back.
var borderWidths = goog.style.getBorderBox(bestParent);
offsetLeftForReal += borderWidths.left;
} else if (goog.userAgent.isDocumentMode(8)) {
// When calculating an element's offsetLeft, IE8-Standards Mode erroneously
// adds the border width to the actual distance. So we need to subtract it.
var borderWidths = goog.style.getBorderBox(bestParent);
offsetLeftForReal -= borderWidths.left;
}
if (goog.style.isRightToLeft(bestParent)) {
// Right edge of the element relative to the left edge of its parent.
var elementRightOffset = offsetLeftForReal + element.offsetWidth;
// Distance from the parent's right edge to the element's right edge.
return bestParent.clientWidth - elementRightOffset;
}
return offsetLeftForReal;
};
/**
* Sets the element's scrollLeft attribute so it is correctly scrolled by
* offsetStart pixels. This takes into account whether the element is RTL and
* the nuances of different browsers. To scroll to the "beginning" of an
* element use getOffsetStart to obtain the element's offsetStart value and then
* pass the value to setScrollOffset.
* @see getOffsetStart
* @param {Element} element The element to set scrollLeft on.
* @param {number} offsetStart The number of pixels to scroll the element.
* If this value is < 0, 0 is used.
*/
goog.style.bidi.setScrollOffset = function(element, offsetStart) {
offsetStart = Math.max(offsetStart, 0);
// In LTR and in "mirrored" browser RTL (such as IE), we set scrollLeft to
// the number of pixels to scroll.
// Otherwise, in RTL, we need to account for different browser behavior.
if (!goog.style.isRightToLeft(element)) {
element.scrollLeft = offsetStart;
} else if (goog.userAgent.GECKO) {
// Negative scroll-left positions in RTL.
element.scrollLeft = -offsetStart;
} else if (!(goog.userAgent.IE && goog.userAgent.isVersion('8'))) {
// Take the current scrollLeft value and move to the right by the
// offsetStart to get to the left edge of the element, and then by
// the clientWidth of the element to get to the right edge.
element.scrollLeft =
element.scrollWidth - offsetStart - element.clientWidth;
} else {
element.scrollLeft = offsetStart;
}
};
/**
* Sets the element's left style attribute in LTR or right style attribute in
* RTL. Also clears the left attribute in RTL and the right attribute in LTR.
* @param {Element} elem The element to position.
* @param {number} left The left position in LTR; will be set as right in RTL.
* @param {?number} top The top position. If null only the left/right is set.
* @param {boolean} isRtl Whether we are in RTL mode.
*/
goog.style.bidi.setPosition = function(elem, left, top, isRtl) {
if (!goog.isNull(top)) {
elem.style.top = top + 'px';
}
if (isRtl) {
elem.style.right = left + 'px';
elem.style.left = '';
} else {
elem.style.left = left + 'px';
elem.style.right = '';
}
};
|
