/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @fileoverview Bidi utility functions.
*/
goog.provide('goog.style.bidi');
goog.require('goog.dom');
goog.require('goog.style');
goog.require('goog.userAgent');
goog.require('goog.userAgent.platform');
goog.require('goog.userAgent.product');
goog.require('goog.userAgent.product.isVersion');
/**
* 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) {
'use strict';
var isRtl = goog.style.isRightToLeft(element);
if (isRtl && goog.style.bidi.usesNegativeScrollLeftInRtl_()) {
return -element.scrollLeft;
} else if (isRtl && !goog.userAgent.EDGE_OR_IE) {
// ScrollLeft starts at the maximum positive value and decreases towards
// 0 as the element is scrolled towards the left. However, for overflow
// visible, there is no scrollLeft and the value always stays correctly at 0
var overflowX = goog.style.getComputedOverflowX(element);
if (overflowX == 'visible') {
return element.scrollLeft;
} else {
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, analogous 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) {
'use strict';
element = /** @type {!HTMLElement} */ (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 && !goog.userAgent.isVersionOrHigher(58)) {
// When calculating an element's offsetLeft, Firefox 57 and below
// erroneously subtracts the border width from the actual distance.
// So we need to add it back. (Fixed in FireFox 58+)
var borderWidths = goog.style.getBorderBox(bestParent);
offsetLeftForReal += borderWidths.left;
} else if (
goog.userAgent.isDocumentModeOrHigher(8) &&
!goog.userAgent.isDocumentModeOrHigher(9)) {
// When calculating an element's offsetLeft, IE8/9-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) {
'use strict';
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.style.bidi.usesNegativeScrollLeftInRtl_()) {
element.scrollLeft = -offsetStart;
} else if (!goog.userAgent.EDGE_OR_IE) {
// 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;
}
};
/**
* @return {boolean} Whether the current browser returns negative scrollLeft
* values for RTL elements. If true, then scrollLeft starts at 0 and then
* becomes more negative as the element is scrolled towards the left.
* @private
*/
goog.style.bidi.usesNegativeScrollLeftInRtl_ = function() {
'use strict';
var isSafari10Plus =
goog.userAgent.product.SAFARI && goog.userAgent.product.isVersion(10);
var isIOS10Plus = goog.userAgent.IOS && goog.userAgent.platform.isVersion(10);
const isChrome85Plus =
goog.userAgent.product.CHROME && goog.userAgent.product.isVersion(85);
return goog.userAgent.GECKO || isSafari10Plus || isIOS10Plus ||
isChrome85Plus;
};
/**
* 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) {
'use strict';
if (top !== null) {
elem.style.top = top + 'px';
}
if (isRtl) {
elem.style.right = left + 'px';
elem.style.left = '';
} else {
elem.style.left = left + 'px';
elem.style.right = '';
}
};
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