b38dea0597
Share Gaia assets and adapters, keep private profiles and development documents local, and update both public READMEs.
44 lines
1.2 KiB
JavaScript
Executable file
44 lines
1.2 KiB
JavaScript
Executable file
/* exported StickyHeader */
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function StickyHeader(scrollable, sticky) {
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'use strict';
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var headers = scrollable.getElementsByTagName('header');
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var stickyPosition;
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var stickyStyle = sticky.style;
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this._throttledRefresh = function() {
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var display = false;
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if (stickyPosition === undefined) {
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stickyPosition = sticky.offsetHeight + sticky.offsetTop;
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}
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for (var i = 1, length = headers.length; i < length; i++) {
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if (headers[i].offsetTop - scrollable.scrollTop > stickyPosition) {
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// While reflecting a header, make sure to not reflect a header
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// that is not displayed.
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var lookupIndex = 1;
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var header = headers[i - lookupIndex];
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while (header && header.offsetHeight === 0) {
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lookupIndex++;
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header = headers[i - lookupIndex];
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}
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stickyStyle.backgroundImage = '-moz-element(#' + header.id + ')';
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display = true;
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break;
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}
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}
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sticky.classList.toggle('has-content', display);
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this.throttle = null;
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}.bind(this);
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this.refresh = function() {
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if (!this.throttle) {
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this.throttle = setTimeout(this._throttledRefresh, 0);
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}
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}.bind(this);
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scrollable.addEventListener('scroll', this.refresh);
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}
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