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Diffstat (limited to 'catapult/third_party/polymer/components/iron-overlay-behavior/iron-focusables-helper.html')
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diff --git a/catapult/third_party/polymer/components/iron-overlay-behavior/iron-focusables-helper.html b/catapult/third_party/polymer/components/iron-overlay-behavior/iron-focusables-helper.html new file mode 100644 index 00000000..084ad7d2 --- /dev/null +++ b/catapult/third_party/polymer/components/iron-overlay-behavior/iron-focusables-helper.html @@ -0,0 +1,220 @@ +<!doctype html> +<!-- +@license +Copyright (c) 2016 The Polymer Project Authors. All rights reserved. +This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt +The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt +The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt +Code distributed by Google as part of the polymer project is also +subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt +--> +<link rel="import" href="../polymer/polymer.html"> + +<script> + (function() { + 'use strict'; + + var p = Element.prototype; + var matches = p.matches || p.matchesSelector || p.mozMatchesSelector || + p.msMatchesSelector || p.oMatchesSelector || p.webkitMatchesSelector; + + Polymer.IronFocusablesHelper = { + + /** + * Returns a sorted array of tabbable nodes, including the root node. + * It searches the tabbable nodes in the light and shadow dom of the chidren, + * sorting the result by tabindex. + * @param {!Node} node + * @return {Array<HTMLElement>} + */ + getTabbableNodes: function(node) { + var result = []; + // If there is at least one element with tabindex > 0, we need to sort + // the final array by tabindex. + var needsSortByTabIndex = this._collectTabbableNodes(node, result); + if (needsSortByTabIndex) { + return this._sortByTabIndex(result); + } + return result; + }, + + /** + * Returns if a element is focusable. + * @param {!HTMLElement} element + * @return {boolean} + */ + isFocusable: function(element) { + // From http://stackoverflow.com/a/1600194/4228703: + // There isn't a definite list, it's up to the browser. The only + // standard we have is DOM Level 2 HTML https://www.w3.org/TR/DOM-Level-2-HTML/html.html, + // according to which the only elements that have a focus() method are + // HTMLInputElement, HTMLSelectElement, HTMLTextAreaElement and + // HTMLAnchorElement. This notably omits HTMLButtonElement and + // HTMLAreaElement. + // Referring to these tests with tabbables in different browsers + // http://allyjs.io/data-tables/focusable.html + + // Elements that cannot be focused if they have [disabled] attribute. + if (matches.call(element, 'input, select, textarea, button, object')) { + return matches.call(element, ':not([disabled])'); + } + // Elements that can be focused even if they have [disabled] attribute. + return matches.call(element, + 'a[href], area[href], iframe, [tabindex], [contentEditable]'); + }, + + /** + * Returns if a element is tabbable. To be tabbable, a element must be + * focusable, visible, and with a tabindex !== -1. + * @param {!HTMLElement} element + * @return {boolean} + */ + isTabbable: function(element) { + return this.isFocusable(element) && + matches.call(element, ':not([tabindex="-1"])') && + this._isVisible(element); + }, + + /** + * Returns the normalized element tabindex. If not focusable, returns -1. + * It checks for the attribute "tabindex" instead of the element property + * `tabIndex` since browsers assign different values to it. + * e.g. in Firefox `<div contenteditable>` has `tabIndex = -1` + * @param {!HTMLElement} element + * @return {!number} + * @private + */ + _normalizedTabIndex: function(element) { + if (this.isFocusable(element)) { + var tabIndex = element.getAttribute('tabindex') || 0; + return Number(tabIndex); + } + return -1; + }, + + /** + * Searches for nodes that are tabbable and adds them to the `result` array. + * Returns if the `result` array needs to be sorted by tabindex. + * @param {!Node} node The starting point for the search; added to `result` + * if tabbable. + * @param {!Array<HTMLElement>} result + * @return {boolean} + * @private + */ + _collectTabbableNodes: function(node, result) { + // If not an element or not visible, no need to explore children. + if (node.nodeType !== Node.ELEMENT_NODE || !this._isVisible(node)) { + return false; + } + var element = /** @type {HTMLElement} */ (node); + var tabIndex = this._normalizedTabIndex(element); + var needsSortByTabIndex = tabIndex > 0; + if (tabIndex >= 0) { + result.push(element); + } + + // In ShadowDOM v1, tab order is affected by the order of distrubution. + // E.g. getTabbableNodes(#root) in ShadowDOM v1 should return [#A, #B]; + // in ShadowDOM v0 tab order is not affected by the distrubution order, + // in fact getTabbableNodes(#root) returns [#B, #A]. + // <div id="root"> + // <!-- shadow --> + // <slot name="a"> + // <slot name="b"> + // <!-- /shadow --> + // <input id="A" slot="a"> + // <input id="B" slot="b" tabindex="1"> + // </div> + // TODO(valdrin) support ShadowDOM v1 when upgrading to Polymer v2.0. + var children; + if (element.localName === 'content') { + children = Polymer.dom(element).getDistributedNodes(); + } else { + // Use shadow root if possible, will check for distributed nodes. + children = Polymer.dom(element.root || element).children; + } + for (var i = 0; i < children.length; i++) { + // Ensure method is always invoked to collect tabbable children. + var needsSort = this._collectTabbableNodes(children[i], result); + needsSortByTabIndex = needsSortByTabIndex || needsSort; + } + return needsSortByTabIndex; + }, + + /** + * Returns false if the element has `visibility: hidden` or `display: none` + * @param {!HTMLElement} element + * @return {boolean} + * @private + */ + _isVisible: function(element) { + // Check inline style first to save a re-flow. If looks good, check also + // computed style. + var style = element.style; + if (style.visibility !== 'hidden' && style.display !== 'none') { + style = window.getComputedStyle(element); + return (style.visibility !== 'hidden' && style.display !== 'none'); + } + return false; + }, + + /** + * Sorts an array of tabbable elements by tabindex. Returns a new array. + * @param {!Array<HTMLElement>} tabbables + * @return {Array<HTMLElement>} + * @private + */ + _sortByTabIndex: function(tabbables) { + // Implement a merge sort as Array.prototype.sort does a non-stable sort + // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort + var len = tabbables.length; + if (len < 2) { + return tabbables; + } + var pivot = Math.ceil(len / 2); + var left = this._sortByTabIndex(tabbables.slice(0, pivot)); + var right = this._sortByTabIndex(tabbables.slice(pivot)); + return this._mergeSortByTabIndex(left, right); + }, + + /** + * Merge sort iterator, merges the two arrays into one, sorted by tab index. + * @param {!Array<HTMLElement>} left + * @param {!Array<HTMLElement>} right + * @return {Array<HTMLElement>} + * @private + */ + _mergeSortByTabIndex: function(left, right) { + var result = []; + while ((left.length > 0) && (right.length > 0)) { + if (this._hasLowerTabOrder(left[0], right[0])) { + result.push(right.shift()); + } else { + result.push(left.shift()); + } + } + + return result.concat(left, right); + }, + + /** + * Returns if element `a` has lower tab order compared to element `b` + * (both elements are assumed to be focusable and tabbable). + * Elements with tabindex = 0 have lower tab order compared to elements + * with tabindex > 0. + * If both have same tabindex, it returns false. + * @param {!HTMLElement} a + * @param {!HTMLElement} b + * @return {boolean} + * @private + */ + _hasLowerTabOrder: function(a, b) { + // Normalize tabIndexes + // e.g. in Firefox `<div contenteditable>` has `tabIndex = -1` + var ati = Math.max(a.tabIndex, 0); + var bti = Math.max(b.tabIndex, 0); + return (ati === 0 || bti === 0) ? bti > ati : ati > bti; + } + }; + })(); +</script> |