blob: 09625406be5261a857a5378bc6af694842cd234c [file] [log] [blame]
/**
* @license
* Copyright (C) 2017 The Android Open Source Project
*
* 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.
*/
(function() {
'use strict';
Polymer({
is: 'gr-page-nav',
_legacyUndefinedCheck: true,
properties: {
_headerHeight: Number,
},
attached() {
this.listen(window, 'scroll', '_handleBodyScroll');
},
detached() {
this.unlisten(window, 'scroll', '_handleBodyScroll');
},
_handleBodyScroll() {
if (this._headerHeight === undefined) {
let top = this._getOffsetTop(this);
for (let offsetParent = this.offsetParent;
offsetParent;
offsetParent = this._getOffsetParent(offsetParent)) {
top += this._getOffsetTop(offsetParent);
}
this._headerHeight = top;
}
this.$.nav.classList.toggle('pinned',
this._getScrollY() >= this._headerHeight);
},
/* Functions used for test purposes */
_getOffsetParent(element) {
if (!element || !element.offsetParent) { return ''; }
return element.offsetParent;
},
_getOffsetTop(element) {
return element.offsetTop;
},
_getScrollY() {
return window.scrollY;
},
});
})();