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| <!-- | |
| Copyright (c) 2014 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 | |
| --> | |
| <!-- | |
| `core-scroll-header-panel` contains a header section and a content section. The | |
| header is initially on the top part of the view but it scrolls away with the | |
| rest of the scrollable content. Upon scrolling slightly up at any point, the | |
| header scrolls back into view. This saves screen space and allows users to | |
| access important controls by easily moving them back to the view. | |
| __Important:__ The `core-scroll-header-panel` will not display if its parent does not have a height. | |
| Using [layout attributes](http://www.polymer-project.org/docs/polymer/layout-attrs.html), you can easily make the `core-scroll-header-panel` fill the screen | |
| <body fullbleed layout vertical> | |
| <core-scroll-header-panel flex> | |
| <core-toolbar> | |
| <div>Hello World!</div> | |
| </core-toolbar> | |
| </core-scroll-header-panel> | |
| </body> | |
| or, if you would prefer to do it in CSS, just give `html`, `body`, and `core-scroll-header-panel` a height of 100%: | |
| html, body { | |
| height: 100%; | |
| margin: 0; | |
| } | |
| core-scroll-header-panel { | |
| height: 100%; | |
| } | |
| `core-scroll-header-panel` works well with `core-toolbar` but can use any element | |
| that represents a header by adding a `core-header` class to it. | |
| <core-scroll-header-panel> | |
| <core-toolbar>Header</core-toolbar> | |
| <div>Content goes here...</div> | |
| </core-scroll-header-panel> | |
| @group Polymer Core Elements | |
| @element core-scroll-header-panel | |
| @mixins Polymer.CoreResizable https://github.com/polymer/core-resizable | |
| @homepage github.io | |
| --> | |
| <link rel="import" href="../polymer/polymer.html"> | |
| <link rel="import" href="../core-resizable/core-resizable.html"> | |
| <polymer-element name="core-scroll-header-panel"> | |
| <template> | |
| <link rel="stylesheet" href="core-scroll-header-panel.css"> | |
| <div id="mainContainer"> | |
| <content id="mainContent" select=":not(core-toolbar):not(.core-header)"></content> | |
| </div> | |
| <div id="headerContainer"> | |
| <div class="bg-container"> | |
| <div id="condensedHeaderBg"></div> | |
| <div id="headerBg"></div> | |
| </div> | |
| <content id="headerContent" select="core-toolbar, .core-header"></content> | |
| </div> | |
| </template> | |
| <script> | |
| (function() { | |
| Polymer(Polymer.mixin({ | |
| /** | |
| * Fired when the content has been scrolled. | |
| * | |
| * @event scroll | |
| */ | |
| /** | |
| * Fired when the header is transformed. | |
| * | |
| * @event core-header-transform | |
| */ | |
| publish: { | |
| /** | |
| * If true, the header's height will condense to `_condensedHeaderHeight` | |
| * as the user scrolls down from the top of the content area. | |
| * | |
| * @attribute condenses | |
| * @type boolean | |
| * @default false | |
| */ | |
| condenses: false, | |
| /** | |
| * If true, no cross-fade transition from one background to another. | |
| * | |
| * @attribute noDissolve | |
| * @type boolean | |
| * @default false | |
| */ | |
| noDissolve: false, | |
| /** | |
| * If true, the header doesn't slide back in when scrolling back up. | |
| * | |
| * @attribute noReveal | |
| * @type boolean | |
| * @default false | |
| */ | |
| noReveal: false, | |
| /** | |
| * If true, the header is fixed to the top and never moves away. | |
| * | |
| * @attribute fixed | |
| * @type boolean | |
| * @default false | |
| */ | |
| fixed: false, | |
| /** | |
| * If true, the condensed header is always shown and does not move away. | |
| * | |
| * @attribute keepCondensedHeader | |
| * @type boolean | |
| * @default false | |
| */ | |
| keepCondensedHeader: false, | |
| /** | |
| * The height of the header when it is at its full size. | |
| * | |
| * By default, the height will be measured when it is ready. If the height | |
| * changes later the user needs to either set this value to reflect the | |
| * new height or invoke `measureHeaderHeight()`. | |
| * | |
| * @attribute headerHeight | |
| * @type number | |
| * @default 0 | |
| */ | |
| headerHeight: 0, | |
| /** | |
| * The height of the header when it is condensed. | |
| * | |
| * By default, `_condensedHeaderHeight` is 1/3 of `headerHeight` unless | |
| * this is specified. | |
| * | |
| * @attribute condensedHeaderHeight | |
| * @type number | |
| * @default 0 | |
| */ | |
| condensedHeaderHeight: 0, | |
| /** | |
| * By default, the top part of the header stays when the header is being | |
| * condensed. Set this to true if you want the top part of the header | |
| * to be scrolled away. | |
| * | |
| * @attribute scrollAwayTopbar | |
| * @type boolean | |
| * @default false | |
| */ | |
| scrollAwayTopbar: false | |
| }, | |
| prevScrollTop: 0, | |
| headerMargin: 0, | |
| y: 0, | |
| observe: { | |
| 'headerMargin fixed': 'setup' | |
| }, | |
| eventDelegates: { | |
| 'core-resize': 'measureHeaderHeight' | |
| }, | |
| attached: function() { | |
| this.resizableAttachedHandler(); | |
| }, | |
| ready: function() { | |
| this._scrollHandler = this.scroll.bind(this); | |
| this.scroller.addEventListener('scroll', this._scrollHandler); | |
| }, | |
| detached: function() { | |
| this.scroller.removeEventListener('scroll', this._scrollHandler); | |
| this.resizableDetachedHandler(); | |
| }, | |
| domReady: function() { | |
| this.async('measureHeaderHeight'); | |
| }, | |
| get header() { | |
| return this.$.headerContent.getDistributedNodes()[0]; | |
| }, | |
| /** | |
| * Returns the scrollable element. | |
| * | |
| * @property scroller | |
| * @type Object | |
| */ | |
| get scroller() { | |
| return this.$.mainContainer; | |
| }, | |
| /** | |
| * Invoke this to tell `core-scroll-header-panel` to re-measure the header's | |
| * height. | |
| * | |
| * @method measureHeaderHeight | |
| */ | |
| measureHeaderHeight: function() { | |
| var header = this.header; | |
| if (header && header.offsetHeight) { | |
| this.headerHeight = header.offsetHeight; | |
| } | |
| }, | |
| headerHeightChanged: function() { | |
| if (!this.condensedHeaderHeight) { | |
| // assume _condensedHeaderHeight is 1/3 of the headerHeight | |
| this._condensedHeaderHeight = this.headerHeight * 1 / 3; | |
| } | |
| this.condensedHeaderHeightChanged(); | |
| }, | |
| condensedHeaderHeightChanged: function() { | |
| if (this.condensedHeaderHeight) { | |
| this._condensedHeaderHeight = this.condensedHeaderHeight; | |
| } | |
| if (this.headerHeight) { | |
| this.headerMargin = this.headerHeight - this._condensedHeaderHeight; | |
| } | |
| }, | |
| condensesChanged: function() { | |
| if (this.condenses) { | |
| this.scroll(); | |
| } else { | |
| // reset transform/opacity set on the header | |
| this.condenseHeader(null); | |
| } | |
| }, | |
| setup: function() { | |
| var s = this.scroller.style; | |
| s.paddingTop = this.fixed ? '' : this.headerHeight + 'px'; | |
| s.top = this.fixed ? this.headerHeight + 'px' : ''; | |
| if (this.fixed) { | |
| this.transformHeader(null); | |
| } else { | |
| this.scroll(); | |
| } | |
| }, | |
| transformHeader: function(y) { | |
| var s = this.$.headerContainer.style; | |
| this.translateY(s, -y); | |
| if (this.condenses) { | |
| this.condenseHeader(y); | |
| } | |
| this.fire('core-header-transform', {y: y, height: this.headerHeight, | |
| condensedHeight: this._condensedHeaderHeight}); | |
| }, | |
| condenseHeader: function(y) { | |
| var reset = y == null; | |
| // adjust top bar in core-header so the top bar stays at the top | |
| if (!this.scrollAwayTopbar && this.header.$ && this.header.$.topBar) { | |
| this.translateY(this.header.$.topBar.style, | |
| reset ? null : Math.min(y, this.headerMargin)); | |
| } | |
| // transition header bg | |
| var hbg = this.$.headerBg.style; | |
| if (!this.noDissolve) { | |
| hbg.opacity = reset ? '' : (this.headerMargin - y) / this.headerMargin; | |
| } | |
| // adjust header bg so it stays at the center | |
| this.translateY(hbg, reset ? null : y / 2); | |
| // transition condensed header bg | |
| var chbg = this.$.condensedHeaderBg.style; | |
| if (!this.noDissolve) { | |
| chbg = this.$.condensedHeaderBg.style; | |
| chbg.opacity = reset ? '' : y / this.headerMargin; | |
| // adjust condensed header bg so it stays at the center | |
| this.translateY(chbg, reset ? null : y / 2); | |
| } | |
| }, | |
| translateY: function(s, y) { | |
| var t = y == null ? '' : 'translate3d(0, ' + y + 'px, 0)'; | |
| setTransform(s, t); | |
| }, | |
| scroll: function(event) { | |
| if (!this.header) { | |
| return; | |
| } | |
| var sTop = this.scroller.scrollTop; | |
| var y = Math.min(this.keepCondensedHeader ? | |
| this.headerMargin : this.headerHeight, Math.max(0, | |
| (this.noReveal ? sTop : this.y + sTop - this.prevScrollTop))); | |
| if (this.condenses && this.prevScrollTop >= sTop && sTop > this.headerMargin) { | |
| y = Math.max(y, this.headerMargin); | |
| } | |
| if (!event || !this.fixed && y !== this.y) { | |
| this.transformHeader(y); | |
| } | |
| this.prevScrollTop = Math.max(sTop, 0); | |
| this.y = y; | |
| if (event) { | |
| this.fire('scroll', {target: this.scroller}, this, false); | |
| } | |
| } | |
| }, Polymer.CoreResizable)); | |
| //determine proper transform mechanizm | |
| if (document.documentElement.style.transform !== undefined) { | |
| var setTransform = function(style, string) { | |
| style.transform = string; | |
| } | |
| } else { | |
| var setTransform = function(style, string) { | |
| style.webkitTransform = string; | |
| } | |
| } | |
| })(); | |
| </script> | |
| </polymer-element> |