app-drawer-layout.html

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<link rel="import" href="../../polymer/polymer.html">
<link rel="import" href="../../iron-media-query/iron-media-query.html">
<link rel="import" href="../app-layout-behavior/app-layout-behavior.html">

<!--
app-drawer-layout is a wrapper element that positions an app-drawer and other content. When
the viewport width is smaller than `responsiveWidth`, this element changes to narrow layout.
In narrow layout, the drawer will be stacked on top of the main content. The drawer will slide
in/out to hide/reveal the main content.

By default the drawer is aligned to the start, which is left in LTR layouts:

```html
<app-drawer-layout>
  <app-drawer slot="drawer">
    drawer content
  </app-drawer>
  <div>
    main content
  </div>
</app-drawer-layout>
```

Align the drawer at the end:

```html
<app-drawer-layout>
  <app-drawer slot="drawer" align="end">
     drawer content
  </app-drawer>
  <div>
    main content
  </div>
</app-drawer-layout>
```

With an app-header-layout:

```html
<app-drawer-layout>
  <app-drawer slot="drawer">
    drawer-content
  </app-drawer>
  <app-header-layout>
    <app-header slot="header">
      <app-toolbar>
        <div main-title>App name</div>
      </app-toolbar>
    </app-header>

    main content

  </app-header-layout>
</app-drawer-layout>
```

Add the `drawer-toggle` attribute to elements inside `app-drawer-layout` that toggle the drawer on click events:

```html
<app-drawer-layout>
  <app-drawer slot="drawer">
    drawer-content
  </app-drawer>
  <app-header-layout>
    <app-header slot="header">
      <app-toolbar>
        <paper-icon-button icon="menu" drawer-toggle></paper-icon-button>
        <div main-title>App name</div>
      </app-toolbar>
    </app-header>

    main content

  </app-header-layout>
</app-drawer-layout>
```

**NOTE:** With app-layout 2.0, the `drawer-toggle` element needs to be manually hidden
when app-drawer-layout is not in narrow layout. To add this, add the following CSS rule where
app-drawer-layout is used:

```css
app-drawer-layout:not([narrow]) [drawer-toggle] {
  display: none;
}
```

Add the `fullbleed` attribute to app-drawer-layout to make it fit the size of its container:

```html
<app-drawer-layout fullbleed>
  <app-drawer slot="drawer">
     drawer content
  </app-drawer>
  <div>
    main content
  </div>
</app-drawer-layout>
```

### Styling

Custom property                          | Description                          | Default
-----------------------------------------|--------------------------------------|---------
`--app-drawer-width`                     | Width of the drawer                  | 256px
`--app-drawer-layout-content-transition` | Transition for the content container | none

**NOTE:** If you use <app-drawer> with <app-drawer-layout> and specify a value for
`--app-drawer-width`, that value must be accessible by both elements. This can be done by
defining the value on the `:host` that contains <app-drawer-layout> (or `html` if outside
a shadow root):

```css
:host {
  --app-drawer-width: 300px;
}
```

@group App Elements
@element app-drawer-layout
@demo app-drawer-layout/demo/index.html
-->

<dom-module id="app-drawer-layout">
  <template>
    <style>
      :host {
        display: block;
        /**
         * Force app-drawer-layout to have its own stacking context so that its parent can
         * control the stacking of it relative to other elements.
         */
        position: relative;
        z-index: 0;
      }

      :host ::slotted([slot=drawer]) {
        z-index: 1;
      }

      :host([fullbleed]) {
        @apply --layout-fit;
      }

      #contentContainer {
        /* Create a stacking context here so that all children appear below the header. */
        position: relative;
        z-index: 0;
        height: 100%;
        transition: var(--app-drawer-layout-content-transition, none);
      }

      #contentContainer[drawer-position=left] {
        margin-left: var(--app-drawer-width, 256px);
      }

      #contentContainer[drawer-position=right] {
        margin-right: var(--app-drawer-width, 256px);
      }
    </style>

    <slot id="drawerSlot" name="drawer"></slot>

    <div id="contentContainer" drawer-position$="[[_drawerPosition]]">
      <slot></slot>
    </div>

    <iron-media-query
        query="[[_computeMediaQuery(forceNarrow, responsiveWidth)]]"
        on-query-matches-changed="_onQueryMatchesChanged"></iron-media-query>
  </template>

  <script>
    Polymer({
      is: 'app-drawer-layout',

      behaviors: [Polymer.AppLayoutBehavior],

      properties: {
        /**
         * If true, ignore `responsiveWidth` setting and force the narrow layout.
         */
        forceNarrow: {type: Boolean, value: false},

        /**
         * If the viewport's width is smaller than this value, the panel will change
         * to narrow layout. In the mode the drawer will be closed.
         */
        responsiveWidth: {type: String, value: '640px'},

        /**
         * Returns true if it is in narrow layout. This is useful if you need to
         * show/hide elements based on the layout.
         */
        narrow:
            {type: Boolean, reflectToAttribute: true, readOnly: true, notify: true},

        /**
         * If true, the drawer will initially be opened when in narrow layout mode.
         */
        openedWhenNarrow: {type: Boolean, value: false},

        _drawerPosition: {type: String}
      },

      listeners: {'click': '_clickHandler'},

      observers: ['_narrowChanged(narrow)'],

      /**
       * A reference to the app-drawer element.
       *
       * @property drawer
       */
      get drawer() {
        return Polymer.dom(this.$.drawerSlot).getDistributedNodes()[0];
      },

      attached: function() {
        // Disable drawer transitions until after app-drawer-layout sets the initial
        // opened state.
        var drawer = this.drawer;
        if (drawer) {
          drawer.setAttribute('no-transition', '');
        }
      },

      _clickHandler: function(e) {
        var target = Polymer.dom(e).localTarget;
        if (target && target.hasAttribute('drawer-toggle')) {
          var drawer = this.drawer;
          if (drawer && !drawer.persistent) {
            drawer.toggle();
          }
        }
      },

      _updateLayoutStates: function() {
        var drawer = this.drawer;
        if (!this.isAttached || !drawer) {
          return;
        }

        this._drawerPosition = this.narrow ? null : drawer.position;
        if (this._drawerNeedsReset) {
          if (this.narrow) {
            drawer.opened = this.openedWhenNarrow;
            drawer.persistent = false;
          } else {
            drawer.opened = drawer.persistent = true;
          }
          if (drawer.hasAttribute('no-transition')) {
            // Enable drawer transitions after app-drawer-layout sets the initial
            // opened state.
            Polymer.RenderStatus.afterNextRender(this, function() {
              drawer.removeAttribute('no-transition');
            });
          }
          this._drawerNeedsReset = false;
        }
      },

      _narrowChanged: function() {
        this._drawerNeedsReset = true;
        this.resetLayout();
      },

      _onQueryMatchesChanged: function(event) {
        this._setNarrow(event.detail.value);
      },

      _computeMediaQuery: function(forceNarrow, responsiveWidth) {
        return forceNarrow ? '(min-width: 0px)' :
                             '(max-width: ' + responsiveWidth + ')';
      }
    });
  </script>
</dom-module>