[WIP] Make menus and tabs accessible with ARIA standards

packages/commands/src/index.ts

@@ -313,6 +313,21 @@ class CommandRegistry {
     return cmd ? cmd.isToggled.call(undefined, args) : false;
   }
 
+  /**
+   * Test whether a specific command is toggleable.
+   *
+   * @param id - The id of the command of interest.
+   *
+   * @param args - The arguments for the command.
+   *
+   * @returns A boolean indicating whether the command is toggleable,
+   *   or `false` if the command is not registered.
+   */
+  isToggleable(id: string, args: ReadonlyJSONObject = JSONExt.emptyObject): boolean {
+    let cmd = this._commands[id];
+    return cmd ? cmd.isToggleable : false;
+  }
+
   /**
    * Test whether a specific command is visible.
    *
@@ -759,6 +774,20 @@ namespace CommandRegistry {
      */
     isToggled?: CommandFunc<boolean>;
 
+    /**
+     * A function which indicates whether the command is toggleable.
+     *
+     * #### Notes
+     * Visual representations may use this value to display a toggled command in
+     * a different form, such as a check box for a menu item or a depressed
+     * state for a toggle button. This attribute also allows for accessible
+     * interfaces to notify the user that the command corresponds to some state.
+     *
+     * The default value is `true` if an `isToggled` function is given, `false`
+     * otherwise.
+     */
+    isToggleable?: boolean;
+
     /**
      * A function which indicates whether the command is visible.
      *
@@ -1147,6 +1176,7 @@ namespace Private {
     readonly dataset: CommandFunc<Dataset>;
     readonly isEnabled: CommandFunc<boolean>;
     readonly isToggled: CommandFunc<boolean>;
+    readonly isToggleable: boolean;
     readonly isVisible: CommandFunc<boolean>;
   }
 
@@ -1167,6 +1197,7 @@ namespace Private {
       dataset: asFunc(options.dataset, emptyDatasetFunc),
       isEnabled: options.isEnabled || trueFunc,
       isToggled: options.isToggled || falseFunc,
+      isToggleable: options.isToggleable || !!options.isToggled,
       isVisible: options.isVisible || trueFunc
     };
   }

packages/virtualdom/src/index.ts

@@ -124,6 +124,66 @@ type ElementAttrNames = (
 );
 
 
+/**
+ * The names of ARIA attributes for HTML elements.
+ *
+ * The attribute names are collected from
+ * https://www.w3.org/TR/html5/infrastructure.html#element-attrdef-aria-role
+ */
+export
+type ARIAAttrNames = (
+  'aria-activedescendant' |
+  'aria-atomic' |
+  'aria-autocomplete' |
+  'aria-busy' |
+  'aria-checked' |
+  'aria-colcount' |
+  'aria-colindex' |
+  'aria-colspan' |
+  'aria-controls' |
+  'aria-current' |
+  'aria-describedby' |
+  'aria-details' |
+  'aria-dialog' |
+  'aria-disabled' |
+  'aria-dropeffect' |
+  'aria-errormessage' |
+  'aria-expanded' |
+  'aria-flowto' |
+  'aria-grabbed' |
+  'aria-haspopup' |
+  'aria-hidden' |
+  'aria-invalid' |
+  'aria-keyshortcuts' |
+  'aria-label' |
+  'aria-labelledby' |
+  'aria-level' |
+  'aria-live' |
+  'aria-multiline' |
+  'aria-multiselectable' |
+  'aria-orientation' |
+  'aria-owns' |
+  'aria-placeholder' |
+  'aria-posinset' |
+  'aria-pressed' |
+  'aria-readonly' |
+  'aria-relevant' |
+  'aria-required' |
+  'aria-roledescription' |
+  'aria-rowcount' |
+  'aria-rowindex' |
+  'aria-rowspan' |
+  'aria-selected' |
+  'aria-setsize' |
+  'aria-sort' |
+  'aria-valuemax' |
+  'aria-valuemin' |
+  'aria-valuenow' |
+  'aria-valuetext' |
+  'role'
+);
+
+
 /**
  * The names of the supported HTML5 CSS property names.
  *
@@ -599,6 +659,18 @@ type ElementBaseAttrs = {
   readonly [T in ElementAttrNames]?: string;
 };
 
+/**
+ * The ARIA attributes for a virtual element node.
+ *
+ * These are the attributes which are applied to a real DOM element via
+ * `element.setAttribute()`. The supported attribute names are defined
+ * by the `ARIAAttrNames` type.
+ */
+export
+type ElementARIAAttrs = {
+  readonly [T in ARIAAttrNames]?: string;
+};
+
 
 /**
  * The inline event listener attributes for a virtual element node.
@@ -655,12 +727,13 @@ type ElementSpecialAttrs = {
 /**
  * The full set of attributes supported by a virtual element node.
  *
- * This is the combination of the base element attributes, the inline
- * element event listeners, and the special element attributes.
+ * This is the combination of the base element attributes, the ARIA attributes,
+ * the inline element event listeners, and the special element attributes.
  */
 export
 type ElementAttrs = (
   ElementBaseAttrs &
+  ElementARIAAttrs &
   ElementEventAttrs &
   ElementSpecialAttrs
 );

packages/widgets/src/docklayout.ts

@@ -633,6 +633,8 @@ class DockLayout extends Layout {
       return;
     }
 
+    Private.removeAria(widget);
+
     // If there are multiple tabs, just remove the widget's tab.
     if (tabNode.tabBar.titles.length > 1) {
       tabNode.tabBar.removeTab(widget.title);
@@ -764,6 +766,7 @@ class DockLayout extends Layout {
       let tabNode = new Private.TabLayoutNode(this._createTabBar());
       tabNode.tabBar.addTab(widget.title);
       this._root = tabNode;
+      Private.addAria(widget, tabNode.tabBar);
       return;
     }
 
@@ -789,6 +792,7 @@ class DockLayout extends Layout {
 
     // Insert the widget's tab relative to the target index.
     refNode.tabBar.insertTab(index + (after ? 1 : 0), widget.title);
+    Private.addAria(widget, refNode.tabBar);
   }
 
   /**
@@ -809,6 +813,7 @@ class DockLayout extends Layout {
     // Create the tab layout node to hold the widget.
     let tabNode = new Private.TabLayoutNode(this._createTabBar());
     tabNode.tabBar.addTab(widget.title);
+    Private.addAria(widget, tabNode.tabBar);
 
     // Set the root if it does not exist.
     if (!this._root) {
@@ -1976,6 +1981,19 @@ namespace Private {
     }
   }
 
+  export
+  async function addAria(widget: Widget, tabBar: TabBar<Widget>) {
+    let tabId = tabBar.renderer.createTabKey({title: widget.title, current: false, zIndex: 0});
+    widget.node.setAttribute('role', 'tabpanel');
+    widget.node.setAttribute('aria-labelledby', tabId);
+  }
+
+  export
+  async function removeAria(widget: Widget) {
+    widget.node.removeAttribute('role');
+    widget.node.removeAttribute('aria-labelledby');
+  }
+
   /**
    * Normalize a tab area config and collect the visited widgets.
    */
@@ -2065,6 +2083,7 @@ namespace Private {
     each(config.widgets, widget => {
       widget.hide();
       tabBar.addTab(widget.title);
+      Private.addAria(widget, tabBar);
     });
 
     // Set the current index of the tab bar.

packages/widgets/src/menu.ts

@@ -34,7 +34,7 @@ import {
 } from '@phosphor/signaling';
 
 import {
-  ElementDataset, VirtualDOM, VirtualElement, h
+  ARIAAttrNames, ElementARIAAttrs, ElementDataset, VirtualDOM, VirtualElement, h
 } from '@phosphor/virtualdom';
 
 import {
@@ -1143,8 +1143,9 @@ namespace Menu {
     renderItem(data: IRenderData): VirtualElement {
       let className = this.createItemClass(data);
       let dataset = this.createItemDataset(data);
+      let aria = this.createItemARIA(data);
       return (
-        h.li({ className, dataset },
+        h.li({ className, dataset, ...aria },
           this.renderIcon(data),
           this.renderLabel(data),
           this.renderShortcut(data),
@@ -1269,6 +1270,21 @@ namespace Menu {
       return extra ? `${name} ${extra}` : name;
     }
 
+    createItemARIA(data: IRenderData): ElementARIAAttrs {
+      let aria: {[T in ARIAAttrNames]?: string} = {};
+      switch (data.item.type) {
+      case 'separator':
+        aria.role = 'presentation';
+        break;
+      case 'submenu':
+        aria['aria-haspopup'] = 'true';
+        break;
+      default:
+        aria.role = 'menuitem';
+      }
+      return aria;
+    }
+
     /**
      * Create the render content for the label node.
      *
@@ -1342,6 +1358,7 @@ namespace Private {
     let node = document.createElement('div');
     let content = document.createElement('ul');
     content.className = 'p-Menu-content';
+    content.setAttribute('role', 'menu');
     node.appendChild(content);
     node.tabIndex = -1;
     return node;

packages/widgets/src/menubar.ts

@@ -22,7 +22,7 @@ import {
 } from '@phosphor/messaging';
 
 import {
-  ElementDataset, VirtualDOM, VirtualElement, h
+  ElementARIAAttrs, ElementDataset, VirtualDOM, VirtualElement, h
 } from '@phosphor/virtualdom';
 
 import {
@@ -747,8 +747,9 @@ namespace MenuBar {
     renderItem(data: IRenderData): VirtualElement {
       let className = this.createItemClass(data);
       let dataset = this.createItemDataset(data);
+      let aria = this.createItemARIA(data);
       return (
-        h.li({ className, dataset },
+        h.li({ className, dataset, ...aria},
           this.renderIcon(data),
           this.renderLabel(data)
         )
@@ -808,6 +809,10 @@ namespace MenuBar {
       return data.title.dataset;
     }
 
+    createItemARIA(data: IRenderData): ElementARIAAttrs {
+      return {role: 'menuitem', 'aria-haspopup': 'true'};
+    }
+
     /**
      * Create the class name for the menu bar item icon.
      *
@@ -870,6 +875,7 @@ namespace Private {
     let node = document.createElement('div');
     let content = document.createElement('ul');
     content.className = 'p-MenuBar-content';
+    content.setAttribute('role', 'menubar');
     node.appendChild(content);
     node.tabIndex = -1;
     return node;