Merge pull request #132 from telamonian/aria-tabs-lumino-update

Add ARIA roles to tabs - lumino update

Author: blink1073

packages/widgets/src/docklayout.ts

@@ -639,6 +639,8 @@ 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);
@@ -770,6 +772,7 @@ 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;
     }
 
@@ -795,6 +798,7 @@ 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);
   }
 
   /**
@@ -815,6 +819,7 @@ 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) {
@@ -1988,6 +1993,22 @@ namespace Private {
     }
   }
 
+  export
+  function addAria(widget: Widget, tabBar: TabBar<Widget>) {
+    widget.node.setAttribute('role', 'tabpanel');
+    let renderer = tabBar.renderer;
+    if (renderer instanceof TabBar.Renderer) {
+      let tabId = renderer.createTabKey({ title: widget.title, current: false, zIndex: 0 });
+      widget.node.setAttribute('aria-labelledby', tabId);  
+    }
+  }
+
+  export
+  function removeAria(widget: Widget) {
+    widget.node.removeAttribute('role');
+    widget.node.removeAttribute('aria-labelledby');
+  }
+
   /**
    * Normalize a tab area config and collect the visited widgets.
    */
@@ -2077,6 +2098,7 @@ 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/tabbar.ts

@@ -32,7 +32,7 @@ import {
 } from '@lumino/signaling';
 
 import {
-  ElementDataset, ElementInlineStyle, VirtualDOM, VirtualElement, h
+  ElementARIAAttrs, ElementDataset, ElementInlineStyle, VirtualDOM, VirtualElement, h
 } from '@lumino/virtualdom';
 
 import {
@@ -65,15 +65,16 @@ class TabBar<T> extends Widget {
     /* <DEPRECATED> */
     this.addClass('p-TabBar');
     /* </DEPRECATED> */
+    this.contentNode.setAttribute('role', 'tablist');
     this.setFlag(Widget.Flag.DisallowLayout);
     this.tabsMovable = options.tabsMovable || false;
     this.titlesEditable = options.titlesEditable || false;
     this.allowDeselect = options.allowDeselect || false;
     this.insertBehavior = options.insertBehavior || 'select-tab-if-needed';
+    this.name = options.name || '';
+    this.orientation = options.orientation || 'horizontal';
     this.removeBehavior = options.removeBehavior || 'select-tab-after';
     this.renderer = options.renderer || TabBar.defaultRenderer;
-    this._orientation = options.orientation || 'horizontal';
-    this.dataset['orientation'] = this._orientation;
   }
 
   /**
@@ -268,6 +269,25 @@ class TabBar<T> extends Widget {
     });
   }
 
+  /**
+   * Get the name of the tab bar.
+   */
+  get name(): string {
+    return this._name;
+  }
+
+  /**
+   * Set the name of the tab bar.
+   */
+  set name(value: string) {
+    this._name = value;
+    if (value) {
+      this.contentNode.setAttribute('aria-label', value);
+    } else {
+      this.contentNode.removeAttribute('aria-label');
+    }
+  }
+
   /**
    * Get the orientation of the tab bar.
    *
@@ -296,6 +316,7 @@ class TabBar<T> extends Widget {
     // Toggle the orientation values.
     this._orientation = value;
     this.dataset['orientation'] = value;
+    this.contentNode.setAttribute('aria-orientation', value);
   }
 
   /**
@@ -997,6 +1018,9 @@ class TabBar<T> extends Widget {
     let ci = this._currentIndex;
     let bh = this.insertBehavior;
 
+
+    // TODO: do we need to do an update to update the aria-selected attribute?
+
     // Handle the behavior where the new tab is always selected,
     // or the behavior where the new tab is selected if needed.
     if (bh === 'select-tab' || (bh === 'select-tab-if-needed' && ci === -1)) {
@@ -1050,6 +1074,8 @@ class TabBar<T> extends Widget {
       return;
     }
 
+    // TODO: do we need to do an update to adjust the aria-selected value?
+
     // No tab gets selected if the tab bar is empty.
     if (this._titles.length === 0) {
       this._currentIndex = -1;
@@ -1110,6 +1136,7 @@ class TabBar<T> extends Widget {
     this.update();
   }
 
+  private _name: string;
   private _currentIndex = -1;
   private _titles: Title<T>[] = [];
   private _orientation: TabBar.Orientation;
@@ -1201,6 +1228,13 @@ namespace TabBar {
    */
   export
   interface IOptions<T> {
+    /**
+     * Name of the tab bar.
+     *
+     * This is used for accessibility reasons. The default is the empty string.
+     */
+    name?: string;
+
     /**
      * The layout orientation of the tab bar.
      *
@@ -1430,11 +1464,13 @@ namespace TabBar {
     renderTab(data: IRenderData<any>): VirtualElement {
       let title = data.title.caption;
       let key = this.createTabKey(data);
+      let id = key;
       let style = this.createTabStyle(data);
       let className = this.createTabClass(data);
       let dataset = this.createTabDataset(data);
+      let aria = this.createTabARIA(data);
       return (
-        h.li({ key, className, title, style, dataset },
+        h.li({ id, key, className, title, style, dataset, ...aria },
           this.renderIcon(data),
           this.renderLabel(data),
           this.renderCloseIcon(data)
@@ -1568,6 +1604,17 @@ namespace TabBar {
       return data.title.dataset;
     }
 
+    /**
+     * Create the ARIA attributes for a tab.
+     *
+     * @param data - The data to use for the tab.
+     *
+     * @returns The ARIA attributes for the tab.
+     */
+    createTabARIA(data: IRenderData<any>): ElementARIAAttrs {
+      return {role: 'tab', 'aria-selected': data.current.toString()};
+    }
+
     /**
      * Create the class name for the tab icon.
      *
@@ -1730,6 +1777,7 @@ namespace Private {
   function createNode(): HTMLDivElement {
     let node = document.createElement('div');
     let content = document.createElement('ul');
+    content.setAttribute('role', 'tablist');
     content.className = 'lm-TabBar-content';
     /* <DEPRECATED> */
     content.classList.add('p-TabBar-content');

packages/widgets/src/tabpanel.ts

@@ -272,6 +272,14 @@ class TabPanel extends Widget {
     }
     this.stackedPanel.insertWidget(index, widget);
     this.tabBar.insertTab(index, widget.title);
+
+    widget.node.setAttribute('role', 'tabpanel');
+
+    let renderer = this.tabBar.renderer
+    if (renderer instanceof TabBar.Renderer) {
+      let tabId = renderer.createTabKey({title: widget.title, current: false, zIndex: 0});
+      widget.node.setAttribute('aria-labelledby', tabId);
+    }
   }
 
   /**
@@ -331,6 +339,8 @@ class TabPanel extends Widget {
    * Handle the `widgetRemoved` signal from the stacked panel.
    */
   private _onWidgetRemoved(sender: StackedPanel, widget: Widget): void {
+    widget.node.removeAttribute('role');
+    widget.node.removeAttribute('aria-labelledby');
     this.tabBar.removeTab(widget.title);
   }