MOBILE-3745 tabs: Add keyboard a11y to tabs

src/core/classes/aria-role-tab.ts

@@ -0,0 +1,137 @@
+// (C) Copyright 2015 Moodle Pty Ltd.
+//
+// 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.
+
+export class CoreAriaRoleTab<T = unknown> {
+
+    componentInstance: T;
+
+    constructor(componentInstance: T) {
+        this.componentInstance = componentInstance;
+    }
+
+    /**
+     * A11y key functionallity that prevents keyDown events.
+     *
+     * @param e Event.
+     */
+    keyDown(e: KeyboardEvent): void {
+        if (e.key == ' ' ||
+            e.key == 'Enter' ||
+            e.key == 'Home' ||
+            e.key == 'End' ||
+            (this.isHorizontal() && (e.key == 'ArrowRight' || e.key == 'ArrowLeft')) ||
+            (!this.isHorizontal() && (e.key == 'ArrowUp' ||e.key == 'ArrowDown'))
+        ) {
+            e.preventDefault();
+            e.stopPropagation();
+        }
+    }
+
+    /**
+     * A11y key functionallity.
+     *
+     * Enter or Space: When a tab has focus, activates the tab, causing its associated panel to be displayed.
+     * Right Arrow: When a tab has focus: Moves focus to the next tab. If focus is on the last tab, moves focus to the first tab.
+     * Left Arrow: When a tab has focus: Moves focus to the previous tab. If focus is on the first tab, moves focus to the last tab.
+     * Home: When a tab has focus, moves focus to the first tab.
+     * End: When a tab has focus, moves focus to the last tab.
+     * https://www.w3.org/TR/wai-aria-practices-1.1/examples/tabs/tabs-2/tabs.html
+     *
+     * @param tabFindIndex Tab finable index.
+     * @param e Event.
+     * @return Promise resolved when done.
+     */
+    keyUp(tabFindIndex: string, e: KeyboardEvent): void {
+        if (e.key == ' ' || e.key == 'Enter') {
+            this.selectTab(tabFindIndex, e);
+
+            return;
+        }
+
+        e.preventDefault();
+        e.stopPropagation();
+
+        const tabs = this.getSelectableTabs();
+
+        let index = tabs.findIndex((tab) => tabFindIndex == tab.findIndex);
+
+        const previousKey = this.isHorizontal() ? 'ArrowLeft' : 'ArrowUp';
+        const nextKey = this.isHorizontal() ? 'ArrowRight' : 'ArrowDown';
+
+        switch (e.key) {
+            case nextKey:
+                index++;
+                if (index >= tabs.length) {
+                    index = 0;
+                }
+                break;
+            case 'Home':
+                index = 0;
+                break;
+            case previousKey:
+                index--;
+                if (index < 0) {
+                    index = tabs.length - 1;
+                }
+                break;
+            case 'End':
+                index = tabs.length - 1;
+                break;
+            default:
+                return;
+        }
+
+        const tabId = tabs[index].id;
+
+        // @todo Pages should match aria-controls id.
+        const tabElement = document.querySelector<HTMLIonTabButtonElement>(`ion-tab-button[aria-controls=${tabId}]`);
+
+        tabElement?.focus();
+    }
+
+    /**
+     * Selects the tab.
+     *
+     * @param tabId Tab identifier.
+     * @param e Event.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    selectTab(tabId: string, e: Event): void {
+        //
+    }
+
+    /**
+     * Return all the selectable tabs.
+     *
+     * @returns all the selectable tabs.
+     */
+    getSelectableTabs(): CoreAriaRoleTabFindable[] {
+        return [];
+    }
+
+    /**
+     * Returns if tabs are displayed horizontal or not.
+     *
+     * @returns Where the tabs are displayed horizontal.
+     */
+    isHorizontal(): boolean {
+        return true;
+    }
+
+}
+
+export type CoreAriaRoleTabFindable = {
+    id: string;
+    findIndex: string;
+};

src/core/classes/tabs.ts

@@ -31,6 +31,7 @@ import { Subscription } from 'rxjs';
 
 import { Platform, Translate } from '@singletons';
 import { CoreSettingsHelper } from '@features/settings/services/settings-helper';
+import { CoreAriaRoleTab, CoreAriaRoleTabFindable } from './aria-role-tab';
 
 /**
  * Class to abstract some common code for tabs.
@@ -89,10 +90,13 @@ export class CoreTabsBaseComponent<T extends CoreTabBase> implements OnInit, Aft
     protected slidesSwiperLoaded = false;
     protected scrollElements: Record<string | number, HTMLElement> = {}; // Scroll elements for each loaded tab.
 
+    tabAction: CoreTabsRoleTab<T>;
+
     constructor(
         protected element: ElementRef,
     ) {
         this.backButtonFunction = this.backButtonClicked.bind(this);
+        this.tabAction = new CoreTabsRoleTab(this);
     }
 
     /**
@@ -632,6 +636,30 @@ export class CoreTabsBaseComponent<T extends CoreTabBase> implements OnInit, Aft
 
 }
 
+/**
+ * Helper class to manage rol tab.
+ */
+class CoreTabsRoleTab<T extends CoreTabBase> extends CoreAriaRoleTab<CoreTabsBaseComponent<T>> {
+
+    /**
+     * @inheritdoc
+     */
+    selectTab(tabId: string, e: Event): void {
+        this.componentInstance.selectTab(tabId, e);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    getSelectableTabs(): CoreAriaRoleTabFindable[] {
+        return this.componentInstance.tabs.filter((tab) => tab.enabled).map((tab) => ({
+            id: tab.id!,
+            findIndex: tab.id!,
+        }));
+    }
+
+}
+
 /**
  * Data for each tab.
  */

src/core/components/tabs-outlet/core-tabs-outlet.html

@@ -7,15 +7,28 @@
             </ion-col>
             <ion-col class="ion-no-padding" size="10">
                 <ion-slides (ionSlideDidChange)="slideChanged()" [options]="slidesOpts" [dir]="direction" role="tablist"
-                    [attr.aria-label]="description" aria-hidden="false">
+                    [attr.aria-label]="description">
                     <ng-container *ngFor="let tab of tabs">
-                        <ion-slide [hidden]="!hideUntil" [attr.aria-selected]="selected == tab.id" class="tab-slide" role="tab"
+                        <ion-slide
-                            [attr.aria-label]="tab.title | translate" [attr.aria-controls]="tab.id" [id]="tab.id! + '-tab'"
+                            role="presentation"
-                            [tabindex]="selected == tab.id ? null : -1">
+                            [hidden]="!hideUntil"
-                            <ion-tab-button (ionTabButtonClick)="selectTab(tab.id, $event)" [tab]="tab.page" [layout]="layout"
+                            [id]="tab.id! + '-tab'"
-                                class="{{tab.class}}" [attr.aria-label]="tab.title | translate">
+                            class="tab-slide"
-                                <ion-icon *ngIf="tab.icon" aria-hidden="true"></ion-icon>
+                            [class.selected]="selected == tab.id">
-                                <ion-label aria-hidden="true">{{ tab.title | translate}}</ion-label>
+                            <ion-tab-button
+                                (ionTabButtonClick)="selectTab(tab.id, $event)"
+                                (keydown)="tabAction.keyDown($event)"
+                                (keyup)="tabAction.keyUp(tab.id, $event)"
+                                [tab]="tab.page"
+                                [layout]="layout"
+                                class="{{tab.class}}"
+                                role="tab"
+                                [attr.aria-controls]="tab.id"
+                                [attr.aria-selected]="selected == tab.id"
+                                [tabindex]="selected == tab.id ? 0 : -1"
+                            >
+                                <ion-icon *ngIf="tab.icon" [name]="tab.icon" aria-hidden="true"></ion-icon>
+                                <ion-label>{{ tab.title | translate}}</ion-label>
                                 <ion-badge *ngIf="tab.badge">{{ tab.badge }}</ion-badge>
                             </ion-tab-button>
                         </ion-slide>

src/core/components/tabs-outlet/tabs-outlet.ts

@@ -45,7 +45,8 @@ import { CoreTabBase, CoreTabsBaseComponent } from '@classes/tabs';
  * Tab contents will only be shown if that tab is selected.
  *
  * @todo: Test RTL and tab history.
- * @todo: This should behave like the split-view in relation to routing (maybe we could reuse some code from CoreItemsListManager).
+ * @todo: This should behave like the split-view in relation to routing (maybe we could reuse some code from
+ *  CorePageItemsListManager).
  */
 @Component({
     selector: 'core-tabs-outlet',

src/core/components/tabs/core-tabs.html

@@ -6,15 +6,30 @@
         </ion-col>
         <ion-col class="ion-no-padding" size="10">
             <ion-slides (ionSlideDidChange)="slideChanged()" [options]="slidesOpts" [dir]="direction" role="tablist"
-                [attr.aria-label]="description" aria-hidden="false">
+                [attr.aria-label]="description">
                 <ng-container *ngFor="let tab of tabs">
-                    <ion-slide *ngIf="tab.enabled" [hidden]="!hideUntil" [attr.aria-selected]="selected == tab.id"
+                    <ion-slide
-                        class="tab-slide {{tab.class}}" role="tab" [attr.aria-label]="tab.title | translate"
+                        *ngIf="tab.enabled"
-                        [attr.aria-controls]="tab.id" [id]="tab.id! + '-tab'" [tabindex]="selected == tab.id ? null : -1"
+                        role="presentation"
-                        (click)="selectTab(tab.id, $event)" [attr.aria-label]="tab.title | translate">
+                        [hidden]="!hideUntil"
+                        class="tab-slide"
+                        [id]="tab.id! + '-tab'"
+                        [class.selected]="selected == tab.id">
+                        <ion-tab-button
+                            (click)="selectTab(tab.id, $event)"
+                            (keydown)="tabAction.keyDown($event)"
+                            (keyup)="tabAction.keyUp(tab.id, $event)"
+                            class="{{tab.class}}"
+                            [layout]="layout"
+                            role="tab"
+                            [attr.aria-controls]="tab.id"
+                            [attr.aria-selected]="selected == tab.id"
+                            [tabindex]="selected == tab.id ? 0 : -1"
+                        >
                             <ion-icon *ngIf="tab.icon" [name]="tab.icon" aria-hidden="true"></ion-icon>
-                        <ion-label aria-hidden="true">{{ tab.title | translate}}</ion-label>
+                            <ion-label>{{ tab.title | translate}}</ion-label>
                             <ion-badge *ngIf="tab.badge">{{ tab.badge }}</ion-badge>
+                        </ion-tab-button>
                     </ion-slide>
                 </ng-container>
             </ion-slides>

src/core/components/tabs/tab.ts

@@ -84,6 +84,7 @@ export class CoreTabComponent implements OnInit, OnDestroy, CoreTabBase {
 
         this.element.setAttribute('role', 'tabpanel');
         this.element.setAttribute('tabindex', '0');
+        this.element.setAttribute('aria-hidden', 'true');
     }
 
     /**
@@ -113,6 +114,7 @@ export class CoreTabComponent implements OnInit, OnDestroy, CoreTabBase {
 
         this.tabElement = this.tabElement || document.getElementById(this.id + '-tab');
         this.tabElement?.setAttribute('aria-selected', 'true');
+        this.element.setAttribute('aria-hidden', 'false');
 
         this.loaded = true;
         this.ionSelect.emit(this);
@@ -128,6 +130,8 @@ export class CoreTabComponent implements OnInit, OnDestroy, CoreTabBase {
     unselectTab(): void {
         this.tabElement?.setAttribute('aria-selected', 'false');
         this.element.classList.remove('selected');
+        this.element.setAttribute('aria-hidden', 'true');
+
         this.showHideNavBarButtons(false);
     }
 

src/core/components/tabs/tabs.scss

@@ -30,6 +30,7 @@
             overflow: hidden;
 
             ion-tab-button {
+                max-width: 100%;
                 ion-label {
                     font-size: 16px;
                     font-weight: 400;
@@ -44,7 +45,8 @@
                 }
             }
 
-            &[aria-selected=true] {
+            &[aria-selected=true],
+            &.selected {
                 color: var(--color-active);
                 border-bottom-color: var(--border-color-active);
                 ion-tab-button {

src/core/components/tabs/tabs.ts

@@ -45,6 +45,7 @@ import { CoreTabComponent } from './tab';
 export class CoreTabsComponent extends CoreTabsBaseComponent<CoreTabComponent> implements AfterViewInit {
 
     @Input() parentScrollable = false; // Determine if the scroll should be in the parent content or the tab itself.
+    @Input() layout: 'icon-top' | 'icon-start' | 'icon-end' | 'icon-bottom' | 'icon-hide' | 'label-hide' = 'icon-hide';
 
     @ViewChild('originalTabs') originalTabsRef?: ElementRef;
 

src/core/features/mainmenu/pages/menu/menu.html

@@ -3,17 +3,38 @@
     <ion-tab-bar slot="bottom" [hidden]="hidden">
         <ion-spinner *ngIf="!loaded"></ion-spinner>
 
-        <ion-tab-button (ionTabButtonClick)="tabClicked($event, tab.page)" [hidden]="!loaded && tab.hide" *ngFor="let tab of tabs"
+        <ion-tab-button
-            [tab]="tab.page" [disabled]="tab.hide" layout="label-hide"  class="{{tab.class}}"
+            *ngFor="let tab of tabs"
-            [attr.aria-label]="tab.title | translate">
+            (click)="tabClicked($event, tab.page)"
+            (keydown)="tabAction.keyDown($event)"
+            (keyup)="tabAction.keyUp(tab.page, $event)"
+            [hidden]="!loaded && tab.hide"
+            [tab]="tab.page"
+            [disabled]="tab.hide"
+            layout="label-hide"
+            class="{{tab.class}}"
+            [tabindex]="selectedTab == tab.page ? 0 : -1"
+            [attr.aria-controls]="tab.id"
+            [attr.aria-label]="tab.title | translate"
+        >
             <ion-icon [name]="tab.icon" aria-hidden="true"></ion-icon>
             <ion-label aria-hidden="true">{{ tab.title | translate }}</ion-label>
             <ion-badge *ngIf="tab.badge">{{ tab.badge }}</ion-badge>
         </ion-tab-button>
 
-        <ion-tab-button (ionTabButtonClick)="tabClicked($event, morePageName)" [hidden]="!loaded" [tab]="morePageName" layout="label-hide">
+        <ion-tab-button
-            <ion-icon name="fas-bars" [attr.aria-labelledby]="'mainmenu-tab-more'"></ion-icon>
+            (click)="tabClicked($event, morePageName)"
-            <ion-label id="mainmenu-tab-more">{{ 'core.more' | translate }}</ion-label>
+            (keydown)="tabAction.keyDown($event)"
+            (keyup)="tabAction.keyUp(morePageName, $event)"
+            [hidden]="!loaded"
+            [tab]="morePageName"
+            layout="label-hide"
+            [tabindex]="selectedTab == morePageName ? 0 : -1"
+            [attr.aria-controls]="morePageName"
+            [attr.aria-label]="'core.more' | translate"
+        >
+            <ion-icon name="fas-bars" aria-hidden="true"></ion-icon>
+            <ion-label aria-hidden="true">{{ 'core.more' | translate }}</ion-label>
         </ion-tab-button>
     </ion-tab-bar>
 </ion-tabs>

src/core/features/mainmenu/pages/menu/menu.scss

@@ -29,7 +29,6 @@
             height: 100%;
             flex-direction: column;
             ion-tab-button {
-                display: contents;
                 width: 100%;
                 ion-badge {
                     top: calc(50% - 20px);

src/core/features/mainmenu/pages/menu/menu.ts

@@ -25,6 +25,8 @@ import { CoreMainMenu, CoreMainMenuProvider } from '../../services/mainmenu';
 import { CoreMainMenuDelegate, CoreMainMenuHandlerToDisplay } from '../../services/mainmenu-delegate';
 import { CoreDomUtils } from '@services/utils/dom';
 import { Translate } from '@singletons';
+import { CoreUtils } from '@services/utils/utils';
+import { CoreAriaRoleTab, CoreAriaRoleTabFindable } from '@classes/aria-role-tab';
 
 /**
  * Page that displays the main menu of the app.
@@ -40,20 +42,22 @@ export class CoreMainMenuPage implements OnInit, OnDestroy {
     allHandlers?: CoreMainMenuHandlerToDisplay[];
     loaded = false;
     showTabs = false;
-    tabsPlacement = 'bottom';
+    tabsPlacement: 'bottom' | 'side' = 'bottom';
     hidden = false;
     morePageName = CoreMainMenuProvider.MORE_PAGE_NAME;
+    selectedTab?: string;
 
     protected subscription?: Subscription;
     protected keyboardObserver?: CoreEventObserver;
     protected resizeFunction: () => void;
     protected backButtonFunction: (event: BackButtonEvent) => void;
     protected selectHistory: string[] = [];
-    protected selectedTab?: string;
     protected firstSelectedTab?: string;
 
     @ViewChild('mainTabs') mainTabs?: IonTabs;
 
+    tabAction: CoreMainMenuRoleTab;
+
     constructor(
         protected route: ActivatedRoute,
         protected changeDetector: ChangeDetectorRef,
@@ -61,6 +65,7 @@ export class CoreMainMenuPage implements OnInit, OnDestroy {
     ) {
         this.resizeFunction = this.initHandlers.bind(this);
         this.backButtonFunction = this.backButtonClicked.bind(this);
+        this.tabAction = new CoreMainMenuRoleTab(this);
     }
 
     /**
@@ -111,10 +116,11 @@ export class CoreMainMenuPage implements OnInit, OnDestroy {
                 const handler = handlers[i];
 
                 // Check if the handler is already in the tabs list. If so, use it.
-                const tab = this.tabs.find((tab) => tab.title == handler.title && tab.icon == handler.icon);
+                const tab = this.tabs.find((tab) => tab.page == handler.page);
 
                 tab ? tab.hide = false : null;
                 handler.hide = false;
+                handler.id = handler.id || 'core-mainmenu-' + CoreUtils.getUniqueId('CoreMainMenuPage');
 
                 newTabs.push(tab || handler);
             }
@@ -246,3 +252,42 @@ export class CoreMainMenuPage implements OnInit, OnDestroy {
     }
 
 }
+
+/**
+ * Helper class to manage rol tab.
+ */
+class CoreMainMenuRoleTab extends CoreAriaRoleTab<CoreMainMenuPage> {
+
+    /**
+     * @inheritdoc
+     */
+    selectTab(tabId: string, e: Event): void {
+        this.componentInstance.tabClicked(e, tabId);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    getSelectableTabs(): CoreAriaRoleTabFindable[] {
+        const allTabs: CoreAriaRoleTabFindable[] =
+            this.componentInstance.tabs.filter((tab) => !tab.hide).map((tab) => ({
+                id: tab.id || tab.page,
+                findIndex: tab.page,
+            }));
+
+        allTabs.push({
+            id: this.componentInstance.morePageName,
+            findIndex: this.componentInstance.morePageName,
+        });
+
+        return allTabs;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    isHorizontal(): boolean {
+        return this.componentInstance.tabsPlacement == 'bottom';
+    }
+
+}

src/core/features/mainmenu/services/mainmenu-delegate.ts

@@ -89,6 +89,11 @@ export interface CoreMainMenuHandlerToDisplay extends CoreDelegateToDisplay, Cor
      * Hide tab. Used then resizing.
      */
     hide?: boolean;
+
+    /**
+     * Used to control tabs.
+     */
+    id?: string;
 }
 
 /**

src/core/features/mainmenu/services/mainmenu.ts

@@ -179,7 +179,7 @@ export class CoreMainMenuProvider {
      *
      * @return Tabs placement including side value.
      */
-    getTabPlacement(): string {
+    getTabPlacement(): 'bottom' | 'side' {
         const tablet = !!(window.innerWidth && window.innerWidth >= 576 && (window.innerHeight >= 576 ||
                 ((CoreApp.isKeyboardVisible() || CoreApp.isKeyboardOpening()) && window.innerHeight >= 200)));