fix(menu): always focus first menu item

* Switches to always focusing the first menu item, even when opening by mouse. The focus styling will only apply when focused by keyboard.
* Adds the ability to set the focus origin through the `FocusKeyManager`.

Fixes #9252.

Author: crisbeto

src/cdk/a11y/focus-key-manager.ts

@@ -7,6 +7,7 @@
  */
 
 import {ListKeyManager, ListKeyManagerOption} from './list-key-manager';
+import {FocusOrigin} from './focus-monitor';
 
 /**
  * This is the interface for focusable items (used by the FocusKeyManager).
@@ -15,10 +16,21 @@ import {ListKeyManager, ListKeyManagerOption} from './list-key-manager';
  */
 export interface FocusableOption extends ListKeyManagerOption {
   /** Focuses the `FocusableOption`. */
-  focus(): void;
+  focus(origin?: FocusOrigin): void;
 }
 
 export class FocusKeyManager<T> extends ListKeyManager<FocusableOption & T> {
+  private _origin: FocusOrigin = 'program';
+
+  /**
+   * Sets the focus origin that will be passed in to the items for any subsequent `focus` calls.
+   * @param origin Focus origin to be used when focusing items.
+   */
+  setFocusOrigin(origin: FocusOrigin): this {
+    this._origin = origin;
+    return this;
+  }
+
   /**
    * This method sets the active item to the item at the specified index.
    * It also adds focuses the newly active item.
@@ -27,7 +39,7 @@ export class FocusKeyManager<T> extends ListKeyManager<FocusableOption & T> {
     super.setActiveItem(index);
 
     if (this.activeItem) {
-      this.activeItem.focus();
+      this.activeItem.focus(this._origin);
     }
   }
 }

src/cdk/a11y/list-key-manager.spec.ts

@@ -6,12 +6,13 @@ import {createKeyboardEvent} from '../testing/event-objects';
 import {ActiveDescendantKeyManager} from './activedescendant-key-manager';
 import {FocusKeyManager} from './focus-key-manager';
 import {ListKeyManager} from './list-key-manager';
+import {FocusOrigin} from './focus-monitor';
 
 
 class FakeFocusable {
   constructor(private _label = '') { }
   disabled = false;
-  focus() {}
+  focus(_focusOrigin?: FocusOrigin) {}
   getLabel() { return this._label; }
 }
 
@@ -626,6 +627,21 @@ describe('Key managers', () => {
       expect(itemList.items[1].focus).not.toHaveBeenCalledTimes(1);
     });
 
+    it('should be able to set the focus origin', () => {
+      keyManager.setFocusOrigin('mouse');
+
+      keyManager.onKeydown(fakeKeyEvents.downArrow);
+      expect(itemList.items[1].focus).toHaveBeenCalledWith('mouse');
+
+      keyManager.onKeydown(fakeKeyEvents.downArrow);
+      expect(itemList.items[2].focus).toHaveBeenCalledWith('mouse');
+
+      keyManager.setFocusOrigin('keyboard');
+
+      keyManager.onKeydown(fakeKeyEvents.upArrow);
+      expect(itemList.items[1].focus).toHaveBeenCalledWith('keyboard');
+    });
+
   });
 
   describe('ActiveDescendantKeyManager', () => {

src/lib/menu/_menu-theme.scss

@@ -26,7 +26,8 @@
   }
 
   .mat-menu-item:hover,
-  .mat-menu-item:focus,
+  .mat-menu-item.cdk-program-focused,
+  .mat-menu-item.cdk-keyboard-focused,
   .mat-menu-item-highlighted {
     &:not([disabled]) {
       background: mat-color($background, 'hover');

src/lib/menu/menu-directive.ts

@@ -40,6 +40,7 @@ import {MatMenuItem} from './menu-item';
 import {MatMenuPanel} from './menu-panel';
 import {MenuPositionX, MenuPositionY} from './menu-positions';
 import {coerceBooleanProperty} from '@angular/cdk/coercion';
+import {FocusOrigin} from '@angular/cdk/a11y';
 
 
 /** Default `mat-menu` options that can be overridden. */
@@ -228,16 +229,17 @@ export class MatMenu implements AfterContentInit, MatMenuPanel, OnDestroy {
   }
 
   /**
-   * Focus the first item in the menu. This method is used by the menu trigger
-   * to focus the first item when the menu is opened by the ENTER key.
+   * Focus the first item in the menu.
+   * @param origin Action from which the focus originated. Used to set the correct styling.
    */
-  focusFirstItem() {
-    this._keyManager.setFirstItemActive();
+  focusFirstItem(origin?: FocusOrigin) {
+    // TODO(crisbeto): make the origin required when doing breaking changes.
+    this._keyManager.setFocusOrigin(origin).setFirstItemActive();
   }
 
   /**
-   * Resets the active item in the menu. This is used when the menu is opened by mouse,
-   * allowing the user to start from the first option when pressing the down arrow.
+   * Resets the active item in the menu. This is used when the menu is opened, allowing
+   * the user to start from the first option when pressing the down arrow.
    */
   resetActiveItem() {
     this._keyManager.setActiveItem(-1);

src/lib/menu/menu-item.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {FocusableOption} from '@angular/cdk/a11y';
+import {FocusableOption, FocusMonitor, FocusOrigin} from '@angular/cdk/a11y';
 import {
   ChangeDetectionStrategy,
   Component,
@@ -64,16 +64,34 @@ export class MatMenuItem extends _MatMenuItemMixinBase
   /** Whether the menu item acts as a trigger for a sub-menu. */
   _triggersSubmenu: boolean = false;
 
-  constructor(private _elementRef: ElementRef) {
+  constructor(
+    private _elementRef: ElementRef,
+    // TODO(crisbeto): switch to a required param when doing breaking changes.
+    private _focusMonitor?: FocusMonitor) {
     super();
+
+    if (_focusMonitor) {
+      // Start monitoring the element so it gets the appropriate focused classes. We want
+      // to show the focus style for menu items only when the focus was not caused by a
+      // mouse or touch interaction.
+      _focusMonitor.monitor(this._getHostElement(), false);
+    }
   }
 
   /** Focuses the menu item. */
-  focus(): void {
-    this._getHostElement().focus();
+  focus(origin: FocusOrigin = 'program'): void {
+    if (this._focusMonitor) {
+      this._focusMonitor.focusVia(this._getHostElement(), origin);
+    } else {
+      this._getHostElement().focus();
+    }
   }
 
   ngOnDestroy() {
+    if (this._focusMonitor) {
+      this._focusMonitor.stopMonitoring(this._getHostElement());
+    }
+
     this._hovered.complete();
   }
 

src/lib/menu/menu-module.ts

@@ -14,6 +14,7 @@ import {MatMenu, MAT_MENU_DEFAULT_OPTIONS} from './menu-directive';
 import {MatMenuItem} from './menu-item';
 import {MatMenuTrigger, MAT_MENU_SCROLL_STRATEGY_PROVIDER} from './menu-trigger';
 import {MatRippleModule} from '@angular/material/core';
+import {A11yModule} from '@angular/cdk/a11y';
 
 
 @NgModule({
@@ -22,6 +23,7 @@ import {MatRippleModule} from '@angular/material/core';
     CommonModule,
     MatRippleModule,
     MatCommonModule,
+    A11yModule,
   ],
   exports: [MatMenu, MatMenuItem, MatMenuTrigger, MatCommonModule],
   declarations: [MatMenu, MatMenuItem, MatMenuTrigger],

src/lib/menu/menu-panel.ts

@@ -9,6 +9,7 @@
 import {EventEmitter, TemplateRef} from '@angular/core';
 import {MenuPositionX, MenuPositionY} from './menu-positions';
 import {Direction} from '@angular/cdk/bidi';
+import {FocusOrigin} from '@angular/cdk/a11y';
 
 /**
  * Interface for a custom menu panel that can be used with `matMenuTriggerFor`.
@@ -22,7 +23,7 @@ export interface MatMenuPanel {
   close: EventEmitter<void | 'click' | 'keydown'>;
   parentMenu?: MatMenuPanel | undefined;
   direction?: Direction;
-  focusFirstItem: () => void;
+  focusFirstItem: (origin?: FocusOrigin) => void;
   resetActiveItem: () => void;
   setPositionClasses: (x: MenuPositionX, y: MenuPositionY) => void;
   setElevation?(depth: number): void;

src/lib/menu/menu-trigger.ts

@@ -234,19 +234,7 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
     this.menu.direction = this.dir;
     this._setMenuElevation();
     this._setIsMenuOpen(true);
-
-    // If the menu was opened by mouse, we focus the root node, which allows for the keyboard
-    // interactions to work. Otherwise, if the menu was opened by keyboard, we focus the first item.
-    if (this._openedByMouse) {
-      let rootNode = this._overlayRef!.overlayElement.firstElementChild as HTMLElement;
-
-      if (rootNode) {
-        this.menu.resetActiveItem();
-        rootNode.focus();
-      }
-    } else {
-      this.menu.focusFirstItem();
-    }
+    this.menu.focusFirstItem(this._openedByMouse ? 'mouse' : 'program');
   }
 
   /** Updates the menu elevation based on the amount of parent menus that it has. */

src/lib/menu/menu.spec.ts

@@ -230,22 +230,20 @@ describe('MatMenu', () => {
     expect(fixture.componentInstance.items.last.getLabel()).toBe('Item with an icon');
   });
 
-  it('should focus the menu panel root node when it was opened by mouse', () => {
+  it('should set the proper focus origin when opening by mouse', fakeAsync(() => {
     const fixture = TestBed.createComponent(SimpleMenu);
-
     fixture.detectChanges();
+    spyOn(fixture.componentInstance.items.first, 'focus').and.callThrough();
 
     const triggerEl = fixture.componentInstance.triggerEl.nativeElement;
 
     dispatchFakeEvent(triggerEl, 'mousedown');
     triggerEl.click();
     fixture.detectChanges();
+    tick(500);
 
-    const panel = overlayContainerElement.querySelector('.mat-menu-panel')!;
-
-    expect(panel).toBeTruthy('Expected the panel to be rendered.');
-    expect(document.activeElement).toBe(panel, 'Expected the panel to be focused.');
-  });
+    expect(fixture.componentInstance.items.first.focus).toHaveBeenCalledWith('mouse');
+  }));
 
   it('should close the menu when using the CloseScrollStrategy', fakeAsync(() => {
     const scrolledSubject = new Subject();
@@ -1068,6 +1066,7 @@ describe('MatMenu', () => {
 
         instance.alternateTrigger.openMenu();
         fixture.detectChanges();
+        tick(500);
 
         lastMenu = overlay.querySelector('.mat-menu-panel') as HTMLElement;
 
@@ -1121,6 +1120,7 @@ describe('MatMenu', () => {
       compileTestComponent();
       instance.rootTriggerEl.nativeElement.click();
       fixture.detectChanges();
+      tick(500);
       expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(1, 'Expected one open menu');
 
       instance.showLazy = true;
@@ -1130,6 +1130,8 @@ describe('MatMenu', () => {
 
       dispatchMouseEvent(lazyTrigger, 'mouseenter');
       fixture.detectChanges();
+      tick(500);
+
       expect(lazyTrigger.classList)
           .toContain('mat-menu-item-highlighted', 'Expected the trigger to be highlighted');
       expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(2, 'Expected two open menus');
@@ -1157,10 +1159,12 @@ describe('MatMenu', () => {
 
       repeaterFixture.componentInstance.rootTriggerEl.nativeElement.click();
       repeaterFixture.detectChanges();
+      tick(500);
       expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(1, 'Expected one open menu');
 
       dispatchMouseEvent(overlay.querySelector('.level-one-trigger')!, 'mouseenter');
       repeaterFixture.detectChanges();
+      tick(500);
       expect(overlay.querySelectorAll('.mat-menu-panel').length).toBe(2, 'Expected two open menus');
     }));