feat(tabs): adds focus/select events (#649)

closes #569

src/components/tabs/README.md

@@ -28,3 +28,11 @@ A basic tab group would have the following markup.
 | Name | Type | Description |
 | --- | --- | --- |
 | `selectedIndex` | `number` | The index of the currently active tab. |
+| `focusIndex` | `number` | The index of the currently active tab. |
+
+### Events
+
+| Name | Type | Description |
+| --- | --- | --- |
+| `focusChange` | `Event` | Fired when focus changes from one label to another |
+| `selectedChange` | `Event` | Fired when the selected tab changes |

src/components/tabs/tab-group.html

@@ -3,23 +3,23 @@
      (keydown.arrowLeft)="focusPreviousTab()"
      (keydown.enter)="selectedIndex = focusIndex">
   <div class="md-tab-label" role="tab" md-tab-label-wrapper
-       *ngFor="let label of labels; let i = index"
+       *ngFor="let tab of tabs; let i = index"
        [id]="getTabLabelId(i)"
        [tabIndex]="selectedIndex == i ? 0 : -1"
        [attr.aria-controls]="getTabContentId(i)"
        [attr.aria-selected]="selectedIndex == i"
        [class.md-active]="selectedIndex == i"
        (click)="focusIndex = selectedIndex = i">
-    <template [portalHost]="label"></template>
+    <template [portalHost]="tab.label"></template>
   </div>
   <md-ink-bar></md-ink-bar>
 </div>
 <div class="md-tab-body-wrapper">
   <div class="md-tab-body"
-       *ngFor="let content of contents; let i = index"
+       *ngFor="let tab of tabs; let i = index"
        [id]="getTabContentId(i)"
        [class.md-active]="selectedIndex == i"
        [attr.aria-labelledby]="getTabLabelId(i)">
-    <template role="tabpanel" [portalHost]="content" *ngIf="selectedIndex == i"></template>
+    <template role="tabpanel" [portalHost]="tab.content" *ngIf="selectedIndex == i"></template>
   </div>
 </div>

src/components/tabs/tab-group.spec.ts

@@ -4,7 +4,9 @@ import {
     beforeEach,
     inject,
     describe,
-    async
+    async,
+    fakeAsync,
+    tick
 } from '@angular/core/testing';
 import {TestComponentBuilder, ComponentFixture} from '@angular/compiler/testing';
 import {MD_TABS_DIRECTIVES, MdTabGroup} from './tabs';
@@ -47,44 +49,80 @@ describe('MdTabGroup', () => {
       checkSelectedIndex(2);
     });
 
-    it('should cycle through tab focus with focusNextTab/focusPreviousTab functions', () => {
+    it('should cycle through tab focus with focusNextTab/focusPreviousTab functions',
+        fakeAsync(() => {
+      let testComponent = fixture.componentInstance;
       let tabComponent = fixture.debugElement.query(By.css('md-tab-group')).componentInstance;
+
+      spyOn(testComponent, 'handleFocus').and.callThrough();
+      fixture.detectChanges();
+
       tabComponent.focusIndex = 0;
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(0);
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(1);
+      expect(testComponent.focusEvent.index).toBe(0);
 
       tabComponent.focusNextTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(1);
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(2);
+      expect(testComponent.focusEvent.index).toBe(1);
 
       tabComponent.focusNextTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(2);
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(3);
+      expect(testComponent.focusEvent.index).toBe(2);
 
       tabComponent.focusNextTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(2); // should stop at 2
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(3);
+      expect(testComponent.focusEvent.index).toBe(2);
 
       tabComponent.focusPreviousTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(1);
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(4);
+      expect(testComponent.focusEvent.index).toBe(1);
 
       tabComponent.focusPreviousTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(0);
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(5);
+      expect(testComponent.focusEvent.index).toBe(0);
 
       tabComponent.focusPreviousTab();
       fixture.detectChanges();
+      tick();
       expect(tabComponent.focusIndex).toBe(0); // should stop at 0
-    });
+      expect(testComponent.handleFocus).toHaveBeenCalledTimes(5);
+      expect(testComponent.focusEvent.index).toBe(0);
+    }));
+
+    it('should change tabs based on selectedIndex', fakeAsync(() => {
+      let component = fixture.componentInstance;
+      let tabComponent = fixture.debugElement.query(By.css('md-tab-group')).componentInstance;
+
+      spyOn(component, 'handleSelection').and.callThrough();
 
-    it('should change tabs based on selectedIndex', () => {
-      let component = fixture.debugElement.componentInstance;
       checkSelectedIndex(1);
 
-      component.selectedIndex = 2;
+      tabComponent.selectedIndex = 2;
+
       checkSelectedIndex(2);
-    });
+      tick();
+
+      expect(component.handleSelection).toHaveBeenCalledTimes(1);
+      expect(component.selectEvent.index).toBe(2);
+    }));
   });
 
   describe('async tabs', () => {
@@ -131,7 +169,10 @@ describe('MdTabGroup', () => {
 @Component({
   selector: 'test-app',
   template: `
-    <md-tab-group class="tab-group" [selectedIndex]="selectedIndex">
+    <md-tab-group class="tab-group"
+        [selectedIndex]="selectedIndex"
+        (focusChange)="handleFocus($event)"
+        (selectChange)="handleSelection($event)">
       <md-tab>
         <template md-tab-label>Tab One</template>
         <template md-tab-content>Tab one content</template>
@@ -150,6 +191,14 @@ describe('MdTabGroup', () => {
 })
 class SimpleTabsTestApp {
   selectedIndex: number = 1;
+  focusEvent: any;
+  selectEvent: any;
+  handleFocus(event: any) {
+    this.focusEvent = event;
+  }
+  handleSelection(event: any) {
+    this.selectEvent = event;
+  }
 }
 
 @Component({

src/components/tabs/tabs.ts

@@ -1,4 +1,13 @@
-import {Component, Input, ViewChildren, NgZone} from '@angular/core';
+import {
+    ContentChild,
+    Directive,
+    Component,
+    Input,
+    Output,
+    ViewChildren,
+    NgZone,
+    EventEmitter
+} from '@angular/core';
 import {QueryList} from '@angular/core';
 import {ContentChildren} from '@angular/core';
 import {PortalHostDirective} from '@angular2-material/core/portal/portal-directives';
@@ -6,10 +15,25 @@ import {MdTabLabel} from './tab-label';
 import {MdTabContent} from './tab-content';
 import {MdTabLabelWrapper} from './tab-label-wrapper';
 import {MdInkBar} from './ink-bar';
+import {Observable} from 'rxjs/Observable';
 
 /** Used to generate unique ID's for each tab component */
 let nextId = 0;
 
+/** A simple change event emitted on focus or selection changes. */
+export class MdTabChangeEvent {
+  index: number;
+  tab: MdTab;
+}
+
+@Directive({
+  selector: 'md-tab'
+})
+export class MdTab {
+  @ContentChild(MdTabLabel) label: MdTabLabel;
+  @ContentChild(MdTabContent) content: MdTabContent;
+}
+
 /**
  * Material design tab-group component.  Supports basic tab pairs (label + content) and includes
  * animated ink-bar, keyboard navigation, and screen reader.
@@ -24,15 +48,35 @@ let nextId = 0;
 })
 export class MdTabGroup {
   /** @internal */
-  @ContentChildren(MdTabLabel) labels: QueryList<MdTabLabel>;
-
-  /** @internal */
-  @ContentChildren(MdTabContent) contents: QueryList<MdTabContent>;
+  @ContentChildren(MdTab) tabs: QueryList<MdTab>;
 
   @ViewChildren(MdTabLabelWrapper) private _labelWrappers: QueryList<MdTabLabelWrapper>;
   @ViewChildren(MdInkBar) private _inkBar: QueryList<MdInkBar>;
 
-  @Input() selectedIndex: number = 0;
+  private _isInitialized: boolean = false;
+
+  private _selectedIndex: number = 0;
+  @Input()
+  set selectedIndex(value: number) {
+    this._selectedIndex = value;
+
+    if (this._isInitialized) {
+      this._onSelectChange.emit(this._createChangeEvent(value));
+    }
+  }
+  get selectedIndex(): number {
+    return this._selectedIndex;
+  }
+
+  private _onFocusChange: EventEmitter<MdTabChangeEvent> = new EventEmitter<MdTabChangeEvent>();
+  @Output('focusChange') get focusChange(): Observable<MdTabChangeEvent> {
+    return this._onFocusChange.asObservable();
+  }
+
+  private _onSelectChange: EventEmitter<MdTabChangeEvent> = new EventEmitter<MdTabChangeEvent>();
+  @Output('selectChange') get selectChange(): Observable<MdTabChangeEvent> {
+    return this._onSelectChange.asObservable();
+  }
 
   private _focusIndex: number = 0;
   private _groupId: number;
@@ -52,6 +96,7 @@ export class MdTabGroup {
         this._updateInkBar();
       });
     });
+    this._isInitialized = true;
   }
 
   /** Tells the ink-bar to align itself to the current label wrapper */
@@ -77,11 +122,25 @@ export class MdTabGroup {
   /** When the focus index is set, we must manually send focus to the correct label */
   set focusIndex(value: number) {
     this._focusIndex = value;
+
+    if (this._isInitialized) {
+      this._onFocusChange.emit(this._createChangeEvent(value));
+    }
+
     if (this._labelWrappers && this._labelWrappers.length) {
       this._labelWrappers.toArray()[value].focus();
     }
   }
 
+  private _createChangeEvent(index: number): MdTabChangeEvent {
+    const event = new MdTabChangeEvent;
+    event.index = index;
+    if (this.tabs && this.tabs.length) {
+      event.tab = this.tabs.toArray()[index];
+    }
+    return event;
+  }
+
   /**
    * Returns a unique id for each tab label element
    * @internal
@@ -113,4 +172,4 @@ export class MdTabGroup {
   }
 }
 
-export const MD_TABS_DIRECTIVES = [MdTabGroup, MdTabLabel, MdTabContent];
+export const MD_TABS_DIRECTIVES = [MdTabGroup, MdTabLabel, MdTabContent, MdTab];