fix(tabs): re-align ink bar on direction change

Re-aligns the ink bar if the user's layout direction changed.

Fixes #3615.

Author: crisbeto

src/lib/tabs/tab-header.spec.ts

@@ -11,10 +11,12 @@ import {RIGHT_ARROW, LEFT_ARROW, ENTER} from '../core/keyboard/keycodes';
 import {FakeViewportRuler} from '../core/overlay/position/fake-viewport-ruler';
 import {ViewportRuler} from '../core/overlay/position/viewport-ruler';
 import {dispatchKeyboardEvent} from '../core/testing/dispatch-events';
+import {Subject} from 'rxjs/Subject';
 
 
 describe('MdTabHeader', () => {
   let dir: LayoutDirection = 'ltr';
+  let dirChange = new Subject();
   let fixture: ComponentFixture<SimpleTabHeaderApp>;
   let appComponent: SimpleTabHeaderApp;
 
@@ -29,7 +31,9 @@ describe('MdTabHeader', () => {
         SimpleTabHeaderApp,
       ],
       providers: [
-        {provide: Dir, useFactory: () => { return {value: dir}; }},
+        {provide: Dir, useFactory: () => {
+          return {value: dir,  dirChange: dirChange.asObservable()};
+        }},
         {provide: ViewportRuler, useClass: FakeViewportRuler},
       ]
     });
@@ -211,7 +215,7 @@ interface Tab {
            *ngFor="let tab of tabs; let i = index"
            [disabled]="!!tab.disabled"
            (click)="selectedIndex = i">
-         {{tab.label}}  
+         {{tab.label}}
       </div>
     </md-tab-header>
   </div>

src/lib/tabs/tab-header.ts

@@ -12,12 +12,14 @@ import {
   Optional,
   AfterContentChecked,
   AfterContentInit,
+  OnDestroy,
 } from '@angular/core';
 import {RIGHT_ARROW, LEFT_ARROW, ENTER, Dir, LayoutDirection} from '../core';
 import {MdTabLabelWrapper} from './tab-label-wrapper';
 import {MdInkBar} from './ink-bar';
-import 'rxjs/add/operator/map';
+import {Subscription} from 'rxjs/Subscription';
 import {applyCssTransform} from '../core/style/apply-transform';
+import 'rxjs/add/operator/map';
 
 /**
  * The directions that scrolling can go in when the header's tabs exceed the header width. 'After'
@@ -51,7 +53,7 @@ const EXAGGERATED_OVERSCROLL = 60;
     '[class.mat-tab-header-rtl]': "_getLayoutDirection() == 'rtl'",
   }
 })
-export class MdTabHeader implements AfterContentChecked, AfterContentInit {
+export class MdTabHeader implements AfterContentChecked, AfterContentInit, OnDestroy {
   @ContentChildren(MdTabLabelWrapper) _labelWrappers: QueryList<MdTabLabelWrapper>;
 
   @ViewChild(MdInkBar) _inkBar: MdInkBar;
@@ -67,6 +69,9 @@ export class MdTabHeader implements AfterContentChecked, AfterContentInit {
   /** Whether the header should scroll to the selected index after the view has been checked. */
   private _selectedIndexChanged = false;
 
+  /** Subscription to changes in the layout direction. */
+  private _directionChange: Subscription;
+
   /** Whether the controls for pagination should be displayed */
   _showPaginationControls = false;
 
@@ -149,6 +154,17 @@ export class MdTabHeader implements AfterContentChecked, AfterContentInit {
    */
   ngAfterContentInit() {
     this._alignInkBarToSelectedTab();
+
+    if (this._dir) {
+      this._directionChange = this._dir.dirChange.subscribe(() => this._alignInkBarToSelectedTab());
+    }
+  }
+
+  ngOnDestroy() {
+    if (this._directionChange) {
+      this._directionChange.unsubscribe();
+      this._directionChange = null;
+    }
   }
 
   /**

src/lib/tabs/tab-nav-bar/tab-nav-bar.ts

@@ -4,12 +4,17 @@ import {
   ViewChild,
   ElementRef,
   ViewEncapsulation,
-  Directive, NgZone, Inject, Optional,
+  Directive,
+  NgZone,
+  Inject,
+  Optional,
+  OnDestroy,
 } from '@angular/core';
 import {MdInkBar} from '../ink-bar';
 import {MdRipple} from '../../core/ripple/index';
 import {ViewportRuler} from '../../core/overlay/position/viewport-ruler';
-import {MD_RIPPLE_GLOBAL_OPTIONS, RippleGlobalOptions} from '../../core/ripple/ripple';
+import {MD_RIPPLE_GLOBAL_OPTIONS, RippleGlobalOptions, Dir} from '../../core';
+import {Subscription} from 'rxjs/Subscription';
 
 /**
  * Navigation component matching the styles of the tab group header.
@@ -25,12 +30,19 @@ import {MD_RIPPLE_GLOBAL_OPTIONS, RippleGlobalOptions} from '../../core/ripple/r
   },
   encapsulation: ViewEncapsulation.None,
 })
-export class MdTabNavBar {
+export class MdTabNavBar implements OnDestroy {
+  private _directionChange: Subscription;
   _activeLinkChanged: boolean;
   _activeLinkElement: ElementRef;
 
   @ViewChild(MdInkBar) _inkBar: MdInkBar;
 
+  constructor(@Optional() private _dir: Dir, private _ngZone: NgZone) {
+    if (_dir) {
+      this._directionChange = _dir.dirChange.subscribe(() => this._alignInkBar());
+    }
+  }
+
   /** Notifies the component that the active link has been changed. */
   updateActiveLink(element: ElementRef) {
     this._activeLinkChanged = this._activeLinkElement != element;
@@ -40,10 +52,26 @@ export class MdTabNavBar {
   /** Checks if the active link has been changed and, if so, will update the ink bar. */
   ngAfterContentChecked(): void {
     if (this._activeLinkChanged) {
-      this._inkBar.alignToElement(this._activeLinkElement.nativeElement);
+      this._alignInkBar();
       this._activeLinkChanged = false;
     }
   }
+
+  ngOnDestroy() {
+    if (this._directionChange) {
+      this._directionChange.unsubscribe();
+      this._directionChange = null;
+    }
+  }
+
+  /** Aligns the ink bar to the active link. */
+  private _alignInkBar(): void {
+    this._ngZone.runOutsideAngular(() => {
+      requestAnimationFrame(() => {
+        this._inkBar.alignToElement(this._activeLinkElement.nativeElement);
+      });
+    });
+  }
 }
 
 /**