feat(chips): Add left/right arrow functionality. (#2332)

In order to maintain consistentcy with the md1 chips, add the ability
to use the left/right arrow keys to navigate chips.

References #120.

src/demo-app/chips/chips-demo.scss

@@ -17,7 +17,7 @@
     }
   }
 
-  md-basic-chip {
+  .md-basic-chip {
     margin: auto 10px;
   }
 }

src/lib/chips/_chips-theme.scss

@@ -22,12 +22,12 @@
   $selected-background: if($is-dark-theme, md-color($background, app-bar), #808080);
   $selected-foreground: if($is-dark-theme, md-color($foreground, text), $light-selected-foreground);
 
-  .md-chip {
+  .md-chip:not(.md-basic-chip) {
     background-color: $unselected-background;
     color: $unselected-foreground;
   }
 
-  .md-chip.md-chip-selected {
+  .md-chip.md-chip-selected:not(.md-basic-chip) {
     background-color: $selected-background;
     color: $selected-foreground;
 

src/lib/chips/chip-list.spec.ts

@@ -4,7 +4,15 @@ import {By} from '@angular/platform-browser';
 import {MdChip, MdChipList, MdChipsModule} from './index';
 import {ListKeyManager} from '../core/a11y/list-key-manager';
 import {FakeEvent} from '../core/a11y/list-key-manager.spec';
-import {SPACE} from '../core/keyboard/keycodes';
+import {SPACE, LEFT_ARROW, RIGHT_ARROW} from '../core/keyboard/keycodes';
+
+class FakeKeyboardEvent extends FakeEvent {
+  constructor(keyCode: number, protected target: HTMLElement) {
+    super(keyCode);
+
+    this.target = target;
+  }
+}
 
 describe('MdChipList', () => {
   let fixture: ComponentFixture<any>;
@@ -101,6 +109,50 @@ describe('MdChipList', () => {
   });
 
   describe('keyboard behavior', () => {
+    beforeEach(() => {
+      manager = chipListInstance._keyManager;
+    });
+
+    it('left arrow focuses previous item', () => {
+      let nativeChips = chipListNativeElement.querySelectorAll('md-chip');
+      let lastNativeChip = nativeChips[nativeChips.length - 1] as HTMLElement;
+
+      let LEFT_EVENT = new FakeKeyboardEvent(LEFT_ARROW, lastNativeChip) as any;
+      let array = chips.toArray();
+      let lastIndex = array.length - 1;
+      let lastItem = array[lastIndex];
+
+      // Focus the last item in the array
+      lastItem.focus();
+      expect(manager.focusedItemIndex).toEqual(lastIndex);
+
+      // Press the LEFT arrow
+      chipListInstance._keydown(LEFT_EVENT);
+      fixture.detectChanges();
+
+      // It focuses the next-to-last item
+      expect(manager.focusedItemIndex).toEqual(lastIndex - 1);
+    });
+
+    it('right arrow focuses next item', () => {
+      let nativeChips = chipListNativeElement.querySelectorAll('md-chip');
+      let firstNativeChip = nativeChips[0] as HTMLElement;
+
+      let RIGHT_EVENT: KeyboardEvent = new FakeKeyboardEvent(RIGHT_ARROW, firstNativeChip) as any;
+      let array = chips.toArray();
+      let firstItem = array[0];
+
+      // Focus the last item in the array
+      firstItem.focus();
+      expect(manager.focusedItemIndex).toEqual(0);
+
+      // Press the RIGHT arrow
+      chipListInstance._keydown(RIGHT_EVENT);
+      fixture.detectChanges();
+
+      // It focuses the next-to-last item
+      expect(manager.focusedItemIndex).toEqual(1);
+    });
 
     describe('when selectable is true', () => {
       beforeEach(() => {
@@ -109,7 +161,10 @@ describe('MdChipList', () => {
       });
 
       it('SPACE selects/deselects the currently focused chip', () => {
-        let SPACE_EVENT: KeyboardEvent = new FakeEvent(SPACE) as KeyboardEvent;
+        let nativeChips = chipListNativeElement.querySelectorAll('md-chip');
+        let firstNativeChip = nativeChips[0] as HTMLElement;
+
+        let SPACE_EVENT: KeyboardEvent = new FakeKeyboardEvent(SPACE, firstNativeChip) as any;
         let firstChip: MdChip = chips.toArray()[0];
 
         spyOn(testComponent, 'chipSelect');
@@ -181,6 +236,9 @@ class StaticChipList {
   selectable: boolean = true;
   remove: Number;
 
-  chipSelect(index: Number) {}
-  chipDeselect(index: Number) {}
+  chipSelect(index: Number) {
+  }
+
+  chipDeselect(index: Number) {
+  }
 }

src/lib/chips/chip-list.ts

@@ -14,7 +14,7 @@ import {
 import {MdChip} from './chip';
 import {ListKeyManager} from '../core/a11y/list-key-manager';
 import {coerceBooleanProperty} from '../core/coercion/boolean-property';
-import {SPACE} from '../core/keyboard/keycodes';
+import {SPACE, LEFT_ARROW, RIGHT_ARROW} from '../core/keyboard/keycodes';
 
 /**
  * A material design chips component (named ChipList for it's similarity to the List component).
@@ -98,18 +98,31 @@ export class MdChipList implements AfterContentInit {
 
   /** Passes relevant key presses to our key manager. */
   _keydown(event: KeyboardEvent) {
-    switch (event.keyCode) {
-      case SPACE:
-        // If we are selectable, toggle the focused chip
-        if (this.selectable) {
-          this._toggleSelectOnFocusedChip();
-        }
-
-        // Always prevent space from scrolling the page since the list has focus
-        event.preventDefault();
-        break;
-      default:
-        this._keyManager.onKeydown(event);
+    let target = event.target as HTMLElement;
+
+    // If they are on a chip, check for space/left/right, otherwise pass to our key manager
+    if (target && target.classList.contains('md-chip')) {
+      switch (event.keyCode) {
+        case SPACE:
+          // If we are selectable, toggle the focused chip
+          if (this.selectable) {
+            this._toggleSelectOnFocusedChip();
+          }
+
+          // Always prevent space from scrolling the page since the list has focus
+          event.preventDefault();
+          break;
+        case LEFT_ARROW:
+          this._keyManager.focusPreviousItem();
+          event.preventDefault();
+          break;
+        case RIGHT_ARROW:
+          this._keyManager.focusNextItem();
+          event.preventDefault();
+          break;
+        default:
+          this._keyManager.onKeydown(event);
+      }
     }
   }
 

src/lib/chips/chip.spec.ts

@@ -38,8 +38,9 @@ describe('Chips', () => {
       document.body.removeChild(chipNativeElement);
     });
 
-    it('does not add the `md-chip` class', () => {
-      expect(chipNativeElement.classList).not.toContain('md-chip');
+    it('adds the `md-basic-chip` class', () => {
+      expect(chipNativeElement.classList).toContain('md-chip');
+      expect(chipNativeElement.classList).toContain('md-basic-chip');
     });
   });
 
@@ -69,6 +70,10 @@ describe('Chips', () => {
         expect(chipNativeElement.classList).toContain('md-chip');
       });
 
+      it('does not add the `md-basic-chip` class', () => {
+        expect(chipNativeElement.classList).not.toContain('md-basic-chip');
+      });
+
       it('emits focus on click', () => {
         spyOn(chipInstance, 'focus').and.callThrough();
 

src/lib/chips/chip.ts

@@ -136,8 +136,12 @@ export class MdChip implements Focusable, OnInit, OnDestroy {
   private _addDefaultCSSClass() {
     let el: HTMLElement = this._elementRef.nativeElement;
 
-    if (el.nodeName.toLowerCase() == 'md-chip' || el.hasAttribute('md-chip')) {
-      el.classList.add('md-chip');
+    // Always add the `md-chip` class
+    el.classList.add('md-chip');
+
+    // If we are a basic chip, also add the `md-basic-chip` class for :not() targeting
+    if (el.nodeName.toLowerCase() == 'md-basic-chip' || el.hasAttribute('md-basic-chip')) {
+      el.classList.add('md-basic-chip');
     }
   }
 

src/lib/chips/chips.scss

@@ -15,7 +15,7 @@ $md-chips-chip-margin: $md-chip-horizontal-padding / 4;
   /*
    * Only apply the margins to chips
    */
-  .md-chip {
+  .md-chip:not(.md-basic-chip) {
     margin: 0 $md-chips-chip-margin 0 $md-chips-chip-margin;
 
     // Remove the margin from the first element (in both LTR and RTL)
@@ -50,7 +50,7 @@ $md-chips-chip-margin: $md-chip-horizontal-padding / 4;
   }
 }
 
-.md-chip {
+.md-chip:not(.md-basic-chip) {
   display: inline-block;
   padding: $md-chip-vertical-padding $md-chip-horizontal-padding
     $md-chip-vertical-padding $md-chip-horizontal-padding;
@@ -63,7 +63,7 @@ $md-chips-chip-margin: $md-chip-horizontal-padding / 4;
 .md-chip-list-stacked .md-chip-list-wrapper {
   display: block;
 
-  .md-chip {
+  .md-chip:not(.md-basic-chip) {
     display: block;
     margin: 0;
     margin-bottom: $md-chip-vertical-padding;