feat(slider): add thumb-label (#976)

src/components/slider/slider.html

@@ -1,7 +1,8 @@
 <div class="md-slider-wrapper">
   <div class="md-slider-container"
        [class.md-slider-sliding]="isSliding"
-       [class.md-slider-active]="isActive">
+       [class.md-slider-active]="isActive"
+       [class.md-slider-thumb-label-showing]="thumbLabel">
     <div class="md-slider-track-container">
       <div class="md-slider-track"></div>
       <div class="md-slider-track md-slider-track-fill"></div>
@@ -11,6 +12,9 @@
     <div class="md-slider-thumb-container">
       <div class="md-slider-thumb-position">
         <div class="md-slider-thumb"></div>
+        <div class="md-slider-thumb-label">
+          <span class="md-slider-thumb-label-text">{{value}}</span>
+        </div>
       </div>
     </div>
   </div>

src/components/slider/slider.scss

@@ -3,7 +3,7 @@
 
 // This refers to the thickness of the slider. On a horizontal slider this is the height, on a
 // vertical slider this is the width.
-$md-slider-thickness: 20px !default;
+$md-slider-thickness: 48px !default;
 $md-slider-min-size: 128px !default;
 $md-slider-padding: 8px !default;
 
@@ -18,6 +18,16 @@ $md-slider-off-color: rgba(black, 0.26);
 $md-slider-focused-color: rgba(black, 0.38);
 $md-slider-disabled-color: rgba(black, 0.26);
 
+$md-slider-thumb-arrow-height: 16px !default;
+$md-slider-thumb-arrow-width: 28px !default;
+
+$md-slider-thumb-label-size: 28px !default;
+// The thumb has to be moved down so that it appears right over the slider track when visible and
+// on the slider track when not.
+$md-slider-thumb-label-top: ($md-slider-thickness / 2) -
+    ($md-slider-thumb-default-scale * $md-slider-thumb-size / 2) - $md-slider-thumb-label-size -
+    $md-slider-thumb-arrow-height + 10px !default;
+
 /**
  * Uses a container height and an item height to center an item vertically within the container.
  */
@@ -137,6 +147,43 @@ md-slider *::after {
   border-color: md-color($md-accent);
 }
 
+.md-slider-thumb-label {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+
+  position: absolute;
+  left: -($md-slider-thumb-label-size / 2);
+  top: $md-slider-thumb-label-top;
+  width: $md-slider-thumb-label-size;
+  height: $md-slider-thumb-label-size;
+  border-radius: 50%;
+
+  transform: scale(0.4) translate3d(0, (-$md-slider-thumb-label-top + 10) / 0.4, 0) rotate(45deg);
+  transition: 300ms $swift-ease-in-out-timing-function;
+  transition-property: transform, border-radius;
+
+  background-color: md-color($md-accent);
+}
+
+.md-slider-thumb-label-text {
+  z-index: 1;
+  font-size: 12px;
+  font-weight: bold;
+  opacity: 0;
+  transform: rotate(-45deg);
+  transition: opacity 300ms $swift-ease-in-out-timing-function;
+  color: white;
+}
+
+.md-slider-container:not(.md-slider-thumb-label-showing) .md-slider-thumb-label {
+  display: none;
+}
+
+.md-slider-active.md-slider-thumb-label-showing .md-slider-thumb {
+  transform: scale(0);
+}
+
 .md-slider-sliding .md-slider-thumb-position,
 .md-slider-sliding .md-slider-track-fill {
   transition: none;
@@ -147,7 +194,11 @@ md-slider *::after {
   transform: scale($md-slider-thumb-focus-scale);
 }
 
-.md-slider-disabled .md-slider-thumb::after {
-  background-color: $md-slider-disabled-color;
-  border-color: $md-slider-disabled-color;
+.md-slider-active .md-slider-thumb-label {
+  border-radius: 50% 50% 0;
+  transform: rotate(45deg);
+}
+
+.md-slider-active .md-slider-thumb-label-text {
+  opacity: 1;
 }

src/components/slider/slider.spec.ts

@@ -26,7 +26,8 @@ describe('MdSlider', () => {
         SliderWithValue,
         SliderWithStep,
         SliderWithAutoTickInterval,
-        SliderWithSetTickInterval
+        SliderWithSetTickInterval,
+        SliderWithThumbLabel,
       ],
     });
 
@@ -118,7 +119,7 @@ describe('MdSlider', () => {
       // offset relative to the track, subtract the offset on the track fill.
       let thumbPosition = thumbDimensions.left - trackFillDimensions.left;
       // The track fill width should be equal to the thumb's position.
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
     });
 
     it('should update the thumb position on click', () => {
@@ -144,7 +145,7 @@ describe('MdSlider', () => {
       // offset relative to the track, subtract the offset on the track fill.
       let thumbPosition = thumbDimensions.left - trackFillDimensions.left;
       // The track fill width should be equal to the thumb's position.
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
     });
 
     it('should update the thumb position on slide', () => {
@@ -309,7 +310,7 @@ describe('MdSlider', () => {
 
       // The closest snap is halfway on the slider.
       expect(thumbDimensions.left).toBe(sliderDimensions.width * 0.5 + sliderDimensions.left);
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
     });
 
     it('should snap the thumb and fill to the nearest value on slide', () => {
@@ -325,7 +326,7 @@ describe('MdSlider', () => {
 
       // The closest snap is at the halfway point on the slider.
       expect(thumbDimensions.left).toBe(sliderDimensions.left + sliderDimensions.width * 0.5);
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
 
     });
   });
@@ -410,7 +411,7 @@ describe('MdSlider', () => {
 
       // The closest step is at 75% of the slider.
       expect(thumbDimensions.left).toBe(sliderDimensions.width * 0.75 + sliderDimensions.left);
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
     });
 
     it('should set the correct step value on slide', () => {
@@ -433,7 +434,7 @@ describe('MdSlider', () => {
 
       // The closest snap is at the end of the slider.
       expect(thumbDimensions.left).toBe(sliderDimensions.width + sliderDimensions.left);
-      expect(Math.round(trackFillDimensions.width)).toBe(Math.round(thumbPosition));
+      expect(trackFillDimensions.width).toBe(thumbPosition);
     });
   });
 
@@ -516,6 +517,77 @@ describe('MdSlider', () => {
           + 'black 2px, transparent 2px, transparent)');
     });
   });
+
+  describe('slider with thumb label', () => {
+    let fixture: ComponentFixture<SliderWithThumbLabel>;
+    let sliderDebugElement: DebugElement;
+    let sliderNativeElement: HTMLElement;
+    let sliderInstance: MdSlider;
+    let sliderTrackElement: HTMLElement;
+    let sliderContainerElement: Element;
+    let thumbLabelTextElement: Element;
+
+    beforeEach(async(() => {
+      builder.createAsync(SliderWithThumbLabel).then(f => {
+        fixture = f;
+        fixture.detectChanges();
+
+        sliderDebugElement = fixture.debugElement.query(By.directive(MdSlider));
+        sliderNativeElement = sliderDebugElement.nativeElement;
+        sliderInstance = sliderDebugElement.componentInstance;
+        sliderTrackElement = <HTMLElement>sliderNativeElement.querySelector('.md-slider-track');
+        sliderContainerElement = sliderNativeElement.querySelector('.md-slider-container');
+        thumbLabelTextElement = sliderNativeElement.querySelector('.md-slider-thumb-label-text');
+      });
+    }));
+
+    it('should add the thumb label class to the slider container', () => {
+      expect(sliderContainerElement.classList).toContain('md-slider-thumb-label-showing');
+    });
+
+    it('should update the thumb label text on click', () => {
+      expect(thumbLabelTextElement.textContent).toBe('0');
+
+      dispatchClickEvent(sliderTrackElement, 0.13);
+      fixture.detectChanges();
+
+      // The thumb label text is set to the slider's value. These should always be the same.
+      expect(thumbLabelTextElement.textContent).toBe('13');
+    });
+
+    it('should update the thumb label text on slide', () => {
+      expect(thumbLabelTextElement.textContent).toBe('0');
+
+      dispatchSlideEvent(sliderTrackElement, sliderNativeElement, 0, 0.56, gestureConfig);
+      fixture.detectChanges();
+
+      // The thumb label text is set to the slider's value. These should always be the same.
+      expect(thumbLabelTextElement.textContent).toBe(`${sliderInstance.value}`);
+    });
+
+    it('should show the thumb label on click', () => {
+      expect(sliderContainerElement.classList).not.toContain('md-slider-active');
+      expect(sliderContainerElement.classList).toContain('md-slider-thumb-label-showing');
+
+      dispatchClickEvent(sliderNativeElement, 0.49);
+      fixture.detectChanges();
+
+      // The thumb label appears when the slider is active and the 'md-slider-thumb-label-showing'
+      // class is applied.
+      expect(sliderContainerElement.classList).toContain('md-slider-thumb-label-showing');
+      expect(sliderContainerElement.classList).toContain('md-slider-active');
+    });
+
+    it('should show the thumb label on slide', () => {
+      expect(sliderContainerElement.classList).not.toContain('md-slider-active');
+
+      dispatchSlideEvent(sliderTrackElement, sliderNativeElement, 0, 0.91, gestureConfig);
+      fixture.detectChanges();
+
+      expect(sliderContainerElement.classList).toContain('md-slider-thumb-label-showing');
+      expect(sliderContainerElement.classList).toContain('md-slider-active');
+    });
+  });
 });
 
 // The transition has to be removed in order to test the updated positions without setTimeout.
@@ -572,6 +644,17 @@ class SliderWithAutoTickInterval { }
 })
 class SliderWithSetTickInterval { }
 
+@Component({
+  template: `<md-slider thumb-label></md-slider>`,
+  styles: [`
+    .md-slider-thumb-label, .md-slider-thumb-label-text {
+        transition: none !important;
+    }
+  `],
+  encapsulation: ViewEncapsulation.None
+})
+class SliderWithThumbLabel { }
+
 /**
  * Dispatches a click event from an element.
  * Note: The mouse event truncates the position for the click.

src/components/slider/slider.ts

@@ -47,6 +47,11 @@ export class MdSlider implements AfterContentInit {
   @HostBinding('attr.aria-disabled')
   disabled: boolean = false;
 
+  /** Whether or not to show the thumb label. */
+  @Input('thumb-label')
+  @BooleanFieldValue()
+  thumbLabel: boolean = false;
+
   /** The miniumum value that the slider can have. */
   private _min: number = 0;
 
@@ -341,7 +346,7 @@ export class SliderRenderer {
         <HTMLElement>this._sliderElement.querySelector('.md-slider-thumb-position');
     let fillTrackElement = <HTMLElement>this._sliderElement.querySelector('.md-slider-track-fill');
 
-    let position = percent * width;
+    let position = Math.round(percent * width);
 
     fillTrackElement.style.width = `${position}px`;
     applyCssTransform(thumbPositionElement, `translateX(${position}px)`);

src/demo-app/slider/slider-demo.html

@@ -30,3 +30,6 @@ <h1>Slider with step defined</h1>
 <h1>Slider with set tick interval</h1>
 <md-slider tick-interval="auto"></md-slider>
 <md-slider tick-interval="9"></md-slider>
+
+<h1>Slider with Thumb Label</h1>
+<md-slider thumb-label></md-slider>