feat(radio): support theme color on mat-radio-group

Adds support for setting the color of the entire `mat-radio-group`, rather than having to set it on each button individually.

Fixes #15701.

Author: crisbeto

src/dev-app/radio/radio-demo.html

@@ -13,6 +13,16 @@ <h1>Color Example</h1>
   <mat-radio-button name="group2" color="warn">Warn</mat-radio-button>
 </section>
 
+<h1>Group Color Example</h1>
+<section class="demo-section">
+  <mat-radio-group color="warn">
+    <mat-radio-button name="group3" value="1">Option 1</mat-radio-button>
+    <mat-radio-button name="group3" value="2">Option 2</mat-radio-button>
+    <mat-radio-button name="group3" value="3">Option 3</mat-radio-button>
+    <mat-radio-button name="group3" value="4" color="primary">Option with color override</mat-radio-button>
+  </mat-radio-group>
+</section>
+
 <h1>Dynamic Example</h1>
 <section class="demo-section">
   <div>

src/material/radio/radio.spec.ts

@@ -365,6 +365,25 @@ describe('MatRadio', () => {
       expect(radioNativeElements.every(radioEl => radioEl.classList.contains('mat-accent')))
         .toBe(true, 'Expected every radio element to fallback to accent color if value is falsy.');
     });
+
+    it('should be able to inherit the color from the radio group', () => {
+      groupInstance.color = 'warn';
+      fixture.detectChanges();
+
+      expect(radioNativeElements.every(radioEl => radioEl.classList.contains('mat-warn')))
+        .toBe(true, 'Expected every radio element to have the warn color.');
+    });
+
+    it('should have the individual button color take precedence over the group color', () => {
+      radioInstances[1].color = 'primary';
+      groupInstance.color = 'warn';
+      fixture.detectChanges();
+
+      expect(radioNativeElements[0].classList).toContain('mat-warn');
+      expect(radioNativeElements[1].classList).toContain('mat-primary');
+      expect(radioNativeElements[2].classList).toContain('mat-warn');
+    });
+
   });
 
   describe('group with ngModel', () => {
@@ -702,6 +721,10 @@ describe('MatRadio', () => {
       expect(radio.hasAttribute('name')).toBe(false);
     });
 
+    it('should default the radio color to `accent`', () => {
+      expect(seasonRadioInstances.every(radio => radio.color === 'accent')).toBe(true);
+    });
+
   });
 
   describe('with tabindex', () => {

src/material/radio/radio.ts

@@ -32,15 +32,13 @@ import {
 } from '@angular/core';
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {
-  CanColor,
-  CanColorCtor,
   CanDisableRipple,
   CanDisableRippleCtor,
   HasTabIndex,
   HasTabIndexCtor,
-  mixinColor,
   mixinDisableRipple,
   mixinTabIndex,
+  ThemePalette,
 } from '@angular/material/core';
 import {ANIMATION_MODULE_TYPE} from '@angular/platform-browser/animations';
 
@@ -122,6 +120,9 @@ export class MatRadioGroup implements AfterContentInit, ControlValueAccessor {
   @ContentChildren(forwardRef(() => MatRadioButton), { descendants: true })
   _radios: QueryList<MatRadioButton>;
 
+  /** Theme color for all of the radio buttons in the group. */
+  @Input() color: ThemePalette;
+
   /** Name of the radio button group. All radio buttons inside this group will use this name. */
   @Input()
   get name(): string { return this._name; }
@@ -302,9 +303,9 @@ class MatRadioButtonBase {
 }
 // As per Material design specifications the selection control radio should use the accent color
 // palette by default. https://material.io/guidelines/components/selection-controls.html
-const _MatRadioButtonMixinBase: CanColorCtor & CanDisableRippleCtor & HasTabIndexCtor &
-    typeof MatRadioButtonBase =
-        mixinColor(mixinDisableRipple(mixinTabIndex(MatRadioButtonBase)), 'accent');
+const _MatRadioButtonMixinBase:
+    CanDisableRippleCtor & HasTabIndexCtor & typeof MatRadioButtonBase =
+        mixinDisableRipple(mixinTabIndex(MatRadioButtonBase));
 
 /**
  * A Material design radio-button. Typically placed inside of `<mat-radio-group>` elements.
@@ -314,14 +315,17 @@ const _MatRadioButtonMixinBase: CanColorCtor & CanDisableRippleCtor & HasTabInde
   selector: 'mat-radio-button',
   templateUrl: 'radio.html',
   styleUrls: ['radio.css'],
-  inputs: ['color', 'disableRipple', 'tabIndex'],
+  inputs: ['disableRipple', 'tabIndex'],
   encapsulation: ViewEncapsulation.None,
   exportAs: 'matRadioButton',
   host: {
     'class': 'mat-radio-button',
     '[class.mat-radio-checked]': 'checked',
     '[class.mat-radio-disabled]': 'disabled',
     '[class._mat-animation-noopable]': '_animationMode === "NoopAnimations"',
+    '[class.mat-primary]': 'color === "primary"',
+    '[class.mat-accent]': 'color === "accent"',
+    '[class.mat-warn]': 'color === "warn"',
     // Needs to be -1 so the `focus` event still fires.
     '[attr.tabindex]': '-1',
     '[attr.id]': 'id',
@@ -333,7 +337,7 @@ const _MatRadioButtonMixinBase: CanColorCtor & CanDisableRippleCtor & HasTabInde
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class MatRadioButton extends _MatRadioButtonMixinBase
-    implements OnInit, AfterViewInit, OnDestroy, CanColor, CanDisableRipple, HasTabIndex {
+    implements OnInit, AfterViewInit, OnDestroy, CanDisableRipple, HasTabIndex {
 
   private _uniqueId: string = `mat-radio-${++nextUniqueId}`;
 
@@ -426,6 +430,14 @@ export class MatRadioButton extends _MatRadioButtonMixinBase
     this._required = coerceBooleanProperty(value);
   }
 
+  /** Theme color of the radio button. */
+  @Input()
+  get color(): ThemePalette {
+    return this._color || (this.radioGroup && this.radioGroup.color) || 'accent';
+  }
+  set color(newValue: ThemePalette) { this._color = newValue; }
+  private _color: ThemePalette;
+
   /**
    * Event emitted when the checked state of this radio button changes.
    * Change events are only emitted when the value changes due to user interaction with

tools/public_api_guard/material/radio.d.ts

@@ -1,13 +1,14 @@
 export declare const MAT_RADIO_GROUP_CONTROL_VALUE_ACCESSOR: any;
 
-export declare class MatRadioButton extends _MatRadioButtonMixinBase implements OnInit, AfterViewInit, OnDestroy, CanColor, CanDisableRipple, HasTabIndex {
+export declare class MatRadioButton extends _MatRadioButtonMixinBase implements OnInit, AfterViewInit, OnDestroy, CanDisableRipple, HasTabIndex {
     _animationMode?: string | undefined;
     _inputElement: ElementRef<HTMLInputElement>;
     ariaDescribedby: string;
     ariaLabel: string;
     ariaLabelledby: string;
     readonly change: EventEmitter<MatRadioChange>;
     checked: boolean;
+    color: ThemePalette;
     disabled: boolean;
     id: string;
     readonly inputId: string;
@@ -39,6 +40,7 @@ export declare class MatRadioGroup implements AfterContentInit, ControlValueAcce
     _controlValueAccessorChangeFn: (value: any) => void;
     _radios: QueryList<MatRadioButton>;
     readonly change: EventEmitter<MatRadioChange>;
+    color: ThemePalette;
     disabled: boolean;
     labelPosition: 'before' | 'after';
     name: string;