feat(datepicker): allow for mat-datepicker-toggle icon to be customized

Allows for the consumer to set a different icon for the `mat-datepicker-icon` via the `matDatepickerToggleIcon` directive. The reasoning for the change is that not all consumers might be using the Material icons or they may want to set something different (e.g. a chevron).

Author: crisbeto

src/lib/datepicker/datepicker-module.ts

@@ -22,7 +22,7 @@ import {
 } from './datepicker';
 import {MatDatepickerInput} from './datepicker-input';
 import {MatDatepickerIntl} from './datepicker-intl';
-import {MatDatepickerToggle} from './datepicker-toggle';
+import {MatDatepickerToggle, MatDatepickerToggleIcon} from './datepicker-toggle';
 import {MatMonthView} from './month-view';
 import {MatMultiYearView} from './multi-year-view';
 import {MatYearView} from './year-view';
@@ -44,6 +44,7 @@ import {MatYearView} from './year-view';
     MatDatepickerContent,
     MatDatepickerInput,
     MatDatepickerToggle,
+    MatDatepickerToggleIcon,
     MatMonthView,
     MatYearView,
     MatMultiYearView,
@@ -55,6 +56,7 @@ import {MatYearView} from './year-view';
     MatDatepickerContent,
     MatDatepickerInput,
     MatDatepickerToggle,
+    MatDatepickerToggleIcon,
     MatMonthView,
     MatYearView,
     MatMultiYearView,

src/lib/datepicker/datepicker-toggle.html

@@ -1,10 +1,12 @@
 <button mat-icon-button type="button" [attr.aria-label]="_intl.openCalendarLabel"
         [disabled]="disabled" (click)="_open($event)">
-  <mat-icon>
+  <mat-icon *ngIf="!_customIcon">
     <svg viewBox="0 0 24 24" width="100%" height="100%" fill="currentColor"
         style="vertical-align: top" focusable="false">
       <path d="M0 0h24v24H0z" fill="none"/>
       <path d="M19 3h-1V1h-2v2H8V1H6v2H5c-1.11 0-1.99.9-1.99 2L3 19c0 1.1.89 2 2 2h14c1.1 0 2-.9 2-2V5c0-1.1-.9-2-2-2zm0 16H5V8h14v11zM7 10h5v5H7z"/>
     </svg>
   </mat-icon>
+
+  <ng-content select="[matDatepickerToggleIcon]"></ng-content>
 </button>

src/lib/datepicker/datepicker-toggle.ts

@@ -17,6 +17,8 @@ import {
   OnDestroy,
   SimpleChanges,
   ViewEncapsulation,
+  Directive,
+  ContentChild,
 } from '@angular/core';
 import {merge} from 'rxjs/observable/merge';
 import {of as observableOf} from 'rxjs/observable/of';
@@ -25,6 +27,13 @@ import {MatDatepicker} from './datepicker';
 import {MatDatepickerIntl} from './datepicker-intl';
 
 
+/** Can be used to override the icon of a `matDatepickerToggle`. */
+@Directive({
+  selector: '[matDatepickerToggleIcon]'
+})
+export class MatDatepickerToggleIcon {}
+
+
 @Component({
   moduleId: module.id,
   selector: 'mat-datepicker-toggle',
@@ -53,6 +62,9 @@ export class MatDatepickerToggle<D> implements AfterContentInit, OnChanges, OnDe
   }
   private _disabled: boolean;
 
+  /** Custom icon set by the consumer. */
+  @ContentChild(MatDatepickerToggleIcon) _customIcon: MatDatepickerToggleIcon;
+
   constructor(public _intl: MatDatepickerIntl, private _changeDetectorRef: ChangeDetectorRef) {}
 
   ngOnChanges(changes: SimpleChanges) {

src/lib/datepicker/datepicker.md

@@ -32,6 +32,17 @@ can easily be used as a prefix or suffix on the material input:
 </mat-form-field>
 ```
 
+If you want to customize the icon that is rendered inside the `mat-datepicker-toggle`, you can do so
+by using the `matDatepickerToggleIcon` directive:
+
+```html
+<input [matDatepicker]="myDatepicker">
+<mat-datepicker-toggle [for]="myDatepicker">
+  <img matDatepickerToggleIcon src="my-custom-icon.png">
+</mat-datepicker-toggle>
+<mat-datepicker #myDatepicker></mat-datepicker>
+```
+
 ### Setting the calendar starting view
 
 The `startView` property of `<mat-datepicker>` can be used to set the view that will show up when
@@ -99,7 +110,7 @@ Each validation property has a different error that can be checked:
  * A value that violates the `min` property will have a `matDatepickerMin` error.
  * A value that violates the `max` property will have a `matDatepickerMax` error.
  * A value that violates the `matDatepickerFilter` property will have a `matDatepickerFilter` error.
- 
+
 ### Input and change events
 
 The input's native `(input)` and `(change)` events will only trigger due to user interaction with
@@ -171,7 +182,7 @@ It's also possible to set the locale at runtime using the `setLocale` method of
 The datepicker was built to be date implementation agnostic. This means that it can be made to work
 with a variety of different date implementations. However it also means that developers need to make
 sure to provide the appropriate pieces for the datepicker to work with their chosen implementation.
-The easiest way to ensure this is just to import one of the pre-made modules: 
+The easiest way to ensure this is just to import one of the pre-made modules:
 
 |Module               |Date type|Supported locales                                                      |Dependencies                      |Import from                       |
 |---------------------|---------|-----------------------------------------------------------------------|----------------------------------|----------------------------------|
@@ -338,7 +349,7 @@ In multi-year view:
 
 This error is thrown if you have not provided all of the injectables the datepicker needs to work.
 The easiest way to resolve this is to import the `MatNativeDateModule` or `MatMomentDateModule` in
-your application's root module. See 
+your application's root module. See
 [_Choosing a date implementation_](#choosing-a-date-implementation-and-date-format-settings)) for
 more information.
 

src/lib/datepicker/datepicker.spec.ts

@@ -49,7 +49,7 @@ describe('MatDatepicker', () => {
   }
 
   afterEach(inject([OverlayContainer], (container: OverlayContainer) => {
-    container.getContainerElement().parentNode!.removeChild(container.getContainerElement());
+    container.ngOnDestroy();
   }));
 
   describe('with MatNativeDateModule', () => {
@@ -742,6 +742,19 @@ describe('MatDatepicker', () => {
         }));
     });
 
+    describe('datepicker with custom mat-datepicker-toggle icon', () => {
+      it('should be able to override the mat-datepicker-toggle icon', fakeAsync(() => {
+        const fixture = createComponent(DatepickerWithCustomIcon, [MatNativeDateModule]);
+        fixture.detectChanges();
+
+        expect(fixture.nativeElement.querySelector('.mat-datepicker-toggle .custom-icon'))
+            .toBeTruthy('Expected custom icon to be rendered.');
+
+        expect(fixture.nativeElement.querySelector('.mat-datepicker-toggle mat-icon'))
+            .toBeFalsy('Expected default icon to be removed.');
+      }));
+    });
+
     describe('datepicker inside mat-form-field', () => {
       let fixture: ComponentFixture<FormFieldDatepicker>;
       let testComponent: FormFieldDatepicker;
@@ -1289,6 +1302,16 @@ class DatepickerWithToggle {
   touchUI = true;
 }
 
+@Component({
+  template: `
+    <input [matDatepicker]="d">
+    <mat-datepicker-toggle [for]="d">
+      <div class="custom-icon" matDatepickerToggleIcon></div>
+    </mat-datepicker-toggle>
+    <mat-datepicker #d></mat-datepicker>
+  `,
+})
+class DatepickerWithCustomIcon {}
 
 @Component({
   template: `