feat(datepicker): add animation to calendar popup

Adds an animation when opening and closing the datepicker's calendar.

Author: crisbeto

src/lib/datepicker/datepicker-content.html

@@ -7,6 +7,7 @@
     [maxDate]="datepicker._maxDate"
     [dateFilter]="datepicker._dateFilter"
     [selected]="datepicker._selected"
+    [@fadeInCalendar]="'enter'"
     (selectedChange)="datepicker._select($event)"
     (_userSelection)="datepicker.close()">
 </mat-calendar>

src/lib/datepicker/datepicker-content.scss

@@ -28,6 +28,11 @@ $mat-datepicker-touch-max-height: 788px;
   @include mat-elevation(8);
 
   display: block;
+  transform-origin: top center;
+}
+
+.mat-datepicker-content-above {
+  transform-origin: bottom center;
 }
 
 .mat-calendar {

src/lib/datepicker/datepicker.spec.ts

@@ -7,7 +7,7 @@ import {
   dispatchMouseEvent,
 } from '@angular/cdk/testing';
 import {Component, ViewChild} from '@angular/core';
-import {async, ComponentFixture, inject, TestBed} from '@angular/core/testing';
+import {async, ComponentFixture, inject, TestBed, fakeAsync, flush} from '@angular/core/testing';
 import {FormControl, FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {
   DEC,
@@ -156,7 +156,7 @@ describe('MatDatepicker', () => {
         });
       });
 
-      it('should close the popup when pressing ESCAPE', () => {
+      it('should close the popup when pressing ESCAPE', fakeAsync(() => {
         testComponent.datepicker.open();
         fixture.detectChanges();
 
@@ -168,14 +168,15 @@ describe('MatDatepicker', () => {
 
         dispatchEvent(content, keyboardEvent);
         fixture.detectChanges();
+        flush();
 
         content = document.querySelector('.cdk-overlay-pane mat-datepicker-content')!;
 
         expect(content).toBeFalsy('Expected datepicker to be closed.');
         expect(stopPropagationSpy).toHaveBeenCalled();
         expect(keyboardEvent.defaultPrevented)
             .toBe(true, 'Expected default ESCAPE action to be prevented.');
-      });
+      }));
 
       it('close should close dialog', () => {
         testComponent.touch = true;
@@ -1090,6 +1091,54 @@ describe('MatDatepicker', () => {
       });
     });
   });
+
+  describe('popup animations', () => {
+    let fixture: ComponentFixture<StandardDatepicker>;
+    let testComponent: StandardDatepicker;
+
+    beforeEach(fakeAsync(() => {
+      TestBed.configureTestingModule({
+        imports: [MatDatepickerModule, MatNativeDateModule, NoopAnimationsModule],
+        declarations: [StandardDatepicker],
+      }).compileComponents();
+
+      fixture = TestBed.createComponent(StandardDatepicker);
+      fixture.detectChanges();
+      testComponent = fixture.componentInstance;
+    }));
+
+    it('should not set the `mat-datepicker-content-above` class when opening downwards',
+      fakeAsync(() => {
+        fixture.componentInstance.datepicker.open();
+        fixture.detectChanges();
+        flush();
+        fixture.detectChanges();
+
+        const content =
+            document.querySelector('.cdk-overlay-pane mat-datepicker-content')! as HTMLElement;
+
+        expect(content.classList).not.toContain('mat-datepicker-content-above');
+      }));
+
+    it('should set the `mat-datepicker-content-above` class when opening upwards', fakeAsync(() => {
+      const input = fixture.debugElement.nativeElement.querySelector('input');
+
+      // Push the input to the bottom of the page to force the calendar to open upwards
+      input.style.position = 'fixed';
+      input.style.bottom = '0';
+
+      fixture.componentInstance.datepicker.open();
+      fixture.detectChanges();
+      flush();
+      fixture.detectChanges();
+
+      const content =
+          document.querySelector('.cdk-overlay-pane mat-datepicker-content')! as HTMLElement;
+
+      expect(content.classList).toContain('mat-datepicker-content-above');
+    }));
+
+  });
 });
 
 

src/lib/datepicker/datepicker.ts

@@ -16,6 +16,7 @@ import {
   PositionStrategy,
   RepositionScrollStrategy,
   ScrollStrategy,
+  ConnectedPositionStrategy,
 } from '@angular/cdk/overlay';
 import {ComponentPortal} from '@angular/cdk/portal';
 import {first} from 'rxjs/operators/first';
@@ -35,6 +36,8 @@ import {
   ViewChild,
   ViewContainerRef,
   ViewEncapsulation,
+  ChangeDetectorRef,
+  OnInit,
 } from '@angular/core';
 import {DateAdapter} from '@angular/material/core';
 import {MatDialog, MatDialogRef} from '@angular/material/dialog';
@@ -44,6 +47,7 @@ import {Subscription} from 'rxjs/Subscription';
 import {MatCalendar} from './calendar';
 import {createMissingDateImplError} from './datepicker-errors';
 import {MatDatepickerInput} from './datepicker-input';
+import{trigger, state, style, animate, transition} from '@angular/animations';
 
 
 /** Used to generate a unique ID for each datepicker instance. */
@@ -81,23 +85,73 @@ export const MAT_DATEPICKER_SCROLL_STRATEGY_PROVIDER = {
   styleUrls: ['datepicker-content.css'],
   host: {
     'class': 'mat-datepicker-content',
+    '[@tranformPanel]': '"enter"',
     '[class.mat-datepicker-content-touch]': 'datepicker.touchUi',
+    '[class.mat-datepicker-content-above]': '_isAbove',
     '(keydown)': '_handleKeydown($event)',
   },
+  animations: [
+    trigger('tranformPanel', [
+      state('void', style({opacity: 0, transform: 'scale(1, 0)'})),
+      state('enter', style({opacity: 1, transform: 'scale(1, 1)'})),
+      transition('void => enter', animate('400ms cubic-bezier(0.25, 0.8, 0.25, 1)')),
+      transition('* => void', animate('100ms linear', style({opacity: 0})))
+    ]),
+    trigger('fadeInCalendar', [
+      state('void', style({opacity: 0})),
+      state('enter', style({opacity: 1})),
+      transition('void => *', animate('400ms 100ms cubic-bezier(0.55, 0, 0.55, 0.2)'))
+    ])
+  ],
   exportAs: 'matDatepickerContent',
   encapsulation: ViewEncapsulation.None,
   preserveWhitespaces: false,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class MatDatepickerContent<D> implements AfterContentInit {
-  datepicker: MatDatepicker<D>;
+export class MatDatepickerContent<D> implements AfterContentInit, OnInit, OnDestroy {
+  /** Subscription to changes in the overlay's position. */
+  private _positionChange: Subscription|null;
 
+  /** Reference to the internal calendar component. */
   @ViewChild(MatCalendar) _calendar: MatCalendar<D>;
 
+  /** Reference to the datepicker that created the overlay. */
+  datepicker: MatDatepicker<D>;
+
+  /** Whether the datepicker is above or below the input. */
+  _isAbove: boolean;
+
+  constructor(private _changeDetectorRef: ChangeDetectorRef) {}
+
+  ngOnInit() {
+    if (!this.datepicker._popupRef || this._positionChange) {
+      return;
+    }
+
+    const positionStrategy =
+      this.datepicker._popupRef.getConfig().positionStrategy! as ConnectedPositionStrategy;
+
+    this._positionChange = positionStrategy.onPositionChange.subscribe(change => {
+      const isAbove = change.connectionPair.overlayY === 'bottom';
+
+      if (isAbove !== this._isAbove) {
+        this._isAbove = isAbove;
+        this._changeDetectorRef.markForCheck();
+      }
+    });
+  }
+
   ngAfterContentInit() {
     this._calendar._focusActiveCell();
   }
 
+  ngOnDestroy() {
+    if (this._positionChange) {
+      this._positionChange.unsubscribe();
+      this._positionChange = null;
+    }
+  }
+
   /**
    * Handles keydown event on datepicker content.
    * @param event The event.
@@ -211,7 +265,7 @@ export class MatDatepicker<D> implements OnDestroy {
   }
 
   /** A reference to the overlay when the calendar is opened as a popup. */
-  private _popupRef: OverlayRef;
+  _popupRef: OverlayRef;
 
   /** A reference to the dialog when the calendar is opened as a dialog. */
   private _dialogRef: MatDialogRef<any> | null;