refactor(drag-drop): move logic out of directives

Moves the logic for `CdkDrag` and `CdkDropList` into separate, non-Angular-specific classes. This is a first step towards allowing consumers to attach drag&drop functionality to arbitrary DOM nodes.

Author: crisbeto

src/cdk/drag-drop/drag-handle.ts renamed to src/cdk/drag-drop/directives/drag-handle.ts

@@ -8,8 +8,8 @@
 
 import {Directive, ElementRef, Inject, Optional, Input} from '@angular/core';
 import {coerceBooleanProperty} from '@angular/cdk/coercion';
-import {CDK_DRAG_PARENT} from './drag-parent';
-import {toggleNativeDragInteractions} from './drag-styling';
+import {CDK_DRAG_PARENT} from '../drag-parent';
+import {toggleNativeDragInteractions} from '../drag-styling';
 
 /** Handle that can be used to drag and CdkDrag instance. */
 @Directive({

src/cdk/drag-drop/drag-placeholder.ts renamed to src/cdk/drag-drop/directives/drag-placeholder.ts

@@ -12,7 +12,7 @@ import {
   ChangeDetectionStrategy,
 } from '@angular/core';
 import {TestBed, ComponentFixture, fakeAsync, flush, tick} from '@angular/core/testing';
-import {DragDropModule} from './drag-drop-module';
+import {DragDropModule} from '../drag-drop-module';
 import {
   createMouseEvent,
   dispatchEvent,
@@ -21,13 +21,14 @@ import {
   createTouchEvent,
 } from '@angular/cdk/testing';
 import {Directionality} from '@angular/cdk/bidi';
-import {CdkDrag, CDK_DRAG_CONFIG, CdkDragConfig} from './drag';
-import {CdkDragDrop} from './drag-events';
-import {moveItemInArray} from './drag-utils';
+import {CdkDrag, CDK_DRAG_CONFIG} from './drag';
+import {CdkDragDrop} from '../drag-events';
+import {moveItemInArray} from '../drag-utils';
 import {CdkDropList} from './drop-list';
 import {CdkDragHandle} from './drag-handle';
 import {CdkDropListGroup} from './drop-list-group';
-import {extendStyles} from './drag-styling';
+import {extendStyles} from '../drag-styling';
+import {DragRefConfig} from '../drag-ref';
 
 const ITEM_HEIGHT = 25;
 const ITEM_WIDTH = 75;
@@ -47,7 +48,7 @@ describe('CdkDrag', () => {
             // have to deal with thresholds.
             dragStartThreshold: dragDistance,
             pointerDirectionChangeThreshold: 5
-          } as CdkDragConfig
+          } as DragRefConfig
         },
         ...providers
       ],

src/cdk/drag-drop/drag-preview.ts renamed to src/cdk/drag-drop/directives/drag-preview.ts

@@ -0,0 +1,305 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {Directionality} from '@angular/cdk/bidi';
+import {ViewportRuler} from '@angular/cdk/scrolling';
+import {DOCUMENT} from '@angular/common';
+import {
+  AfterViewInit,
+  ContentChild,
+  ContentChildren,
+  Directive,
+  ElementRef,
+  EventEmitter,
+  Inject,
+  InjectionToken,
+  Input,
+  NgZone,
+  OnDestroy,
+  Optional,
+  Output,
+  QueryList,
+  SkipSelf,
+  ViewContainerRef,
+} from '@angular/core';
+import {coerceBooleanProperty} from '@angular/cdk/coercion';
+import {Observable, Subscription, Observer} from 'rxjs';
+import {startWith, take, map} from 'rxjs/operators';
+import {DragDropRegistry} from '../drag-drop-registry';
+import {
+  CdkDragDrop,
+  CdkDragEnd,
+  CdkDragEnter,
+  CdkDragExit,
+  CdkDragMove,
+  CdkDragStart,
+} from '../drag-events';
+import {CdkDragHandle} from './drag-handle';
+import {CdkDragPlaceholder} from './drag-placeholder';
+import {CdkDragPreview} from './drag-preview';
+import {CDK_DROP_LIST} from '../drop-list-container';
+import {CDK_DRAG_PARENT} from '../drag-parent';
+import {DragRef, DragRefConfig} from '../drag-ref';
+import {DropListRef} from '../drop-list-ref';
+import {CdkDropListInternal as CdkDropList} from './drop-list';
+
+/** Injection token that can be used to configure the behavior of `CdkDrag`. */
+export const CDK_DRAG_CONFIG = new InjectionToken<DragRefConfig>('CDK_DRAG_CONFIG', {
+  providedIn: 'root',
+  factory: CDK_DRAG_CONFIG_FACTORY
+});
+
+/** @docs-private */
+export function CDK_DRAG_CONFIG_FACTORY(): DragRefConfig {
+  return {dragStartThreshold: 5, pointerDirectionChangeThreshold: 5};
+}
+
+/** Element that can be moved inside a CdkDropList container. */
+@Directive({
+  selector: '[cdkDrag]',
+  exportAs: 'cdkDrag',
+  host: {
+    'class': 'cdk-drag',
+    '[class.cdk-drag-dragging]': '_dragRef.isDragging()',
+  },
+  providers: [{provide: CDK_DRAG_PARENT, useExisting: CdkDrag}]
+})
+export class CdkDrag<T = any> implements AfterViewInit, OnDestroy {
+  /** Subscription to the stream that initializes the root element. */
+  private _rootElementInitSubscription = Subscription.EMPTY;
+
+  /** Reference to the underlying drag instance. */
+  _dragRef: DragRef<CdkDrag<T>>;
+
+  /** Elements that can be used to drag the draggable item. */
+  @ContentChildren(CdkDragHandle, {descendants: true}) _handles: QueryList<CdkDragHandle>;
+
+  /** Element that will be used as a template to create the draggable item's preview. */
+  @ContentChild(CdkDragPreview) _previewTemplate: CdkDragPreview;
+
+  /** Template for placeholder element rendered to show where a draggable would be dropped. */
+  @ContentChild(CdkDragPlaceholder) _placeholderTemplate: CdkDragPlaceholder;
+
+  /** Arbitrary data to attach to this drag instance. */
+  @Input('cdkDragData') data: T;
+
+  /** Locks the position of the dragged element along the specified axis. */
+  @Input('cdkDragLockAxis') lockAxis: 'x' | 'y';
+
+  /**
+   * Selector that will be used to determine the root draggable element, starting from
+   * the `cdkDrag` element and going up the DOM. Passing an alternate root element is useful
+   * when trying to enable dragging on an element that you might not have access to.
+   */
+  @Input('cdkDragRootElement') rootElementSelector: string;
+
+  /**
+   * Selector that will be used to determine the element to which the draggable's position will
+   * be constrained. Matching starts from the element's parent and goes up the DOM until a matching
+   * element has been found.
+   */
+  @Input('cdkDragBoundary') boundaryElementSelector: string;
+
+  /** Whether starting to drag this element is disabled. */
+  @Input('cdkDragDisabled')
+  get disabled(): boolean {
+    return this._disabled || (this.dropContainer && this.dropContainer.disabled);
+  }
+  set disabled(value: boolean) {
+    this._disabled = coerceBooleanProperty(value);
+  }
+  private _disabled = false;
+
+  /** Emits when the user starts dragging the item. */
+  @Output('cdkDragStarted') started: EventEmitter<CdkDragStart> = new EventEmitter<CdkDragStart>();
+
+  /** Emits when the user stops dragging an item in the container. */
+  @Output('cdkDragEnded') ended: EventEmitter<CdkDragEnd> = new EventEmitter<CdkDragEnd>();
+
+  /** Emits when the user has moved the item into a new container. */
+  @Output('cdkDragEntered') entered: EventEmitter<CdkDragEnter<any>> =
+      new EventEmitter<CdkDragEnter<any>>();
+
+  /** Emits when the user removes the item its container by dragging it into another container. */
+  @Output('cdkDragExited') exited: EventEmitter<CdkDragExit<any>> =
+      new EventEmitter<CdkDragExit<any>>();
+
+  /** Emits when the user drops the item inside a container. */
+  @Output('cdkDragDropped') dropped: EventEmitter<CdkDragDrop<any>> =
+      new EventEmitter<CdkDragDrop<any>>();
+
+  /**
+   * Emits as the user is dragging the item. Use with caution,
+   * because this event will fire for every pixel that the user has dragged.
+   */
+  @Output('cdkDragMoved') moved: Observable<CdkDragMove<T>> =
+      Observable.create((observer: Observer<CdkDragMove<T>>) => {
+        const subscription = this._dragRef.moved.pipe(map(movedEvent => ({
+          source: this,
+          pointerPosition: movedEvent.pointerPosition,
+          event: movedEvent.event,
+          delta: movedEvent.delta
+        }))).subscribe(observer);
+
+        return () => {
+          subscription.unsubscribe();
+        };
+      });
+
+  constructor(
+    /** Element that the draggable is attached to. */
+    public element: ElementRef<HTMLElement>,
+    /** Droppable container that the draggable is a part of. */
+    @Inject(CDK_DROP_LIST) @Optional() @SkipSelf()
+    public dropContainer: CdkDropList,
+    @Inject(DOCUMENT) private _document: any,
+    private _ngZone: NgZone,
+    private _viewContainerRef: ViewContainerRef,
+    private _viewportRuler: ViewportRuler,
+    private _dragDropRegistry: DragDropRegistry<DragRef, DropListRef>,
+    @Inject(CDK_DRAG_CONFIG) private _config: DragRefConfig,
+    @Optional() private _dir: Directionality) {
+
+    const ref = this._dragRef = new DragRef(element, this._document, this._ngZone,
+      this._viewContainerRef, this._viewportRuler, this._dragDropRegistry,
+      this._config, this.dropContainer ? this.dropContainer._dropListRef : undefined,
+      this._dir);
+    ref.data = this;
+    ref.beforeStarted.subscribe(() => {
+      if (!ref.isDragging()) {
+        ref.disabled = this.disabled;
+        ref.lockAxis = this.lockAxis;
+        ref.withBoundaryElement(this._getBoundaryElement());
+      }
+    });
+    this._proxyEvents(ref);
+  }
+
+  /**
+   * Returns the element that is being used as a placeholder
+   * while the current element is being dragged.
+   */
+  getPlaceholderElement(): HTMLElement {
+    return this._dragRef.getPlaceholderElement();
+  }
+
+  /** Returns the root draggable element. */
+  getRootElement(): HTMLElement {
+    return this._dragRef.getRootElement();
+  }
+
+  /** Resets a standalone drag item to its initial position. */
+  reset(): void {
+    this._dragRef.reset();
+  }
+
+  ngAfterViewInit() {
+    // We need to wait for the zone to stabilize, in order for the reference
+    // element to be in the proper place in the DOM. This is mostly relevant
+    // for draggable elements inside portals since they get stamped out in
+    // their original DOM position and then they get transferred to the portal.
+    this._rootElementInitSubscription = this._ngZone.onStable.asObservable()
+      .pipe(take(1))
+      .subscribe(() => {
+        const rootElement = this._getRootElement();
+
+        if (rootElement.nodeType !== this._document.ELEMENT_NODE) {
+          throw Error(`cdkDrag must be attached to an element node. ` +
+                      `Currently attached to "${rootElement.nodeName}".`);
+        }
+
+        this._dragRef
+          .withRootElement(rootElement)
+          .withPlaceholderTemplate(this._placeholderTemplate)
+          .withPreviewTemplate(this._previewTemplate);
+
+        this._handles.changes
+          .pipe(startWith(this._handles))
+          .subscribe((handleList: QueryList<CdkDragHandle>) => {
+            this._dragRef.withHandles(handleList.filter(handle => handle._parentDrag === this));
+          });
+      });
+  }
+
+  ngOnDestroy() {
+    this._rootElementInitSubscription.unsubscribe();
+    this._dragRef.dispose();
+  }
+
+  /** Gets the root draggable element, based on the `rootElementSelector`. */
+  private _getRootElement(): HTMLElement {
+    const element = this.element.nativeElement;
+    const rootElement = this.rootElementSelector ?
+        getClosestMatchingAncestor(element, this.rootElementSelector) : null;
+
+    return rootElement || element;
+  }
+
+  /** Gets the boundary element, based on the `boundaryElementSelector`. */
+  private _getBoundaryElement() {
+    const selector = this.boundaryElementSelector;
+    return selector ? getClosestMatchingAncestor(this.element.nativeElement, selector) : null;
+  }
+
+  /**
+   * Proxies the events from a DragRef to events that
+   * match the interfaces of the CdkDrag outputs.
+   */
+  private _proxyEvents(ref: DragRef<CdkDrag<T>>) {
+    ref.started.subscribe(() => {
+      this.started.emit({source: this});
+    });
+
+    ref.ended.subscribe(() => {
+      this.ended.emit({source: this});
+    });
+
+    ref.entered.subscribe(event => {
+      this.entered.emit({
+        container: event.container.data,
+        item: this
+      });
+    });
+
+    ref.exited.subscribe(event => {
+      this.exited.emit({
+        container: event.container.data,
+        item: this
+      });
+    });
+
+    ref.dropped.subscribe(event => {
+      this.dropped.emit({
+        previousIndex: event.previousIndex,
+        currentIndex: event.currentIndex,
+        previousContainer: event.previousContainer.data,
+        container: event.container.data,
+        isPointerOverContainer: event.isPointerOverContainer,
+        item: this
+      });
+    });
+  }
+}
+
+/** Gets the closest ancestor of an element that matches a selector. */
+function getClosestMatchingAncestor(element: HTMLElement, selector: string) {
+  let currentElement = element.parentElement as HTMLElement | null;
+
+  while (currentElement) {
+    // IE doesn't support `matches` so we have to fall back to `msMatchesSelector`.
+    if (currentElement.matches ? currentElement.matches(selector) :
+        (currentElement as any).msMatchesSelector(selector)) {
+      return currentElement;
+    }
+
+    currentElement = currentElement.parentElement;
+  }
+
+  return null;
+}
+