text: import { ɵɵdefineInjectable, ɵɵinject, NgZone, Injectable, Inject, InjectionToken, Directive, Input, EventEmitter, ElementRef, ChangeDetectorRef, Optional, SkipSelf, Output, TemplateRef, ViewContainerRef, Self, ContentChildren, ContentChild, NgModule } from '@angular/core';
  import { DOCUMENT } from '@angular/common';
  import { ViewportRuler, ScrollDispatcher, CdkScrollableModule } from '@angular/cdk/scrolling';
  import { normalizePassiveListenerOptions, _getShadowRoot } from '@angular/cdk/platform';
  import { coerceBooleanProperty, coerceElement, coerceArray, coerceNumberProperty } from '@angular/cdk/coercion';
  import { Subject, Subscription, interval, animationFrameScheduler, Observable, merge } from 'rxjs';
  import { takeUntil, startWith, map, take, tap, switchMap } from 'rxjs/operators';
  import { Directionality } from '@angular/cdk/bidi';
  
  /**
   * @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
   */
  /**
   * Shallow-extends a stylesheet object with another stylesheet object.
   * @docs-private
   */
  import * as ɵngcc0 from '@angular/core';
  function extendStyles(dest, source) {
      for (let key in source) {
          if (source.hasOwnProperty(key)) {
              dest[key] = source[key];
          }
      }
      return dest;
  }
  /**
   * Toggles whether the native drag interactions should be enabled for an element.
   * @param element Element on which to toggle the drag interactions.
   * @param enable Whether the drag interactions should be enabled.
   * @docs-private
   */
  function toggleNativeDragInteractions(element, enable) {
      const userSelect = enable ? '' : 'none';
      extendStyles(element.style, {
          touchAction: enable ? '' : 'none',
          webkitUserDrag: enable ? '' : 'none',
          webkitTapHighlightColor: enable ? '' : 'transparent',
          userSelect: userSelect,
          msUserSelect: userSelect,
          webkitUserSelect: userSelect,
          MozUserSelect: userSelect
      });
  }
  
  /**
   * @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
   */
  /** Parses a CSS time value to milliseconds. */
  function parseCssTimeUnitsToMs(value) {
      // Some browsers will return it in seconds, whereas others will return milliseconds.
      const multiplier = value.toLowerCase().indexOf('ms') > -1 ? 1 : 1000;
      return parseFloat(value) * multiplier;
  }
  /** Gets the transform transition duration, including the delay, of an element in milliseconds. */
  function getTransformTransitionDurationInMs(element) {
      const computedStyle = getComputedStyle(element);
      const transitionedProperties = parseCssPropertyValue(computedStyle, 'transition-property');
      const property = transitionedProperties.find(prop => prop === 'transform' || prop === 'all');
      // If there's no transition for `all` or `transform`, we shouldn't do anything.
      if (!property) {
          return 0;
      }
      // Get the index of the property that we're interested in and match
      // it up to the same index in `transition-delay` and `transition-duration`.
      const propertyIndex = transitionedProperties.indexOf(property);
      const rawDurations = parseCssPropertyValue(computedStyle, 'transition-duration');
      const rawDelays = parseCssPropertyValue(computedStyle, 'transition-delay');
      return parseCssTimeUnitsToMs(rawDurations[propertyIndex]) +
          parseCssTimeUnitsToMs(rawDelays[propertyIndex]);
  }
  /** Parses out multiple values from a computed style into an array. */
  function parseCssPropertyValue(computedStyle, name) {
      const value = computedStyle.getPropertyValue(name);
      return value.split(',').map(part => part.trim());
  }
  
  /**
   * @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
   */
  /** Gets a mutable version of an element's bounding `ClientRect`. */
  function getMutableClientRect(element) {
      const clientRect = element.getBoundingClientRect();
      // We need to clone the `clientRect` here, because all the values on it are readonly
      // and we need to be able to update them. Also we can't use a spread here, because
      // the values on a `ClientRect` aren't own properties. See:
      // https://developer.mozilla.org/en-US/docs/Web/API/Element/getBoundingClientRect#Notes
      return {
          top: clientRect.top,
          right: clientRect.right,
          bottom: clientRect.bottom,
          left: clientRect.left,
          width: clientRect.width,
          height: clientRect.height
      };
  }
  /**
   * Checks whether some coordinates are within a `ClientRect`.
   * @param clientRect ClientRect that is being checked.
   * @param x Coordinates along the X axis.
   * @param y Coordinates along the Y axis.
   */
  function isInsideClientRect(clientRect, x, y) {
      const { top, bottom, left, right } = clientRect;
      return y >= top && y <= bottom && x >= left && x <= right;
  }
  /**
   * Updates the top/left positions of a `ClientRect`, as well as their bottom/right counterparts.
   * @param clientRect `ClientRect` that should be updated.
   * @param top Amount to add to the `top` position.
   * @param left Amount to add to the `left` position.
   */
  function adjustClientRect(clientRect, top, left) {
      clientRect.top += top;
      clientRect.bottom = clientRect.top + clientRect.height;
      clientRect.left += left;
      clientRect.right = clientRect.left + clientRect.width;
  }
  /**
   * Checks whether the pointer coordinates are close to a ClientRect.
   * @param rect ClientRect to check against.
   * @param threshold Threshold around the ClientRect.
   * @param pointerX Coordinates along the X axis.
   * @param pointerY Coordinates along the Y axis.
   */
  function isPointerNearClientRect(rect, threshold, pointerX, pointerY) {
      const { top, right, bottom, left, width, height } = rect;
      const xThreshold = width * threshold;
      const yThreshold = height * threshold;
      return pointerY > top - yThreshold && pointerY < bottom + yThreshold &&
          pointerX > left - xThreshold && pointerX < right + xThreshold;
  }
  
  /**
   * @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
   */
  /** Keeps track of the scroll position and dimensions of the parents of an element. */
  class ParentPositionTracker {
      constructor(_document, _viewportRuler) {
          this._document = _document;
          this._viewportRuler = _viewportRuler;
          /** Cached positions of the scrollable parent elements. */
          this.positions = new Map();
      }
      /** Clears the cached positions. */
      clear() {
          this.positions.clear();
      }
      /** Caches the positions. Should be called at the beginning of a drag sequence. */
      cache(elements) {
          this.clear();
          this.positions.set(this._document, {
              scrollPosition: this._viewportRuler.getViewportScrollPosition(),
          });
          elements.forEach(element => {
              this.positions.set(element, {
                  scrollPosition: { top: element.scrollTop, left: element.scrollLeft },
                  clientRect: getMutableClientRect(element)
              });
          });
      }
      /** Handles scrolling while a drag is taking place. */
      handleScroll(event) {
          const target = event.target;
          const cachedPosition = this.positions.get(target);
          if (!cachedPosition) {
              return null;
          }
          // Used when figuring out whether an element is inside the scroll parent. If the scrolled
          // parent is the `document`, we use the `documentElement`, because IE doesn't support
          // `contains` on the `document`.
          const scrolledParentNode = target === this._document ? target.documentElement : target;
          const scrollPosition = cachedPosition.scrollPosition;
          let newTop;
          let newLeft;
          if (target === this._document) {
              const viewportScrollPosition = this._viewportRuler.getViewportScrollPosition();
              newTop = viewportScrollPosition.top;
              newLeft = viewportScrollPosition.left;
          }
          else {
              newTop = target.scrollTop;
              newLeft = target.scrollLeft;
          }
          const topDifference = scrollPosition.top - newTop;
          const leftDifference = scrollPosition.left - newLeft;
          // Go through and update the cached positions of the scroll
          // parents that are inside the element that was scrolled.
          this.positions.forEach((position, node) => {
              if (position.clientRect && target !== node && scrolledParentNode.contains(node)) {
                  adjustClientRect(position.clientRect, topDifference, leftDifference);
              }
          });
          scrollPosition.top = newTop;
          scrollPosition.left = newLeft;
          return { top: topDifference, left: leftDifference };
      }
  }
  
  /**
   * @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
   */
  /** Creates a deep clone of an element. */
  function deepCloneNode(node) {
      const clone = node.cloneNode(true);
      const descendantsWithId = clone.querySelectorAll('[id]');
      const nodeName = node.nodeName.toLowerCase();
      // Remove the `id` to avoid having multiple elements with the same id on the page.
      clone.removeAttribute('id');
      for (let i = 0; i < descendantsWithId.length; i++) {
          descendantsWithId[i].removeAttribute('id');
      }
      if (nodeName === 'canvas') {
          transferCanvasData(node, clone);
      }
      else if (nodeName === 'input' || nodeName === 'select' || nodeName === 'textarea') {
          transferInputData(node, clone);
      }
      transferData('canvas', node, clone, transferCanvasData);
      transferData('input, textarea, select', node, clone, transferInputData);
      return clone;
  }
  /** Matches elements between an element and its clone and allows for their data to be cloned. */
  function transferData(selector, node, clone, callback) {
      const descendantElements = node.querySelectorAll(selector);
      if (descendantElements.length) {
          const cloneElements = clone.querySelectorAll(selector);
          for (let i = 0; i < descendantElements.length; i++) {
              callback(descendantElements[i], cloneElements[i]);
          }
      }
  }
  // Counter for unique cloned radio button names.
  let cloneUniqueId = 0;
  /** Transfers the data of one input element to another. */
  function transferInputData(source, clone) {
      clone.value = source.value;
      // Radio button `name` attributes must be unique for radio button groups
      // otherwise original radio buttons can lose their checked state
      // once the clone is inserted in the DOM.
      if (clone.type === 'radio' && clone.name) {
          clone.name = `mat-clone-${clone.name}-${cloneUniqueId++}`;
      }
  }
  /** Transfers the data of one canvas element to another. */
  function transferCanvasData(source, clone) {
      const context = clone.getContext('2d');
      if (context) {
          // In some cases `drawImage` can throw (e.g. if the canvas size is 0x0).
          // We can't do much about it so just ignore the error.
          try {
              context.drawImage(source, 0, 0);
          }
          catch (_a) { }
      }
  }
  
  /**
   * @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
   */
  /** Options that can be used to bind a passive event listener. */
  const passiveEventListenerOptions = normalizePassiveListenerOptions({ passive: true });
  /** Options that can be used to bind an active event listener. */
  const activeEventListenerOptions = normalizePassiveListenerOptions({ passive: false });
  /**
   * Time in milliseconds for which to ignore mouse events, after
   * receiving a touch event. Used to avoid doing double work for
   * touch devices where the browser fires fake mouse events, in
   * addition to touch events.
   */
  const MOUSE_EVENT_IGNORE_TIME = 800;
  /**
   * Reference to a draggable item. Used to manipulate or dispose of the item.
   */
  class DragRef {
      constructor(element, _config, _document, _ngZone, _viewportRuler, _dragDropRegistry) {
          this._config = _config;
          this._document = _document;
          this._ngZone = _ngZone;
          this._viewportRuler = _viewportRuler;
          this._dragDropRegistry = _dragDropRegistry;
          /**
           * CSS `transform` applied to the element when it isn't being dragged. We need a
           * passive transform in order for the dragged element to retain its new position
           * after the user has stopped dragging and because we need to know the relative
           * position in case they start dragging again. This corresponds to `element.style.transform`.
           */
          this._passiveTransform = { x: 0, y: 0 };
          /** CSS `transform` that is applied to the element while it's being dragged. */
          this._activeTransform = { x: 0, y: 0 };
          /** Emits when the item is being moved. */
          this._moveEvents = new Subject();
          /** Subscription to pointer movement events. */
          this._pointerMoveSubscription = Subscription.EMPTY;
          /** Subscription to the event that is dispatched when the user lifts their pointer. */
          this._pointerUpSubscription = Subscription.EMPTY;
          /** Subscription to the viewport being scrolled. */
          this._scrollSubscription = Subscription.EMPTY;
          /** Subscription to the viewport being resized. */
          this._resizeSubscription = Subscription.EMPTY;
          /** Cached reference to the boundary element. */
          this._boundaryElement = null;
          /** Whether the native dragging interactions have been enabled on the root element. */
          this._nativeInteractionsEnabled = true;
          /** Elements that can be used to drag the draggable item. */
          this._handles = [];
          /** Registered handles that are currently disabled. */
          this._disabledHandles = new Set();
          /** Layout direction of the item. */
          this._direction = 'ltr';
          /**
           * Amount of milliseconds to wait after the user has put their
           * pointer down before starting to drag the element.
           */
          this.dragStartDelay = 0;
          this._disabled = false;
          /** Emits as the drag sequence is being prepared. */
          this.beforeStarted = new Subject();
          /** Emits when the user starts dragging the item. */
          this.started = new Subject();
          /** Emits when the user has released a drag item, before any animations have started. */
          this.released = new Subject();
          /** Emits when the user stops dragging an item in the container. */
          this.ended = new Subject();
          /** Emits when the user has moved the item into a new container. */
          this.entered = new Subject();
          /** Emits when the user removes the item its container by dragging it into another container. */
          this.exited = new Subject();
          /** Emits when the user drops the item inside a container. */
          this.dropped = new Subject();
          /**
           * Emits as the user is dragging the item. Use with caution,
           * because this event will fire for every pixel that the user has dragged.
           */
          this.moved = this._moveEvents;
          /** Handler for the `mousedown`/`touchstart` events. */
          this._pointerDown = (event) => {
              this.beforeStarted.next();
              // Delegate the event based on whether it started from a handle or the element itself.
              if (this._handles.length) {
                  const targetHandle = this._handles.find(handle => {
                      const target = event.target;
                      return !!target && (target === handle || handle.contains(target));
                  });
                  if (targetHandle && !this._disabledHandles.has(targetHandle) && !this.disabled) {
                      this._initializeDragSequence(targetHandle, event);
                  }
              }
              else if (!this.disabled) {
                  this._initializeDragSequence(this._rootElement, event);
              }
          };
          /** Handler that is invoked when the user moves their pointer after they've initiated a drag. */
          this._pointerMove = (event) => {
              // Prevent the default action as early as possible in order to block
              // native actions like dragging the selected text or images with the mouse.
              event.preventDefault();
              const pointerPosition = this._getPointerPositionOnPage(event);
              if (!this._hasStartedDragging) {
                  const distanceX = Math.abs(pointerPosition.x - this._pickupPositionOnPage.x);
                  const distanceY = Math.abs(pointerPosition.y - this._pickupPositionOnPage.y);
                  const isOverThreshold = distanceX + distanceY >= this._config.dragStartThreshold;
                  // Only start dragging after the user has moved more than the minimum distance in either
                  // direction. Note that this is preferrable over doing something like `skip(minimumDistance)`
                  // in the `pointerMove` subscription, because we're not guaranteed to have one move event
                  // per pixel of movement (e.g. if the user moves their pointer quickly).
                  if (isOverThreshold) {
                      const isDelayElapsed = Date.now() >= this._dragStartTime + this._getDragStartDelay(event);
                      if (!isDelayElapsed) {
                          this._endDragSequence(event);
                          return;
                      }
                      // Prevent other drag sequences from starting while something in the container is still
                      // being dragged. This can happen while we're waiting for the drop animation to finish
                      // and can cause errors, because some elements might still be moving around.
                      if (!this._dropContainer || !this._dropContainer.isDragging()) {
                          this._hasStartedDragging = true;
                          this._ngZone.run(() => this._startDragSequence(event));
                      }
                  }
                  return;
              }
              // We only need the preview dimensions if we have a boundary element.
              if (this._boundaryElement) {
                  // Cache the preview element rect if we haven't cached it already or if
                  // we cached it too early before the element dimensions were computed.
                  if (!this._previewRect || (!this._previewRect.width && !this._previewRect.height)) {
                      this._previewRect = (this._preview || this._rootElement).getBoundingClientRect();
                  }
              }
              const constrainedPointerPosition = this._getConstrainedPointerPosition(pointerPosition);
              this._hasMoved = true;
              this._lastKnownPointerPosition = pointerPosition;
              this._updatePointerDirectionDelta(constrainedPointerPosition);
              if (this._dropContainer) {
                  this._updateActiveDropContainer(constrainedPointerPosition, pointerPosition);
              }
              else {
                  const activeTransform = this._activeTransform;
                  activeTransform.x =
                      constrainedPointerPosition.x - this._pickupPositionOnPage.x + this._passiveTransform.x;
                  activeTransform.y =
                      constrainedPointerPosition.y - this._pickupPositionOnPage.y + this._passiveTransform.y;
                  this._applyRootElementTransform(activeTransform.x, activeTransform.y);
                  // Apply transform as attribute if dragging and svg element to work for IE
                  if (typeof SVGElement !== 'undefined' && this._rootElement instanceof SVGElement) {
                      const appliedTransform = `translate(${activeTransform.x} ${activeTransform.y})`;
                      this._rootElement.setAttribute('transform', appliedTransform);
                  }
              }
              // Since this event gets fired for every pixel while dragging, we only
              // want to fire it if the consumer opted into it. Also we have to
              // re-enter the zone because we run all of the events on the outside.
              if (this._moveEvents.observers.length) {
                  this._ngZone.run(() => {
                      this._moveEvents.next({
                          source: this,
                          pointerPosition: constrainedPointerPosition,
                          event,
                          distance: this._getDragDistance(constrainedPointerPosition),
                          delta: this._pointerDirectionDelta
                      });
                  });
              }
          };
          /** Handler that is invoked when the user lifts their pointer up, after initiating a drag. */
          this._pointerUp = (event) => {
              this._endDragSequence(event);
          };
          this.withRootElement(element);
          this._parentPositions = new ParentPositionTracker(_document, _viewportRuler);
          _dragDropRegistry.registerDragItem(this);
      }
      /** Whether starting to drag this element is disabled. */
      get disabled() {
          return this._disabled || !!(this._dropContainer && this._dropContainer.disabled);
      }
      set disabled(value) {
          const newValue = coerceBooleanProperty(value);
          if (newValue !== this._disabled) {
              this._disabled = newValue;
              this._toggleNativeDragInteractions();
          }
      }
      /**
       * Returns the element that is being used as a placeholder
       * while the current element is being dragged.
       */
      getPlaceholderElement() {
          return this._placeholder;
      }
      /** Returns the root draggable element. */
      getRootElement() {
          return this._rootElement;
      }
      /**
       * Gets the currently-visible element that represents the drag item.
       * While dragging this is the placeholder, otherwise it's the root element.
       */
      getVisibleElement() {
          return this.isDragging() ? this.getPlaceholderElement() : this.getRootElement();
      }
      /** Registers the handles that can be used to drag the element. */
      withHandles(handles) {
          this._handles = handles.map(handle => coerceElement(handle));
          this._handles.forEach(handle => toggleNativeDragInteractions(handle, false));
          this._toggleNativeDragInteractions();
          return this;
      }
      /**
       * Registers the template that should be used for the drag preview.
       * @param template Template that from which to stamp out the preview.
       */
      withPreviewTemplate(template) {
          this._previewTemplate = template;
          return this;
      }
      /**
       * Registers the template that should be used for the drag placeholder.
       * @param template Template that from which to stamp out the placeholder.
       */
      withPlaceholderTemplate(template) {
          this._placeholderTemplate = template;
          return this;
      }
      /**
       * Sets an alternate drag root element. The root element is the element that will be moved as
       * the user is dragging. Passing an alternate root element is useful when trying to enable
       * dragging on an element that you might not have access to.
       */
      withRootElement(rootElement) {
          const element = coerceElement(rootElement);
          if (element !== this._rootElement) {
              if (this._rootElement) {
                  this._removeRootElementListeners(this._rootElement);
              }
              this._ngZone.runOutsideAngular(() => {
                  element.addEventListener('mousedown', this._pointerDown, activeEventListenerOptions);
                  element.addEventListener('touchstart', this._pointerDown, passiveEventListenerOptions);
              });
              this._initialTransform = undefined;
              this._rootElement = element;
          }
          if (typeof SVGElement !== 'undefined' && this._rootElement instanceof SVGElement) {
              this._ownerSVGElement = this._rootElement.ownerSVGElement;
          }
          return this;
      }
      /**
       * Element to which the draggable's position will be constrained.
       */
      withBoundaryElement(boundaryElement) {
          this._boundaryElement = boundaryElement ? coerceElement(boundaryElement) : null;
          this._resizeSubscription.unsubscribe();
          if (boundaryElement) {
              this._resizeSubscription = this._viewportRuler
                  .change(10)
                  .subscribe(() => this._containInsideBoundaryOnResize());
          }
          return this;
      }
      /** Removes the dragging functionality from the DOM element. */
      dispose() {
          this._removeRootElementListeners(this._rootElement);
          // Do this check before removing from the registry since it'll
          // stop being considered as dragged once it is removed.
          if (this.isDragging()) {
              // Since we move out the element to the end of the body while it's being
              // dragged, we have to make sure that it's removed if it gets destroyed.
              removeNode(this._rootElement);
          }
          removeNode(this._anchor);
          this._destroyPreview();
          this._destroyPlaceholder();
          this._dragDropRegistry.removeDragItem(this);
          this._removeSubscriptions();
          this.beforeStarted.complete();
          this.started.complete();
          this.released.complete();
          this.ended.complete();
          this.entered.complete();
          this.exited.complete();
          this.dropped.complete();
          this._moveEvents.complete();
          this._handles = [];
          this._disabledHandles.clear();
          this._dropContainer = undefined;
          this._resizeSubscription.unsubscribe();
          this._parentPositions.clear();
          this._boundaryElement = this._rootElement = this._ownerSVGElement = this._placeholderTemplate =
              this._previewTemplate = this._anchor = null;
      }
      /** Checks whether the element is currently being dragged. */
      isDragging() {
          return this._hasStartedDragging && this._dragDropRegistry.isDragging(this);
      }
      /** Resets a standalone drag item to its initial position. */
      reset() {
          this._rootElement.style.transform = this._initialTransform || '';
          this._activeTransform = { x: 0, y: 0 };
          this._passiveTransform = { x: 0, y: 0 };
      }
      /**
       * Sets a handle as disabled. While a handle is disabled, it'll capture and interrupt dragging.
       * @param handle Handle element that should be disabled.
       */
      disableHandle(handle) {
          if (this._handles.indexOf(handle) > -1) {
              this._disabledHandles.add(handle);
          }
      }
      /**
       * Enables a handle, if it has been disabled.
       * @param handle Handle element to be enabled.
       */
      enableHandle(handle) {
          this._disabledHandles.delete(handle);
      }
      /** Sets the layout direction of the draggable item. */
      withDirection(direction) {
          this._direction = direction;
          return this;
      }
      /** Sets the container that the item is part of. */
      _withDropContainer(container) {
          this._dropContainer = container;
      }
      /**
       * Gets the current position in pixels the draggable outside of a drop container.
       */
      getFreeDragPosition() {
          const position = this.isDragging() ? this._activeTransform : this._passiveTransform;
          return { x: position.x, y: position.y };
      }
      /**
       * Sets the current position in pixels the draggable outside of a drop container.
       * @param value New position to be set.
       */
      setFreeDragPosition(value) {
          this._activeTransform = { x: 0, y: 0 };
          this._passiveTransform.x = value.x;
          this._passiveTransform.y = value.y;
          if (!this._dropContainer) {
              this._applyRootElementTransform(value.x, value.y);
          }
          return this;
      }
      /** Updates the item's sort order based on the last-known pointer position. */
      _sortFromLastPointerPosition() {
          const position = this._lastKnownPointerPosition;
          if (position && this._dropContainer) {
              this._updateActiveDropContainer(this._getConstrainedPointerPosition(position), position);
          }
      }
      /** Unsubscribes from the global subscriptions. */
      _removeSubscriptions() {
          this._pointerMoveSubscription.unsubscribe();
          this._pointerUpSubscription.unsubscribe();
          this._scrollSubscription.unsubscribe();
      }
      /** Destroys the preview element and its ViewRef. */
      _destroyPreview() {
          if (this._preview) {
              removeNode(this._preview);
          }
          if (this._previewRef) {
              this._previewRef.destroy();
          }
          this._preview = this._previewRef = null;
      }
      /** Destroys the placeholder element and its ViewRef. */
      _destroyPlaceholder() {
          if (this._placeholder) {
              removeNode(this._placeholder);
          }
          if (this._placeholderRef) {
              this._placeholderRef.destroy();
          }
          this._placeholder = this._placeholderRef = null;
      }
      /**
       * Clears subscriptions and stops the dragging sequence.
       * @param event Browser event object that ended the sequence.
       */
      _endDragSequence(event) {
          // Note that here we use `isDragging` from the service, rather than from `this`.
          // The difference is that the one from the service reflects whether a dragging sequence
          // has been initiated, whereas the one on `this` includes whether the user has passed
          // the minimum dragging threshold.
          if (!this._dragDropRegistry.isDragging(this)) {
              return;
          }
          this._removeSubscriptions();
          this._dragDropRegistry.stopDragging(this);
          this._toggleNativeDragInteractions();
          if (this._handles) {
              this._rootElement.style.webkitTapHighlightColor = this._rootElementTapHighlight;
          }
          if (!this._hasStartedDragging) {
              return;
          }
          this.released.next({ source: this });
          if (this._dropContainer) {
              // Stop scrolling immediately, instead of waiting for the animation to finish.
              this._dropContainer._stopScrolling();
              this._animatePreviewToPlaceholder().then(() => {
                  this._cleanupDragArtifacts(event);
                  this._cleanupCachedDimensions();
                  this._dragDropRegistry.stopDragging(this);
              });
          }
          else {
              // Convert the active transform into a passive one. This means that next time
              // the user starts dragging the item, its position will be calculated relatively
              // to the new passive transform.
              this._passiveTransform.x = this._activeTransform.x;
              this._passiveTransform.y = this._activeTransform.y;
              this._ngZone.run(() => {
                  this.ended.next({
                      source: this,
                      distance: this._getDragDistance(this._getPointerPositionOnPage(event))
                  });
              });
              this._cleanupCachedDimensions();
              this._dragDropRegistry.stopDragging(this);
          }
      }
      /** Starts the dragging sequence. */
      _startDragSequence(event) {
          if (isTouchEvent(event)) {
              this._lastTouchEventTime = Date.now();
          }
          this._toggleNativeDragInteractions();
          const dropContainer = this._dropContainer;
          if (dropContainer) {
              const element = this._rootElement;
              const parent = element.parentNode;
              const preview = this._preview = this._createPreviewElement();
              const placeholder = this._placeholder = this._createPlaceholderElement();
              const anchor = this._anchor = this._anchor || this._document.createComment('');
              // Insert an anchor node so that we can restore the element's position in the DOM.
              parent.insertBefore(anchor, element);
              // We move the element out at the end of the body and we make it hidden, because keeping it in
              // place will throw off the consumer's `:last-child` selectors. We can't remove the element
              // from the DOM completely, because iOS will stop firing all subsequent events in the chain.
              element.style.display = 'none';
              this._document.body.appendChild(parent.replaceChild(placeholder, element));
              getPreviewInsertionPoint(this._document).appendChild(preview);
              this.started.next({ source: this }); // Emit before notifying the container.
              dropContainer.start();
              this._initialContainer = dropContainer;
              this._initialIndex = dropContainer.getItemIndex(this);
          }
          else {
              this.started.next({ source: this });
              this._initialContainer = this._initialIndex = undefined;
          }
          // Important to run after we've called `start` on the parent container
          // so that it has had time to resolve its scrollable parents.
          this._parentPositions.cache(dropContainer ? dropContainer.getScrollableParents() : []);
      }
      /**
       * Sets up the different variables and subscriptions
       * that will be necessary for the dragging sequence.
       * @param referenceElement Element that started the drag sequence.
       * @param event Browser event object that started the sequence.
       */
      _initializeDragSequence(referenceElement, event) {
          // Always stop propagation for the event that initializes
          // the dragging sequence, in order to prevent it from potentially
          // starting another sequence for a draggable parent somewhere up the DOM tree.
          event.stopPropagation();
          const isDragging = this.isDragging();
          const isTouchSequence = isTouchEvent(event);
          const isAuxiliaryMouseButton = !isTouchSequence && event.button !== 0;
          const rootElement = this._rootElement;
          const isSyntheticEvent = !isTouchSequence && this._lastTouchEventTime &&
              this._lastTouchEventTime + MOUSE_EVENT_IGNORE_TIME > Date.now();
          // If the event started from an element with the native HTML drag&drop, it'll interfere
          // with our own dragging (e.g. `img` tags do it by default). Prevent the default action
          // to stop it from happening. Note that preventing on `dragstart` also seems to work, but
          // it's flaky and it fails if the user drags it away quickly. Also note that we only want
          // to do this for `mousedown` since doing the same for `touchstart` will stop any `click`
          // events from firing on touch devices.
          if (event.target && event.target.draggable && event.type === 'mousedown') {
              event.preventDefault();
          }
          // Abort if the user is already dragging or is using a mouse button other than the primary one.
          if (isDragging || isAuxiliaryMouseButton || isSyntheticEvent) {
              return;
          }
          // If we've got handles, we need to disable the tap highlight on the entire root element,
          // otherwise iOS will still add it, even though all the drag interactions on the handle
          // are disabled.
          if (this._handles.length) {
              this._rootElementTapHighlight = rootElement.style.webkitTapHighlightColor || '';
              rootElement.style.webkitTapHighlightColor = 'transparent';
          }
          this._hasStartedDragging = this._hasMoved = false;
          // Avoid multiple subscriptions and memory leaks when multi touch
          // (isDragging check above isn't enough because of possible temporal and/or dimensional delays)
          this._removeSubscriptions();
          this._pointerMoveSubscription = this._dragDropRegistry.pointerMove.subscribe(this._pointerMove);
          this._pointerUpSubscription = this._dragDropRegistry.pointerUp.subscribe(this._pointerUp);
          this._scrollSubscription = this._dragDropRegistry.scroll.subscribe(scrollEvent => {
              this._updateOnScroll(scrollEvent);
          });
          if (this._boundaryElement) {
              this._boundaryRect = getMutableClientRect(this._boundaryElement);
          }
          // If we have a custom preview we can't know ahead of time how large it'll be so we position
          // it next to the cursor. The exception is when the consumer has opted into making the preview
          // the same size as the root element, in which case we do know the size.
          const previewTemplate = this._previewTemplate;
          this._pickupPositionInElement = previewTemplate && previewTemplate.template &&
              !previewTemplate.matchSize ? { x: 0, y: 0 } :
              this._getPointerPositionInElement(referenceElement, event);
          const pointerPosition = this._pickupPositionOnPage = this._lastKnownPointerPosition =
              this._getPointerPositionOnPage(event);
          this._pointerDirectionDelta = { x: 0, y: 0 };
          this._pointerPositionAtLastDirectionChange = { x: pointerPosition.x, y: pointerPosition.y };
          this._dragStartTime = Date.now();
          this._dragDropRegistry.startDragging(this, event);
      }
      /** Cleans up the DOM artifacts that were added to facilitate the element being dragged. */
      _cleanupDragArtifacts(event) {
          // Restore the element's visibility and insert it at its old position in the DOM.
          // It's important that we maintain the position, because moving the element around in the DOM
          // can throw off `NgFor` which does smart diffing and re-creates elements only when necessary,
          // while moving the existing elements in all other cases.
          this._rootElement.style.display = '';
          this._anchor.parentNode.replaceChild(this._rootElement, this._anchor);
          this._destroyPreview();
          this._destroyPlaceholder();
          this._boundaryRect = this._previewRect = undefined;
          // Re-enter the NgZone since we bound `document` events on the outside.
          this._ngZone.run(() => {
              const container = this._dropContainer;
              const currentIndex = container.getItemIndex(this);
              const pointerPosition = this._getPointerPositionOnPage(event);
              const distance = this._getDragDistance(this._getPointerPositionOnPage(event));
              const isPointerOverContainer = container._isOverContainer(pointerPosition.x, pointerPosition.y);
              this.ended.next({ source: this, distance });
              this.dropped.next({
                  item: this,
                  currentIndex,
                  previousIndex: this._initialIndex,
                  container: container,
                  previousContainer: this._initialContainer,
                  isPointerOverContainer,
                  distance
              });
              container.drop(this, currentIndex, this._initialContainer, isPointerOverContainer, distance, this._initialIndex);
              this._dropContainer = this._initialContainer;
          });
      }
      /**
       * Updates the item's position in its drop container, or moves it
       * into a new one, depending on its current drag position.
       */
      _updateActiveDropContainer({ x, y }, { x: rawX, y: rawY }) {
          // Drop container that draggable has been moved into.
          let newContainer = this._initialContainer._getSiblingContainerFromPosition(this, x, y);
          // If we couldn't find a new container to move the item into, and the item has left its
          // initial container, check whether the it's over the initial container. This handles the
          // case where two containers are connected one way and the user tries to undo dragging an
          // item into a new container.
          if (!newContainer && this._dropContainer !== this._initialContainer &&
              this._initialContainer._isOverContainer(x, y)) {
              newContainer = this._initialContainer;
          }
          if (newContainer && newContainer !== this._dropContainer) {
              this._ngZone.run(() => {
                  // Notify the old container that the item has left.
                  this.exited.next({ item: this, container: this._dropContainer });
                  this._dropContainer.exit(this);
                  // Notify the new container that the item has entered.
                  this._dropContainer = newContainer;
                  this._dropContainer.enter(this, x, y, newContainer === this._initialContainer &&
                      // If we're re-entering the initial container and sorting is disabled,
                      // put item the into its starting index to begin with.
                      newContainer.sortingDisabled ? this._initialIndex : undefined);
                  this.entered.next({
                      item: this,
                      container: newContainer,
                      currentIndex: newContainer.getItemIndex(this)
                  });
              });
          }
          this._dropContainer._startScrollingIfNecessary(rawX, rawY);
          this._dropContainer._sortItem(this, x, y, this._pointerDirectionDelta);
          this._preview.style.transform =
              getTransform(x - this._pickupPositionInElement.x, y - this._pickupPositionInElement.y);
      }
      /**
       * Creates the element that will be rendered next to the user's pointer
       * and will be used as a preview of the element that is being dragged.
       */
      _createPreviewElement() {
          const previewConfig = this._previewTemplate;
          const previewClass = this.previewClass;
          const previewTemplate = previewConfig ? previewConfig.template : null;
          let preview;
          if (previewTemplate && previewConfig) {
              // Measure the element before we've inserted the preview
              // since the insertion could throw off the measurement.
              const rootRect = previewConfig.matchSize ? this._rootElement.getBoundingClientRect() : null;
              const viewRef = previewConfig.viewContainer.createEmbeddedView(previewTemplate, previewConfig.context);
              viewRef.detectChanges();
              preview = getRootNode(viewRef, this._document);
              this._previewRef = viewRef;
              if (previewConfig.matchSize) {
                  matchElementSize(preview, rootRect);
              }
              else {
                  preview.style.transform =
                      getTransform(this._pickupPositionOnPage.x, this._pickupPositionOnPage.y);
              }
          }
          else {
              const element = this._rootElement;
              preview = deepCloneNode(element);
              matchElementSize(preview, element.getBoundingClientRect());
          }
          extendStyles(preview.style, {
              // It's important that we disable the pointer events on the preview, because
              // it can throw off the `document.elementFromPoint` calls in the `CdkDropList`.
              pointerEvents: 'none',
              // We have to reset the margin, because it can throw off positioning relative to the viewport.
              margin: '0',
              position: 'fixed',
              top: '0',
              left: '0',
              zIndex: `${this._config.zIndex || 1000}`
          });
          toggleNativeDragInteractions(preview, false);
          preview.classList.add('cdk-drag-preview');
          preview.setAttribute('dir', this._direction);
          if (previewClass) {
              if (Array.isArray(previewClass)) {
                  previewClass.forEach(className => preview.classList.add(className));
              }
              else {
                  preview.classList.add(previewClass);
              }
          }
          return preview;
      }
      /**
       * Animates the preview element from its current position to the location of the drop placeholder.
       * @returns Promise that resolves when the animation completes.
       */
      _animatePreviewToPlaceholder() {
          // If the user hasn't moved yet, the transitionend event won't fire.
          if (!this._hasMoved) {
              return Promise.resolve();
          }
          const placeholderRect = this._placeholder.getBoundingClientRect();
          // Apply the class that adds a transition to the preview.
          this._preview.classList.add('cdk-drag-animating');
          // Move the preview to the placeholder position.
          this._preview.style.transform = getTransform(placeholderRect.left, placeholderRect.top);
          // If the element doesn't have a `transition`, the `transitionend` event won't fire. Since
          // we need to trigger a style recalculation in order for the `cdk-drag-animating` class to
          // apply its style, we take advantage of the available info to figure out whether we need to
          // bind the event in the first place.
          const duration = getTransformTransitionDurationInMs(this._preview);
          if (duration === 0) {
              return Promise.resolve();
          }
          return this._ngZone.runOutsideAngular(() => {
              return new Promise(resolve => {
                  const handler = ((event) => {
                      if (!event || (event.target === this._preview && event.propertyName === 'transform')) {
                          this._preview.removeEventListener('transitionend', handler);
                          resolve();
                          clearTimeout(timeout);
                      }
                  });
                  // If a transition is short enough, the browser might not fire the `transitionend` event.
                  // Since we know how long it's supposed to take, add a timeout with a 50% buffer that'll
                  // fire if the transition hasn't completed when it was supposed to.
                  const timeout = setTimeout(handler, duration * 1.5);
                  this._preview.addEventListener('transitionend', handler);
              });
          });
      }
      /** Creates an element that will be shown instead of the current element while dragging. */
      _createPlaceholderElement() {
          const placeholderConfig = this._placeholderTemplate;
          const placeholderTemplate = placeholderConfig ? placeholderConfig.template : null;
          let placeholder;
          if (placeholderTemplate) {
              this._placeholderRef = placeholderConfig.viewContainer.createEmbeddedView(placeholderTemplate, placeholderConfig.context);
              this._placeholderRef.detectChanges();
              placeholder = getRootNode(this._placeholderRef, this._document);
          }
          else {
              placeholder = deepCloneNode(this._rootElement);
          }
          placeholder.classList.add('cdk-drag-placeholder');
          return placeholder;
      }
      /**
       * Figures out the coordinates at which an element was picked up.
       * @param referenceElement Element that initiated the dragging.
       * @param event Event that initiated the dragging.
       */
      _getPointerPositionInElement(referenceElement, event) {
          const elementRect = this._rootElement.getBoundingClientRect();
          const handleElement = referenceElement === this._rootElement ? null : referenceElement;
          const referenceRect = handleElement ? handleElement.getBoundingClientRect() : elementRect;
          const point = isTouchEvent(event) ? event.targetTouches[0] : event;
          const scrollPosition = this._getViewportScrollPosition();
          const x = point.pageX - referenceRect.left - scrollPosition.left;
          const y = point.pageY - referenceRect.top - scrollPosition.top;
          return {
              x: referenceRect.left - elementRect.left + x,
              y: referenceRect.top - elementRect.top + y
          };
      }
      /** Determines the point of the page that was touched by the user. */
      _getPointerPositionOnPage(event) {
          const scrollPosition = this._getViewportScrollPosition();
          const point = isTouchEvent(event) ?
              // `touches` will be empty for start/end events so we have to fall back to `changedTouches`.
              // Also note that on real devices we're guaranteed for either `touches` or `changedTouches`
              // to have a value, but Firefox in device emulation mode has a bug where both can be empty
              // for `touchstart` and `touchend` so we fall back to a dummy object in order to avoid
              // throwing an error. The value returned here will be incorrect, but since this only
              // breaks inside a developer tool and the value is only used for secondary information,
              // we can get away with it. See https://bugzilla.mozilla.org/show_bug.cgi?id=1615824.
              (event.touches[0] || event.changedTouches[0] || { pageX: 0, pageY: 0 }) : event;
          const x = point.pageX - scrollPosition.left;
          const y = point.pageY - scrollPosition.top;
          // if dragging SVG element, try to convert from the screen coordinate system to the SVG
          // coordinate system
          if (this._ownerSVGElement) {
              const svgMatrix = this._ownerSVGElement.getScreenCTM();
              if (svgMatrix) {
                  const svgPoint = this._ownerSVGElement.createSVGPoint();
                  svgPoint.x = x;
                  svgPoint.y = y;
                  return svgPoint.matrixTransform(svgMatrix.inverse());
              }
          }
          return { x, y };
      }
      /** Gets the pointer position on the page, accounting for any position constraints. */
      _getConstrainedPointerPosition(point) {
          const dropContainerLock = this._dropContainer ? this._dropContainer.lockAxis : null;
          let { x, y } = this.constrainPosition ? this.constrainPosition(point, this) : point;
          if (this.lockAxis === 'x' || dropContainerLock === 'x') {
              y = this._pickupPositionOnPage.y;
          }
          else if (this.lockAxis === 'y' || dropContainerLock === 'y') {
              x = this._pickupPositionOnPage.x;
          }
          if (this._boundaryRect) {
              const { x: pickupX, y: pickupY } = this._pickupPositionInElement;
              const boundaryRect = this._boundaryRect;
              const previewRect = this._previewRect;
              const minY = boundaryRect.top + pickupY;
              const maxY = boundaryRect.bottom - (previewRect.height - pickupY);
              const minX = boundaryRect.left + pickupX;
              const maxX = boundaryRect.right - (previewRect.width - pickupX);
              x = clamp(x, minX, maxX);
              y = clamp(y, minY, maxY);
          }
          return { x, y };
      }
      /** Updates the current drag delta, based on the user's current pointer position on the page. */
      _updatePointerDirectionDelta(pointerPositionOnPage) {
          const { x, y } = pointerPositionOnPage;
          const delta = this._pointerDirectionDelta;
          const positionSinceLastChange = this._pointerPositionAtLastDirectionChange;
          // Amount of pixels the user has dragged since the last time the direction changed.
          const changeX = Math.abs(x - positionSinceLastChange.x);
          const changeY = Math.abs(y - positionSinceLastChange.y);
          // Because we handle pointer events on a per-pixel basis, we don't want the delta
          // to change for every pixel, otherwise anything that depends on it can look erratic.
          // To make the delta more consistent, we track how much the user has moved since the last
          // delta change and we only update it after it has reached a certain threshold.
          if (changeX > this._config.pointerDirectionChangeThreshold) {
              delta.x = x > positionSinceLastChange.x ? 1 : -1;
              positionSinceLastChange.x = x;
          }
          if (changeY > this._config.pointerDirectionChangeThreshold) {
              delta.y = y > positionSinceLastChange.y ? 1 : -1;
              positionSinceLastChange.y = y;
          }
          return delta;
      }
      /** Toggles the native drag interactions, based on how many handles are registered. */
      _toggleNativeDragInteractions() {
          if (!this._rootElement || !this._handles) {
              return;
          }
          const shouldEnable = this._handles.length > 0 || !this.isDragging();
          if (shouldEnable !== this._nativeInteractionsEnabled) {
              this._nativeInteractionsEnabled = shouldEnable;
              toggleNativeDragInteractions(this._rootElement, shouldEnable);
          }
      }
      /** Removes the manually-added event listeners from the root element. */
      _removeRootElementListeners(element) {
          element.removeEventListener('mousedown', this._pointerDown, activeEventListenerOptions);
          element.removeEventListener('touchstart', this._pointerDown, passiveEventListenerOptions);
      }
      /**
       * Applies a `transform` to the root element, taking into account any existing transforms on it.
       * @param x New transform value along the X axis.
       * @param y New transform value along the Y axis.
       */
      _applyRootElementTransform(x, y) {
          const transform = getTransform(x, y);
          // Cache the previous transform amount only after the first drag sequence, because
          // we don't want our own transforms to stack on top of each other.
          if (this._initialTransform == null) {
              this._initialTransform = this._rootElement.style.transform || '';
          }
          // Preserve the previous `transform` value, if there was one. Note that we apply our own
          // transform before the user's, because things like rotation can affect which direction
          // the element will be translated towards.
          this._rootElement.style.transform = this._initialTransform ?
              transform + ' ' + this._initialTransform : transform;
      }
      /**
       * Gets the distance that the user has dragged during the current drag sequence.
       * @param currentPosition Current position of the user's pointer.
       */
      _getDragDistance(currentPosition) {
          const pickupPosition = this._pickupPositionOnPage;
          if (pickupPosition) {
              return { x: currentPosition.x - pickupPosition.x, y: currentPosition.y - pickupPosition.y };
          }
          return { x: 0, y: 0 };
      }
      /** Cleans up any cached element dimensions that we don't need after dragging has stopped. */
      _cleanupCachedDimensions() {
          this._boundaryRect = this._previewRect = undefined;
          this._parentPositions.clear();
      }
      /**
       * Checks whether the element is still inside its boundary after the viewport has been resized.
       * If not, the position is adjusted so that the element fits again.
       */
      _containInsideBoundaryOnResize() {
          let { x, y } = this._passiveTransform;
          if ((x === 0 && y === 0) || this.isDragging() || !this._boundaryElement) {
              return;
          }
          const boundaryRect = this._boundaryElement.getBoundingClientRect();
          const elementRect = this._rootElement.getBoundingClientRect();
          // It's possible that the element got hidden away after dragging (e.g. by switching to a
          // different tab). Don't do anything in this case so we don't clear the user's position.
          if ((boundaryRect.width === 0 && boundaryRect.height === 0) ||
              (elementRect.width === 0 && elementRect.height === 0)) {
              return;
          }
          const leftOverflow = boundaryRect.left - elementRect.left;
          const rightOverflow = elementRect.right - boundaryRect.right;
          const topOverflow = boundaryRect.top - elementRect.top;
          const bottomOverflow = elementRect.bottom - boundaryRect.bottom;
          // If the element has become wider than the boundary, we can't
          // do much to make it fit so we just anchor it to the left.
          if (boundaryRect.width > elementRect.width) {
              if (leftOverflow > 0) {
                  x += leftOverflow;
              }
              if (rightOverflow > 0) {
                  x -= rightOverflow;
              }
          }
          else {
              x = 0;
          }
          // If the element has become taller than the boundary, we can't
          // do much to make it fit so we just anchor it to the top.
          if (boundaryRect.height > elementRect.height) {
              if (topOverflow > 0) {
                  y += topOverflow;
              }
              if (bottomOverflow > 0) {
                  y -= bottomOverflow;
              }
          }
          else {
              y = 0;
          }
          if (x !== this._passiveTransform.x || y !== this._passiveTransform.y) {
              this.setFreeDragPosition({ y, x });
          }
      }
      /** Gets the drag start delay, based on the event type. */
      _getDragStartDelay(event) {
          const value = this.dragStartDelay;
          if (typeof value === 'number') {
              return value;
          }
          else if (isTouchEvent(event)) {
              return value.touch;
          }
          return value ? value.mouse : 0;
      }
      /** Updates the internal state of the draggable element when scrolling has occurred. */
      _updateOnScroll(event) {
          const scrollDifference = this._parentPositions.handleScroll(event);
          if (scrollDifference) {
              const target = event.target;
              // ClientRect dimensions are based on the scroll position of the page and its parent node so
              // we have to update the cached boundary ClientRect if the user has scrolled. Check for
              // the `document` specifically since IE doesn't support `contains` on it.
              if (this._boundaryRect && (target === this._document ||
                  (target !== this._boundaryElement && target.contains(this._boundaryElement)))) {
                  adjustClientRect(this._boundaryRect, scrollDifference.top, scrollDifference.left);
              }
              this._pickupPositionOnPage.x += scrollDifference.left;
              this._pickupPositionOnPage.y += scrollDifference.top;
              // If we're in free drag mode, we have to update the active transform, because
              // it isn't relative to the viewport like the preview inside a drop list.
              if (!this._dropContainer) {
                  this._activeTransform.x -= scrollDifference.left;
                  this._activeTransform.y -= scrollDifference.top;
                  this._applyRootElementTransform(this._activeTransform.x, this._activeTransform.y);
              }
          }
      }
      /** Gets the scroll position of the viewport. */
      _getViewportScrollPosition() {
          const cachedPosition = this._parentPositions.positions.get(this._document);
          return cachedPosition ? cachedPosition.scrollPosition :
              this._viewportRuler.getViewportScrollPosition();
      }
  }
  /**
   * Gets a 3d `transform` that can be applied to an element.
   * @param x Desired position of the element along the X axis.
   * @param y Desired position of the element along the Y axis.
   */
  function getTransform(x, y) {
      // Round the transforms since some browsers will
      // blur the elements for sub-pixel transforms.
      return `translate3d(${Math.round(x)}px, ${Math.round(y)}px, 0)`;
  }
  /** Clamps a value between a minimum and a maximum. */
  function clamp(value, min, max) {
      return Math.max(min, Math.min(max, value));
  }
  /**
   * Helper to remove a node from the DOM and to do all the necessary null checks.
   * @param node Node to be removed.
   */
  function removeNode(node) {
      if (node && node.parentNode) {
          node.parentNode.removeChild(node);
      }
  }
  /** Determines whether an event is a touch event. */
  function isTouchEvent(event) {
      // This function is called for every pixel that the user has dragged so we need it to be
      // as fast as possible. Since we only bind mouse events and touch events, we can assume
      // that if the event's name starts with `t`, it's a touch event.
      return event.type[0] === 't';
  }
  /** Gets the element into which the drag preview should be inserted. */
  function getPreviewInsertionPoint(documentRef) {
      // We can't use the body if the user is in fullscreen mode,
      // because the preview will render under the fullscreen element.
      // TODO(crisbeto): dedupe this with the `FullscreenOverlayContainer` eventually.
      return documentRef.fullscreenElement ||
          documentRef.webkitFullscreenElement ||
          documentRef.mozFullScreenElement ||
          documentRef.msFullscreenElement ||
          documentRef.body;
  }
  /**
   * Gets the root HTML element of an embedded view.
   * If the root is not an HTML element it gets wrapped in one.
   */
  function getRootNode(viewRef, _document) {
      const rootNodes = viewRef.rootNodes;
      if (rootNodes.length === 1 && rootNodes[0].nodeType === _document.ELEMENT_NODE) {
          return rootNodes[0];
      }
      const wrapper = _document.createElement('div');
      rootNodes.forEach(node => wrapper.appendChild(node));
      return wrapper;
  }
  /**
   * Matches the target element's size to the source's size.
   * @param target Element that needs to be resized.
   * @param sourceRect Dimensions of the source element.
   */
  function matchElementSize(target, sourceRect) {
      target.style.width = `${sourceRect.width}px`;
      target.style.height = `${sourceRect.height}px`;
      target.style.transform = getTransform(sourceRect.left, sourceRect.top);
  }
  
  /**
   * @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
   */
  /**
   * Moves an item one index in an array to another.
   * @param array Array in which to move the item.
   * @param fromIndex Starting index of the item.
   * @param toIndex Index to which the item should be moved.
   */
  function moveItemInArray(array, fromIndex, toIndex) {
      const from = clamp$1(fromIndex, array.length - 1);
      const to = clamp$1(toIndex, array.length - 1);
      if (from === to) {
          return;
      }
      const target = array[from];
      const delta = to < from ? -1 : 1;
      for (let i = from; i !== to; i += delta) {
          array[i] = array[i + delta];
      }
      array[to] = target;
  }
  /**
   * Moves an item from one array to another.
   * @param currentArray Array from which to transfer the item.
   * @param targetArray Array into which to put the item.
   * @param currentIndex Index of the item in its current array.
   * @param targetIndex Index at which to insert the item.
   */
  function transferArrayItem(currentArray, targetArray, currentIndex, targetIndex) {
      const from = clamp$1(currentIndex, currentArray.length - 1);
      const to = clamp$1(targetIndex, targetArray.length);
      if (currentArray.length) {
          targetArray.splice(to, 0, currentArray.splice(from, 1)[0]);
      }
  }
  /**
   * Copies an item from one array to another, leaving it in its
   * original position in current array.
   * @param currentArray Array from which to copy the item.
   * @param targetArray Array into which is copy the item.
   * @param currentIndex Index of the item in its current array.
   * @param targetIndex Index at which to insert the item.
   *
   */
  function copyArrayItem(currentArray, targetArray, currentIndex, targetIndex) {
      const to = clamp$1(targetIndex, targetArray.length);
      if (currentArray.length) {
          targetArray.splice(to, 0, currentArray[currentIndex]);
      }
  }
  /** Clamps a number between zero and a maximum. */
  function clamp$1(value, max) {
      return Math.max(0, Math.min(max, value));
  }
  
  /**
   * @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
   */
  /**
   * Proximity, as a ratio to width/height, at which a
   * dragged item will affect the drop container.
   */
  const DROP_PROXIMITY_THRESHOLD = 0.05;
  /**
   * Proximity, as a ratio to width/height at which to start auto-scrolling the drop list or the
   * viewport. The value comes from trying it out manually until it feels right.
   */
  const SCROLL_PROXIMITY_THRESHOLD = 0.05;
  /**
   * Number of pixels to scroll for each frame when auto-scrolling an element.
   * The value comes from trying it out manually until it feels right.
   */
  const AUTO_SCROLL_STEP = 2;
  /**
   * Reference to a drop list. Used to manipulate or dispose of the container.
   */
  class DropListRef {
      constructor(element, _dragDropRegistry, _document, _ngZone, _viewportRuler) {
          this._dragDropRegistry = _dragDropRegistry;
          this._ngZone = _ngZone;
          this._viewportRuler = _viewportRuler;
          /** Whether starting a dragging sequence from this container is disabled. */
          this.disabled = false;
          /** Whether sorting items within the list is disabled. */
          this.sortingDisabled = false;
          /**
           * Whether auto-scrolling the view when the user
           * moves their pointer close to the edges is disabled.
           */
          this.autoScrollDisabled = false;
          /**
           * Function that is used to determine whether an item
           * is allowed to be moved into a drop container.
           */
          this.enterPredicate = () => true;
          /** Emits right before dragging has started. */
          this.beforeStarted = new Subject();
          /**
           * Emits when the user has moved a new drag item into this container.
           */
          this.entered = new Subject();
          /**
           * Emits when the user removes an item from the container
           * by dragging it into another container.
           */
          this.exited = new Subject();
          /** Emits when the user drops an item inside the container. */
          this.dropped = new Subject();
          /** Emits as the user is swapping items while actively dragging. */
          this.sorted = new Subject();
          /** Whether an item in the list is being dragged. */
          this._isDragging = false;
          /** Cache of the dimensions of all the items inside the container. */
          this._itemPositions = [];
          /**
           * Keeps track of the item that was last swapped with the dragged item, as well as what direction
           * the pointer was moving in when the swap occured and whether the user's pointer continued to
           * overlap with the swapped item after the swapping occurred.
           */
          this._previousSwap = { drag: null, delta: 0, overlaps: false };
          /** Drop lists that are connected to the current one. */
          this._siblings = [];
          /** Direction in which the list is oriented. */
          this._orientation = 'vertical';
          /** Connected siblings that currently have a dragged item. */
          this._activeSiblings = new Set();
          /** Layout direction of the drop list. */
          this._direction = 'ltr';
          /** Subscription to the window being scrolled. */
          this._viewportScrollSubscription = Subscription.EMPTY;
          /** Vertical direction in which the list is currently scrolling. */
          this._verticalScrollDirection = 0 /* NONE */;
          /** Horizontal direction in which the list is currently scrolling. */
          this._horizontalScrollDirection = 0 /* NONE */;
          /** Used to signal to the current auto-scroll sequence when to stop. */
          this._stopScrollTimers = new Subject();
          /** Shadow root of the current element. Necessary for `elementFromPoint` to resolve correctly. */
          this._cachedShadowRoot = null;
          /** Starts the interval that'll auto-scroll the element. */
          this._startScrollInterval = () => {
              this._stopScrolling();
              interval(0, animationFrameScheduler)
                  .pipe(takeUntil(this._stopScrollTimers))
                  .subscribe(() => {
                  const node = this._scrollNode;
                  if (this._verticalScrollDirection === 1 /* UP */) {
                      incrementVerticalScroll(node, -AUTO_SCROLL_STEP);
                  }
                  else if (this._verticalScrollDirection === 2 /* DOWN */) {
                      incrementVerticalScroll(node, AUTO_SCROLL_STEP);
                  }
                  if (this._horizontalScrollDirection === 1 /* LEFT */) {
                      incrementHorizontalScroll(node, -AUTO_SCROLL_STEP);
                  }
                  else if (this._horizontalScrollDirection === 2 /* RIGHT */) {
                      incrementHorizontalScroll(node, AUTO_SCROLL_STEP);
                  }
              });
          };
          this.element = coerceElement(element);
          this._document = _document;
          this.withScrollableParents([this.element]);
          _dragDropRegistry.registerDropContainer(this);
          this._parentPositions = new ParentPositionTracker(_document, _viewportRuler);
      }
      /** Removes the drop list functionality from the DOM element. */
      dispose() {
          this._stopScrolling();
          this._stopScrollTimers.complete();
          this._viewportScrollSubscription.unsubscribe();
          this.beforeStarted.complete();
          this.entered.complete();
          this.exited.complete();
          this.dropped.complete();
          this.sorted.complete();
          this._activeSiblings.clear();
          this._scrollNode = null;
          this._parentPositions.clear();
          this._dragDropRegistry.removeDropContainer(this);
      }
      /** Whether an item from this list is currently being dragged. */
      isDragging() {
          return this._isDragging;
      }
      /** Starts dragging an item. */
      start() {
          const styles = coerceElement(this.element).style;
          this.beforeStarted.next();
          this._isDragging = true;
          // We need to disable scroll snapping while the user is dragging, because it breaks automatic
          // scrolling. The browser seems to round the value based on the snapping points which means
          // that we can't increment/decrement the scroll position.
          this._initialScrollSnap = styles.msScrollSnapType || styles.scrollSnapType || '';
          styles.scrollSnapType = styles.msScrollSnapType = 'none';
          this._cacheItems();
          this._siblings.forEach(sibling => sibling._startReceiving(this));
          this._viewportScrollSubscription.unsubscribe();
          this._listenToScrollEvents();
      }
      /**
       * Emits an event to indicate that the user moved an item into the container.
       * @param item Item that was moved into the container.
       * @param pointerX Position of the item along the X axis.
       * @param pointerY Position of the item along the Y axis.
       * @param index Index at which the item entered. If omitted, the container will try to figure it
       *   out automatically.
       */
      enter(item, pointerX, pointerY, index) {
          this.start();
          // If sorting is disabled, we want the item to return to its starting
          // position if the user is returning it to its initial container.
          let newIndex;
          if (index == null) {
              newIndex = this.sortingDisabled ? this._draggables.indexOf(item) : -1;
              if (newIndex === -1) {
                  // We use the coordinates of where the item entered the drop
                  // zone to figure out at which index it should be inserted.
                  newIndex = this._getItemIndexFromPointerPosition(item, pointerX, pointerY);
              }
          }
          else {
              newIndex = index;
          }
          const activeDraggables = this._activeDraggables;
          const currentIndex = activeDraggables.indexOf(item);
          const placeholder = item.getPlaceholderElement();
          let newPositionReference = activeDraggables[newIndex];
          // If the item at the new position is the same as the item that is being dragged,
          // it means that we're trying to restore the item to its initial position. In this
          // case we should use the next item from the list as the reference.
          if (newPositionReference === item) {
              newPositionReference = activeDraggables[newIndex + 1];
          }
          // Since the item may be in the `activeDraggables` already (e.g. if the user dragged it
          // into another container and back again), we have to ensure that it isn't duplicated.
          if (currentIndex > -1) {
              activeDraggables.splice(currentIndex, 1);
          }
          // Don't use items that are being dragged as a reference, because
          // their element has been moved down to the bottom of the body.
          if (newPositionReference && !this._dragDropRegistry.isDragging(newPositionReference)) {
              const element = newPositionReference.getRootElement();
              element.parentElement.insertBefore(placeholder, element);
              activeDraggables.splice(newIndex, 0, item);
          }
          else if (this._shouldEnterAsFirstChild(pointerX, pointerY)) {
              const reference = activeDraggables[0].getRootElement();
              reference.parentNode.insertBefore(placeholder, reference);
              activeDraggables.unshift(item);
          }
          else {
              coerceElement(this.element).appendChild(placeholder);
              activeDraggables.push(item);
          }
          // The transform needs to be cleared so it doesn't throw off the measurements.
          placeholder.style.transform = '';
          // Note that the positions were already cached when we called `start` above,
          // but we need to refresh them since the amount of items has changed and also parent rects.
          this._cacheItemPositions();
          this._cacheParentPositions();
          this.entered.next({ item, container: this, currentIndex: this.getItemIndex(item) });
      }
      /**
       * Removes an item from the container after it was dragged into another container by the user.
       * @param item Item that was dragged out.
       */
      exit(item) {
          this._reset();
          this.exited.next({ item, container: this });
      }
      /**
       * Drops an item into this container.
       * @param item Item being dropped into the container.
       * @param currentIndex Index at which the item should be inserted.
       * @param previousContainer Container from which the item got dragged in.
       * @param isPointerOverContainer Whether the user's pointer was over the
       *    container when the item was dropped.
       * @param distance Distance the user has dragged since the start of the dragging sequence.
       * @param previousIndex Index of the item when dragging started.
       *
       * @breaking-change 11.0.0 `previousIndex` parameter to become required.
       */
      drop(item, currentIndex, previousContainer, isPointerOverContainer, distance, previousIndex) {
          this._reset();
          // @breaking-change 11.0.0 Remove this fallback logic once `previousIndex` is a required param.
          if (previousIndex == null) {
              previousIndex = previousContainer.getItemIndex(item);
          }
          this.dropped.next({ item,
              currentIndex,
              previousIndex,
              container: this,
              previousContainer,
              isPointerOverContainer,
              distance
          });
      }
      /**
       * Sets the draggable items that are a part of this list.
       * @param items Items that are a part of this list.
       */
      withItems(items) {
          const previousItems = this._draggables;
          this._draggables = items;
          items.forEach(item => item._withDropContainer(this));
          if (this.isDragging()) {
              const draggedItems = previousItems.filter(item => item.isDragging());
              // If all of the items being dragged were removed
              // from the list, abort the current drag sequence.
              if (draggedItems.every(item => items.indexOf(item) === -1)) {
                  this._reset();
              }
              else {
                  this._cacheItems();
              }
          }
          return this;
      }
      /** Sets the layout direction of the drop list. */
      withDirection(direction) {
          this._direction = direction;
          return this;
      }
      /**
       * Sets the containers that are connected to this one. When two or more containers are
       * connected, the user will be allowed to transfer items between them.
       * @param connectedTo Other containers that the current containers should be connected to.
       */
      connectedTo(connectedTo) {
          this._siblings = connectedTo.slice();
          return this;
      }
      /**
       * Sets the orientation of the container.
       * @param orientation New orientation for the container.
       */
      withOrientation(orientation) {
          this._orientation = orientation;
          return this;
      }
      /**
       * Sets which parent elements are can be scrolled while the user is dragging.
       * @param elements Elements that can be scrolled.
       */
      withScrollableParents(elements) {
          const element = coerceElement(this.element);
          // We always allow the current element to be scrollable
          // so we need to ensure that it's in the array.
          this._scrollableElements =
              elements.indexOf(element) === -1 ? [element, ...elements] : elements.slice();
          return this;
      }
      /** Gets the scrollable parents that are registered with this drop container. */
      getScrollableParents() {
          return this._scrollableElements;
      }
      /**
       * Figures out the index of an item in the container.
       * @param item Item whose index should be determined.
       */
      getItemIndex(item) {
          if (!this._isDragging) {
              return this._draggables.indexOf(item);
          }
          // Items are sorted always by top/left in the cache, however they flow differently in RTL.
          // The rest of the logic still stands no matter what orientation we're in, however
          // we need to invert the array when determining the index.
          const items = this._orientation === 'horizontal' && this._direction === 'rtl' ?
              this._itemPositions.slice().reverse() : this._itemPositions;
          return findIndex(items, currentItem => currentItem.drag === item);
      }
      /**
       * Whether the list is able to receive the item that
       * is currently being dragged inside a connected drop list.
       */
      isReceiving() {
          return this._activeSiblings.size > 0;
      }
      /**
       * Sorts an item inside the container based on its position.
       * @param item Item to be sorted.
       * @param pointerX Position of the item along the X axis.
       * @param pointerY Position of the item along the Y axis.
       * @param pointerDelta Direction in which the pointer is moving along each axis.
       */
      _sortItem(item, pointerX, pointerY, pointerDelta) {
          // Don't sort the item if sorting is disabled or it's out of range.
          if (this.sortingDisabled ||
              !isPointerNearClientRect(this._clientRect, DROP_PROXIMITY_THRESHOLD, pointerX, pointerY)) {
              return;
          }
          const siblings = this._itemPositions;
          const newIndex = this._getItemIndexFromPointerPosition(item, pointerX, pointerY, pointerDelta);
          if (newIndex === -1 && siblings.length > 0) {
              return;
          }
          const isHorizontal = this._orientation === 'horizontal';
          const currentIndex = findIndex(siblings, currentItem => currentItem.drag === item);
          const siblingAtNewPosition = siblings[newIndex];
          const currentPosition = siblings[currentIndex].clientRect;
          const newPosition = siblingAtNewPosition.clientRect;
          const delta = currentIndex > newIndex ? 1 : -1;
          // How many pixels the item's placeholder should be offset.
          const itemOffset = this._getItemOffsetPx(currentPosition, newPosition, delta);
          // How many pixels all the other items should be offset.
          const siblingOffset = this._getSiblingOffsetPx(currentIndex, siblings, delta);
          // Save the previous order of the items before moving the item to its new index.
          // We use this to check whether an item has been moved as a result of the sorting.
          const oldOrder = siblings.slice();
          // Shuffle the array in place.
          moveItemInArray(siblings, currentIndex, newIndex);
          this.sorted.next({
              previousIndex: currentIndex,
              currentIndex: newIndex,
              container: this,
              item
          });
          siblings.forEach((sibling, index) => {
              // Don't do anything if the position hasn't changed.
              if (oldOrder[index] === sibling) {
                  return;
              }
              const isDraggedItem = sibling.drag === item;
              const offset = isDraggedItem ? itemOffset : siblingOffset;
              const elementToOffset = isDraggedItem ? item.getPlaceholderElement() :
                  sibling.drag.getRootElement();
              // Update the offset to reflect the new position.
              sibling.offset += offset;
              // Since we're moving the items with a `transform`, we need to adjust their cached
              // client rects to reflect their new position, as well as swap their positions in the cache.
              // Note that we shouldn't use `getBoundingClientRect` here to update the cache, because the
              // elements may be mid-animation which will give us a wrong result.
              if (isHorizontal) {
                  // Round the transforms since some browsers will
                  // blur the elements, for sub-pixel transforms.
                  elementToOffset.style.transform = `translate3d(${Math.round(sibling.offset)}px, 0, 0)`;
                  adjustClientRect(sibling.clientRect, 0, offset);
              }
              else {
                  elementToOffset.style.transform = `translate3d(0, ${Math.round(sibling.offset)}px, 0)`;
                  adjustClientRect(sibling.clientRect, offset, 0);
              }
          });
          // Note that it's important that we do this after the client rects have been adjusted.
          this._previousSwap.overlaps = isInsideClientRect(newPosition, pointerX, pointerY);
          this._previousSwap.drag = siblingAtNewPosition.drag;
          this._previousSwap.delta = isHorizontal ? pointerDelta.x : pointerDelta.y;
      }
      /**
       * Checks whether the user's pointer is close to the edges of either the
       * viewport or the drop list and starts the auto-scroll sequence.
       * @param pointerX User's pointer position along the x axis.
       * @param pointerY User's pointer position along the y axis.
       */
      _startScrollingIfNecessary(pointerX, pointerY) {
          if (this.autoScrollDisabled) {
              return;
          }
          let scrollNode;
          let verticalScrollDirection = 0 /* NONE */;
          let horizontalScrollDirection = 0 /* NONE */;
          // Check whether we should start scrolling any of the parent containers.
          this._parentPositions.positions.forEach((position, element) => {
              // We have special handling for the `document` below. Also this would be
              // nicer with a  for...of loop, but it requires changing a compiler flag.
              if (element === this._document || !position.clientRect || scrollNode) {
                  return;
              }
              if (isPointerNearClientRect(position.clientRect, DROP_PROXIMITY_THRESHOLD, pointerX, pointerY)) {
                  [verticalScrollDirection, horizontalScrollDirection] = getElementScrollDirections(element, position.clientRect, pointerX, pointerY);
                  if (verticalScrollDirection || horizontalScrollDirection) {
                      scrollNode = element;
                  }
              }
          });
          // Otherwise check if we can start scrolling the viewport.
          if (!verticalScrollDirection && !horizontalScrollDirection) {
              const { width, height } = this._viewportRuler.getViewportSize();
              const clientRect = { width, height, top: 0, right: width, bottom: height, left: 0 };
              verticalScrollDirection = getVerticalScrollDirection(clientRect, pointerY);
              horizontalScrollDirection = getHorizontalScrollDirection(clientRect, pointerX);
              scrollNode = window;
          }
          if (scrollNode && (verticalScrollDirection !== this._verticalScrollDirection ||
              horizontalScrollDirection !== this._horizontalScrollDirection ||
              scrollNode !== this._scrollNode)) {
              this._verticalScrollDirection = verticalScrollDirection;
              this._horizontalScrollDirection = horizontalScrollDirection;
              this._scrollNode = scrollNode;
              if ((verticalScrollDirection || horizontalScrollDirection) && scrollNode) {
                  this._ngZone.runOutsideAngular(this._startScrollInterval);
              }
              else {
                  this._stopScrolling();
              }
          }
      }
      /** Stops any currently-running auto-scroll sequences. */
      _stopScrolling() {
          this._stopScrollTimers.next();
      }
      /** Caches the positions of the configured scrollable parents. */
      _cacheParentPositions() {
          const element = coerceElement(this.element);
          this._parentPositions.cache(this._scrollableElements);
          // The list element is always in the `scrollableElements`
          // so we can take advantage of the cached `ClientRect`.
          this._clientRect = this._parentPositions.positions.get(element).clientRect;
      }
      /** Refreshes the position cache of the items and sibling containers. */
      _cacheItemPositions() {
          const isHorizontal = this._orientation === 'horizontal';
          this._itemPositions = this._activeDraggables.map(drag => {
              const elementToMeasure = drag.getVisibleElement();
              return { drag, offset: 0, clientRect: getMutableClientRect(elementToMeasure) };
          }).sort((a, b) => {
              return isHorizontal ? a.clientRect.left - b.clientRect.left :
                  a.clientRect.top - b.clientRect.top;
          });
      }
      /** Resets the container to its initial state. */
      _reset() {
          this._isDragging = false;
          const styles = coerceElement(this.element).style;
          styles.scrollSnapType = styles.msScrollSnapType = this._initialScrollSnap;
          // TODO(crisbeto): may have to wait for the animations to finish.
          this._activeDraggables.forEach(item => {
              const rootElement = item.getRootElement();
              if (rootElement) {
                  rootElement.style.transform = '';
              }
          });
          this._siblings.forEach(sibling => sibling._stopReceiving(this));
          this._activeDraggables = [];
          this._itemPositions = [];
          this._previousSwap.drag = null;
          this._previousSwap.delta = 0;
          this._previousSwap.overlaps = false;
          this._stopScrolling();
          this._viewportScrollSubscription.unsubscribe();
          this._parentPositions.clear();
      }
      /**
       * Gets the offset in pixels by which the items that aren't being dragged should be moved.
       * @param currentIndex Index of the item currently being dragged.
       * @param siblings All of the items in the list.
       * @param delta Direction in which the user is moving.
       */
      _getSiblingOffsetPx(currentIndex, siblings, delta) {
          const isHorizontal = this._orientation === 'horizontal';
          const currentPosition = siblings[currentIndex].clientRect;
          const immediateSibling = siblings[currentIndex + delta * -1];
          let siblingOffset = currentPosition[isHorizontal ? 'width' : 'height'] * delta;
          if (immediateSibling) {
              const start = isHorizontal ? 'left' : 'top';
              const end = isHorizontal ? 'right' : 'bottom';
              // Get the spacing between the start of the current item and the end of the one immediately
              // after it in the direction in which the user is dragging, or vice versa. We add it to the
              // offset in order to push the element to where it will be when it's inline and is influenced
              // by the `margin` of its siblings.
              if (delta === -1) {
                  siblingOffset -= immediateSibling.clientRect[start] - currentPosition[end];
              }
              else {
                  siblingOffset += currentPosition[start] - immediateSibling.clientRect[end];
              }
          }
          return siblingOffset;
      }
      /**
       * Gets the offset in pixels by which the item that is being dragged should be moved.
       * @param currentPosition Current position of the item.
       * @param newPosition Position of the item where the current item should be moved.
       * @param delta Direction in which the user is moving.
       */
      _getItemOffsetPx(currentPosition, newPosition, delta) {
          const isHorizontal = this._orientation === 'horizontal';
          let itemOffset = isHorizontal ? newPosition.left - currentPosition.left :
              newPosition.top - currentPosition.top;
          // Account for differences in the item width/height.
          if (delta === -1) {
              itemOffset += isHorizontal ? newPosition.width - currentPosition.width :
                  newPosition.height - currentPosition.height;
          }
          return itemOffset;
      }
      /**
       * Checks if pointer is entering in the first position
       * @param pointerX Position of the user's pointer along the X axis.
       * @param pointerY Position of the user's pointer along the Y axis.
       */
      _shouldEnterAsFirstChild(pointerX, pointerY) {
          if (!this._activeDraggables.length) {
              return false;
          }
          const itemPositions = this._itemPositions;
          const isHorizontal = this._orientation === 'horizontal';
          // `itemPositions` are sorted by position while `activeDraggables` are sorted by child index
          // check if container is using some sort of "reverse" ordering (eg: flex-direction: row-reverse)
          const reversed = itemPositions[0].drag !== this._activeDraggables[0];
          if (reversed) {
              const lastItemRect = itemPositions[itemPositions.length - 1].clientRect;
              return isHorizontal ? pointerX >= lastItemRect.right : pointerY >= lastItemRect.bottom;
          }
          else {
              const firstItemRect = itemPositions[0].clientRect;
              return isHorizontal ? pointerX <= firstItemRect.left : pointerY <= firstItemRect.top;
          }
      }
      /**
       * Gets the index of an item in the drop container, based on the position of the user's pointer.
       * @param item Item that is being sorted.
       * @param pointerX Position of the user's pointer along the X axis.
       * @param pointerY Position of the user's pointer along the Y axis.
       * @param delta Direction in which the user is moving their pointer.
       */
      _getItemIndexFromPointerPosition(item, pointerX, pointerY, delta) {
          const isHorizontal = this._orientation === 'horizontal';
          return findIndex(this._itemPositions, ({ drag, clientRect }, _, array) => {
              if (drag === item) {
                  // If there's only one item left in the container, it must be
                  // the dragged item itself so we use it as a reference.
                  return array.length < 2;
              }
              if (delta) {
                  const direction = isHorizontal ? delta.x : delta.y;
                  // If the user is still hovering over the same item as last time, their cursor hasn't left
                  // the item after we made the swap, and they didn't change the direction in which they're
                  // dragging, we don't consider it a direction swap.
                  if (drag === this._previousSwap.drag && this._previousSwap.overlaps &&
                      direction === this._previousSwap.delta) {
                      return false;
                  }
              }
              return isHorizontal ?
                  // Round these down since most browsers report client rects with
                  // sub-pixel precision, whereas the pointer coordinates are rounded to pixels.
                  pointerX >= Math.floor(clientRect.left) && pointerX < Math.floor(clientRect.right) :
                  pointerY >= Math.floor(clientRect.top) && pointerY < Math.floor(clientRect.bottom);
          });
      }
      /** Caches the current items in the list and their positions. */
      _cacheItems() {
          this._activeDraggables = this._draggables.slice();
          this._cacheItemPositions();
          this._cacheParentPositions();
      }
      /**
       * Checks whether the user's pointer is positioned over the container.
       * @param x Pointer position along the X axis.
       * @param y Pointer position along the Y axis.
       */
      _isOverContainer(x, y) {
          return isInsideClientRect(this._clientRect, x, y);
      }
      /**
       * Figures out whether an item should be moved into a sibling
       * drop container, based on its current position.
       * @param item Drag item that is being moved.
       * @param x Position of the item along the X axis.
       * @param y Position of the item along the Y axis.
       */
      _getSiblingContainerFromPosition(item, x, y) {
          return this._siblings.find(sibling => sibling._canReceive(item, x, y));
      }
      /**
       * Checks whether the drop list can receive the passed-in item.
       * @param item Item that is being dragged into the list.
       * @param x Position of the item along the X axis.
       * @param y Position of the item along the Y axis.
       */
      _canReceive(item, x, y) {
          if (!isInsideClientRect(this._clientRect, x, y) || !this.enterPredicate(item, this)) {
              return false;
          }
          const elementFromPoint = this._getShadowRoot().elementFromPoint(x, y);
          // If there's no element at the pointer position, then
          // the client rect is probably scrolled out of the view.
          if (!elementFromPoint) {
              return false;
          }
          const nativeElement = coerceElement(this.element);
          // The `ClientRect`, that we're using to find the container over which the user is
          // hovering, doesn't give us any information on whether the element has been scrolled
          // out of the view or whether it's overlapping with other containers. This means that
          // we could end up transferring the item into a container that's invisible or is positioned
          // below another one. We use the result from `elementFromPoint` to get the top-most element
          // at the pointer position and to find whether it's one of the intersecting drop containers.
          return elementFromPoint === nativeElement || nativeElement.contains(elementFromPoint);
      }
      /**
       * Called by one of the connected drop lists when a dragging sequence has started.
       * @param sibling Sibling in which dragging has started.
       */
      _startReceiving(sibling) {
          const activeSiblings = this._activeSiblings;
          if (!activeSiblings.has(sibling)) {
              activeSiblings.add(sibling);
              this._cacheParentPositions();
              this._listenToScrollEvents();
          }
      }
      /**
       * Called by a connected drop list when dragging has stopped.
       * @param sibling Sibling whose dragging has stopped.
       */
      _stopReceiving(sibling) {
          this._activeSiblings.delete(sibling);
          this._viewportScrollSubscription.unsubscribe();
      }
      /**
       * Starts listening to scroll events on the viewport.
       * Used for updating the internal state of the list.
       */
      _listenToScrollEvents() {
          this._viewportScrollSubscription = this._dragDropRegistry.scroll.subscribe(event => {
              if (this.isDragging()) {
                  const scrollDifference = this._parentPositions.handleScroll(event);
                  if (scrollDifference) {
                      // Since we know the amount that the user has scrolled we can shift all of the
                      // client rectangles ourselves. This is cheaper than re-measuring everything and
                      // we can avoid inconsistent behavior where we might be measuring the element before
                      // its position has changed.
                      this._itemPositions.forEach(({ clientRect }) => {
                          adjustClientRect(clientRect, scrollDifference.top, scrollDifference.left);
                      });
                      // We need two loops for this, because we want all of the cached
                      // positions to be up-to-date before we re-sort the item.
                      this._itemPositions.forEach(({ drag }) => {
                          if (this._dragDropRegistry.isDragging(drag)) {
                              // We need to re-sort the item manually, because the pointer move
                              // events won't be dispatched while the user is scrolling.
                              drag._sortFromLastPointerPosition();
                          }
                      });
                  }
              }
              else if (this.isReceiving()) {
                  this._cacheParentPositions();
              }
          });
      }
      /**
       * Lazily resolves and returns the shadow root of the element. We do this in a function, rather
       * than saving it in property directly on init, because we want to resolve it as late as possible
       * in order to ensure that the element has been moved into the shadow DOM. Doing it inside the
       * constructor might be too early if the element is inside of something like `ngFor` or `ngIf`.
       */
      _getShadowRoot() {
          if (!this._cachedShadowRoot) {
              const shadowRoot = _getShadowRoot(coerceElement(this.element));
              this._cachedShadowRoot = shadowRoot || this._document;
          }
          return this._cachedShadowRoot;
      }
  }
  /**
   * Finds the index of an item that matches a predicate function. Used as an equivalent
   * of `Array.prototype.findIndex` which isn't part of the standard Google typings.
   * @param array Array in which to look for matches.
   * @param predicate Function used to determine whether an item is a match.
   */
  function findIndex(array, predicate) {
      for (let i = 0; i < array.length; i++) {
          if (predicate(array[i], i, array)) {
              return i;
          }
      }
      return -1;
  }
  /**
   * Increments the vertical scroll position of a node.
   * @param node Node whose scroll position should change.
   * @param amount Amount of pixels that the `node` should be scrolled.
   */
  function incrementVerticalScroll(node, amount) {
      if (node === window) {
          node.scrollBy(0, amount);
      }
      else {
          // Ideally we could use `Element.scrollBy` here as well, but IE and Edge don't support it.
          node.scrollTop += amount;
      }
  }
  /**
   * Increments the horizontal scroll position of a node.
   * @param node Node whose scroll position should change.
   * @param amount Amount of pixels that the `node` should be scrolled.
   */
  function incrementHorizontalScroll(node, amount) {
      if (node === window) {
          node.scrollBy(amount, 0);
      }
      else {
          // Ideally we could use `Element.scrollBy` here as well, but IE and Edge don't support it.
          node.scrollLeft += amount;
      }
  }
  /**
   * Gets whether the vertical auto-scroll direction of a node.
   * @param clientRect Dimensions of the node.
   * @param pointerY Position of the user's pointer along the y axis.
   */
  function getVerticalScrollDirection(clientRect, pointerY) {
      const { top, bottom, height } = clientRect;
      const yThreshold = height * SCROLL_PROXIMITY_THRESHOLD;
      if (pointerY >= top - yThreshold && pointerY <= top + yThreshold) {
          return 1 /* UP */;
      }
      else if (pointerY >= bottom - yThreshold && pointerY <= bottom + yThreshold) {
          return 2 /* DOWN */;
      }
      return 0 /* NONE */;
  }
  /**
   * Gets whether the horizontal auto-scroll direction of a node.
   * @param clientRect Dimensions of the node.
   * @param pointerX Position of the user's pointer along the x axis.
   */
  function getHorizontalScrollDirection(clientRect, pointerX) {
      const { left, right, width } = clientRect;
      const xThreshold = width * SCROLL_PROXIMITY_THRESHOLD;
      if (pointerX >= left - xThreshold && pointerX <= left + xThreshold) {
          return 1 /* LEFT */;
      }
      else if (pointerX >= right - xThreshold && pointerX <= right + xThreshold) {
          return 2 /* RIGHT */;
      }
      return 0 /* NONE */;
  }
  /**
   * Gets the directions in which an element node should be scrolled,
   * assuming that the user's pointer is already within it scrollable region.
   * @param element Element for which we should calculate the scroll direction.
   * @param clientRect Bounding client rectangle of the element.
   * @param pointerX Position of the user's pointer along the x axis.
   * @param pointerY Position of the user's pointer along the y axis.
   */
  function getElementScrollDirections(element, clientRect, pointerX, pointerY) {
      const computedVertical = getVerticalScrollDirection(clientRect, pointerY);
      const computedHorizontal = getHorizontalScrollDirection(clientRect, pointerX);
      let verticalScrollDirection = 0 /* NONE */;
      let horizontalScrollDirection = 0 /* NONE */;
      // Note that we here we do some extra checks for whether the element is actually scrollable in
      // a certain direction and we only assign the scroll direction if it is. We do this so that we
      // can allow other elements to be scrolled, if the current element can't be scrolled anymore.
      // This allows us to handle cases where the scroll regions of two scrollable elements overlap.
      if (computedVertical) {
          const scrollTop = element.scrollTop;
          if (computedVertical === 1 /* UP */) {
              if (scrollTop > 0) {
                  verticalScrollDirection = 1 /* UP */;
              }
          }
          else if (element.scrollHeight - scrollTop > element.clientHeight) {
              verticalScrollDirection = 2 /* DOWN */;
          }
      }
      if (computedHorizontal) {
          const scrollLeft = element.scrollLeft;
          if (computedHorizontal === 1 /* LEFT */) {
              if (scrollLeft > 0) {
                  horizontalScrollDirection = 1 /* LEFT */;
              }
          }
          else if (element.scrollWidth - scrollLeft > element.clientWidth) {
              horizontalScrollDirection = 2 /* RIGHT */;
          }
      }
      return [verticalScrollDirection, horizontalScrollDirection];
  }
  
  /**
   * @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
   */
  /** Event options that can be used to bind an active, capturing event. */
  const activeCapturingEventOptions = normalizePassiveListenerOptions({
      passive: false,
      capture: true
  });
  /**
   * Service that keeps track of all the drag item and drop container
   * instances, and manages global event listeners on the `document`.
   * @docs-private
   */
  // Note: this class is generic, rather than referencing CdkDrag and CdkDropList directly, in order
  // to avoid circular imports. If we were to reference them here, importing the registry into the
  // classes that are registering themselves will introduce a circular import.
  class DragDropRegistry {
      constructor(_ngZone, _document) {
          this._ngZone = _ngZone;
          /** Registered drop container instances. */
          this._dropInstances = new Set();
          /** Registered drag item instances. */
          this._dragInstances = new Set();
          /** Drag item instances that are currently being dragged. */
          this._activeDragInstances = new Set();
          /** Keeps track of the event listeners that we've bound to the `document`. */
          this._globalListeners = new Map();
          /**
           * Emits the `touchmove` or `mousemove` events that are dispatched
           * while the user is dragging a drag item instance.
           */
          this.pointerMove = new Subject();
          /**
           * Emits the `touchend` or `mouseup` events that are dispatched
           * while the user is dragging a drag item instance.
           */
          this.pointerUp = new Subject();
          /** Emits when the viewport has been scrolled while the user is dragging an item. */
          this.scroll = new Subject();
          /**
           * Event listener that will prevent the default browser action while the user is dragging.
           * @param event Event whose default action should be prevented.
           */
          this._preventDefaultWhileDragging = (event) => {
              if (this._activeDragInstances.size) {
                  event.preventDefault();
              }
          };
          this._document = _document;
      }
      /** Adds a drop container to the registry. */
      registerDropContainer(drop) {
          if (!this._dropInstances.has(drop)) {
              this._dropInstances.add(drop);
          }
      }
      /** Adds a drag item instance to the registry. */
      registerDragItem(drag) {
          this._dragInstances.add(drag);
          // The `touchmove` event gets bound once, ahead of time, because WebKit
          // won't preventDefault on a dynamically-added `touchmove` listener.
          // See https://bugs.webkit.org/show_bug.cgi?id=184250.
          if (this._dragInstances.size === 1) {
              this._ngZone.runOutsideAngular(() => {
                  // The event handler has to be explicitly active,
                  // because newer browsers make it passive by default.
                  this._document.addEventListener('touchmove', this._preventDefaultWhileDragging, activeCapturingEventOptions);
              });
          }
      }
      /** Removes a drop container from the registry. */
      removeDropContainer(drop) {
          this._dropInstances.delete(drop);
      }
      /** Removes a drag item instance from the registry. */
      removeDragItem(drag) {
          this._dragInstances.delete(drag);
          this.stopDragging(drag);
          if (this._dragInstances.size === 0) {
              this._document.removeEventListener('touchmove', this._preventDefaultWhileDragging, activeCapturingEventOptions);
          }
      }
      /**
       * Starts the dragging sequence for a drag instance.
       * @param drag Drag instance which is being dragged.
       * @param event Event that initiated the dragging.
       */
      startDragging(drag, event) {
          // Do not process the same drag twice to avoid memory leaks and redundant listeners
          if (this._activeDragInstances.has(drag)) {
              return;
          }
          this._activeDragInstances.add(drag);
          if (this._activeDragInstances.size === 1) {
              const isTouchEvent = event.type.startsWith('touch');
              const moveEvent = isTouchEvent ? 'touchmove' : 'mousemove';
              const upEvent = isTouchEvent ? 'touchend' : 'mouseup';
              // We explicitly bind __active__ listeners here, because newer browsers will default to
              // passive ones for `mousemove` and `touchmove`. The events need to be active, because we
              // use `preventDefault` to prevent the page from scrolling while the user is dragging.
              this._globalListeners
                  .set(moveEvent, {
                  handler: (e) => this.pointerMove.next(e),
                  options: activeCapturingEventOptions
              })
                  .set(upEvent, {
                  handler: (e) => this.pointerUp.next(e),
                  options: true
              })
                  .set('scroll', {
                  handler: (e) => this.scroll.next(e),
                  // Use capturing so that we pick up scroll changes in any scrollable nodes that aren't
                  // the document. See https://github.com/angular/components/issues/17144.
                  options: true
              })
                  // Preventing the default action on `mousemove` isn't enough to disable text selection
                  // on Safari so we need to prevent the selection event as well. Alternatively this can
                  // be done by setting `user-select: none` on the `body`, however it has causes a style
                  // recalculation which can be expensive on pages with a lot of elements.
                  .set('selectstart', {
                  handler: this._preventDefaultWhileDragging,
                  options: activeCapturingEventOptions
              });
              this._ngZone.runOutsideAngular(() => {
                  this._globalListeners.forEach((config, name) => {
                      this._document.addEventListener(name, config.handler, config.options);
                  });
              });
          }
      }
      /** Stops dragging a drag item instance. */
      stopDragging(drag) {
          this._activeDragInstances.delete(drag);
          if (this._activeDragInstances.size === 0) {
              this._clearGlobalListeners();
          }
      }
      /** Gets whether a drag item instance is currently being dragged. */
      isDragging(drag) {
          return this._activeDragInstances.has(drag);
      }
      ngOnDestroy() {
          this._dragInstances.forEach(instance => this.removeDragItem(instance));
          this._dropInstances.forEach(instance => this.removeDropContainer(instance));
          this._clearGlobalListeners();
          this.pointerMove.complete();
          this.pointerUp.complete();
      }
      /** Clears out the global event listeners from the `document`. */
      _clearGlobalListeners() {
          this._globalListeners.forEach((config, name) => {
              this._document.removeEventListener(name, config.handler, config.options);
          });
          this._globalListeners.clear();
      }
  }
  DragDropRegistry.ɵfac = function DragDropRegistry_Factory(t) { return new (t || DragDropRegistry)(ɵngcc0.ɵɵinject(NgZone), ɵngcc0.ɵɵinject(DOCUMENT)); };
  DragDropRegistry.ɵprov = ɵɵdefineInjectable({ factory: function DragDropRegistry_Factory() { return new DragDropRegistry(ɵɵinject(NgZone), ɵɵinject(DOCUMENT)); }, token: DragDropRegistry, providedIn: "root" });
  DragDropRegistry.ctorParameters = () => [
      { type: NgZone },
      { type: undefined, decorators: [{ type: Inject, args: [DOCUMENT,] }] }
  ];
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(DragDropRegistry, [{
          type: Injectable,
          args: [{ providedIn: 'root' }]
      }], function () { return [{ type: NgZone }, { type: undefined, decorators: [{
                  type: Inject,
                  args: [DOCUMENT]
              }] }]; }, null); })();
  
  /**
   * @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
   */
  /** Default configuration to be used when creating a `DragRef`. */
  const DEFAULT_CONFIG = {
      dragStartThreshold: 5,
      pointerDirectionChangeThreshold: 5
  };
  /**
   * Service that allows for drag-and-drop functionality to be attached to DOM elements.
   */
  class DragDrop {
      constructor(_document, _ngZone, _viewportRuler, _dragDropRegistry) {
          this._document = _document;
          this._ngZone = _ngZone;
          this._viewportRuler = _viewportRuler;
          this._dragDropRegistry = _dragDropRegistry;
      }
      /**
       * Turns an element into a draggable item.
       * @param element Element to which to attach the dragging functionality.
       * @param config Object used to configure the dragging behavior.
       */
      createDrag(element, config = DEFAULT_CONFIG) {
          return new DragRef(element, config, this._document, this._ngZone, this._viewportRuler, this._dragDropRegistry);
      }
      /**
       * Turns an element into a drop list.
       * @param element Element to which to attach the drop list functionality.
       */
      createDropList(element) {
          return new DropListRef(element, this._dragDropRegistry, this._document, this._ngZone, this._viewportRuler);
      }
  }
  DragDrop.ɵfac = function DragDrop_Factory(t) { return new (t || DragDrop)(ɵngcc0.ɵɵinject(DOCUMENT), ɵngcc0.ɵɵinject(NgZone), ɵngcc0.ɵɵinject(ViewportRuler), ɵngcc0.ɵɵinject(DragDropRegistry)); };
  DragDrop.ɵprov = ɵɵdefineInjectable({ factory: function DragDrop_Factory() { return new DragDrop(ɵɵinject(DOCUMENT), ɵɵinject(NgZone), ɵɵinject(ViewportRuler), ɵɵinject(DragDropRegistry)); }, token: DragDrop, providedIn: "root" });
  DragDrop.ctorParameters = () => [
      { type: undefined, decorators: [{ type: Inject, args: [DOCUMENT,] }] },
      { type: NgZone },
      { type: ViewportRuler },
      { type: DragDropRegistry }
  ];
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(DragDrop, [{
          type: Injectable,
          args: [{ providedIn: 'root' }]
      }], function () { return [{ type: undefined, decorators: [{
                  type: Inject,
                  args: [DOCUMENT]
              }] }, { type: NgZone }, { type: ViewportRuler }, { type: DragDropRegistry }]; }, null); })();
  
  /**
   * @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
   */
  /**
   * Injection token that can be used for a `CdkDrag` to provide itself as a parent to the
   * drag-specific child directive (`CdkDragHandle`, `CdkDragPreview` etc.). Used primarily
   * to avoid circular imports.
   * @docs-private
   */
  const CDK_DRAG_PARENT = new InjectionToken('CDK_DRAG_PARENT');
  
  /**
   * @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
   */
  
  /**
   * @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
   */
  /**
   * Injection token that can be used to reference instances of `CdkDropListGroup`. It serves as
   * alternative token to the actual `CdkDropListGroup` class which could cause unnecessary
   * retention of the class and its directive metadata.
   */
  const CDK_DROP_LIST_GROUP = new InjectionToken('CdkDropListGroup');
  /**
   * Declaratively connects sibling `cdkDropList` instances together. All of the `cdkDropList`
   * elements that are placed inside a `cdkDropListGroup` will be connected to each other
   * automatically. Can be used as an alternative to the `cdkDropListConnectedTo` input
   * from `cdkDropList`.
   */
  class CdkDropListGroup {
      constructor() {
          /** Drop lists registered inside the group. */
          this._items = new Set();
          this._disabled = false;
      }
      /** Whether starting a dragging sequence from inside this group is disabled. */
      get disabled() { return this._disabled; }
      set disabled(value) {
          this._disabled = coerceBooleanProperty(value);
      }
      ngOnDestroy() {
          this._items.clear();
      }
  }
  CdkDropListGroup.ɵfac = function CdkDropListGroup_Factory(t) { return new (t || CdkDropListGroup)(); };
  CdkDropListGroup.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDropListGroup, selectors: [["", "cdkDropListGroup", ""]], inputs: { disabled: ["cdkDropListGroupDisabled", "disabled"] }, exportAs: ["cdkDropListGroup"], features: [ɵngcc0.ɵɵProvidersFeature([{ provide: CDK_DROP_LIST_GROUP, useExisting: CdkDropListGroup }])] });
  CdkDropListGroup.propDecorators = {
      disabled: [{ type: Input, args: ['cdkDropListGroupDisabled',] }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDropListGroup, [{
          type: Directive,
          args: [{
                  selector: '[cdkDropListGroup]',
                  exportAs: 'cdkDropListGroup',
                  providers: [{ provide: CDK_DROP_LIST_GROUP, useExisting: CdkDropListGroup }]
              }]
      }], function () { return []; }, { disabled: [{
              type: Input,
              args: ['cdkDropListGroupDisabled']
          }] }); })();
  
  /**
   * @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
   */
  /**
   * Injection token that can be used to configure the
   * behavior of the drag&drop-related components.
   */
  const CDK_DRAG_CONFIG = new InjectionToken('CDK_DRAG_CONFIG');
  
  /**
   * @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
   */
  /** Counter used to generate unique ids for drop zones. */
  let _uniqueIdCounter = 0;
  /**
   * Injection token that can be used to reference instances of `CdkDropList`. It serves as
   * alternative token to the actual `CdkDropList` class which could cause unnecessary
   * retention of the class and its directive metadata.
   */
  const CDK_DROP_LIST = new InjectionToken('CdkDropList');
  const ɵ0 = undefined;
  /** Container that wraps a set of draggable items. */
  class CdkDropList {
      constructor(
      /** Element that the drop list is attached to. */
      element, dragDrop, _changeDetectorRef, _dir, _group, 
      /**
       * @deprecated _scrollDispatcher parameter to become required.
       * @breaking-change 11.0.0
       */
      _scrollDispatcher, config) {
          this.element = element;
          this._changeDetectorRef = _changeDetectorRef;
          this._dir = _dir;
          this._group = _group;
          this._scrollDispatcher = _scrollDispatcher;
          /** Emits when the list has been destroyed. */
          this._destroyed = new Subject();
          /**
           * Other draggable containers that this container is connected to and into which the
           * container's items can be transferred. Can either be references to other drop containers,
           * or their unique IDs.
           */
          this.connectedTo = [];
          /**
           * Unique ID for the drop zone. Can be used as a reference
           * in the `connectedTo` of another `CdkDropList`.
           */
          this.id = `cdk-drop-list-${_uniqueIdCounter++}`;
          /**
           * Function that is used to determine whether an item
           * is allowed to be moved into a drop container.
           */
          this.enterPredicate = () => true;
          /** Emits when the user drops an item inside the container. */
          this.dropped = new EventEmitter();
          /**
           * Emits when the user has moved a new drag item into this container.
           */
          this.entered = new EventEmitter();
          /**
           * Emits when the user removes an item from the container
           * by dragging it into another container.
           */
          this.exited = new EventEmitter();
          /** Emits as the user is swapping items while actively dragging. */
          this.sorted = new EventEmitter();
          /**
           * Keeps track of the items that are registered with this container. Historically we used to
           * do this with a `ContentChildren` query, however queries don't handle transplanted views very
           * well which means that we can't handle cases like dragging the headers of a `mat-table`
           * correctly. What we do instead is to have the items register themselves with the container
           * and then we sort them based on their position in the DOM.
           */
          this._unsortedItems = new Set();
          this._dropListRef = dragDrop.createDropList(element);
          this._dropListRef.data = this;
          if (config) {
              this._assignDefaults(config);
          }
          this._dropListRef.enterPredicate = (drag, drop) => {
              return this.enterPredicate(drag.data, drop.data);
          };
          this._setupInputSyncSubscription(this._dropListRef);
          this._handleEvents(this._dropListRef);
          CdkDropList._dropLists.push(this);
          if (_group) {
              _group._items.add(this);
          }
      }
      /** Whether starting a dragging sequence from this container is disabled. */
      get disabled() {
          return this._disabled || (!!this._group && this._group.disabled);
      }
      set disabled(value) {
          // Usually we sync the directive and ref state right before dragging starts, in order to have
          // a single point of failure and to avoid having to use setters for everything. `disabled` is
          // a special case, because it can prevent the `beforeStarted` event from firing, which can lock
          // the user in a disabled state, so we also need to sync it as it's being set.
          this._dropListRef.disabled = this._disabled = coerceBooleanProperty(value);
      }
      /** Registers an items with the drop list. */
      addItem(item) {
          this._unsortedItems.add(item);
          if (this._dropListRef.isDragging()) {
              this._syncItemsWithRef();
          }
      }
      /** Removes an item from the drop list. */
      removeItem(item) {
          this._unsortedItems.delete(item);
          if (this._dropListRef.isDragging()) {
              this._syncItemsWithRef();
          }
      }
      /** Gets the registered items in the list, sorted by their position in the DOM. */
      getSortedItems() {
          return Array.from(this._unsortedItems).sort((a, b) => {
              const documentPosition = a._dragRef.getVisibleElement().compareDocumentPosition(b._dragRef.getVisibleElement());
              // `compareDocumentPosition` returns a bitmask so we have to use a bitwise operator.
              // https://developer.mozilla.org/en-US/docs/Web/API/Node/compareDocumentPosition
              // tslint:disable-next-line:no-bitwise
              return documentPosition & Node.DOCUMENT_POSITION_FOLLOWING ? -1 : 1;
          });
      }
      ngOnDestroy() {
          const index = CdkDropList._dropLists.indexOf(this);
          if (index > -1) {
              CdkDropList._dropLists.splice(index, 1);
          }
          if (this._group) {
              this._group._items.delete(this);
          }
          this._unsortedItems.clear();
          this._dropListRef.dispose();
          this._destroyed.next();
          this._destroyed.complete();
      }
      /** Syncs the inputs of the CdkDropList with the options of the underlying DropListRef. */
      _setupInputSyncSubscription(ref) {
          if (this._dir) {
              this._dir.change
                  .pipe(startWith(this._dir.value), takeUntil(this._destroyed))
                  .subscribe(value => ref.withDirection(value));
          }
          ref.beforeStarted.subscribe(() => {
              const siblings = coerceArray(this.connectedTo).map(drop => {
                  if (typeof drop === 'string') {
                      const correspondingDropList = CdkDropList._dropLists.find(list => list.id === drop);
                      if (!correspondingDropList && (typeof ngDevMode === 'undefined' || ngDevMode)) {
                          console.warn(`CdkDropList could not find connected drop list with id "${drop}"`);
                      }
                      return correspondingDropList;
                  }
                  return drop;
              });
              if (this._group) {
                  this._group._items.forEach(drop => {
                      if (siblings.indexOf(drop) === -1) {
                          siblings.push(drop);
                      }
                  });
              }
              // Note that we resolve the scrollable parents here so that we delay the resolution
              // as long as possible, ensuring that the element is in its final place in the DOM.
              // @breaking-change 11.0.0 Remove null check for _scrollDispatcher once it's required.
              if (!this._scrollableParentsResolved && this._scrollDispatcher) {
                  const scrollableParents = this._scrollDispatcher
                      .getAncestorScrollContainers(this.element)
                      .map(scrollable => scrollable.getElementRef().nativeElement);
                  this._dropListRef.withScrollableParents(scrollableParents);
                  // Only do this once since it involves traversing the DOM and the parents
                  // shouldn't be able to change without the drop list being destroyed.
                  this._scrollableParentsResolved = true;
              }
              ref.disabled = this.disabled;
              ref.lockAxis = this.lockAxis;
              ref.sortingDisabled = coerceBooleanProperty(this.sortingDisabled);
              ref.autoScrollDisabled = coerceBooleanProperty(this.autoScrollDisabled);
              ref
                  .connectedTo(siblings.filter(drop => drop && drop !== this).map(list => list._dropListRef))
                  .withOrientation(this.orientation);
          });
      }
      /** Handles events from the underlying DropListRef. */
      _handleEvents(ref) {
          ref.beforeStarted.subscribe(() => {
              this._syncItemsWithRef();
              this._changeDetectorRef.markForCheck();
          });
          ref.entered.subscribe(event => {
              this.entered.emit({
                  container: this,
                  item: event.item.data,
                  currentIndex: event.currentIndex
              });
          });
          ref.exited.subscribe(event => {
              this.exited.emit({
                  container: this,
                  item: event.item.data
              });
              this._changeDetectorRef.markForCheck();
          });
          ref.sorted.subscribe(event => {
              this.sorted.emit({
                  previousIndex: event.previousIndex,
                  currentIndex: event.currentIndex,
                  container: this,
                  item: event.item.data
              });
          });
          ref.dropped.subscribe(event => {
              this.dropped.emit({
                  previousIndex: event.previousIndex,
                  currentIndex: event.currentIndex,
                  previousContainer: event.previousContainer.data,
                  container: event.container.data,
                  item: event.item.data,
                  isPointerOverContainer: event.isPointerOverContainer,
                  distance: event.distance
              });
              // Mark for check since all of these events run outside of change
              // detection and we're not guaranteed for something else to have triggered it.
              this._changeDetectorRef.markForCheck();
          });
      }
      /** Assigns the default input values based on a provided config object. */
      _assignDefaults(config) {
          const { lockAxis, draggingDisabled, sortingDisabled, listAutoScrollDisabled, listOrientation } = config;
          this.disabled = draggingDisabled == null ? false : draggingDisabled;
          this.sortingDisabled = sortingDisabled == null ? false : sortingDisabled;
          this.autoScrollDisabled = listAutoScrollDisabled == null ? false : listAutoScrollDisabled;
          this.orientation = listOrientation || 'vertical';
          if (lockAxis) {
              this.lockAxis = lockAxis;
          }
      }
      /** Syncs up the registered drag items with underlying drop list ref. */
      _syncItemsWithRef() {
          this._dropListRef.withItems(this.getSortedItems().map(item => item._dragRef));
      }
  }
  CdkDropList.ɵfac = function CdkDropList_Factory(t) { return new (t || CdkDropList)(ɵngcc0.ɵɵdirectiveInject(ElementRef), ɵngcc0.ɵɵdirectiveInject(DragDrop), ɵngcc0.ɵɵdirectiveInject(ChangeDetectorRef), ɵngcc0.ɵɵdirectiveInject(Directionality, 8), ɵngcc0.ɵɵdirectiveInject(CDK_DROP_LIST_GROUP, 12), ɵngcc0.ɵɵdirectiveInject(ScrollDispatcher), ɵngcc0.ɵɵdirectiveInject(CDK_DRAG_CONFIG, 8)); };
  CdkDropList.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDropList, selectors: [["", "cdkDropList", ""], ["cdk-drop-list"]], hostAttrs: [1, "cdk-drop-list"], hostVars: 7, hostBindings: function CdkDropList_HostBindings(rf, ctx) { if (rf & 2) {
          ɵngcc0.ɵɵhostProperty("id", ctx.id);
          ɵngcc0.ɵɵclassProp("cdk-drop-list-disabled", ctx.disabled)("cdk-drop-list-dragging", ctx._dropListRef.isDragging())("cdk-drop-list-receiving", ctx._dropListRef.isReceiving());
      } }, inputs: { connectedTo: ["cdkDropListConnectedTo", "connectedTo"], id: "id", enterPredicate: ["cdkDropListEnterPredicate", "enterPredicate"], disabled: ["cdkDropListDisabled", "disabled"], sortingDisabled: ["cdkDropListSortingDisabled", "sortingDisabled"], autoScrollDisabled: ["cdkDropListAutoScrollDisabled", "autoScrollDisabled"], orientation: ["cdkDropListOrientation", "orientation"], lockAxis: ["cdkDropListLockAxis", "lockAxis"], data: ["cdkDropListData", "data"] }, outputs: { dropped: "cdkDropListDropped", entered: "cdkDropListEntered", exited: "cdkDropListExited", sorted: "cdkDropListSorted" }, exportAs: ["cdkDropList"], features: [ɵngcc0.ɵɵProvidersFeature([
              // Prevent child drop lists from picking up the same group as their parent.
              { provide: CDK_DROP_LIST_GROUP, useValue: ɵ0 },
              { provide: CDK_DROP_LIST, useExisting: CdkDropList },
          ])] });
  /** Keeps track of the drop lists that are currently on the page. */
  CdkDropList._dropLists = [];
  CdkDropList.ctorParameters = () => [
      { type: ElementRef },
      { type: DragDrop },
      { type: ChangeDetectorRef },
      { type: Directionality, decorators: [{ type: Optional }] },
      { type: CdkDropListGroup, decorators: [{ type: Optional }, { type: Inject, args: [CDK_DROP_LIST_GROUP,] }, { type: SkipSelf }] },
      { type: ScrollDispatcher },
      { type: undefined, decorators: [{ type: Optional }, { type: Inject, args: [CDK_DRAG_CONFIG,] }] }
  ];
  CdkDropList.propDecorators = {
      connectedTo: [{ type: Input, args: ['cdkDropListConnectedTo',] }],
      data: [{ type: Input, args: ['cdkDropListData',] }],
      orientation: [{ type: Input, args: ['cdkDropListOrientation',] }],
      id: [{ type: Input }],
      lockAxis: [{ type: Input, args: ['cdkDropListLockAxis',] }],
      disabled: [{ type: Input, args: ['cdkDropListDisabled',] }],
      sortingDisabled: [{ type: Input, args: ['cdkDropListSortingDisabled',] }],
      enterPredicate: [{ type: Input, args: ['cdkDropListEnterPredicate',] }],
      autoScrollDisabled: [{ type: Input, args: ['cdkDropListAutoScrollDisabled',] }],
      dropped: [{ type: Output, args: ['cdkDropListDropped',] }],
      entered: [{ type: Output, args: ['cdkDropListEntered',] }],
      exited: [{ type: Output, args: ['cdkDropListExited',] }],
      sorted: [{ type: Output, args: ['cdkDropListSorted',] }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDropList, [{
          type: Directive,
          args: [{
                  selector: '[cdkDropList], cdk-drop-list',
                  exportAs: 'cdkDropList',
                  providers: [
                      // Prevent child drop lists from picking up the same group as their parent.
                      { provide: CDK_DROP_LIST_GROUP, useValue: ɵ0 },
                      { provide: CDK_DROP_LIST, useExisting: CdkDropList },
                  ],
                  host: {
                      'class': 'cdk-drop-list',
                      '[id]': 'id',
                      '[class.cdk-drop-list-disabled]': 'disabled',
                      '[class.cdk-drop-list-dragging]': '_dropListRef.isDragging()',
                      '[class.cdk-drop-list-receiving]': '_dropListRef.isReceiving()'
                  }
              }]
      }], function () { return [{ type: ElementRef }, { type: DragDrop }, { type: ChangeDetectorRef }, { type: Directionality, decorators: [{
                  type: Optional
              }] }, { type: CdkDropListGroup, decorators: [{
                  type: Optional
              }, {
                  type: Inject,
                  args: [CDK_DROP_LIST_GROUP]
              }, {
                  type: SkipSelf
              }] }, { type: ScrollDispatcher }, { type: undefined, decorators: [{
                  type: Optional
              }, {
                  type: Inject,
                  args: [CDK_DRAG_CONFIG]
              }] }]; }, { connectedTo: [{
              type: Input,
              args: ['cdkDropListConnectedTo']
          }], id: [{
              type: Input
          }], enterPredicate: [{
              type: Input,
              args: ['cdkDropListEnterPredicate']
          }], dropped: [{
              type: Output,
              args: ['cdkDropListDropped']
          }], entered: [{
              type: Output,
              args: ['cdkDropListEntered']
          }], exited: [{
              type: Output,
              args: ['cdkDropListExited']
          }], sorted: [{
              type: Output,
              args: ['cdkDropListSorted']
          }], disabled: [{
              type: Input,
              args: ['cdkDropListDisabled']
          }], sortingDisabled: [{
              type: Input,
              args: ['cdkDropListSortingDisabled']
          }], autoScrollDisabled: [{
              type: Input,
              args: ['cdkDropListAutoScrollDisabled']
          }], orientation: [{
              type: Input,
              args: ['cdkDropListOrientation']
          }], lockAxis: [{
              type: Input,
              args: ['cdkDropListLockAxis']
          }], data: [{
              type: Input,
              args: ['cdkDropListData']
          }] }); })();
  
  /**
   * @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
   */
  /**
   * Injection token that can be used to reference instances of `CdkDragHandle`. It serves as
   * alternative token to the actual `CdkDragHandle` class which could cause unnecessary
   * retention of the class and its directive metadata.
   */
  const CDK_DRAG_HANDLE = new InjectionToken('CdkDragHandle');
  /** Handle that can be used to drag a CdkDrag instance. */
  class CdkDragHandle {
      constructor(element, parentDrag) {
          this.element = element;
          /** Emits when the state of the handle has changed. */
          this._stateChanges = new Subject();
          this._disabled = false;
          this._parentDrag = parentDrag;
      }
      /** Whether starting to drag through this handle is disabled. */
      get disabled() { return this._disabled; }
      set disabled(value) {
          this._disabled = coerceBooleanProperty(value);
          this._stateChanges.next(this);
      }
      ngOnDestroy() {
          this._stateChanges.complete();
      }
  }
  CdkDragHandle.ɵfac = function CdkDragHandle_Factory(t) { return new (t || CdkDragHandle)(ɵngcc0.ɵɵdirectiveInject(ElementRef), ɵngcc0.ɵɵdirectiveInject(CDK_DRAG_PARENT, 12)); };
  CdkDragHandle.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDragHandle, selectors: [["", "cdkDragHandle", ""]], hostAttrs: [1, "cdk-drag-handle"], inputs: { disabled: ["cdkDragHandleDisabled", "disabled"] }, features: [ɵngcc0.ɵɵProvidersFeature([{ provide: CDK_DRAG_HANDLE, useExisting: CdkDragHandle }])] });
  CdkDragHandle.ctorParameters = () => [
      { type: ElementRef },
      { type: undefined, decorators: [{ type: Inject, args: [CDK_DRAG_PARENT,] }, { type: Optional }, { type: SkipSelf }] }
  ];
  CdkDragHandle.propDecorators = {
      disabled: [{ type: Input, args: ['cdkDragHandleDisabled',] }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDragHandle, [{
          type: Directive,
          args: [{
                  selector: '[cdkDragHandle]',
                  host: {
                      'class': 'cdk-drag-handle'
                  },
                  providers: [{ provide: CDK_DRAG_HANDLE, useExisting: CdkDragHandle }]
              }]
      }], function () { return [{ type: ElementRef }, { type: undefined, decorators: [{
                  type: Inject,
                  args: [CDK_DRAG_PARENT]
              }, {
                  type: Optional
              }, {
                  type: SkipSelf
              }] }]; }, { disabled: [{
              type: Input,
              args: ['cdkDragHandleDisabled']
          }] }); })();
  
  /**
   * @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
   */
  /**
   * Injection token that can be used to reference instances of `CdkDragPlaceholder`. It serves as
   * alternative token to the actual `CdkDragPlaceholder` class which could cause unnecessary
   * retention of the class and its directive metadata.
   */
  const CDK_DRAG_PLACEHOLDER = new InjectionToken('CdkDragPlaceholder');
  /**
   * Element that will be used as a template for the placeholder of a CdkDrag when
   * it is being dragged. The placeholder is displayed in place of the element being dragged.
   */
  class CdkDragPlaceholder {
      constructor(templateRef) {
          this.templateRef = templateRef;
      }
  }
  CdkDragPlaceholder.ɵfac = function CdkDragPlaceholder_Factory(t) { return new (t || CdkDragPlaceholder)(ɵngcc0.ɵɵdirectiveInject(TemplateRef)); };
  CdkDragPlaceholder.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDragPlaceholder, selectors: [["ng-template", "cdkDragPlaceholder", ""]], inputs: { data: "data" }, features: [ɵngcc0.ɵɵProvidersFeature([{ provide: CDK_DRAG_PLACEHOLDER, useExisting: CdkDragPlaceholder }])] });
  CdkDragPlaceholder.ctorParameters = () => [
      { type: TemplateRef }
  ];
  CdkDragPlaceholder.propDecorators = {
      data: [{ type: Input }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDragPlaceholder, [{
          type: Directive,
          args: [{
                  selector: 'ng-template[cdkDragPlaceholder]',
                  providers: [{ provide: CDK_DRAG_PLACEHOLDER, useExisting: CdkDragPlaceholder }]
              }]
      }], function () { return [{ type: TemplateRef }]; }, { data: [{
              type: Input
          }] }); })();
  
  /**
   * @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
   */
  /**
   * Injection token that can be used to reference instances of `CdkDragPreview`. It serves as
   * alternative token to the actual `CdkDragPreview` class which could cause unnecessary
   * retention of the class and its directive metadata.
   */
  const CDK_DRAG_PREVIEW = new InjectionToken('CdkDragPreview');
  /**
   * Element that will be used as a template for the preview
   * of a CdkDrag when it is being dragged.
   */
  class CdkDragPreview {
      constructor(templateRef) {
          this.templateRef = templateRef;
          this._matchSize = false;
      }
      /** Whether the preview should preserve the same size as the item that is being dragged. */
      get matchSize() { return this._matchSize; }
      set matchSize(value) { this._matchSize = coerceBooleanProperty(value); }
  }
  CdkDragPreview.ɵfac = function CdkDragPreview_Factory(t) { return new (t || CdkDragPreview)(ɵngcc0.ɵɵdirectiveInject(TemplateRef)); };
  CdkDragPreview.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDragPreview, selectors: [["ng-template", "cdkDragPreview", ""]], inputs: { matchSize: "matchSize", data: "data" }, features: [ɵngcc0.ɵɵProvidersFeature([{ provide: CDK_DRAG_PREVIEW, useExisting: CdkDragPreview }])] });
  CdkDragPreview.ctorParameters = () => [
      { type: TemplateRef }
  ];
  CdkDragPreview.propDecorators = {
      data: [{ type: Input }],
      matchSize: [{ type: Input }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDragPreview, [{
          type: Directive,
          args: [{
                  selector: 'ng-template[cdkDragPreview]',
                  providers: [{ provide: CDK_DRAG_PREVIEW, useExisting: CdkDragPreview }]
              }]
      }], function () { return [{ type: TemplateRef }]; }, { matchSize: [{
              type: Input
          }], data: [{
              type: Input
          }] }); })();
  
  /**
   * @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
   */
  /** Element that can be moved inside a CdkDropList container. */
  class CdkDrag {
      constructor(
      /** Element that the draggable is attached to. */
      element, 
      /** Droppable container that the draggable is a part of. */
      dropContainer, _document, _ngZone, _viewContainerRef, config, _dir, dragDrop, _changeDetectorRef, _selfHandle) {
          this.element = element;
          this.dropContainer = dropContainer;
          this._document = _document;
          this._ngZone = _ngZone;
          this._viewContainerRef = _viewContainerRef;
          this._dir = _dir;
          this._changeDetectorRef = _changeDetectorRef;
          this._selfHandle = _selfHandle;
          this._destroyed = new Subject();
          /** Emits when the user starts dragging the item. */
          this.started = new EventEmitter();
          /** Emits when the user has released a drag item, before any animations have started. */
          this.released = new EventEmitter();
          /** Emits when the user stops dragging an item in the container. */
          this.ended = new EventEmitter();
          /** Emits when the user has moved the item into a new container. */
          this.entered = new EventEmitter();
          /** Emits when the user removes the item its container by dragging it into another container. */
          this.exited = new EventEmitter();
          /** Emits when the user drops the item inside a container. */
          this.dropped = new EventEmitter();
          /**
           * Emits as the user is dragging the item. Use with caution,
           * because this event will fire for every pixel that the user has dragged.
           */
          this.moved = new Observable((observer) => {
              const subscription = this._dragRef.moved.pipe(map(movedEvent => ({
                  source: this,
                  pointerPosition: movedEvent.pointerPosition,
                  event: movedEvent.event,
                  delta: movedEvent.delta,
                  distance: movedEvent.distance
              }))).subscribe(observer);
              return () => {
                  subscription.unsubscribe();
              };
          });
          this._dragRef = dragDrop.createDrag(element, {
              dragStartThreshold: config && config.dragStartThreshold != null ?
                  config.dragStartThreshold : 5,
              pointerDirectionChangeThreshold: config && config.pointerDirectionChangeThreshold != null ?
                  config.pointerDirectionChangeThreshold : 5,
              zIndex: config === null || config === void 0 ? void 0 : config.zIndex
          });
          this._dragRef.data = this;
          if (config) {
              this._assignDefaults(config);
          }
          // Note that usually the container is assigned when the drop list is picks up the item, but in
          // some cases (mainly transplanted views with OnPush, see #18341) we may end up in a situation
          // where there are no items on the first change detection pass, but the items get picked up as
          // soon as the user triggers another pass by dragging. This is a problem, because the item would
          // have to switch from standalone mode to drag mode in the middle of the dragging sequence which
          // is too late since the two modes save different kinds of information. We work around it by
          // assigning the drop container both from here and the list.
          if (dropContainer) {
              this._dragRef._withDropContainer(dropContainer._dropListRef);
              dropContainer.addItem(this);
          }
          this._syncInputs(this._dragRef);
          this._handleEvents(this._dragRef);
      }
      /** Whether starting to drag this element is disabled. */
      get disabled() {
          return this._disabled || (this.dropContainer && this.dropContainer.disabled);
      }
      set disabled(value) {
          this._disabled = coerceBooleanProperty(value);
          this._dragRef.disabled = this._disabled;
      }
      /**
       * Returns the element that is being used as a placeholder
       * while the current element is being dragged.
       */
      getPlaceholderElement() {
          return this._dragRef.getPlaceholderElement();
      }
      /** Returns the root draggable element. */
      getRootElement() {
          return this._dragRef.getRootElement();
      }
      /** Resets a standalone drag item to its initial position. */
      reset() {
          this._dragRef.reset();
      }
      /**
       * Gets the pixel coordinates of the draggable outside of a drop container.
       */
      getFreeDragPosition() {
          return this._dragRef.getFreeDragPosition();
      }
      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._ngZone.onStable
              .pipe(take(1), takeUntil(this._destroyed))
              .subscribe(() => {
              this._updateRootElement();
              // Listen for any newly-added handles.
              this._handles.changes.pipe(startWith(this._handles), 
              // Sync the new handles with the DragRef.
              tap((handles) => {
                  const childHandleElements = handles
                      .filter(handle => handle._parentDrag === this)
                      .map(handle => handle.element);
                  // Usually handles are only allowed to be a descendant of the drag element, but if
                  // the consumer defined a different drag root, we should allow the drag element
                  // itself to be a handle too.
                  if (this._selfHandle && this.rootElementSelector) {
                      childHandleElements.push(this.element);
                  }
                  this._dragRef.withHandles(childHandleElements);
              }), 
              // Listen if the state of any of the handles changes.
              switchMap((handles) => {
                  return merge(...handles.map(item => {
                      return item._stateChanges.pipe(startWith(item));
                  }));
              }), takeUntil(this._destroyed)).subscribe(handleInstance => {
                  // Enabled/disable the handle that changed in the DragRef.
                  const dragRef = this._dragRef;
                  const handle = handleInstance.element.nativeElement;
                  handleInstance.disabled ? dragRef.disableHandle(handle) : dragRef.enableHandle(handle);
              });
              if (this.freeDragPosition) {
                  this._dragRef.setFreeDragPosition(this.freeDragPosition);
              }
          });
      }
      ngOnChanges(changes) {
          const rootSelectorChange = changes['rootElementSelector'];
          const positionChange = changes['freeDragPosition'];
          // We don't have to react to the first change since it's being
          // handled in `ngAfterViewInit` where it needs to be deferred.
          if (rootSelectorChange && !rootSelectorChange.firstChange) {
              this._updateRootElement();
          }
          // Skip the first change since it's being handled in `ngAfterViewInit`.
          if (positionChange && !positionChange.firstChange && this.freeDragPosition) {
              this._dragRef.setFreeDragPosition(this.freeDragPosition);
          }
      }
      ngOnDestroy() {
          if (this.dropContainer) {
              this.dropContainer.removeItem(this);
          }
          this._destroyed.next();
          this._destroyed.complete();
          this._dragRef.dispose();
      }
      /** Syncs the root element with the `DragRef`. */
      _updateRootElement() {
          const element = this.element.nativeElement;
          const rootElement = this.rootElementSelector ?
              getClosestMatchingAncestor(element, this.rootElementSelector) : element;
          if (rootElement && rootElement.nodeType !== this._document.ELEMENT_NODE &&
              (typeof ngDevMode === 'undefined' || ngDevMode)) {
              throw Error(`cdkDrag must be attached to an element node. ` +
                  `Currently attached to "${rootElement.nodeName}".`);
          }
          this._dragRef.withRootElement(rootElement || element);
      }
      /** Gets the boundary element, based on the `boundaryElement` value. */
      _getBoundaryElement() {
          const boundary = this.boundaryElement;
          if (!boundary) {
              return null;
          }
          if (typeof boundary === 'string') {
              return getClosestMatchingAncestor(this.element.nativeElement, boundary);
          }
          const element = coerceElement(boundary);
          if ((typeof ngDevMode === 'undefined' || ngDevMode) &&
              !element.contains(this.element.nativeElement)) {
              throw Error('Draggable element is not inside of the node passed into cdkDragBoundary.');
          }
          return element;
      }
      /** Syncs the inputs of the CdkDrag with the options of the underlying DragRef. */
      _syncInputs(ref) {
          ref.beforeStarted.subscribe(() => {
              if (!ref.isDragging()) {
                  const dir = this._dir;
                  const dragStartDelay = this.dragStartDelay;
                  const placeholder = this._placeholderTemplate ? {
                      template: this._placeholderTemplate.templateRef,
                      context: this._placeholderTemplate.data,
                      viewContainer: this._viewContainerRef
                  } : null;
                  const preview = this._previewTemplate ? {
                      template: this._previewTemplate.templateRef,
                      context: this._previewTemplate.data,
                      matchSize: this._previewTemplate.matchSize,
                      viewContainer: this._viewContainerRef
                  } : null;
                  ref.disabled = this.disabled;
                  ref.lockAxis = this.lockAxis;
                  ref.dragStartDelay = (typeof dragStartDelay === 'object' && dragStartDelay) ?
                      dragStartDelay : coerceNumberProperty(dragStartDelay);
                  ref.constrainPosition = this.constrainPosition;
                  ref.previewClass = this.previewClass;
                  ref
                      .withBoundaryElement(this._getBoundaryElement())
                      .withPlaceholderTemplate(placeholder)
                      .withPreviewTemplate(preview);
                  if (dir) {
                      ref.withDirection(dir.value);
                  }
              }
          });
      }
      /** Handles the events from the underlying `DragRef`. */
      _handleEvents(ref) {
          ref.started.subscribe(() => {
              this.started.emit({ source: this });
              // Since all of these events run outside of change detection,
              // we need to ensure that everything is marked correctly.
              this._changeDetectorRef.markForCheck();
          });
          ref.released.subscribe(() => {
              this.released.emit({ source: this });
          });
          ref.ended.subscribe(event => {
              this.ended.emit({ source: this, distance: event.distance });
              // Since all of these events run outside of change detection,
              // we need to ensure that everything is marked correctly.
              this._changeDetectorRef.markForCheck();
          });
          ref.entered.subscribe(event => {
              this.entered.emit({
                  container: event.container.data,
                  item: this,
                  currentIndex: event.currentIndex
              });
          });
          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,
                  distance: event.distance
              });
          });
      }
      /** Assigns the default input values based on a provided config object. */
      _assignDefaults(config) {
          const { lockAxis, dragStartDelay, constrainPosition, previewClass, boundaryElement, draggingDisabled, rootElementSelector } = config;
          this.disabled = draggingDisabled == null ? false : draggingDisabled;
          this.dragStartDelay = dragStartDelay || 0;
          if (lockAxis) {
              this.lockAxis = lockAxis;
          }
          if (constrainPosition) {
              this.constrainPosition = constrainPosition;
          }
          if (previewClass) {
              this.previewClass = previewClass;
          }
          if (boundaryElement) {
              this.boundaryElement = boundaryElement;
          }
          if (rootElementSelector) {
              this.rootElementSelector = rootElementSelector;
          }
      }
  }
  CdkDrag.ɵfac = function CdkDrag_Factory(t) { return new (t || CdkDrag)(ɵngcc0.ɵɵdirectiveInject(ElementRef), ɵngcc0.ɵɵdirectiveInject(CDK_DROP_LIST, 12), ɵngcc0.ɵɵdirectiveInject(DOCUMENT), ɵngcc0.ɵɵdirectiveInject(NgZone), ɵngcc0.ɵɵdirectiveInject(ViewContainerRef), ɵngcc0.ɵɵdirectiveInject(CDK_DRAG_CONFIG, 8), ɵngcc0.ɵɵdirectiveInject(Directionality, 8), ɵngcc0.ɵɵdirectiveInject(DragDrop), ɵngcc0.ɵɵdirectiveInject(ChangeDetectorRef), ɵngcc0.ɵɵdirectiveInject(CDK_DRAG_HANDLE, 10)); };
  CdkDrag.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: CdkDrag, selectors: [["", "cdkDrag", ""]], contentQueries: function CdkDrag_ContentQueries(rf, ctx, dirIndex) { if (rf & 1) {
          ɵngcc0.ɵɵcontentQuery(dirIndex, CDK_DRAG_PREVIEW, true);
          ɵngcc0.ɵɵcontentQuery(dirIndex, CDK_DRAG_PLACEHOLDER, true);
          ɵngcc0.ɵɵcontentQuery(dirIndex, CDK_DRAG_HANDLE, true);
      } if (rf & 2) {
          var _t;
          ɵngcc0.ɵɵqueryRefresh(_t = ɵngcc0.ɵɵloadQuery()) && (ctx._previewTemplate = _t.first);
          ɵngcc0.ɵɵqueryRefresh(_t = ɵngcc0.ɵɵloadQuery()) && (ctx._placeholderTemplate = _t.first);
          ɵngcc0.ɵɵqueryRefresh(_t = ɵngcc0.ɵɵloadQuery()) && (ctx._handles = _t);
      } }, hostAttrs: [1, "cdk-drag"], hostVars: 4, hostBindings: function CdkDrag_HostBindings(rf, ctx) { if (rf & 2) {
          ɵngcc0.ɵɵclassProp("cdk-drag-disabled", ctx.disabled)("cdk-drag-dragging", ctx._dragRef.isDragging());
      } }, inputs: { disabled: ["cdkDragDisabled", "disabled"], dragStartDelay: ["cdkDragStartDelay", "dragStartDelay"], lockAxis: ["cdkDragLockAxis", "lockAxis"], constrainPosition: ["cdkDragConstrainPosition", "constrainPosition"], previewClass: ["cdkDragPreviewClass", "previewClass"], boundaryElement: ["cdkDragBoundary", "boundaryElement"], rootElementSelector: ["cdkDragRootElement", "rootElementSelector"], data: ["cdkDragData", "data"], freeDragPosition: ["cdkDragFreeDragPosition", "freeDragPosition"] }, outputs: { started: "cdkDragStarted", released: "cdkDragReleased", ended: "cdkDragEnded", entered: "cdkDragEntered", exited: "cdkDragExited", dropped: "cdkDragDropped", moved: "cdkDragMoved" }, exportAs: ["cdkDrag"], features: [ɵngcc0.ɵɵProvidersFeature([{ provide: CDK_DRAG_PARENT, useExisting: CdkDrag }]), ɵngcc0.ɵɵNgOnChangesFeature] });
  CdkDrag.ctorParameters = () => [
      { type: ElementRef },
      { type: undefined, decorators: [{ type: Inject, args: [CDK_DROP_LIST,] }, { type: Optional }, { type: SkipSelf }] },
      { type: undefined, decorators: [{ type: Inject, args: [DOCUMENT,] }] },
      { type: NgZone },
      { type: ViewContainerRef },
      { type: undefined, decorators: [{ type: Optional }, { type: Inject, args: [CDK_DRAG_CONFIG,] }] },
      { type: Directionality, decorators: [{ type: Optional }] },
      { type: DragDrop },
      { type: ChangeDetectorRef },
      { type: CdkDragHandle, decorators: [{ type: Optional }, { type: Self }, { type: Inject, args: [CDK_DRAG_HANDLE,] }] }
  ];
  CdkDrag.propDecorators = {
      _handles: [{ type: ContentChildren, args: [CDK_DRAG_HANDLE, { descendants: true },] }],
      _previewTemplate: [{ type: ContentChild, args: [CDK_DRAG_PREVIEW,] }],
      _placeholderTemplate: [{ type: ContentChild, args: [CDK_DRAG_PLACEHOLDER,] }],
      data: [{ type: Input, args: ['cdkDragData',] }],
      lockAxis: [{ type: Input, args: ['cdkDragLockAxis',] }],
      rootElementSelector: [{ type: Input, args: ['cdkDragRootElement',] }],
      boundaryElement: [{ type: Input, args: ['cdkDragBoundary',] }],
      dragStartDelay: [{ type: Input, args: ['cdkDragStartDelay',] }],
      freeDragPosition: [{ type: Input, args: ['cdkDragFreeDragPosition',] }],
      disabled: [{ type: Input, args: ['cdkDragDisabled',] }],
      constrainPosition: [{ type: Input, args: ['cdkDragConstrainPosition',] }],
      previewClass: [{ type: Input, args: ['cdkDragPreviewClass',] }],
      started: [{ type: Output, args: ['cdkDragStarted',] }],
      released: [{ type: Output, args: ['cdkDragReleased',] }],
      ended: [{ type: Output, args: ['cdkDragEnded',] }],
      entered: [{ type: Output, args: ['cdkDragEntered',] }],
      exited: [{ type: Output, args: ['cdkDragExited',] }],
      dropped: [{ type: Output, args: ['cdkDragDropped',] }],
      moved: [{ type: Output, args: ['cdkDragMoved',] }]
  };
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(CdkDrag, [{
          type: Directive,
          args: [{
                  selector: '[cdkDrag]',
                  exportAs: 'cdkDrag',
                  host: {
                      'class': 'cdk-drag',
                      '[class.cdk-drag-disabled]': 'disabled',
                      '[class.cdk-drag-dragging]': '_dragRef.isDragging()'
                  },
                  providers: [{ provide: CDK_DRAG_PARENT, useExisting: CdkDrag }]
              }]
      }], function () { return [{ type: ElementRef }, { type: undefined, decorators: [{
                  type: Inject,
                  args: [CDK_DROP_LIST]
              }, {
                  type: Optional
              }, {
                  type: SkipSelf
              }] }, { type: undefined, decorators: [{
                  type: Inject,
                  args: [DOCUMENT]
              }] }, { type: NgZone }, { type: ViewContainerRef }, { type: undefined, decorators: [{
                  type: Optional
              }, {
                  type: Inject,
                  args: [CDK_DRAG_CONFIG]
              }] }, { type: Directionality, decorators: [{
                  type: Optional
              }] }, { type: DragDrop }, { type: ChangeDetectorRef }, { type: CdkDragHandle, decorators: [{
                  type: Optional
              }, {
                  type: Self
              }, {
                  type: Inject,
                  args: [CDK_DRAG_HANDLE]
              }] }]; }, { started: [{
              type: Output,
              args: ['cdkDragStarted']
          }], released: [{
              type: Output,
              args: ['cdkDragReleased']
          }], ended: [{
              type: Output,
              args: ['cdkDragEnded']
          }], entered: [{
              type: Output,
              args: ['cdkDragEntered']
          }], exited: [{
              type: Output,
              args: ['cdkDragExited']
          }], dropped: [{
              type: Output,
              args: ['cdkDragDropped']
          }], moved: [{
              type: Output,
              args: ['cdkDragMoved']
          }], disabled: [{
              type: Input,
              args: ['cdkDragDisabled']
          }], dragStartDelay: [{
              type: Input,
              args: ['cdkDragStartDelay']
          }], lockAxis: [{
              type: Input,
              args: ['cdkDragLockAxis']
          }], constrainPosition: [{
              type: Input,
              args: ['cdkDragConstrainPosition']
          }], previewClass: [{
              type: Input,
              args: ['cdkDragPreviewClass']
          }], boundaryElement: [{
              type: Input,
              args: ['cdkDragBoundary']
          }], rootElementSelector: [{
              type: Input,
              args: ['cdkDragRootElement']
          }], _handles: [{
              type: ContentChildren,
              args: [CDK_DRAG_HANDLE, { descendants: true }]
          }], _previewTemplate: [{
              type: ContentChild,
              args: [CDK_DRAG_PREVIEW]
          }], _placeholderTemplate: [{
              type: ContentChild,
              args: [CDK_DRAG_PLACEHOLDER]
          }], data: [{
              type: Input,
              args: ['cdkDragData']
          }], freeDragPosition: [{
              type: Input,
              args: ['cdkDragFreeDragPosition']
          }] }); })();
  /** Gets the closest ancestor of an element that matches a selector. */
  function getClosestMatchingAncestor(element, selector) {
      let currentElement = element.parentElement;
      while (currentElement) {
          // IE doesn't support `matches` so we have to fall back to `msMatchesSelector`.
          if (currentElement.matches ? currentElement.matches(selector) :
              currentElement.msMatchesSelector(selector)) {
              return currentElement;
          }
          currentElement = currentElement.parentElement;
      }
      return null;
  }
  
  /**
   * @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
   */
  class DragDropModule {
  }
  DragDropModule.ɵmod = ɵngcc0.ɵɵdefineNgModule({ type: DragDropModule });
  DragDropModule.ɵinj = ɵngcc0.ɵɵdefineInjector({ factory: function DragDropModule_Factory(t) { return new (t || DragDropModule)(); }, providers: [
          DragDrop,
      ], imports: [CdkScrollableModule] });
  (function () { (typeof ngJitMode === "undefined" || ngJitMode) && ɵngcc0.ɵɵsetNgModuleScope(DragDropModule, { declarations: function () { return [CdkDropList, CdkDropListGroup, CdkDrag, CdkDragHandle, CdkDragPreview, CdkDragPlaceholder]; }, exports: function () { return [CdkScrollableModule, CdkDropList, CdkDropListGroup, CdkDrag, CdkDragHandle, CdkDragPreview, CdkDragPlaceholder]; } }); })();
  /*@__PURE__*/ (function () { ɵngcc0.ɵsetClassMetadata(DragDropModule, [{
          type: NgModule,
          args: [{
                  declarations: [
                      CdkDropList,
                      CdkDropListGroup,
                      CdkDrag,
                      CdkDragHandle,
                      CdkDragPreview,
                      CdkDragPlaceholder,
                  ],
                  exports: [
                      CdkScrollableModule,
                      CdkDropList,
                      CdkDropListGroup,
                      CdkDrag,
                      CdkDragHandle,
                      CdkDragPreview,
                      CdkDragPlaceholder,
                  ],
                  providers: [
                      DragDrop,
                  ]
              }]
      }], null, null); })();
  
  /**
   * @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
   */
  
  /**
   * Generated bundle index. Do not edit.
   */
  
  export { CDK_DRAG_CONFIG, CDK_DRAG_HANDLE, CDK_DRAG_PARENT, CDK_DRAG_PLACEHOLDER, CDK_DRAG_PREVIEW, CDK_DROP_LIST, CDK_DROP_LIST_GROUP, CdkDrag, CdkDragHandle, CdkDragPlaceholder, CdkDragPreview, CdkDropList, CdkDropListGroup, DragDrop, DragDropModule, DragDropRegistry, DragRef, DropListRef, copyArrayItem, moveItemInArray, transferArrayItem };
  
  //# sourceMappingURL=drag-drop.js.map