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drag-ref.ts
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1685 lines (1442 loc) · 63.1 KB
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/**
* @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.dev/license
*/
import {isFakeMousedownFromScreenReader, isFakeTouchstartFromScreenReader} from '../a11y';
import {Direction} from '../bidi';
interface DocumentWithFullscreen extends Document {
webkitFullscreenElement?: Element;
mozFullScreenElement?: Element;
msFullscreenElement?: Element;
}
import {coerceElement} from '../coercion';
import {_getEventTarget, _getShadowRoot} from '../platform';
import {ViewportRuler} from '../scrolling';
import {
DOCUMENT,
ElementRef,
EmbeddedViewRef,
Injector,
NgZone,
Renderer2,
RendererFactory2,
TemplateRef,
ViewContainerRef,
signal,
} from '@angular/core';
import {Observable, Subject, Subscription} from 'rxjs';
import {deepCloneNode} from './dom/clone-node';
import {adjustDomRect, getMutableClientRect, isOverflowingParent} from './dom/dom-rect';
import {ParentPositionTracker} from './dom/parent-position-tracker';
import {getRootNode} from './dom/root-node';
import {
DragCSSStyleDeclaration,
combineTransforms,
getTransform,
toggleNativeDragInteractions,
toggleVisibility,
} from './dom/styling';
import {DragDropRegistry} from './drag-drop-registry';
import type {DropListRef} from './drop-list-ref';
import {DragPreviewTemplate, PreviewRef} from './preview-ref';
/** Object that can be used to configure the behavior of DragRef. */
export interface DragRefConfig {
/**
* Minimum amount of pixels that the user should
* drag, before the CDK initiates a drag sequence.
*/
dragStartThreshold: number;
/**
* Amount the pixels the user should drag before the CDK
* considers them to have changed the drag direction.
*/
pointerDirectionChangeThreshold: number;
/** `z-index` for the absolutely-positioned elements that are created by the drag item. */
zIndex?: number;
/** Ref that the current drag item is nested in. */
parentDragRef?: DragRef;
}
/** Function that can be used to constrain the position of a dragged element. */
export type DragConstrainPosition = (
userPointerPosition: Point,
dragRef: DragRef,
dimensions: DOMRect,
pickupPositionInElement: Point,
) => Point;
/** Options that can be used to bind a passive event listener. */
const passiveEventListenerOptions = {passive: true};
/** Options that can be used to bind an active event listener. */
const activeEventListenerOptions = {passive: false};
/** Event options that can be used to bind an active, capturing event. */
const activeCapturingEventOptions = {
passive: false,
capture: true,
};
/**
* 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;
/** Class applied to the drag placeholder. */
const PLACEHOLDER_CLASS = 'cdk-drag-placeholder';
// TODO(crisbeto): add an API for moving a draggable up/down the
// list programmatically. Useful for keyboard controls.
/** Template that can be used to create a drag helper element (e.g. a preview or a placeholder). */
interface DragHelperTemplate<T = any> {
template: TemplateRef<T> | null;
viewContainer: ViewContainerRef;
context: T;
}
/** Point on the page or within an element. */
export interface Point {
x: number;
y: number;
}
/** Inline styles to be set as `!important` while dragging. */
const dragImportantProperties = new Set([
// Needs to be important, because some `mat-table` sets `position: sticky !important`. See #22781.
'position',
]);
/**
* Possible places into which the preview of a drag item can be inserted.
* - `global` - Preview will be inserted at the bottom of the `<body>`. The advantage is that
* you don't have to worry about `overflow: hidden` or `z-index`, but the item won't retain
* its inherited styles.
* - `parent` - Preview will be inserted into the parent of the drag item. The advantage is that
* inherited styles will be preserved, but it may be clipped by `overflow: hidden` or not be
* visible due to `z-index`. Furthermore, the preview is going to have an effect over selectors
* like `:nth-child` and some flexbox configurations.
* - `ElementRef<HTMLElement> | HTMLElement` - Preview will be inserted into a specific element.
* Same advantages and disadvantages as `parent`.
*/
export type PreviewContainer = 'global' | 'parent' | ElementRef<HTMLElement> | HTMLElement;
/**
* Creates a `DragRef` for an element, turning it into a draggable item.
* @param injector Injector used to resolve dependencies.
* @param element Element to which to attach the dragging functionality.
* @param config Object used to configure the dragging behavior.
*/
export function createDragRef<T = unknown>(
injector: Injector,
element: ElementRef<HTMLElement> | HTMLElement,
config: DragRefConfig = {
dragStartThreshold: 5,
pointerDirectionChangeThreshold: 5,
},
): DragRef<T> {
const renderer =
injector.get(Renderer2, null, {optional: true}) ||
injector.get(RendererFactory2).createRenderer(null, null);
return new DragRef(
element,
config,
injector.get(DOCUMENT),
injector.get(NgZone),
injector.get(ViewportRuler),
injector.get(DragDropRegistry),
renderer,
);
}
/**
* Reference to a draggable item. Used to manipulate or dispose of the item.
*/
export class DragRef<T = any> {
private _rootElementCleanups: (() => void)[] | undefined;
private _cleanupShadowRootSelectStart: (() => void) | undefined;
/** Element displayed next to the user's pointer while the element is dragged. */
private _preview: PreviewRef | null = null;
/** Container into which to insert the preview. */
private _previewContainer: PreviewContainer | undefined;
/** Reference to the view of the placeholder element. */
private _placeholderRef: EmbeddedViewRef<any> | null = null;
/** Element that is rendered instead of the draggable item while it is being sorted. */
private _placeholder!: HTMLElement;
/** Coordinates within the element at which the user picked up the element. */
private _pickupPositionInElement!: Point;
/** Coordinates on the page at which the user picked up the element. */
private _pickupPositionOnPage!: Point;
/**
* Marker node used to save the place in the DOM where the element was
* picked up so that it can be restored at the end of the drag sequence.
*/
private _marker!: Comment;
/**
* Element indicating the position from which the item was picked up initially.
*/
private _anchor: HTMLElement | null = null;
/**
* 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`.
*/
private _passiveTransform: Point = {x: 0, y: 0};
/** CSS `transform` that is applied to the element while it's being dragged. */
private _activeTransform: Point = {x: 0, y: 0};
/** Inline `transform` value that the element had before the first dragging sequence. */
private _initialTransform?: string;
/**
* Whether the dragging sequence has been started. Doesn't
* necessarily mean that the element has been moved.
*/
private _hasStartedDragging = signal(false);
/** Whether the element has moved since the user started dragging it. */
private _hasMoved = false;
/** Drop container in which the DragRef resided when dragging began. */
private _initialContainer!: DropListRef;
/** Index at which the item started in its initial container. */
private _initialIndex!: number;
/** Cached positions of scrollable parent elements. */
private _parentPositions: ParentPositionTracker;
/** Emits when the item is being moved. */
private readonly _moveEvents = new Subject<{
source: DragRef;
pointerPosition: {x: number; y: number};
event: MouseEvent | TouchEvent;
distance: Point;
delta: {x: -1 | 0 | 1; y: -1 | 0 | 1};
}>();
/** Keeps track of the direction in which the user is dragging along each axis. */
private _pointerDirectionDelta!: {x: -1 | 0 | 1; y: -1 | 0 | 1};
/** Pointer position at which the last change in the delta occurred. */
private _pointerPositionAtLastDirectionChange!: Point;
/** Position of the pointer at the last pointer event. */
private _lastKnownPointerPosition!: Point;
/**
* Root DOM node of the drag instance. This is the element that will
* be moved around as the user is dragging.
*/
private _rootElement!: HTMLElement;
/**
* Nearest ancestor SVG, relative to which coordinates are calculated if dragging SVGElement
*/
private _ownerSVGElement: SVGSVGElement | null = null;
/**
* Inline style value of `-webkit-tap-highlight-color` at the time the
* dragging was started. Used to restore the value once we're done dragging.
*/
private _rootElementTapHighlight!: string;
/** Subscription to pointer movement events. */
private _pointerMoveSubscription = Subscription.EMPTY;
/** Subscription to the event that is dispatched when the user lifts their pointer. */
private _pointerUpSubscription = Subscription.EMPTY;
/** Subscription to the viewport being scrolled. */
private _scrollSubscription = Subscription.EMPTY;
/** Subscription to the viewport being resized. */
private _resizeSubscription = Subscription.EMPTY;
/**
* Time at which the last touch event occurred. Used to avoid firing the same
* events multiple times on touch devices where the browser will fire a fake
* mouse event for each touch event, after a certain time.
*/
private _lastTouchEventTime!: number;
/** Time at which the last dragging sequence was started. */
private _dragStartTime!: number;
/** Cached reference to the boundary element. */
private _boundaryElement: HTMLElement | null = null;
/** Whether the native dragging interactions have been enabled on the root element. */
private _nativeInteractionsEnabled = true;
/** Client rect of the root element when the dragging sequence has started. */
private _initialDomRect?: DOMRect;
/** Cached dimensions of the preview element. Should be read via `_getPreviewRect`. */
private _previewRect?: DOMRect;
/** Cached dimensions of the boundary element. */
private _boundaryRect?: DOMRect;
/** Element that will be used as a template to create the draggable item's preview. */
private _previewTemplate?: DragPreviewTemplate | null;
/** Template for placeholder element rendered to show where a draggable would be dropped. */
private _placeholderTemplate?: DragHelperTemplate | null;
/** Elements that can be used to drag the draggable item. */
private _handles: HTMLElement[] = [];
/** Registered handles that are currently disabled. */
private _disabledHandles = new Set<HTMLElement>();
/** Droppable container that the draggable is a part of. */
private _dropContainer?: DropListRef;
/** Layout direction of the item. */
private _direction: Direction = 'ltr';
/** Ref that the current drag item is nested in. */
private _parentDragRef: DragRef<unknown> | null = null;
/**
* Cached shadow root that the element is placed in. `null` means that the element isn't in
* the shadow DOM and `undefined` means that it hasn't been resolved yet. Should be read via
* `_getShadowRoot`, not directly.
*/
private _cachedShadowRoot: ShadowRoot | null | undefined;
/** Axis along which dragging is locked. */
lockAxis: 'x' | 'y' | null = null;
/**
* Amount of milliseconds to wait after the user has put their
* pointer down before starting to drag the element.
*/
dragStartDelay: number | {touch: number; mouse: number} = 0;
/** Class to be added to the preview element. */
previewClass: string | string[] | undefined;
/**
* If the parent of the dragged element has a `scale` transform, it can throw off the
* positioning when the user starts dragging. Use this input to notify the CDK of the scale.
*/
scale: number = 1;
/** Whether starting to drag this element is disabled. */
get disabled(): boolean {
return this._disabled || !!(this._dropContainer && this._dropContainer.disabled);
}
set disabled(value: boolean) {
if (value !== this._disabled) {
this._disabled = value;
this._toggleNativeDragInteractions();
this._handles.forEach(handle => toggleNativeDragInteractions(handle, value));
}
}
private _disabled = false;
/** Emits as the drag sequence is being prepared. */
readonly beforeStarted = new Subject<void>();
/** Emits when the user starts dragging the item. */
readonly started = new Subject<{source: DragRef; event: MouseEvent | TouchEvent}>();
/** Emits when the user has released a drag item, before any animations have started. */
readonly released = new Subject<{source: DragRef; event: MouseEvent | TouchEvent}>();
/** Emits when the user stops dragging an item in the container. */
readonly ended = new Subject<{
source: DragRef;
distance: Point;
dropPoint: Point;
event: MouseEvent | TouchEvent;
}>();
/** Emits when the user has moved the item into a new container. */
readonly entered = new Subject<{container: DropListRef; item: DragRef; currentIndex: number}>();
/** Emits when the user removes the item its container by dragging it into another container. */
readonly exited = new Subject<{container: DropListRef; item: DragRef}>();
/** Emits when the user drops the item inside a container. */
readonly dropped = new Subject<{
previousIndex: number;
currentIndex: number;
item: DragRef;
container: DropListRef;
previousContainer: DropListRef;
distance: Point;
dropPoint: Point;
isPointerOverContainer: boolean;
event: MouseEvent | TouchEvent;
}>();
/**
* Emits as the user is dragging the item. Use with caution,
* because this event will fire for every pixel that the user has dragged.
*/
readonly moved: Observable<{
source: DragRef;
pointerPosition: {x: number; y: number};
event: MouseEvent | TouchEvent;
distance: Point;
delta: {x: -1 | 0 | 1; y: -1 | 0 | 1};
}> = this._moveEvents;
/** Arbitrary data that can be attached to the drag item. */
data!: T;
/**
* Function that can be used to customize the logic of how the position of the drag item
* is limited while it's being dragged. Gets called with a point containing the current position
* of the user's pointer on the page, a reference to the item being dragged and its dimensions.
* Should return a point describing where the item should be rendered.
*/
constrainPosition?: DragConstrainPosition;
constructor(
element: ElementRef<HTMLElement> | HTMLElement,
private _config: DragRefConfig,
private _document: Document,
private _ngZone: NgZone,
private _viewportRuler: ViewportRuler,
private _dragDropRegistry: DragDropRegistry,
private _renderer: Renderer2,
) {
this.withRootElement(element).withParent(_config.parentDragRef || null);
this._parentPositions = new ParentPositionTracker(_document);
_dragDropRegistry.registerDragItem(this);
}
/**
* Returns the element that is being used as a placeholder
* while the current element is being dragged.
*/
getPlaceholderElement(): HTMLElement {
return this._placeholder;
}
/** Returns the root draggable element. */
getRootElement(): HTMLElement {
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(): HTMLElement {
return this.isDragging() ? this.getPlaceholderElement() : this.getRootElement();
}
/** Registers the handles that can be used to drag the element. */
withHandles(handles: (HTMLElement | ElementRef<HTMLElement>)[]): this {
this._handles = handles.map(handle => coerceElement(handle));
this._handles.forEach(handle => toggleNativeDragInteractions(handle, this.disabled));
this._toggleNativeDragInteractions();
// Delete any lingering disabled handles that may have been destroyed. Note that we re-create
// the set, rather than iterate over it and filter out the destroyed handles, because while
// the ES spec allows for sets to be modified while they're being iterated over, some polyfills
// use an array internally which may throw an error.
const disabledHandles = new Set<HTMLElement>();
this._disabledHandles.forEach(handle => {
if (this._handles.indexOf(handle) > -1) {
disabledHandles.add(handle);
}
});
this._disabledHandles = disabledHandles;
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: DragPreviewTemplate | null): this {
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: DragHelperTemplate | null): this {
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: ElementRef<HTMLElement> | HTMLElement): this {
const element = coerceElement(rootElement);
if (element !== this._rootElement) {
this._removeRootElementListeners();
const renderer = this._renderer;
this._rootElementCleanups = this._ngZone.runOutsideAngular(() => [
renderer.listen(element, 'mousedown', this._pointerDown, activeEventListenerOptions),
renderer.listen(element, 'touchstart', this._pointerDown, passiveEventListenerOptions),
renderer.listen(element, 'dragstart', this._nativeDragStart, activeEventListenerOptions),
]);
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: ElementRef<HTMLElement> | HTMLElement | null): this {
this._boundaryElement = boundaryElement ? coerceElement(boundaryElement) : null;
this._resizeSubscription.unsubscribe();
if (boundaryElement) {
this._resizeSubscription = this._viewportRuler
.change(10)
.subscribe(() => this._containInsideBoundaryOnResize());
}
return this;
}
/** Sets the parent ref that the ref is nested in. */
withParent(parent: DragRef<unknown> | null): this {
this._parentDragRef = parent;
return this;
}
/** Removes the dragging functionality from the DOM element. */
dispose() {
this._removeRootElementListeners();
// 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.
this._rootElement?.remove();
}
this._marker?.remove();
this._destroyPreview();
this._destroyPlaceholder();
this._dragDropRegistry.removeDragItem(this);
this._removeListeners();
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._marker =
this._parentDragRef =
null!;
}
/** Checks whether the element is currently being dragged. */
isDragging(): boolean {
return this._hasStartedDragging() && this._dragDropRegistry.isDragging(this);
}
/** Resets a standalone drag item to its initial position. */
reset(): void {
this._rootElement.style.transform = this._initialTransform || '';
this._activeTransform = {x: 0, y: 0};
this._passiveTransform = {x: 0, y: 0};
}
/** Resets drag item to end of boundary element. */
resetToBoundary(): void {
if (
// can be null if the drag item was never dragged.
this._boundaryElement &&
this._rootElement &&
// check if we are overflowing off our boundary element
isOverflowingParent(
this._boundaryElement.getBoundingClientRect(),
this._rootElement.getBoundingClientRect(),
)
) {
const parentRect = this._boundaryElement.getBoundingClientRect();
const childRect = this._rootElement.getBoundingClientRect();
let offsetX = 0;
let offsetY = 0;
// check if we are overflowing from left or right
if (childRect.left < parentRect.left) {
offsetX = parentRect.left - childRect.left;
} else if (childRect.right > parentRect.right) {
offsetX = parentRect.right - childRect.right;
}
// check if we are overflowing from top or bottom
if (childRect.top < parentRect.top) {
offsetY = parentRect.top - childRect.top;
} else if (childRect.bottom > parentRect.bottom) {
offsetY = parentRect.bottom - childRect.bottom;
}
const currentLeft = this._activeTransform.x;
const currentTop = this._activeTransform.y;
let x = currentLeft + offsetX,
y = currentTop + offsetY;
this._rootElement.style.transform = getTransform(x, y);
this._activeTransform = {x, y};
this._passiveTransform = {x, y};
}
}
/**
* 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: HTMLElement) {
if (!this._disabledHandles.has(handle) && this._handles.indexOf(handle) > -1) {
this._disabledHandles.add(handle);
toggleNativeDragInteractions(handle, true);
}
}
/**
* Enables a handle, if it has been disabled.
* @param handle Handle element to be enabled.
*/
enableHandle(handle: HTMLElement) {
if (this._disabledHandles.has(handle)) {
this._disabledHandles.delete(handle);
toggleNativeDragInteractions(handle, this.disabled);
}
}
/** Sets the layout direction of the draggable item. */
withDirection(direction: Direction): this {
this._direction = direction;
return this;
}
/** Sets the container that the item is part of. */
_withDropContainer(container: DropListRef) {
this._dropContainer = container;
}
/**
* Gets the current position in pixels the draggable outside of a drop container.
*/
getFreeDragPosition(): Readonly<Point> {
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: Point): this {
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;
}
/**
* Sets the container into which to insert the preview element.
* @param value Container into which to insert the preview.
*/
withPreviewContainer(value: PreviewContainer): this {
this._previewContainer = value;
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. */
private _removeListeners() {
this._pointerMoveSubscription.unsubscribe();
this._pointerUpSubscription.unsubscribe();
this._scrollSubscription.unsubscribe();
this._cleanupShadowRootSelectStart?.();
this._cleanupShadowRootSelectStart = undefined;
}
/** Destroys the preview element and its ViewRef. */
private _destroyPreview() {
this._preview?.destroy();
this._preview = null;
}
/** Destroys the placeholder element and its ViewRef. */
private _destroyPlaceholder() {
this._anchor?.remove();
this._placeholder?.remove();
this._placeholderRef?.destroy();
this._placeholder = this._anchor = this._placeholderRef = null!;
}
/** Handler for the `mousedown`/`touchstart` events. */
private _pointerDown = (event: MouseEvent | TouchEvent) => {
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._getTargetHandle(event);
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. */
private _pointerMove = (event: MouseEvent | TouchEvent) => {
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 preferable 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);
const container = this._dropContainer;
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 (!container || (!container.isDragging() && !container.isReceiving())) {
// Prevent the default action as soon as the dragging sequence is considered as
// "started" since waiting for the next event can allow the device to begin scrolling.
if (event.cancelable) {
event.preventDefault();
}
this._hasStartedDragging.set(true);
this._ngZone.run(() => this._startDragSequence(event));
}
}
return;
}
// We prevent the default action down here so that we know that dragging has started. This is
// important for touch devices where doing this too early can unnecessarily block scrolling,
// if there's a dragging delay.
if (event.cancelable) {
event.preventDefault();
}
const constrainedPointerPosition = this._getConstrainedPointerPosition(pointerPosition);
this._hasMoved = true;
this._lastKnownPointerPosition = pointerPosition;
this._updatePointerDirectionDelta(constrainedPointerPosition);
if (this._dropContainer) {
this._updateActiveDropContainer(constrainedPointerPosition, pointerPosition);
} else {
// If there's a position constraint function, we want the element's top/left to be at the
// specific position on the page. Use the initial position as a reference if that's the case.
const offset = this.constrainPosition ? this._initialDomRect! : this._pickupPositionOnPage;
const activeTransform = this._activeTransform;
activeTransform.x = constrainedPointerPosition.x - offset.x + this._passiveTransform.x;
activeTransform.y = constrainedPointerPosition.y - offset.y + this._passiveTransform.y;
this._applyRootElementTransform(activeTransform.x, activeTransform.y);
}
// 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. */
private _pointerUp = (event: MouseEvent | TouchEvent) => {
this._endDragSequence(event);
};
/**
* Clears subscriptions and stops the dragging sequence.
* @param event Browser event object that ended the sequence.
*/
private _endDragSequence(event: MouseEvent | TouchEvent) {
// 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._removeListeners();
this._dragDropRegistry.stopDragging(this);
this._toggleNativeDragInteractions();
if (this._handles) {
(this._rootElement.style as DragCSSStyleDeclaration).webkitTapHighlightColor =
this._rootElementTapHighlight;
}
if (!this._hasStartedDragging()) {
return;
}
this.released.next({source: this, event});
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;
const pointerPosition = this._getPointerPositionOnPage(event);
this._passiveTransform.y = this._activeTransform.y;
this._ngZone.run(() => {
this.ended.next({
source: this,
distance: this._getDragDistance(pointerPosition),
dropPoint: pointerPosition,
event,
});
});
this._cleanupCachedDimensions();
this._dragDropRegistry.stopDragging(this);
}
}
/** Starts the dragging sequence. */
private _startDragSequence(event: MouseEvent | TouchEvent) {
if (isTouchEvent(event)) {
this._lastTouchEventTime = Date.now();
}
this._toggleNativeDragInteractions();
// Needs to happen before the root element is moved.
const shadowRoot = this._getShadowRoot();
const dropContainer = this._dropContainer;
if (shadowRoot) {
// In some browsers the global `selectstart` that we maintain in the `DragDropRegistry`
// doesn't cross the shadow boundary so we have to prevent it at the shadow root (see #28792).
this._ngZone.runOutsideAngular(() => {
this._cleanupShadowRootSelectStart = this._renderer.listen(
shadowRoot,
'selectstart',
shadowDomSelectStart,
activeCapturingEventOptions,
);
});
}
if (dropContainer) {
const element = this._rootElement;
const parent = element.parentNode as HTMLElement;
const placeholder = (this._placeholder = this._createPlaceholderElement());
const marker = (this._marker =
this._marker ||
this._document.createComment(
typeof ngDevMode === 'undefined' || ngDevMode ? 'cdk-drag-marker' : '',
));
// Insert a marker node so that we can restore the element's position in the DOM.
parent.insertBefore(marker, element);
// There's no risk of transforms stacking when inside a drop container so
// we can keep the initial transform up to date any time dragging starts.
this._initialTransform = element.style.transform || '';
// Create the preview after the initial transform has
// been cached, because it can be affected by the transform.
this._preview = new PreviewRef(
this._document,
this._rootElement,
this._direction,
this._initialDomRect!,
this._previewTemplate || null,
this.previewClass || null,
this._pickupPositionOnPage,
this._initialTransform,
this._config.zIndex || 1000,
this._renderer,
);
this._preview.attach(this._getPreviewInsertionPoint(parent, shadowRoot));
// 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.
toggleVisibility(element, false, dragImportantProperties);
this._document.body.appendChild(parent.replaceChild(placeholder, element));
this.started.next({source: this, event}); // Emit before notifying the container.
dropContainer.start();
this._initialContainer = dropContainer;
this._initialIndex = dropContainer.getItemIndex(this);
} else {
this.started.next({source: this, event});
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.
*/
private _initializeDragSequence(referenceElement: HTMLElement, event: MouseEvent | TouchEvent) {
// Stop propagation if the item is inside another
// draggable so we don't start multiple drag sequences.
if (this._parentDragRef) {
event.stopPropagation();
}
const isDragging = this.isDragging();
const isTouchSequence = isTouchEvent(event);
const isAuxiliaryMouseButton = !isTouchSequence && (event as MouseEvent).button !== 0;
const rootElement = this._rootElement;
const target = _getEventTarget(event);
const isSyntheticEvent =
!isTouchSequence &&
this._lastTouchEventTime &&
this._lastTouchEventTime + MOUSE_EVENT_IGNORE_TIME > Date.now();
const isFakeEvent = isTouchSequence
? isFakeTouchstartFromScreenReader(event as TouchEvent)
: isFakeMousedownFromScreenReader(event as MouseEvent);
// 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`