/
HTML5BackendImpl.ts
705 lines (609 loc) · 19.9 KB
/
HTML5BackendImpl.ts
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import {
Backend,
DragDropManager,
DragDropActions,
DragDropMonitor,
HandlerRegistry,
Identifier,
XYCoord,
Unsubscribe,
} from 'dnd-core'
import { EnterLeaveCounter } from './EnterLeaveCounter'
import {
getNodeClientOffset,
getEventClientOffset,
getDragPreviewOffset,
} from './OffsetUtils'
import {
createNativeDragSource,
matchNativeItemType,
} from './NativeDragSources'
import * as NativeTypes from './NativeTypes'
import { NativeDragSource } from './NativeDragSources/NativeDragSource'
import { OptionsReader } from './OptionsReader'
import { HTML5BackendContext, HTML5BackendOptions } from './types'
type RootNode = Node & { __isReactDndBackendSetUp: boolean | undefined }
export class HTML5BackendImpl implements Backend {
private options: OptionsReader
// React-Dnd Components
private actions: DragDropActions
private monitor: DragDropMonitor
private registry: HandlerRegistry
// Internal State
private enterLeaveCounter: EnterLeaveCounter
private sourcePreviewNodes: Map<string, Element> = new Map()
private sourcePreviewNodeOptions: Map<string, any> = new Map()
private sourceNodes: Map<string, Element> = new Map()
private sourceNodeOptions: Map<string, any> = new Map()
private dragStartSourceIds: string[] | null = null
private dropTargetIds: string[] = []
private dragEnterTargetIds: string[] = []
private currentNativeSource: NativeDragSource | null = null
private currentNativeHandle: Identifier | null = null
private currentDragSourceNode: Element | null = null
private altKeyPressed = false
private mouseMoveTimeoutTimer: number | null = null
private asyncEndDragFrameId: number | null = null
private dragOverTargetIds: string[] | null = null
public constructor(
manager: DragDropManager,
globalContext?: HTML5BackendContext,
options?: HTML5BackendOptions,
) {
this.options = new OptionsReader(globalContext, options)
this.actions = manager.getActions()
this.monitor = manager.getMonitor()
this.registry = manager.getRegistry()
this.enterLeaveCounter = new EnterLeaveCounter(this.isNodeInDocument)
}
/**
* Generate profiling statistics for the HTML5Backend.
*/
public profile(): Record<string, number> {
return {
sourcePreviewNodes: this.sourcePreviewNodes.size,
sourcePreviewNodeOptions: this.sourcePreviewNodeOptions.size,
sourceNodeOptions: this.sourceNodeOptions.size,
sourceNodes: this.sourceNodes.size,
dragStartSourceIds: this.dragStartSourceIds?.length || 0,
dropTargetIds: this.dropTargetIds.length,
dragEnterTargetIds: this.dragEnterTargetIds.length,
dragOverTargetIds: this.dragOverTargetIds?.length || 0,
}
}
// public for test
public get window(): Window | undefined {
return this.options.window
}
public get document(): Document | undefined {
return this.options.document
}
/**
* Get the root element to use for event subscriptions
*/
private get rootElement(): Node | undefined {
return this.options.rootElement as Node
}
public setup(): void {
const root = this.rootElement as RootNode | undefined
if (root === undefined) {
return
}
if (root.__isReactDndBackendSetUp) {
throw new Error('Cannot have two HTML5 backends at the same time.')
}
root.__isReactDndBackendSetUp = true
this.addEventListeners(root)
}
public teardown(): void {
const root = this.rootElement as RootNode
if (root === undefined) {
return
}
root.__isReactDndBackendSetUp = false
this.removeEventListeners(this.rootElement as Element)
this.clearCurrentDragSourceNode()
if (this.asyncEndDragFrameId) {
this.window?.cancelAnimationFrame(this.asyncEndDragFrameId)
}
}
public connectDragPreview(
sourceId: string,
node: Element,
options: any,
): Unsubscribe {
this.sourcePreviewNodeOptions.set(sourceId, options)
this.sourcePreviewNodes.set(sourceId, node)
return (): void => {
this.sourcePreviewNodes.delete(sourceId)
this.sourcePreviewNodeOptions.delete(sourceId)
}
}
public connectDragSource(
sourceId: string,
node: Element,
options: any,
): Unsubscribe {
this.sourceNodes.set(sourceId, node)
this.sourceNodeOptions.set(sourceId, options)
const handleDragStart = (e: any) => this.handleDragStart(e, sourceId)
const handleSelectStart = (e: any) => this.handleSelectStart(e)
node.setAttribute('draggable', 'true')
node.addEventListener('dragstart', handleDragStart)
node.addEventListener('selectstart', handleSelectStart)
return (): void => {
this.sourceNodes.delete(sourceId)
this.sourceNodeOptions.delete(sourceId)
node.removeEventListener('dragstart', handleDragStart)
node.removeEventListener('selectstart', handleSelectStart)
node.setAttribute('draggable', 'false')
}
}
public connectDropTarget(targetId: string, node: HTMLElement): Unsubscribe {
const handleDragEnter = (e: DragEvent) => this.handleDragEnter(e, targetId)
const handleDragOver = (e: DragEvent) => this.handleDragOver(e, targetId)
const handleDrop = (e: DragEvent) => this.handleDrop(e, targetId)
node.addEventListener('dragenter', handleDragEnter)
node.addEventListener('dragover', handleDragOver)
node.addEventListener('drop', handleDrop)
return (): void => {
node.removeEventListener('dragenter', handleDragEnter)
node.removeEventListener('dragover', handleDragOver)
node.removeEventListener('drop', handleDrop)
}
}
private addEventListeners(target: Node) {
// SSR Fix (https://github.com/react-dnd/react-dnd/pull/813
if (!target.addEventListener) {
return
}
target.addEventListener(
'dragstart',
this.handleTopDragStart as EventListener,
)
target.addEventListener('dragstart', this.handleTopDragStartCapture, true)
target.addEventListener('dragend', this.handleTopDragEndCapture, true)
target.addEventListener(
'dragenter',
this.handleTopDragEnter as EventListener,
)
target.addEventListener(
'dragenter',
this.handleTopDragEnterCapture as EventListener,
true,
)
target.addEventListener(
'dragleave',
this.handleTopDragLeaveCapture as EventListener,
true,
)
target.addEventListener('dragover', this.handleTopDragOver as EventListener)
target.addEventListener('dragover', this.handleTopDragOverCapture, true)
target.addEventListener('drop', this.handleTopDrop as EventListener)
target.addEventListener(
'drop',
this.handleTopDropCapture as EventListener,
true,
)
}
private removeEventListeners(target: Node) {
// SSR Fix (https://github.com/react-dnd/react-dnd/pull/813
if (!target.removeEventListener) {
return
}
target.removeEventListener('dragstart', this.handleTopDragStart as any)
target.removeEventListener(
'dragstart',
this.handleTopDragStartCapture,
true,
)
target.removeEventListener('dragend', this.handleTopDragEndCapture, true)
target.removeEventListener(
'dragenter',
this.handleTopDragEnter as EventListener,
)
target.removeEventListener(
'dragenter',
this.handleTopDragEnterCapture as EventListener,
true,
)
target.removeEventListener(
'dragleave',
this.handleTopDragLeaveCapture as EventListener,
true,
)
target.removeEventListener(
'dragover',
this.handleTopDragOver as EventListener,
)
target.removeEventListener('dragover', this.handleTopDragOverCapture, true)
target.removeEventListener('drop', this.handleTopDrop as EventListener)
target.removeEventListener(
'drop',
this.handleTopDropCapture as EventListener,
true,
)
}
private getCurrentSourceNodeOptions() {
const sourceId = this.monitor.getSourceId() as string
const sourceNodeOptions = this.sourceNodeOptions.get(sourceId)
return {
dropEffect: this.altKeyPressed ? 'copy' : 'move',
...(sourceNodeOptions || {}),
}
}
private getCurrentDropEffect() {
if (this.isDraggingNativeItem()) {
// It makes more sense to default to 'copy' for native resources
return 'copy'
}
return this.getCurrentSourceNodeOptions().dropEffect
}
private getCurrentSourcePreviewNodeOptions() {
const sourceId = this.monitor.getSourceId() as string
const sourcePreviewNodeOptions = this.sourcePreviewNodeOptions.get(sourceId)
return {
anchorX: 0.5,
anchorY: 0.5,
captureDraggingState: false,
...(sourcePreviewNodeOptions || {}),
}
}
private getSourceClientOffset = (sourceId: string): XYCoord | null => {
const source = this.sourceNodes.get(sourceId)
return (source && getNodeClientOffset(source as HTMLElement)) || null
}
private isDraggingNativeItem() {
const itemType = this.monitor.getItemType()
return Object.keys(NativeTypes).some(
(key: string) => (NativeTypes as any)[key] === itemType,
)
}
private beginDragNativeItem(type: string, dataTransfer?: DataTransfer) {
this.clearCurrentDragSourceNode()
this.currentNativeSource = createNativeDragSource(type, dataTransfer)
this.currentNativeHandle = this.registry.addSource(
type,
this.currentNativeSource,
)
this.actions.beginDrag([this.currentNativeHandle])
}
private endDragNativeItem = (): void => {
if (!this.isDraggingNativeItem()) {
return
}
this.actions.endDrag()
if (this.currentNativeHandle) {
this.registry.removeSource(this.currentNativeHandle)
}
this.currentNativeHandle = null
this.currentNativeSource = null
}
private isNodeInDocument = (node: Node | null | undefined): boolean => {
// Check the node either in the main document or in the current context
return Boolean(
node &&
this.document &&
this.document.body &&
document.body.contains(node),
)
}
private endDragIfSourceWasRemovedFromDOM = (): void => {
const node = this.currentDragSourceNode
if (node == null || this.isNodeInDocument(node)) {
return
}
if (this.clearCurrentDragSourceNode() && this.monitor.isDragging()) {
this.actions.endDrag()
}
}
private setCurrentDragSourceNode(node: Element | null) {
this.clearCurrentDragSourceNode()
this.currentDragSourceNode = node
// A timeout of > 0 is necessary to resolve Firefox issue referenced
// See:
// * https://github.com/react-dnd/react-dnd/pull/928
// * https://github.com/react-dnd/react-dnd/issues/869
const MOUSE_MOVE_TIMEOUT = 1000
// Receiving a mouse event in the middle of a dragging operation
// means it has ended and the drag source node disappeared from DOM,
// so the browser didn't dispatch the dragend event.
//
// We need to wait before we start listening for mousemove events.
// This is needed because the drag preview needs to be drawn or else it fires an 'mousemove' event
// immediately in some browsers.
//
// See:
// * https://github.com/react-dnd/react-dnd/pull/928
// * https://github.com/react-dnd/react-dnd/issues/869
//
this.mouseMoveTimeoutTimer = (setTimeout(() => {
return this.rootElement?.addEventListener(
'mousemove',
this.endDragIfSourceWasRemovedFromDOM,
true,
)
}, MOUSE_MOVE_TIMEOUT) as any) as number
}
private clearCurrentDragSourceNode() {
if (this.currentDragSourceNode) {
this.currentDragSourceNode = null
if (this.rootElement) {
this.window?.clearTimeout(this.mouseMoveTimeoutTimer || undefined)
this.rootElement.removeEventListener(
'mousemove',
this.endDragIfSourceWasRemovedFromDOM,
true,
)
}
this.mouseMoveTimeoutTimer = null
return true
}
return false
}
public handleTopDragStartCapture = (): void => {
this.clearCurrentDragSourceNode()
this.dragStartSourceIds = []
}
public handleDragStart(e: DragEvent, sourceId: string): void {
if (e.defaultPrevented) {
return
}
if (!this.dragStartSourceIds) {
this.dragStartSourceIds = []
}
this.dragStartSourceIds.unshift(sourceId)
}
public handleTopDragStart = (e: DragEvent): void => {
if (e.defaultPrevented) {
return
}
const { dragStartSourceIds } = this
this.dragStartSourceIds = null
const clientOffset = getEventClientOffset(e)
// Avoid crashing if we missed a drop event or our previous drag died
if (this.monitor.isDragging()) {
this.actions.endDrag()
}
// Don't publish the source just yet (see why below)
this.actions.beginDrag(dragStartSourceIds || [], {
publishSource: false,
getSourceClientOffset: this.getSourceClientOffset,
clientOffset,
})
const { dataTransfer } = e
const nativeType = matchNativeItemType(dataTransfer)
if (this.monitor.isDragging()) {
if (dataTransfer && typeof dataTransfer.setDragImage === 'function') {
// Use custom drag image if user specifies it.
// If child drag source refuses drag but parent agrees,
// use parent's node as drag image. Neither works in IE though.
const sourceId: string = this.monitor.getSourceId() as string
const sourceNode = this.sourceNodes.get(sourceId)
const dragPreview = this.sourcePreviewNodes.get(sourceId) || sourceNode
if (dragPreview) {
const {
anchorX,
anchorY,
offsetX,
offsetY,
} = this.getCurrentSourcePreviewNodeOptions()
const anchorPoint = { anchorX, anchorY }
const offsetPoint = { offsetX, offsetY }
const dragPreviewOffset = getDragPreviewOffset(
sourceNode as HTMLElement,
dragPreview as HTMLElement,
clientOffset,
anchorPoint,
offsetPoint,
)
dataTransfer.setDragImage(
dragPreview,
dragPreviewOffset.x,
dragPreviewOffset.y,
)
}
}
try {
// Firefox won't drag without setting data
dataTransfer?.setData('application/json', {} as any)
} catch (err) {
// IE doesn't support MIME types in setData
}
// Store drag source node so we can check whether
// it is removed from DOM and trigger endDrag manually.
this.setCurrentDragSourceNode(e.target as Element)
// Now we are ready to publish the drag source.. or are we not?
const { captureDraggingState } = this.getCurrentSourcePreviewNodeOptions()
if (!captureDraggingState) {
// Usually we want to publish it in the next tick so that browser
// is able to screenshot the current (not yet dragging) state.
//
// It also neatly avoids a situation where render() returns null
// in the same tick for the source element, and browser freaks out.
setTimeout(() => this.actions.publishDragSource(), 0)
} else {
// In some cases the user may want to override this behavior, e.g.
// to work around IE not supporting custom drag previews.
//
// When using a custom drag layer, the only way to prevent
// the default drag preview from drawing in IE is to screenshot
// the dragging state in which the node itself has zero opacity
// and height. In this case, though, returning null from render()
// will abruptly end the dragging, which is not obvious.
//
// This is the reason such behavior is strictly opt-in.
this.actions.publishDragSource()
}
} else if (nativeType) {
// A native item (such as URL) dragged from inside the document
this.beginDragNativeItem(nativeType)
} else if (
dataTransfer &&
!dataTransfer.types &&
((e.target && !(e.target as Element).hasAttribute) ||
!(e.target as Element).hasAttribute('draggable'))
) {
// Looks like a Safari bug: dataTransfer.types is null, but there was no draggable.
// Just let it drag. It's a native type (URL or text) and will be picked up in
// dragenter handler.
return
} else {
// If by this time no drag source reacted, tell browser not to drag.
e.preventDefault()
}
}
public handleTopDragEndCapture = (): void => {
if (this.clearCurrentDragSourceNode() && this.monitor.isDragging()) {
// Firefox can dispatch this event in an infinite loop
// if dragend handler does something like showing an alert.
// Only proceed if we have not handled it already.
this.actions.endDrag()
}
}
public handleTopDragEnterCapture = (e: DragEvent): void => {
this.dragEnterTargetIds = []
const isFirstEnter = this.enterLeaveCounter.enter(e.target)
if (!isFirstEnter || this.monitor.isDragging()) {
return
}
const { dataTransfer } = e
const nativeType = matchNativeItemType(dataTransfer)
if (nativeType) {
// A native item (such as file or URL) dragged from outside the document
this.beginDragNativeItem(nativeType, dataTransfer as DataTransfer)
}
}
public handleDragEnter(e: DragEvent, targetId: string): void {
this.dragEnterTargetIds.unshift(targetId)
}
public handleTopDragEnter = (e: DragEvent): void => {
const { dragEnterTargetIds } = this
this.dragEnterTargetIds = []
if (!this.monitor.isDragging()) {
// This is probably a native item type we don't understand.
return
}
this.altKeyPressed = e.altKey
// If the target changes position as the result of `dragenter`, `dragover` might still
// get dispatched despite target being no longer there. The easy solution is to check
// whether there actually is a target before firing `hover`.
if (dragEnterTargetIds.length > 0) {
this.actions.hover(dragEnterTargetIds, {
clientOffset: getEventClientOffset(e),
})
}
const canDrop = dragEnterTargetIds.some((targetId) =>
this.monitor.canDropOnTarget(targetId),
)
if (canDrop) {
// IE requires this to fire dragover events
e.preventDefault()
if (e.dataTransfer) {
e.dataTransfer.dropEffect = this.getCurrentDropEffect()
}
}
}
public handleTopDragOverCapture = (): void => {
this.dragOverTargetIds = []
}
public handleDragOver(e: DragEvent, targetId: string): void {
if (this.dragOverTargetIds === null) {
this.dragOverTargetIds = []
}
this.dragOverTargetIds.unshift(targetId)
}
public handleTopDragOver = (e: DragEvent): void => {
const { dragOverTargetIds } = this
this.dragOverTargetIds = []
if (!this.monitor.isDragging()) {
// This is probably a native item type we don't understand.
// Prevent default "drop and blow away the whole document" action.
e.preventDefault()
if (e.dataTransfer) {
e.dataTransfer.dropEffect = 'none'
}
return
}
this.altKeyPressed = e.altKey
this.actions.hover(dragOverTargetIds || [], {
clientOffset: getEventClientOffset(e),
})
const canDrop = (dragOverTargetIds || []).some((targetId) =>
this.monitor.canDropOnTarget(targetId),
)
if (canDrop) {
// Show user-specified drop effect.
e.preventDefault()
if (e.dataTransfer) {
e.dataTransfer.dropEffect = this.getCurrentDropEffect()
}
} else if (this.isDraggingNativeItem()) {
// Don't show a nice cursor but still prevent default
// "drop and blow away the whole document" action.
e.preventDefault()
} else {
e.preventDefault()
if (e.dataTransfer) {
e.dataTransfer.dropEffect = 'none'
}
}
}
public handleTopDragLeaveCapture = (e: DragEvent): void => {
if (this.isDraggingNativeItem()) {
e.preventDefault()
}
const isLastLeave = this.enterLeaveCounter.leave(e.target)
if (!isLastLeave) {
return
}
if (this.isDraggingNativeItem()) {
setTimeout(() => this.endDragNativeItem(), 0)
}
}
public handleTopDropCapture = (e: DragEvent): void => {
this.dropTargetIds = []
if (this.isDraggingNativeItem()) {
e.preventDefault()
this.currentNativeSource?.loadDataTransfer(e.dataTransfer)
}
this.enterLeaveCounter.reset()
}
public handleDrop(e: DragEvent, targetId: string): void {
this.dropTargetIds.unshift(targetId)
}
public handleTopDrop = (e: DragEvent): void => {
const { dropTargetIds } = this
this.dropTargetIds = []
this.actions.hover(dropTargetIds, {
clientOffset: getEventClientOffset(e),
})
this.actions.drop({ dropEffect: this.getCurrentDropEffect() })
if (this.isDraggingNativeItem()) {
this.endDragNativeItem()
} else if (this.monitor.isDragging()) {
this.actions.endDrag()
}
}
public handleSelectStart = (e: DragEvent): void => {
const target = e.target as HTMLElement & { dragDrop: () => void }
// Only IE requires us to explicitly say
// we want drag drop operation to start
if (typeof target.dragDrop !== 'function') {
return
}
// Inputs and textareas should be selectable
if (
target.tagName === 'INPUT' ||
target.tagName === 'SELECT' ||
target.tagName === 'TEXTAREA' ||
target.isContentEditable
) {
return
}
// For other targets, ask IE
// to enable drag and drop
e.preventDefault()
target.dragDrop()
}
}