TargetConnector.ts
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import { shallowEqual } from '@react-dnd/shallowequal'
import type { Backend, Identifier, Unsubscribe } from 'dnd-core'
import type { RefObject } from 'react'
import type { DropTargetOptions } from '../types/index.js'
import { isRef } from './isRef.js'
import type { Connector } from './SourceConnector.js'
import { wrapConnectorHooks } from './wrapConnectorHooks.js'
export class TargetConnector implements Connector {
public hooks = wrapConnectorHooks({
dropTarget: (node: any, options: DropTargetOptions) => {
this.clearDropTarget()
this.dropTargetOptions = options
if (isRef(node)) {
this.dropTargetRef = node
} else {
this.dropTargetNode = node
}
this.reconnect()
},
})
private handlerId: Identifier | null = null
// The drop target may either be attached via ref or connect function
private dropTargetRef: RefObject<any> | null = null
private dropTargetNode: any
private dropTargetOptionsInternal: DropTargetOptions | null = null
private unsubscribeDropTarget: Unsubscribe | undefined
private lastConnectedHandlerId: Identifier | null = null
private lastConnectedDropTarget: any = null
private lastConnectedDropTargetOptions: DropTargetOptions | null = null
private readonly backend: Backend
public constructor(backend: Backend) {
this.backend = backend
}
public get connectTarget(): any {
return this.dropTarget
}
public reconnect(): void {
// if nothing has changed then don't resubscribe
const didChange =
this.didHandlerIdChange() ||
this.didDropTargetChange() ||
this.didOptionsChange()
if (didChange) {
this.disconnectDropTarget()
}
const dropTarget = this.dropTarget
if (!this.handlerId) {
return
}
if (!dropTarget) {
this.lastConnectedDropTarget = dropTarget
return
}
if (didChange) {
this.lastConnectedHandlerId = this.handlerId
this.lastConnectedDropTarget = dropTarget
this.lastConnectedDropTargetOptions = this.dropTargetOptions
this.unsubscribeDropTarget = this.backend.connectDropTarget(
this.handlerId,
dropTarget,
this.dropTargetOptions,
)
}
}
public receiveHandlerId(newHandlerId: Identifier | null): void {
if (newHandlerId === this.handlerId) {
return
}
this.handlerId = newHandlerId
this.reconnect()
}
public get dropTargetOptions(): DropTargetOptions {
return this.dropTargetOptionsInternal
}
public set dropTargetOptions(options: DropTargetOptions) {
this.dropTargetOptionsInternal = options
}
private didHandlerIdChange(): boolean {
return this.lastConnectedHandlerId !== this.handlerId
}
private didDropTargetChange(): boolean {
return this.lastConnectedDropTarget !== this.dropTarget
}
private didOptionsChange(): boolean {
return !shallowEqual(
this.lastConnectedDropTargetOptions,
this.dropTargetOptions,
)
}
public disconnectDropTarget() {
if (this.unsubscribeDropTarget) {
this.unsubscribeDropTarget()
this.unsubscribeDropTarget = undefined
}
}
private get dropTarget() {
return (
this.dropTargetNode || (this.dropTargetRef && this.dropTargetRef.current)
)
}
private clearDropTarget() {
this.dropTargetRef = null
this.dropTargetNode = null
}
}