vue-react-dnd/src/createSourceConnector.js

Vue Drag and Drop Library based on react-dnd

import areOptionsEqual from './areOptionsEqual'

export default function createSourceConnector (backend) {
  let currentHandlerId

  let currentDragSourceNode
  let currentDragSourceOptions
  let disconnectCurrentDragSource

  let currentDragPreviewNode
  let currentDragPreviewOptions
  let disconnectCurrentDragPreview

  function reconnectDragSource () {
    if (disconnectCurrentDragSource) {
      disconnectCurrentDragSource()
      disconnectCurrentDragSource = null
    }

    if (currentHandlerId && currentDragSourceNode) {
      disconnectCurrentDragSource = backend.connectDragSource(
        currentHandlerId,
        currentDragSourceNode,
        currentDragSourceOptions
      )
    }
  }

  function reconnectDragPreview () {
    if (disconnectCurrentDragPreview) {
      disconnectCurrentDragPreview()
      disconnectCurrentDragPreview = null
    }

    if (currentHandlerId && currentDragPreviewNode) {
      disconnectCurrentDragPreview = backend.connectDragPreview(
        currentHandlerId,
        currentDragPreviewNode,
        currentDragPreviewOptions
      )
    }
  }

  function receiveHandlerId (handlerId) {
    if (handlerId === currentHandlerId) {
      return
    }

    currentHandlerId = handlerId
    reconnectDragSource()
    reconnectDragPreview()
  }

  const hooks = {
    dragSource: function connectDragSource (node, options) {
      if (
        node === currentDragSourceNode &&
                    areOptionsEqual(options, currentDragSourceOptions)
      ) {
        return
      }

      currentDragSourceNode = node
      currentDragSourceOptions = options

      reconnectDragSource()
    },

    dragPreview: function connectDragPreview (node, options) {
      if (
        node === currentDragPreviewNode &&
                    areOptionsEqual(options, currentDragPreviewOptions)
      ) {
        return
      }

      currentDragPreviewNode = node
      currentDragPreviewOptions = options

      reconnectDragPreview()
    }
  }

  return {
    receiveHandlerId,
    hooks
  }
}