@interactjs/actions/drag/plugin.ts

import Scope from '@interactjs/core/scope'
import is from '@interactjs/utils/is'

declare module '@interactjs/core/Interactable' {
  interface Interactable {
    draggable: DraggableMethod
  }
}

declare module '@interactjs/core/defaultOptions' {
  interface ActionDefaults {
    drag: Interact.DraggableOptions
  }
}

declare module '@interactjs/core/scope' {
  interface ActionMap {
    drag?: typeof drag
  }
}

export type DragEvent = Interact.InteractEvent<'drag'>

export type DraggableMethod = Interact.ActionMethod<Interact.DraggableOptions>

function install (scope: Scope) {
  const {
    actions,
    Interactable,
    defaults,
  } = scope

  Interactable.prototype.draggable = drag.draggable

  actions.map.drag = drag
  actions.methodDict.drag = 'draggable'

  defaults.actions.drag = drag.defaults
}

function beforeMove ({ interaction }) {
  if (interaction.prepared.name !== 'drag') { return }

  const axis = interaction.prepared.axis

  if (axis === 'x') {
    interaction.coords.cur.page.y   = interaction.coords.start.page.y
    interaction.coords.cur.client.y = interaction.coords.start.client.y

    interaction.coords.velocity.client.y = 0
    interaction.coords.velocity.page.y   = 0
  }
  else if (axis === 'y') {
    interaction.coords.cur.page.x   = interaction.coords.start.page.x
    interaction.coords.cur.client.x = interaction.coords.start.client.x

    interaction.coords.velocity.client.x = 0
    interaction.coords.velocity.page.x   = 0
  }
}

function move ({ iEvent, interaction }) {
  if (interaction.prepared.name !== 'drag') { return }

  const axis = interaction.prepared.axis

  if (axis === 'x' || axis === 'y') {
    const opposite = axis === 'x' ? 'y' : 'x'

    iEvent.page[opposite]   = interaction.coords.start.page[opposite]
    iEvent.client[opposite] = interaction.coords.start.client[opposite]
    iEvent.delta[opposite] = 0
  }
}

/**
 * ```js
 * interact(element).draggable({
 *     onstart: function (event) {},
 *     onmove : function (event) {},
 *     onend  : function (event) {},
 *
 *     // the axis in which the first movement must be
 *     // for the drag sequence to start
 *     // 'xy' by default - any direction
 *     startAxis: 'x' || 'y' || 'xy',
 *
 *     // 'xy' by default - don't restrict to one axis (move in any direction)
 *     // 'x' or 'y' to restrict movement to either axis
 *     // 'start' to restrict movement to the axis the drag started in
 *     lockAxis: 'x' || 'y' || 'xy' || 'start',
 *
 *     // max number of drags that can happen concurrently
 *     // with elements of this Interactable. Infinity by default
 *     max: Infinity,
 *
 *     // max number of drags that can target the same element+Interactable
 *     // 1 by default
 *     maxPerElement: 2
 * })
 *
 * var isDraggable = interact('element').draggable(); // true
 * ```
 *
 * Get or set whether drag actions can be performed on the target
 *
 * @alias Interactable.prototype.draggable
 *
 * @param {boolean | object} [options] true/false or An object with event
 * listeners to be fired on drag events (object makes the Interactable
 * draggable)
 * @return {boolean | Interactable} boolean indicating if this can be the
 * target of drag events, or this Interctable
 */
const draggable: DraggableMethod = function draggable (this: Interact.Interactable, options?: Interact.DraggableOptions | boolean): any {
  if (is.object(options)) {
    this.options.drag.enabled = options.enabled !== false
    this.setPerAction('drag', options)
    this.setOnEvents('drag', options)

    if (/^(xy|x|y|start)$/.test(options.lockAxis)) {
      this.options.drag.lockAxis = options.lockAxis
    }
    if (/^(xy|x|y)$/.test(options.startAxis)) {
      this.options.drag.startAxis = options.startAxis
    }

    return this
  }

  if (is.bool(options)) {
    this.options.drag.enabled = options

    return this
  }

  return this.options.drag
}

const drag: Interact.Plugin = {
  id: 'actions/drag',
  install,
  listeners: {
    'interactions:before-action-move': beforeMove,
    'interactions:action-resume': beforeMove,

    // dragmove
    'interactions:action-move': move,
    'auto-start:check': arg => {
      const { interaction, interactable, buttons } = arg
      const dragOptions = interactable.options.drag

      if (
        !(dragOptions && dragOptions.enabled) ||
        // check mouseButton setting if the pointer is down
        (interaction.pointerIsDown &&
         /mouse|pointer/.test(interaction.pointerType) &&
       (buttons & interactable.options.drag.mouseButtons) === 0)
      ) {
        return undefined
      }

      arg.action = {
        name: 'drag',
        axis: (dragOptions.lockAxis === 'start'
          ? dragOptions.startAxis
          : dragOptions.lockAxis),
      }

      return false
    },
  },
  draggable,
  beforeMove,
  move,
  defaults: {
    startAxis : 'xy',
    lockAxis  : 'xy',
  } as Interact.DropzoneOptions,

  getCursor () {
    return 'move'
  },
}

export default drag