feat(Workflow): add modules

src/@core/utils/workflow.ts

@@ -0,0 +1,120 @@
+import { useVueFlow } from '@vue-flow/core'
+import { ref, watch } from 'vue'
+
+let id = 0
+
+/**
+ * @returns {string} - A unique id.
+ */
+function getId() {
+  return `dndnode_${id++}`
+}
+
+/**
+ * In a real world scenario you'd want to avoid creating refs in a global scope like this as they might not be cleaned up properly.
+ * @type {{draggedType: Ref<string|null>, isDragOver: Ref<boolean>, isDragging: Ref<boolean>}}
+ */
+const state = {
+  /**
+   * The type of the node being dragged.
+   */
+  draggedType: ref(null),
+  isDragOver: ref(false),
+  isDragging: ref(false),
+}
+
+export default function useDragAndDrop() {
+  const { draggedType, isDragOver, isDragging } = state
+
+  const { addNodes, screenToFlowCoordinate, onNodesInitialized, updateNode } = useVueFlow()
+
+  watch(isDragging, dragging => {
+    document.body.style.userSelect = dragging ? 'none' : ''
+  })
+
+  function onDragStart(event: any, type: any) {
+    if (event.dataTransfer) {
+      event.dataTransfer.setData('application/vueflow', type)
+      event.dataTransfer.effectAllowed = 'move'
+    }
+
+    draggedType.value = type
+    isDragging.value = true
+
+    document.addEventListener('drop', onDragEnd)
+  }
+
+  /**
+   * Handles the drag over event.
+   *
+   * @param {DragEvent} event
+   */
+  function onDragOver(event: any) {
+    event.preventDefault()
+
+    if (draggedType.value) {
+      isDragOver.value = true
+
+      if (event.dataTransfer) {
+        event.dataTransfer.dropEffect = 'move'
+      }
+    }
+  }
+
+  function onDragLeave() {
+    isDragOver.value = false
+  }
+
+  function onDragEnd() {
+    isDragging.value = false
+    isDragOver.value = false
+    draggedType.value = null
+    document.removeEventListener('drop', onDragEnd)
+  }
+
+  /**
+   * Handles the drop event.
+   *
+   * @param {DragEvent} event
+   */
+  function onDrop(event: any) {
+    const position = screenToFlowCoordinate({
+      x: event.clientX,
+      y: event.clientY,
+    })
+
+    const nodeId = getId()
+
+    const newNode = {
+      id: nodeId,
+      type: draggedType.value || undefined,
+      position,
+      data: { label: nodeId },
+    }
+
+    /**
+     * Align node position after drop, so it's centered to the mouse
+     *
+     * We can hook into events even in a callback, and we can remove the event listener after it's been called.
+     */
+    const { off } = onNodesInitialized(() => {
+      updateNode(nodeId, node => ({
+        position: { x: node.position.x - node.dimensions.width / 2, y: node.position.y - node.dimensions.height / 2 },
+      }))
+
+      off()
+    })
+
+    addNodes(newNode)
+  }
+
+  return {
+    draggedType,
+    isDragOver,
+    isDragging,
+    onDragStart,
+    onDragLeave,
+    onDragOver,
+    onDrop,
+  }
+}