chore(examples): add undirectional

example/src/Undirectional/CustomNode.tsx

@@ -0,0 +1,19 @@
+import React, { memo, FC, CSSProperties } from 'react';
+
+import { Handle, Position, NodeProps } from 'react-flow-renderer';
+
+const nodeStyles: CSSProperties = { padding: '10px 15px', border: '1px solid #ddd' };
+
+const CustomNode: FC<NodeProps> = () => {
+  return (
+    <div style={nodeStyles}>
+      <div>node</div>
+      <Handle type="source" id="left" position={Position.Left} />
+      <Handle type="source" id="right" position={Position.Right} />
+      <Handle type="source" id="top" position={Position.Top} />
+      <Handle type="source" id="bottom" position={Position.Bottom} />
+    </div>
+  );
+};
+
+export default memo(CustomNode);

example/src/Undirectional/index.tsx

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+import React, { useState, useCallback } from 'react';
+
+import ReactFlow, {
+  NodeTypesType,
+  addEdge,
+  useZoomPanHelper,
+  ReactFlowProvider,
+  Elements,
+  Connection,
+  Edge,
+  ElementId,
+  ConnectionLineType,
+  ConnectionMode,
+} from 'react-flow-renderer';
+import CustomNode from './CustomNode';
+
+const initialElements: Elements = [
+  {
+    id: '1',
+    type: 'custom',
+    position: { x: 150, y: 100 },
+  },
+  {
+    id: '2',
+    type: 'custom',
+    position: { x: 300, y: 100 },
+  },
+  {
+    id: '3',
+    type: 'custom',
+    position: { x: 450, y: 100 },
+  },
+];
+
+const nodeTypes: NodeTypesType = {
+  custom: CustomNode,
+};
+
+let id = 4;
+const getId = (): ElementId => `${id++}`;
+
+const UpdateNodeInternalsFlow = () => {
+  const [elements, setElements] = useState<Elements>(initialElements);
+  const onConnect = (params: Connection | Edge) =>
+    setElements((els) => addEdge({ ...params, type: 'smoothstep' }, els));
+  const { project } = useZoomPanHelper();
+
+  const onPaneClick = useCallback(
+    (evt) =>
+      setElements((els) =>
+        els.concat({
+          id: getId(),
+          position: project({ x: evt.clientX, y: evt.clientY - 40 }),
+          type: 'custom',
+        })
+      ),
+    [project]
+  );
+
+  return (
+    <ReactFlow
+      elements={elements}
+      nodeTypes={nodeTypes}
+      onConnect={onConnect}
+      onPaneClick={onPaneClick}
+      connectionLineType={ConnectionLineType.SmoothStep}
+      connectionMode={ConnectionMode.Loose}
+    />
+  );
+};
+
+const WrappedFlow = () => (
+  <ReactFlowProvider>
+    <UpdateNodeInternalsFlow />
+  </ReactFlowProvider>
+);
+
+export default WrappedFlow;