react-flow-implementation

React Flow 实现

快速开始

import { useCallback } from 'react';
import { ReactFlow, useNodesState, useEdgesState, addEdge } from '@xyflow/react';
import '@xyflow/react/dist/style.css';

const initialNodes = [
  { id: '1', position: { x: 0, y: 0 }, data: { label: 'Node 1' } },
  { id: '2', position: { x: 200, y: 100 }, data: { label: 'Node 2' } },
];

const initialEdges = [{ id: 'e1-2', source: '1', target: '2' }];

export default function Flow() {
  const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);
  const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);

  const onConnect = useCallback(
    (connection) => setEdges((eds) => addEdge(connection, eds)),
    [setEdges]
  );

  return (
    <div style={{ width: '100%', height: '100vh' }}>
      <ReactFlow
        nodes={nodes}
        edges={edges}
        onNodesChange={onNodesChange}
        onEdgesChange={onEdgesChange}
        onConnect={onConnect}
        fitView
      />
    </div>
  );
}

实现检查关卡

按顺序运行这些检查；不要因为“看起来没问题”就跳过。

1. 页面上的样式 — 通过条件： 渲染 <ReactFlow /> 的构建包导入了 @xyflow/react/dist/style.css（或等效的 CSS 流程），确保节点和边可见，且点击目标与视觉效果相符。
2. useReactFlow 边界 — 通过条件： 每个 useReactFlow() 调用者都是 <ReactFlowProvider> 的后代，且该 Provider 包装的树与 <ReactFlow /> 位于同一棵树中（或者你有意拆分了 store，并且能够指出两个根节点）。
3. 稳定的 nodeTypes / edgeTypes — 通过条件： 这些映射是模块级常量，或使用依赖稳定的 useMemo，而不是在渲染 <ReactFlow /> 的组件中每次渲染都创建新的 { ... } 字面量。
4. 句柄与边匹配 — 通过条件： 对于具有多个 Handle id 的节点，每条必须连接到特定句柄的边都设置了相应的 sourceHandle / targetHandle（或者你有意接受默认句柄解析方式）。

有关 MiniMap、Controls、Background、NodeToolbar 和 NodeResizer 的模式，请参阅 ADDITIONAL_COMPONENTS.md。

核心模式

TypeScript 类型

import type { Node, Edge, NodeProps, BuiltInNode } from '@xyflow/react';

// Define custom node type with data shape
type CustomNode = Node<{ value: number; label: string }, 'custom'>;

// Combine with built-in nodes
type MyNode = CustomNode | BuiltInNode;
type MyEdge = Edge<{ weight?: number }>;

// Use throughout app
const [nodes, setNodes] = useNodesState<MyNode>(initialNodes);

自定义节点

import { memo } from 'react';
import { Handle, Position, type NodeProps } from '@xyflow/react';

// Define node type
type CounterNode = Node<{ count: number }, 'counter'>;

// Always wrap in memo for performance
const CounterNode = memo(function CounterNode({ data, isConnectable }: NodeProps<CounterNode>) {
  return (
    <>
      <Handle type="target" position={Position.Top} isConnectable={isConnectable} />
      <div className="counter-node">
        Count: {data.count}
        {/* nodrag prevents dragging when interacting with button */}
        <button className="nodrag" onClick={() => console.log('clicked')}>
          Increment
        </button>
      </div>
      <Handle type="source" position={Position.Bottom} isConnectable={isConnectable} />
    </>
  );
});

// Register in nodeTypes (define OUTSIDE component to avoid re-renders)
const nodeTypes = { counter: CounterNode };

// Use in ReactFlow
<ReactFlow nodeTypes={nodeTypes} ... />

多个句柄

// Use handle IDs when a node has multiple handles of same type
<Handle type="source" position={Position.Right} id="a" />
<Handle type="source" position={Position.Right} id="b" style={{ top: 20 }} />

// Connect with specific handles
const edge = {
  id: 'e1-2',
  source: '1',
  sourceHandle: 'a',
  target: '2',
  targetHandle: null
};

自定义边

import { BaseEdge, EdgeProps, getSmoothStepPath } from '@xyflow/react';

function CustomEdge({ id, sourceX, sourceY, targetX, targetY, sourcePosition, targetPosition, data }: EdgeProps) {
  const [edgePath, labelX, labelY] = getSmoothStepPath({
    sourceX, sourceY, sourcePosition,
    targetX, targetY, targetPosition,
  });

  return (
    <>
      <BaseEdge id={id} path={edgePath} />
      <text x={labelX} y={labelY} className="edge-label">{data?.label}</text>
    </>
  );
}

const edgeTypes = { custom: CustomEdge };

状态管理

受控模式（推荐用于生产环境）

// External state with change handlers
const [nodes, setNodes] = useState<Node[]>(initialNodes);
const [edges, setEdges] = useState<Edge[]>(initialEdges);

const onNodesChange = useCallback(
  (changes) => setNodes((nds) => applyNodeChanges(changes, nds)),
  []
);

const onEdgesChange = useCallback(
  (changes) => setEdges((eds) => applyEdgeChanges(changes, eds)),
  []
);

<ReactFlow
  nodes={nodes}
  edges={edges}
  onNodesChange={onNodesChange}
  onEdgesChange={onEdgesChange}
/>

使用 useReactFlow

import { useReactFlow, ReactFlowProvider } from '@xyflow/react';

function FlowControls() {
  const {
    getNodes, setNodes, addNodes, updateNodeData,
    getEdges, setEdges, addEdges,
    fitView, zoomIn, zoomOut, setViewport,
    deleteElements, toObject,
  } = useReactFlow();

  const addNode = () => {
    addNodes({ id: `${Date.now()}`, position: { x: 100, y: 100 }, data: { label: 'New' } });
  };

  return <button onClick={addNode}>Add Node</button>;
}

// Must wrap in provider when using useReactFlow
function App() {
  return (
    <ReactFlowProvider>
      <Flow />
      <FlowControls />
    </ReactFlowProvider>
  );
}

更新节点数据

const { updateNodeData } = useReactFlow();

// Merge with existing data
updateNodeData(nodeId, { label: 'Updated' });

// Replace data entirely
updateNodeData(nodeId, { newField: 'value' }, { replace: true });

视口与适应视图

// Fit on initial render
<ReactFlow fitView fitViewOptions={{ padding: 0.2, maxZoom: 1 }} />

// Programmatic control
const { fitView, setViewport, getViewport, zoomTo } = useReactFlow();

// Fit to specific nodes
fitView({ nodes: [{ id: '1' }, { id: '2' }], duration: 500 });

// Set exact viewport
setViewport({ x: 100, y: 100, zoom: 1.5 }, { duration: 300 });

连接验证

const isValidConnection = useCallback((connection: Connection) => {
  // Prevent self-connections
  if (connection.source === connection.target) return false;

  // Custom validation logic
  const sourceNode = getNode(connection.source);
  const targetNode = getNode(connection.target);

  return sourceNode?.type !== targetNode?.type;
}, []);

<ReactFlow isValidConnection={isValidConnection} />

常用属性参考

<ReactFlow
  // Core data
  nodes={nodes}
  edges={edges}
  onNodesChange={onNodesChange}
  onEdgesChange={onEdgesChange}

  // Custom types (define OUTSIDE component)
  nodeTypes={nodeTypes}
  edgeTypes={edgeTypes}

  // Connections
  onConnect={onConnect}
  connectionMode={ConnectionMode.Loose}  // Allow target-to-target
  isValidConnection={isValidConnection}

  // Viewport
  fitView
  minZoom={0.1}
  maxZoom={4}
  defaultViewport={{ x: 0, y: 0, zoom: 1 }}

  // Interaction
  nodesDraggable={true}
  nodesConnectable={true}
  elementsSelectable={true}
  panOnDrag={true}
  zoomOnScroll={true}

  // Additional components
  <MiniMap />
  <Controls />
  <Background variant={BackgroundVariant.Dots} />
</ReactFlow>

用于交互的 CSS 类

类	效果
nodrag	点击元素时禁止拖动
nowheel	禁止通过滚轮事件缩放
nopan	禁止从元素开始平移
nokey	禁止键盘事件（用于输入框）

其他组件

有关 MiniMap、Controls、Background、NodeToolbar、NodeResizer，请参阅 ADDITIONAL_COMPONENTS.md。