橡皮擦工具

这个示例展示了如何创建一个橡皮工具，它允许你通过擦除来删除节点和边。它由两部分组成：

🌐 This example shows how to create an eraser tool that allows you to delete nodes and edges by wiping them out. It’s made up of two parts:

Eraser 组件负责处理擦除逻辑和橡皮痕迹的渲染。
响应 toBeDeleted 标志的自定义 ErasableNode 和 ErasableEdge。

确定小径是否与节点相交相对简单——然而检测小径与边的交点则稍复杂一些：我们通过 SVG 路径元素的 getPointAtLength 方法在边上采样点，构建一条折线，然后可以用它来检测与橡皮擦轨迹的交点。这是性能与精度之间的权衡——你可以尝试调整 sampleDistance 变量，看看它对橡皮擦轨迹的影响。

🌐 Determining if the trail intersects with a node is fairly straight forward - however detecting intersections between the trail and an edge is a bit more complex: We sample points along the edge through the getPointAtLength method of the SVG path element, construct a polyline that we can then use to detect intersections with the eraser trail. This is a trade-off between performance and accuracy - you can play around with the sampleDistance variable to see the effect it has on the eraser trail.


import { useCallback, useState } from 'react';
import {
  ReactFlow,
  useNodesState,
  useEdgesState,
  addEdge,
  Controls,
  Background,
  Panel,
} from '@xyflow/react';
 
import { ErasableNode } from './ErasableNode';
import { ErasableEdge } from './ErasableEdge';
import { Eraser } from './Eraser';
 
import '@xyflow/react/dist/style.css';
 
const initialNodes = [
  {
    id: '1',
    type: 'erasable-node',
    position: { x: 0, y: 0 },
    data: { label: 'Hello' },
  },
  {
    id: '2',
    type: 'erasable-node',
    position: { x: 300, y: 0 },
    data: { label: 'World' },
  },
];
 
const initialEdges = [
  {
    id: '1->2',
    type: 'erasable-edge',
    source: '1',
    target: '2',
  },
];
 
const nodeTypes = {
  'erasable-node': ErasableNode,
};
 
const edgeTypes = {
  'erasable-edge': ErasableEdge,
};
 
const defaultEdgeOptions = {
  type: 'erasable-edge',
};
 
export default function EraserFlow() {
  const [nodes, _, onNodesChange] = useNodesState(initialNodes);
  const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);
  const onConnect = useCallback((params) => setEdges((els) => addEdge(params, els)), []);
 
  const [isEraserActive, setIsEraserActive] = useState(true);
 
  return (
    <ReactFlow
      nodes={nodes}
      nodeTypes={nodeTypes}
      edges={edges}
      edgeTypes={edgeTypes}
      onNodesChange={onNodesChange}
      onEdgesChange={onEdgesChange}
      onConnect={onConnect}
      fitView
      defaultEdgeOptions={defaultEdgeOptions}
    >
      <Controls />
      <Background />
 
      {isEraserActive && <Eraser />}
 
      <Panel position="top-left">
        <div className="xy-theme__button-group">
          <button
            className={`xy-theme__button ${isEraserActive ? 'active' : ''}`}
            onClick={() => setIsEraserActive(true)}
          >
            Eraser Mode
          </button>
          <button
            className={`xy-theme__button ${!isEraserActive ? 'active' : ''}`}
            onClick={() => setIsEraserActive(false)}
          >
            Selection Mode
          </button>
        </div>
      </Panel>
    </ReactFlow>
  );
}