npm package: @krhsiung/react-flow-smart-edge
Description: Custom Edges for React Flow that never intersect with other nodes, using pathfinding.
Author: Tiso Alvarez Puccinelli
Latest version: 3.0.2

# React Flow Smart Edge

Custom Edges for React Flow that never intersect with other nodes, using pathfinding.

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![Smart Edge](https://raw.githubusercontent.com/tisoap/react-flow-smart-edge/main/.github/images/example.gif)

## Install

With `npm`:

```bash
npm install @tisoap/react-flow-smart-edge
```

With `yarn`:

```bash
yarn add @tisoap/react-flow-smart-edge
```

This package is only compatible with [**version 11 or newer** of React Flow Edge](https://reactflow.dev/docs/guides/migrate-to-v11/).

## Support

Like this project and want to show your support? Buy me a coffee:

[![ko-fi](https://ko-fi.com/img/githubbutton_sm.svg)](https://ko-fi.com/J3J472RAJ)

_Really_ like this project? Sponsor me on GitHub:

[![GitHub Sponsors](https://img.shields.io/static/v1?label=Sponsor%20Me&message=%E2%9D%A4&logo=GitHub&color=%23fe8e86)](https://github.com/sponsors/tisoap)

## Usage

This package ships with the following Smart Edges components:

- `SmartBezierEdge`: A smart equivalent to React Flow's [BezierEdge](https://reactflow.dev/docs/api/edges/edge-types/)
- `SmartStraightEdge`: A smart equivalent to React Flow's [StraightEdge](https://reactflow.dev/docs/api/edges/edge-types/)
- `SmartStepEdge`: A smart equivalent to React Flow's [StepEdge](https://reactflow.dev/docs/api/edges/edge-types/)

Each one can be imported individually as a named export.

### Example

```jsx
import React from 'react'
import { ReactFlow } from 'reactflow'
import { SmartBezierEdge } from '@tisoap/react-flow-smart-edge'
import 'reactflow/dist/style.css'

const nodes = [
	{
		id: '1',
		data: { label: 'Node 1' },
		position: { x: 300, y: 100 }
	},
	{
		id: '2',
		data: { label: 'Node 2' },
		position: { x: 300, y: 200 }
	}
]

const edges = [
	{
		id: 'e21',
		source: '2',
		target: '1',
		type: 'smart'
	}
]

// You can give any name to your edge types
// https://reactflow.dev/docs/api/edges/custom-edges/
const edgeTypes = {
	smart: SmartBezierEdge
}

export const Graph = (props) => {
	const { children, ...rest } = props

	return (
		<ReactFlow
			defaultNodes={nodes}
			defaultEdges={edges}
			edgeTypes={edgeTypes}
			{...rest}
		>
			{children}
		</ReactFlow>
	)
}
```

## Edge Options

All smart edges will take the exact same options as a [React Flow Edge](https://reactflow.dev/docs/api/edges/edge-options/).

## Custom Smart Edges

You can have more control over how the edge is rerendered by creating a [custom edge](https://reactflow.dev/docs/api/edges/custom-edges/) and using the provided `getSmartEdge` function. It takes an object with the following keys:

- `sourcePosition`, `targetPosition`, `sourceX`, `sourceY`, `targetX` and `targetY`: The same values your [custom edge](https://reactflow.dev/docs/examples/edges/custom-edge/) will take as props
- `nodes`: An array containing all graph nodes, you can get it from the [`useNodes` hook](https://reactflow.dev/docs/api/hooks/use-nodes/)

### Example

Just like you can use `getBezierPath` from `reactflow` to create a [custom edge with a button](https://reactflow.dev/docs/examples/edges/edge-with-button/), you can do the same with `getSmartEdge`:

```jsx
import React from 'react'
import { useNodes, BezierEdge } from 'reactflow'
import { getSmartEdge } from '@tisoap/react-flow-smart-edge'

const foreignObjectSize = 200

export function SmartEdgeWithButtonLabel(props) {
	const {
		id,
		sourcePosition,
		targetPosition,
		sourceX,
		sourceY,
		targetX,
		targetY,
		style,
		markerStart,
		markerEnd
	} = props

	const nodes = useNodes()

	const getSmartEdgeResponse = getSmartEdge({
		sourcePosition,
		targetPosition,
		sourceX,
		sourceY,
		targetX,
		targetY,
		nodes
	})

	// If the value returned is null, it means "getSmartEdge" was unable to find
	// a valid path, and you should do something else instead
	if (getSmartEdgeResponse === null) {
		return <BezierEdge {...props} />
	}

	const { edgeCenterX, edgeCenterY, svgPathString } = getSmartEdgeResponse

	return (
		<>
			<path
				style={style}
				className='react-flow__edge-path'
				d={svgPathString}
				markerEnd={markerEnd}
				markerStart={markerStart}
			/>
			<foreignObject
				width={foreignObjectSize}
				height={foreignObjectSize}
				x={edgeCenterX - foreignObjectSize / 2}
				y={edgeCenterY - foreignObjectSize / 2}
				requiredExtensions='http://www.w3.org/1999/xhtml'
			>
				<button
					onClick={(event) => {
						event.stopPropagation()
						alert(`remove ${id}`)
					}}
				>
					X
				</button>
			</foreignObject>
		</>
	)
}
```

## Advanced Custom Smart Edges

The `getSmartEdge` function also accepts an optional object `options`, which allows you to configure aspects of the path-finding algorithm. You may use it like so:

```js
const myOptions = {
	// your configuration goes here
	nodePadding: 20,
	gridRatio: 15
}

// ...

const getSmartEdgeResponse = getSmartEdge({
	sourcePosition,
	targetPosition,
	sourceX,
	sourceY,
	targetX,
	targetY,
	nodes,
	// Pass down options in the getSmartEdge object
	options: myOptions
})
```

The `options` object accepts the following keys (they're all optional):

- `nodePadding`: How many pixels of padding are added around nodes, or by how much should the edge avoid the walls of a node. Default `10`, minimum `2`.
- `gridRatio`: The size in pixels of each square grid cell used for path-finding. Smaller values for a more accurate path, bigger for faster path-finding. Default `10`, minimum `2`.
- `drawEdge`: Allows you to change the function responsible to draw the SVG line, by default it's the same used by `SmartBezierEdge` ([more below](#drawedge))
- `generatePath`: Allows you to change the function for the path-finding, by default it's the same used by `SmartBezierEdge` ([more below](#generatepath))

### `drawEdge`

With the `drawEdge` option, you can change the function used to generate the final [SVG path string](https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Paths), used to draw the line. By default it's the `svgDrawSmoothLinePath` function (same as used by the `SmartBezierEdge`), but the package also includes `svgDrawStraightLinePath` (same as used by the `SmartStraightEdge` and `SmartStepEdge`), or you can provide your own.

```jsx
import {
	getSmartEdge,
	// Available built-in SVG draw functions
	svgDrawSmoothLinePath,
	svgDrawStraightLinePath
} from '@tisoap/react-flow-smart-edge'

// Using provided SVG draw functions:
const result = getSmartEdge({
	// ...
	options: {
		drawEdge: svgDrawSmoothLinePath
	}
})

// ...or using your own custom function
const result = getSmartEdge({
	// ...
	options: {
		drawEdge: (source, target, path) => {
			// your code goes here
			// ...
			return svgPath
		}
	}
})
```

The function you provided must comply with this signature:

```ts
type SVGDrawFunction = (
	source: XYPosition, // The starting {x, y} point
	target: XYPosition, // The ending  {x, y} point
	path: number[][] // The sequence of points [x, y] the line must follow
) => string // A string to be used in the "d" property of the SVG line
```

For inspiration on how to implement your own, you can check the [`drawSvgPath.ts` source code](https://github.com/tisoap/react-flow-smart-edge/blob/main/src/functions/drawSvgPath.ts).

### `generatePath`

With the `generatePath` option, you can change the function used to do [Pathfinding](https://en.wikipedia.org/wiki/Pathfinding). By default, it's the `pathfindingAStarDiagonal` function (same as used by the `SmartBezierEdge`), but the package also includes `pathfindingAStarNoDiagonal` (used by `SmartStraightEdge`) and `pathfindingJumpPointNoDiagonal` (used by `SmartStepEdge`), or your can provide your own. The built-in functions use the [`pathfinding` dependency](https://www.npmjs.com/package/pathfinding#advanced-usage) behind the scenes.

```jsx
import {
	getSmartEdge,
	// Available built-in pathfinding functions
	pathfindingAStarDiagonal,
	pathfindingAStarNoDiagonal,
	pathfindingJumpPointNoDiagonal
} from '@tisoap/react-flow-smart-edge'

// Using provided pathfinding functions:
const result = getSmartEdge({
	// ...
	options: {
		generatePath: pathfindingJumpPointNoDiagonal
	}
})

// ...or using your own custom function
const result = getSmartEdge({
	// ...
	options: {
		generatePath: (grid, start, end) => {
			// your code goes here
			// ...
			return { fullPath, smoothedPath }
		}
	}
})
```

The function you provide must comply with this signature:

```ts
type PathFindingFunction = (
	grid: Grid, // Grid representation of the graph
	start: XYPosition, // The starting {x, y} point
	end: XYPosition // The ending  {x, y} point
) => {
	fullPath: number[][] // Array of points [x, y] representing the full path with all points
	smoothedPath: number[][] // Array of points [x, y] representing a smaller, compressed path
} | null // The function should return null if it was unable to do pathfinding
```

For inspiration on how to implement your own, you can check the [`generatePath.ts` source code](https://github.com/tisoap/react-flow-smart-edge/blob/main/src/functions/generatePath.ts) and the [`pathfinding` dependency](https://www.npmjs.com/package/pathfinding#advanced-usage) documentation.

### Advanced Examples

```jsx
import {
	getSmartEdge,
	svgDrawSmoothLinePath,
	svgDrawStraightLinePath
	pathfindingAStarDiagonal,
	pathfindingAStarNoDiagonal,
	pathfindingJumpPointNoDiagonal
} from '@tisoap/react-flow-smart-edge'

// ...

// Same as importing "SmartBezierEdge" directly
const bezierResult = getSmartEdge({
	// ...
	options: {
		drawEdge: svgDrawSmoothLinePath,
		generatePath: pathfindingAStarDiagonal,
	}
})

// Same as importing "SmartStepEdge" directly
const stepResult = getSmartEdge({
	// ...
	options: {
		drawEdge: svgDrawStraightLinePath,
		generatePath: pathfindingJumpPointNoDiagonal,
	}
})

// Same as importing "SmartStraightEdge" directly
const straightResult = getSmartEdge({
	// ...
	options: {
		drawEdge: svgDrawStraightLinePath,
		generatePath: pathfindingAStarNoDiagonal,
	}
})
```

## Storybook

You can see live Storybook examples by visiting [this page](https://tisoap.github.io/react-flow-smart-edge/), and see their source code [here](https://github.com/tisoap/react-flow-smart-edge/blob/main/src/stories/SmartEdge.stories.tsx).

## License

This project is [MIT](https://github.com/tisoap/react-flow-smart-edge/blob/main/LICENSE) licensed.