curved-arrows v0.3.0

Curved Arrows

A set of functions for drawing S-curved arrows between points and shapes.

• getArrow - For point-to-point arrows (has glitches, not ready yet).
• getBoxToBoxArrow - For rectangle-to-rectangle arrows.

👉 Demo | How it works

You may also want to see steveruizok's perfect-arrows, it's smarter but the start point and the end point are less predictable.

Installation

npm i curved-arrows

or

yarn add curved-arrows

Usage

The functions in this library has similar arguments and return values to steveruizok's perfect-arrows. Notable differences are options and the return values containing two control points, one for start point and one end point, instead of one, to represent an S-curve.

The return values provide only the information needed to draw an arrow. You'll need to draw the arrow yourself using your technology of choice. See below for an example using React and SVG.

getArrow(x0, y0, x1, y1, options)

The getArrow function accepts the position of two points and returns an array containing this information:

• four points: start, end, and two control points (one for start, one for end)
• two angles: end and start

You can use this information to draw an S-curve and arrow heads. You can use the options object to tweak the return values.

const arrowHeadSize = 9
const arrow = getArrow(0, 0, 100, 200, {
  padStart: 0,
  padEnd: arrowHeadSize,
})
const [sx, sy, c1x, c1y, c2x, c2y, ex, ey, ae, as] = arrow

Arguments

Options

Returns

getBoxToBoxArrow(x0, y0, w0, h0, x1, y1, w1, h1, options)

The getBoxToBoxArrow function accepts the position and dimensions of two boxes (or rectangles) and returns an array containing this information:

• four points: start, end, and two control points (one for start, one for end)
• two angles: end and start

You can use this information to draw an S-curve and arrow heads. You can use the options object to tweak the return values.

Note: The options and values returned by getBoxToBoxArrow are in the same format as the options and values for getArrow.

const arrowHeadSize = 9
const arrow = getArrow(0, 0, 200, 100, 300, 50, 200, 100, {
  padStart: 0,
  padEnd: arrowHeadSize,
})
const [sx, sy, c1x, c1y, c2x, c2y, ex, ey, ae, as] = arrow

Arguments

Options

See options in getArrow above. (Both functions use the same options object.)

Returns

See returns in getArrow above. (Both functions return the same set of values.)

Example: A React Arrow Component

import * as React from 'react'
import { getArrow } from 'curved-arrows'

export function Arrow() {
  const p1 = { x: 100, y: 100 }
  const p2 = { x: 300, y: 200 }
  const arrowHeadSize = 9
  const color = 'black'
  const [sx, sy, c1x, c1y, c2x, c2y, ex, ey, ae] = getArrow(p1.x, p1.y, p2.x, p2.y, {
    padEnd: arrowHeadSize,
  })

  return (
    <svg
      width="100%"
      height="100%"
      xmlns="http://www.w3.org/2000/svg">
      <path
        d={`M ${sx} ${sy} C ${c1x} ${c1y}, ${c2x} ${c2y}, ${ex} ${ey}`}
        stroke={color}
        strokeWidth={arrowHeadSize / 2}
        fill="none"
      />
      <polygon
        points={`0,${-arrowHeadSize} ${arrowHeadSize *
          2},0, 0,${arrowHeadSize}`}
        transform={`translate(${ex}, ${ey}) rotate(${ae})`}
        fill={color}
      />
    </svg>
  )
}

Author

@hialexwang