Security News
Cloudflare Adds Security.txt Setup Wizard
Cloudflare has launched a setup wizard allowing users to easily create and manage a security.txt file for vulnerability disclosure on their websites.
perfect-freehand
Advanced tools
Draw perfect pressure-sensitive freehand strokes.
🔗 Try out a demo.
💰 Using this library in a commercial product? Consider becoming a sponsor.
npm install perfect-freehand
or
yarn add perfect-freehand
This package's default export is a function that:
[x, y]
import getStroke from 'perfect-freehand'
You may format your input points as array or an object. In both cases, the value for pressure is optional (it will default to .5
).
getStroke([
[0, 0, 0],
[10, 5, 0.5],
[20, 8, 0.3],
])
getStroke([
{ x: 0, y: 0, pressure: 0 },
{ x: 10, y: 5, pressure: 0.5 },
{ x: 20, y: 8, pressure: 0.3 },
])
The options object is optional, as are each of its properties.
Property | Type | Default | Description |
---|---|---|---|
size | number | 8 | The base size (diameter) of the stroke. |
thinning | number | .5 | The effect of pressure on the stroke's size. |
smoothing | number | .5 | How much to soften the stroke's edges. |
streamline | number | .5 | How much to streamline the stroke. |
simulatePressure | boolean | true | Whether to simulate pressure based on velocity. |
easing | function | t => t | An easing function to apply to each point's pressure. |
start | { } | Tapering options for the start of the line. | |
end | { } | Tapering options for the end of the line. | |
last | boolean | true | Whether the stroke is complete. |
Note: When the last
property is true
, the line's end will be drawn at the last input point, rather than slightly behind it.
The start
and end
options accept an object:
Property | Type | Default | Description |
---|---|---|---|
cap | boolean | true | Whether to draw a cap. |
taper | number | 0 | The distance to taper. |
easing | function | t => t | An easing function for the tapering effect. |
Note: The cap
property has no effect when taper
is more than zero.
getStroke(myPoints, {
size: 8,
thinning: 0.5,
smoothing: 0.5,
streamline: 0.5,
easing: (t) => t * t * t,
simulatePressure: true,
last: true,
start: {
taper: 20,
easing: (t) => t * t * t,
},
end: {
taper: 20,
easing: (t) => t * t * t,
},
})
Tip: To create a stroke with a steady line, set the
thinning
option to0
.
Tip: To create a stroke that gets thinner with pressure instead of thicker, use a negative number for the
thinning
option.
While getStroke
returns an array of points representing the outline of a stroke, it's up to you to decide how you will render these points.
The function below will turn the points returned by getStroke
into SVG path data.
function getSvgPathFromStroke(stroke) {
if (!stroke.length) return ''
const d = stroke.reduce(
(acc, [x0, y0], i, arr) => {
const [x1, y1] = arr[(i + 1) % arr.length]
acc.push(x0, y0, (x0 + x1) / 2, (y0 + y1) / 2)
return acc
},
['M', ...stroke[0], 'Q']
)
d.push('Z')
return d.join(' ')
}
To use this function, first use perfect-freehand to turn your input points into a stroke outline, then pass the result to getSvgPathFromStroke
.
import getStroke from 'perfect-freehand'
const myStroke = getStroke(myInputPoints)
const pathData = getSvgPathFromStroke(myStroke)
You could then pass this string either to an SVG path element:
<path d={pathData} />
Or, if you are rendering with HTML Canvas, you can pass the result to a Path2D
constructor).
const myPath = new Path2D(pathData)
ctx.fill(myPath)
To render a stroke as a "flattened" polygon, add the polygon-clipping
package and use the following function together with the getSvgPathFromStroke
.
import polygonClipping from 'polygon-clipping'
function getFlatSvgPathFromStroke(stroke) {
const poly = polygonClipping.union([stroke])
const d = []
for (let face of poly) {
for (let points of face) {
d.push(getSvgPathFromStroke(points))
}
}
return d.join(' ')
}
Tip: For implementations in Typescript, see the example project included in this repository.
import * as React from 'react'
import getStroke from 'perfect-freehand'
import { getSvgPathFromStroke } from './utils'
export default function Example() {
const [points, setPoints] = React.useState()
function handlePointerDown(e) {
e.preventDefault()
setPoints([[e.pageX, e.pageY, e.pressure]])
}
function handlePointerMove(e) {
if (e.buttons === 1) {
e.preventDefault()
setPoints([...points, [e.pageX, e.pageY, e.pressure]])
}
}
return (
<svg
onPointerDown={handlePointerDown}
onPointerMove={handlePointerMove}
style={{ touchAction: 'none' }}
>
{points && (
<path
d={getSvgPathFromStroke(
getStroke(points, {
size: 24,
thinning: 0.5,
smoothing: 0.5,
streamline: 0.5,
})
)}
/>
)}
</svg>
)
}
StrokeOptions
A TypeScript type for the options object.
import { StrokeOptions } from 'perfect-freehand'
For advanced usage, the library also exports smaller functions that getStroke
uses to generate its SVG data. While you can use getStroke
's data to render strokes with an HTML canvas (via the Path2D element) or with SVG paths, these new functions will allow you to create paths in other rendering technologies.
getStrokePoints
import { strokePoints } from 'perfect-freehand'
const strokePoints = getStrokePoints(rawInputPoints)
Accepts an array of points (formatted either as [x, y, pressure]
or { x: number, y: number, pressure: number}
) and a streamline value. Returns a set of streamlined points as [x, y, pressure, angle, distance, lengthAtPoint]
. The path's total length will be the length of the last point in the array.
getOutlinePoints
Accepts an array of points (formatted as [x, y, pressure, angle, distance, length]
, i.e. the output of getStrokePoints
) and returns an array of points ([x, y]
) defining the outline of a pressure-sensitive stroke.
import { getOutlinePoints } from 'perfect-freehand'
const outlinePoints = getOutlinePoints(strokePoints)
Please open an issue for support.
Have an idea or casual question? Visit the discussion page.
FAQs
Draw perfect pressure-sensitive freehand strokes.
The npm package perfect-freehand receives a total of 72,377 weekly downloads. As such, perfect-freehand popularity was classified as popular.
We found that perfect-freehand demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
Cloudflare has launched a setup wizard allowing users to easily create and manage a security.txt file for vulnerability disclosure on their websites.
Security News
The Socket Research team breaks down a malicious npm package targeting the legitimate DOMPurify library. It uses obfuscated code to hide that it is exfiltrating browser and crypto wallet data.
Security News
ENISA’s 2024 report highlights the EU’s top cybersecurity threats, including rising DDoS attacks, ransomware, supply chain vulnerabilities, and weaponized AI.