This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The PaintWorklet
interface of the CSS Painting API programmatically generates an image where a CSS property expects a file. Access this interface through CSS.paintWorklet
.
Properties
PaintWorklet.devicePixelRatio
- Returns the current device's ratio of physical pixels to logical pixels.
Event handlers
None.
Methods
This interface inherits methods from Worklet
.
PaintWorklet.registerPaint()
- Registers a class programmatically generate an image where a CSS property expects a file.
CSS.PaintWorklet.addModule()
- The
addModule()
method, inhertied from theWorklet
interface loads the module in the given JavaScript file and adds it to the current PaintWorklet.
Examples
The following three examples go together to show creating, loading, and using a PaintWorklet
.
Create a PaintWorklet
The following shows an example worklet module. This should be in a separate js file. Note that registerPaint()
is called without a reference to PaintWorklet
.
class CheckerboardPainter { paint(ctx, geom, properties) { // Use `ctx` as if it was a normal canvas const colors = ['red', 'green', 'blue']; const size = 32; for(let y = 0; y < geom.height/size; y++) { for(let x = 0; x < geom.width/size; x++) { const color = colors[(x + y) % colors.length]; ctx.beginPath(); ctx.fillStyle = color; ctx.rect(x * size, y * size, size, size); ctx.fill(); } } } } // Register our class under a specific name registerPaint('checkerboard', CheckerboardPainter);
Load a PaintWorklet
The following example demonstrates loading the above worklet from its js file and does so by feature detection.
<script> if ('paintWorklet' in CSS) { CSS.paintWorklet.addModule('checkerboard.js'); } </script>
Use a PaintWorklet
This example shows how to use a PaintWorklet
in a stylesheet, including the simplest way to provide a fallback if PaintWorklet
isn't supported.
<style> textarea { background-image: url(checkerboard); background-image: paint(checkerboard); } </style> <textarea></textarea>
You can also use the @supports
at-rule.
@supports (background: paint(id)) { background-image: paint(checkerboard); }
Specifications
Specification | Status | Comment |
---|---|---|
CSS Painting API Level 1 The definition of 'PaintWorkletGlobalScope' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
PaintWorkletGlobalScope | Chrome Full support 65 | Edge Full support ≤79 | Firefox ? | IE No support No | Opera ? | Safari ? | WebView Android Full support 65 | Chrome Android Full support 65 | Firefox Android ? | Opera Android ? | Safari iOS ? | Samsung Internet Android Full support 9.0 |
devicePixelRatio | Chrome Full support 65 | Edge Full support ≤79 | Firefox ? | IE No support No | Opera ? | Safari ? | WebView Android Full support 65 | Chrome Android Full support 65 | Firefox Android ? | Opera Android ? | Safari iOS ? | Samsung Internet Android Full support 9.0 |
registerPaint | Chrome Full support 65 | Edge Full support ≤79 | Firefox ? | IE No support No | Opera ? | Safari ? | WebView Android Full support 65 | Chrome Android Full support 65 | Firefox Android ? | Opera Android ? | Safari iOS ? | Samsung Internet Android Full support 9.0 |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown