css/css-paint-api/background-image-alpha.https.html

<!DOCTYPE html>
<html class="reftest-wait">
<link rel="help" href="https://drafts.css-houdini.org/css-paint-api/">
<link rel="match" href="background-image-alpha-ref.html">
<style>
.container {
  width: 100px;
  height: 100px;
}

#canvas-opaque {
  background-image: paint(opaque);
}

#canvas-nonopaque {
  background-image: paint(nonOpaque);
}

#background {
  background-color: yellow;
  display: inline-block;
}
</style>
<script src="/common/reftest-wait.js"></script>
<script src="/common/worklet-reftest.js"></script>
<body>
<div id="background">
  <div id="canvas-opaque" class="container"></div>
  <div id="canvas-nonopaque" class="container"></div>
</div>

<script id="code" type="text/worklet">
registerPaint('opaque', class {
    static get contextOptions() { return {alpha: false}; }
    paint(ctx, geom) {
        ctx.fillStyle = 'blue';
        ctx.fillRect(20, 20, 60, 60);
    }
});

registerPaint('nonOpaque', class {
    static get contextOptions() { return {alpha: true}; }
    paint(ctx, geom) {
        ctx.fillStyle = 'blue';
        ctx.fillRect(20, 20, 60, 60);
    }
});
</script>

<script>
    importWorkletAndTerminateTestAfterAsyncPaint(CSS.paintWorklet, document.getElementById('code').textContent);
</script>
</body>
</html>