Tools/TestWebKitAPI/Tests/WebKitCocoa/canvas-image-data.html

<!DOCTYPE html>
<html>
<head>
<style>
canvas {
    width: 160px;
    height: 160px;
    display: block;
}
</style>
</head>
<body>
<strong>Source</strong>
<canvas id="source" width="320" height="320"></canvas>
<strong>Destination</strong>
<canvas id="destination" width="320" height="320"></canvas>
<script>
const sourceCanvas = document.getElementById("source");
const sourceContext = sourceCanvas.getContext("2d");
sourceContext.save();
sourceContext.strokeStyle = "red";
sourceContext.fillStyle = "rgba(200, 100, 100, 0.25)";
sourceContext.lineWidth = 4;
sourceContext.rect(40, 40, 240, 240);
sourceContext.stroke();
sourceContext.fill();
sourceContext.restore();

const imageData = sourceContext.getImageData(0, 0, 320, 320);
const destinationCanvas = document.getElementById("destination");
const destinationContext = destinationCanvas.getContext("2d");
destinationContext.putImageData(imageData, 0, 0, 0, 0, 320, 320);
</script>
</body>
</html>