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<!DOCTYPE html>
<meta charset="utf8">
<body>
<output id="result"></output>
<script>
window.onload = async () => {
parent.postMessage("ready", "*");
}
window.addEventListener("message", async function listener(event) {
if (event.data[0] == "gimme") {
var iframe = document.createElement("iframe");
iframe.src = "about:blank?foo";
document.body.append(iframe);
function test() {
function give_inner_result() {
const canvas = document.createElement("canvas");
canvas.width = 100;
canvas.height = 100;
const context = canvas.getContext("2d");
context.fillStyle = "#EE2222";
context.fillRect(0, 0, 100, 100);
context.fillStyle = "#2222EE";
context.fillRect(20, 20, 100, 100);
// Add the canvas element to the document
document.body.appendChild(canvas);
const imageData = context.getImageData(0, 0, 100, 100);
return imageData.data;
}
window.parent.document.querySelector("#result").textContent = JSON.stringify(give_inner_result());
}
iframe.contentWindow.eval(`(${test})()`);
function give_result() {
const canvas = document.createElement("canvas");
canvas.width = 100;
canvas.height = 100;
const context = canvas.getContext("2d");
context.fillStyle = "#EE2222";
context.fillRect(0, 0, 100, 100);
context.fillStyle = "#2222EE";
context.fillRect(20, 20, 100, 100);
// Add the canvas element to the document
document.body.appendChild(canvas);
const imageData = context.getImageData(0, 0, 100, 100);
return imageData.data;
}
let myResult = give_result();
parent.postMessage({mine: myResult, theirs: JSON.parse(document.querySelector("#result").textContent)}, "*")
// Fun fact - without clearing the text content of the element, the test will hang on shutdown
// Guess how many hours it took to figure _that_ out?
document.querySelector("#result").textContent = '';
}
});
</script>
</body>