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<!DOCTYPE html>
<canvas id="c" width="1" height="1"></canvas>
<img id="img" src="image_green-1x1.png">
<script>
window.onmessage = function(ev) {
if (ev.data != "start") {
parent.postMessage({ msg: "unknown_message", data: ev.data }, "*");
return;
}
// Set document.domain to itself, so we trigger the
// "set effective script origin" cases.
// eslint-disable-next-line no-self-assign
document.domain = document.domain
var ctx = document.getElementById("c").getContext("2d");
ctx.drawImage(document.getElementById("img"), 0, 0);
try {
var data = ctx.getImageData(0, 0, 1, 1).data;
parent.postMessage(
{
msg: "color",
data: "rgba(" + data[0] + ", " + data[1] + ", " + data[2] + ", " + data[3]/255 + ")"
},
"*");
} catch (e) {
parent.postMessage({ msg: "exception", data: e.toString() }, "*");
}
parent.postMessage({ msg: "done" }, "*");
}
</script>