Credo funzioni solamente se provato online…
codice:
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Esempio</title>
<script type="text/javascript">
function getSnapshot () {
var oSnapCVS = document.getElementById("snapshot");
oSnapCVS.getContext("2d").drawWindow(window, 0, 0, oSnapCVS.width, oSnapCVS.height, "rgb(255,255,255)");
}
</script>
<style type="text/css">
#snapshot {
border: 1px solid black;
}
</style>
</head>
<body>
<input type="button" onclick="getSnapshot();" value="Snapshot!" />
<canvas id="snapshot" width="800" height="600"></canvas>
</body>
</html>