CanvasBlocker/test/test.js

(function(){
	function show(container, url){
		container.querySelector(".display").src = url;
		var buffer = new TextEncoder("utf-8").encode(url);
		crypto.subtle.digest("SHA-256", buffer).then(function(hash){
			var chunks = [];
			(new Uint32Array(hash)).forEach(function(num){
				chunks.push(num.toString(16));
			});
			container.querySelector(".hash").textContent = chunks.map(function(chunk){
				return "0".repeat(8 - chunk.length) + chunk;
			}).join("");
		});
	}
	
	if (location.search !== "?notInitial"){
		show(document.getElementById("top"), topTest());
		show(document.getElementById("iframe"), iframeTest());
	}
	document.querySelector("#top button").addEventListener("click", function(){show(document.getElementById("top"), topTest());});
	document.querySelector("#iframe button").addEventListener("click", function(){show(document.getElementById("iframe"), iframeTest());});
}());

function draw(canvas){
	canvas.setAttribute("width", 220);
	canvas.setAttribute("height", 30);
	
	var fp_text = "BrowserLeaks,com <canvas> 10";
	
	var ctx = canvas.getContext('2d');
	ctx.textBaseline = "top";
	ctx.font = "14px 'Arial'";
	ctx.textBaseline = "alphabetic";
	ctx.fillStyle = "#f60";
	ctx.fillRect(125, 1, 62, 20);
	ctx.fillStyle = "#069";
	ctx.fillText(fp_text, 2, 15);
	ctx.fillStyle = "rgba(102, 204, 0, 07)";
	ctx.fillText(fp_text, 4, 17);
	
	return ctx;
}

function topTest(){
	// create window canvas
	var canvas = document.createElement('canvas');
	// draw image in window canvas
	draw(canvas);
	return canvas.toDataURL();
}

function iframeTest(){

	// create window canvas
	var canvas = document.createElement('canvas');

	// draw image in window canvas
	draw(canvas);

	// create iframe canvas and ctx
	var iframe_canvas = document.querySelector("#iframe iframe").contentDocument.createElement('canvas');
	iframe_canvas.setAttribute("width", 220);
	iframe_canvas.setAttribute("height", 30);
	var iframe_ctx = iframe_canvas.getContext('2d');

	// copy image from window canvas to iframe ctx
	iframe_ctx.drawImage(canvas, 0, 0);

	return iframe_canvas.toDataURL();
}