How to set color to transparency when drawing on canvas
Description
We can specify a fillStyle or strokeStyle value using the rgba function instead of rgb. We can also use the globalAlpha drawing state property.
Example
<!--from w w w.jav a 2 s. co m-->
<!DOCTYPE HTML>
<html>
<head>
<style>
canvas {
border: thin solid black
}
body>* {
float: left;
}
</style>
</head>
<body>
<canvas id="canvas" width="800" height="820">
Your browser doesn't support the <code>canvas</code> element
</canvas>
<script>
var ctx = document.getElementById("canvas").getContext("2d");
ctx.fillStyle = "lightgrey";
ctx.strokeStyle = "black";
ctx.lineWidth = 3;
ctx.font = "100px sans-serif";
ctx.fillText("java2s.com", 10, 100);
ctx.strokeText("java2s.com", 10, 100);
ctx.fillStyle = "red";
ctx.globalAlpha = 0.5;
ctx.fillRect(100, 10, 150, 100);
</script>
</body>
</html>