1304353-text-global-alpha-1-ref.html

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<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<script>

function do_test() {

    var canvas = document.getElementById("test");

    var ctx = canvas.getContext("2d");

    var g = ctx.createLinearGradient(0, 0, canvas.width, canvas.height);

    g.addColorStop(0, "red");

    g.addColorStop(1, "green");

    ctx.fillStyle = g;

    ctx.fillRect(0, 0, canvas.width, canvas.height);

    ctx.fillStyle = "white";

    ctx.font = "bold 24px sans-serif";

    ctx.fillText('globalAlpha = 1.0', 20, 40);

    // for reference, use a fill color with alpha instead of global alpha

    ctx.fillStyle = "rgba(255, 255, 255, 0.5)";

    ctx.fillText('globalAlpha = 0.5', 20, 80);

    ctx.fillStyle = "rgba(255, 255, 255, 0.2)";

    ctx.fillText('globalAlpha = 0.2', 20, 120);

};

</script>

</head>

<body onload="do_test()">

<canvas id="test"></canvas>

</body>

</html>