Using Transparency
We can specify a fillStyle or strokeStyle value using the rgba function instead of rgb. We can also use the globalAlpha drawing state property.
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
<style>
canvas {
border: thin solid black
}
body>* {
float: left;
}
</style>
</head>
<body>
<canvas id="canvas" width="300" height="120">
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("HTML5", 10, 100);
ctx.strokeText("HTML5", 10, 100);
ctx.fillStyle = "red";
ctx.globalAlpha = 0.5;
ctx.fillRect(100, 10, 150, 100);
</script>
</body>
</html>
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HTML CSS Book
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canvas:
- Getting Started with the Canvas Element
- Getting a Canvas Context
- Drawing Rectangles
- Canvas Drawing State
- Setting the Line Join Style
- Using Gradients
- Using Patterns
- Using smaller shapes with an image pattern
- Drawing Images
- Using Video Images
- Using Canvas Images
- Setting the Fill & Stroke Styles
- Saving and Restoring Drawing State
- Drawing Using Paths
- Drawing Arcs
- Drawing Bezier Curves
- Drawing Text
- Using Shadows
- Using Transparency
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