Can I use a BPG image as a <div>
or <body>
background? background: url('bg.bpg');
doesn't work.
There is a Javascript decoder which allows .bpg images to be displayed in <img>
tags, but I want to use one as a <body>
background.
The Javascript BPG decoder works by converting the source .bpg file into an ImageData
object, which can then be drawn to a canvas. So all you need to do is get the canvas as a PNG data string and set that as the body background image:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>BPG background example.</title>
<!-- Decoder script from http://bellard.org/bpg/ -->
<script src="bpgdec8a.js"></script>
<script>
"use strict";
function setBackground(filename)
{
// Create a hidden canvas with the same dimensions as the image.
var canvas = document.createElement("canvas");
canvas.style.visibility = "hidden";
canvas.width = 512;
canvas.height = 512;
document.body.appendChild(canvas);
// Create a drawing context and a BPG decoder.
var ctx = canvas.getContext("2d");
var img = new BPGDecoder(ctx);
// Attempt to load the image.
img.onload = function()
{
// Once the image is ready, draw it to the canvas...
ctx.putImageData(this.imageData, 0, 0);
// ...and copy the canvas to the body background.
document.body.style.background = "url('" + canvas.toDataURL("image/png") + "')";
};
img.load(filename);
}
</script>
</head>
<body onload="setBackground('lena512color.bpg');">
<p>Hello, World!</p>
</body>
</html>
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