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// Utilities for browser environments
mergeInto(Library, {
$Browser: {
// Given binary data for an image, in a format like PNG or JPG, we convert it
// to flat pixel data. We do so using the browser's native code.
decodeImage: function(pixels, format) {
function encodeBase64(data) {
var BASE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
var PAD = '=';
var ret = '';
var leftchar = 0;
var leftbits = 0;
for (var i = 0; i < data.length; i++) {
leftchar = (leftchar << 8) | data[i];
leftbits += 8;
while (leftbits >= 6) {
var curr = (leftchar >> (leftbits-6)) & 0x3f;
leftbits -= 6;
ret += BASE[curr];
}
}
if (leftbits == 2) {
ret += BASE[(leftchar&3) << 4];
ret += PAD + PAD;
} else if (leftbits == 4) {
ret += BASE[(leftchar&0xf) << 2];
ret += PAD;
}
return ret;
}
var img = new Image();
var canvas = document.createElement('canvas');
img.src = 'data:image/' + format + ';base64,' + encodeBase64(pixels);
var ctx = canvas.getContext('2d');
ctx.drawImage(img, 0, 0);
var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
return imageData;
},
}
});
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