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function init() {
function end() {
document.documentElement.className = '';
}
function next() {
compressAndDisplay(original, end);
}
var original = getImageFromDataUrl(sample);
setImgLoadListener(original, next);
}
function compressAndDisplay(image, next) {
var canvas = document.createElement('canvas');
canvas.width = image.naturalWidth;
canvas.height = image.naturalHeight;
var ctx = canvas.getContext('2d');
ctx.drawImage(image, 0, 0);
function gotBlob(blob) {
var img = getImageFromBlob(blob);
setImgLoadListener(img, next);
document.body.appendChild(img);
}
// I want to test passing 'undefined' as quality as well
if ('quality' in window) {
canvas.toBlob(gotBlob, 'image/jpeg', quality);
} else {
canvas.toBlob(gotBlob, 'image/jpeg');
}
}
function setImgLoadListener(img, func) {
if (img.complete) {
func.call(img, { target: img});
} else {
img.addEventListener('load', func);
}
}
function naturalDimensionsHandler(e) {
var img = e.target;
img.width = img.naturalWidth;
img.height = img.naturalHeight;
}
function getImageFromBlob(blob) {
var img = document.createElement('img');
img.src = window.URL.createObjectURL(blob);
setImgLoadListener(img, naturalDimensionsHandler);
setImgLoadListener(img, function(e) {
window.URL.revokeObjectURL(e.target.src);
});
return img;
}
function getImageFromDataUrl(url) {
var img = document.createElement('img');
img.src = url;
setImgLoadListener(img, naturalDimensionsHandler);
return img;
}
init();