Function urlToBlob

Picviewer CE+/dist.user.js:12597–12654

(url, cb, forcePng, tryTimes = 0)

        return ext;
    }
    function urlToBlob(url, cb, forcePng, tryTimes = 0) {
        tryTimes++;
        if (tryTimes > 3) {
            return cb(null, '');
        }
        _GM_xmlhttpRequest({
            method: 'GET',
            url: url.trim(),
            responseType:'blob',
            timeout:20000,
            headers: {
                origin: location.origin,
                referer: location.href,
                accept: "*/*"
            },
            cookie: cookie,
            onload: function(d) {
                let blob = d.response;
                if (!blob.type) return urlToBlob(url, cb, forcePng, tryTimes);
                let ext = extFromMimeAndUrl(blob.type, url);
                if (blob.type && blob.type.indexOf("text/html") === 0 && (blob.size || 0) < 100000) {
                    urlToBlobWithFetch(url, cb);
                    return;
                }
                if (ext === "none") ext = "webp";
                let conversion = formatDict.get(ext);
                if (canvas && (conversion || forcePng)) {
                    var self = this;
                    var a = new FileReader();
                    a.readAsDataURL(blob);
                    a.onload = function (e) {
                        dataURLToCanvas(e.target.result, canvas => {
                            canvas.toBlob(nblob => {
                                if (!nblob) {
                                    cb(blob, ext || "png");
                                } else {
                                    cb(nblob, conversion || "png");
                                }
                            }, "image/" + (conversion || "png"));
                        });
                    };
                    a.onerror = function (e){
                        urlToBlob(url, cb, forcePng, tryTimes);
                    }
                } else if (!blob || !blob.size) {
                    urlToBlob(url, cb, forcePng, tryTimes);
                } else {
                    cb(blob, ext);
                }
            },
            onerror: function(){
                urlToBlob(url, cb, forcePng, tryTimes);
            },
            ontimeout: function(){
                urlToBlob(url, cb, forcePng, tryTimes);
            }
        });
    }