Class ImageSizeFetcher

Picviewer CE+/dist.user.js:12058–12177

    } else GM_fetch = fetch;

    class ImageSizeFetcher {
        constructor(gmXhr, config = {}) {
            if (!gmXhr) throw new Error("GM_xmlhttpRequest is required");
            this.gmXhr = gmXhr;
            this.cache = new Map();
            this.queue = [];
            this.activeCount = 0;
            this.concurrency = config.concurrency || 3;
            this.timeout = config.timeout || 5000;
        }

        async getSize(url, options = {}) {
            const { force = false, strategy = 'auto' } = options;
            if (!url) return null;

            if (!force && this.cache.has(url)) {
                return this.cache.get(url);
            }

            if (url.startsWith('data:')) {
                const size = this._calculateBase64Size(url);
                this.cache.set(url, size);
                return size;
            }

            if (url.startsWith('blob:')) {
                return this._getBlobSize(url);
            }

            if (strategy === 'local-only' || strategy === 'auto') {
                const perfSize = this._getFromPerformance(url);
                if (perfSize !== null) {
                    this.cache.set(url, perfSize);
                    return perfSize;
                }
                if (strategy === 'local-only') return null;
            }

            return this._scheduleRequest(url);
        }

        _calculateBase64Size(dataUrl) {
            const base64Str = dataUrl.split(',')[1];
            if (!base64Str) return 0;
            const len = base64Str.length;
            const padding = (base64Str.match(/=/g) || []).length;
            return (len * 3 / 4) - padding;
        }

        async _getBlobSize(blobUrl) {
            try {
                const response = await fetch(blobUrl);
                const blob = await response.blob();
                return blob.size;
            } catch (e) {
                console.error('Blob fetch failed', e);
                return null;
            }