Google Drive 下載供查看文件/PDF Image Quality Tuning

				
					(() => {
  const JSPDF_URL = 'https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.3.2/jspdf.min.js';

  // 建議：既然來源已經 3200x4526，很清楚了，就不要再 1.5
  const captureScale = 1.0;     // 1.0 = 原生高解析；若你硬要更大可改 1.2（不建議 1.5）
  const jpegQ = 0.92;           // 0.9~0.95 通常夠清楚；1.0 會非常大
  const MODE = 'cover';         // 'cover'滿版裁切；'fit'完整不裁切

  let policy = null;
  if (window.trustedTypes?.createPolicy) {
    try {
      policy = window.trustedTypes.createPolicy('myJspdfPolicy', {
        createScriptURL: (url) => url
      });
    } catch (e) {
      policy = null;
    }
  }

  function getPageSize(pdf) {
    const ps = pdf?.internal?.pageSize;
    const w = (typeof ps.getWidth === 'function') ? ps.getWidth()
            : (typeof ps.width === 'function') ? ps.width()
            : ps.width;
    const h = (typeof ps.getHeight === 'function') ? ps.getHeight()
            : (typeof ps.height === 'function') ? ps.height()
            : ps.height;
    return { w, h };
  }

  const script = document.createElement('script');

  script.onload = () => {
    if (typeof window.jsPDF !== 'function') {
      console.error('jsPDF not available on window.');
      return;
    }

    const imgs = Array.from(document.images).filter(img => img?.src && /^blob:/.test(img.src));
    console.log('[INFO] blob images =', imgs.length);
    if (imgs.length === 0) return;

    // 確認解析度
    const uniq = [...new Set(imgs.map(i => `${i.naturalWidth}x${i.naturalHeight}`))];
    console.log('[INFO] unique natural sizes:', uniq);

    const pdf = new window.jsPDF(); // default page size

    (async () => {
      for (let idx = 0; idx < imgs.length; idx++) {
        const img = imgs[idx];
        if (idx > 0) pdf.addPage();

        const baseW = img.naturalWidth || img.width;
        const baseH = img.naturalHeight || img.height;

        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext('2d');

        canvas.width = Math.round(baseW * captureScale);
        canvas.height = Math.round(baseH * captureScale);

        ctx.setTransform(captureScale, 0, 0, captureScale, 0, 0);
        ctx.imageSmoothingEnabled = true;
        ctx.imageSmoothingQuality = 'high';
        ctx.drawImage(img, 0, 0, baseW, baseH);

        const imgData = canvas.toDataURL('image/jpeg', jpegQ);

        const { w: pageW, h: pageH } = getPageSize(pdf);

        const imgW = canvas.width;
        const imgH = canvas.height;

        const s = (MODE === 'fit')
          ? Math.min(pageW / imgW, pageH / imgH)
          : Math.max(pageW / imgW, pageH / imgH);

        const drawW = imgW * s;
        const drawH = imgH * s;
        const x = (pageW - drawW) / 2;
        const y = (pageH - drawH) / 2;

        pdf.addImage(imgData, 'JPEG', x, y, drawW, drawH);

        if (idx % 5 === 0) await new Promise(r => setTimeout(r, 0));
        if (idx % 10 === 0) console.log(`[INFO] rendered ${idx + 1}/${imgs.length}`);
      }

      pdf.save('download.pdf');
      console.log('[OK] saved download.pdf');
    })();
  };

  script.onerror = (e) => console.error('Failed to load jsPDF:', e);

  script.src = policy ? policy.createScriptURL(JSPDF_URL) : JSPDF_URL;
  document.head.appendChild(script);
})();