UnScriptly/StudioPng.html at main · ByMarkAllan/UnScriptly · GitHub

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<script>
(function () {
  'use strict';

  var plus = window.HTMLStudioPlus;
  if (!plus) return;

  var HTML2CANVAS_URL = 'https://cdn.jsdelivr.net/npm/html2canvas@1.4.1/dist/html2canvas.min.js';
  var rendererSourcePromise = null;

  function $(id) { return document.getElementById(id); }
  function qsa(selector, root) { return Array.prototype.slice.call((root || document).querySelectorAll(selector)); }
  function setStatus(value) { document.documentElement.setAttribute('data-html-studio-png', value); }
  function delay(ms) { return new Promise(function (resolve) { window.setTimeout(resolve, ms); }); }

  function withTimeout(promise, ms, message) {
    var timer;
    return Promise.race([
      Promise.resolve(promise),
      new Promise(function (_, reject) {
        timer = window.setTimeout(function () {
          reject(new Error(message || 'Operation timed out.'));
        }, ms);
      })
    ]).then(function (value) {
      window.clearTimeout(timer);
      return value;
    }, function (error) {
      window.clearTimeout(timer);
      throw error;
    });
  }

  function openPngModal(scope) {
    if (!plus.hasPage()) {
      plus.toast('Import or create a page before exporting PNG.', 'error');
      return;
    }
    if ($('exportModal')) $('exportModal').classList.add('hidden');
    if ($('pngScopeInput')) $('pngScopeInput').value = scope || 'current';
    if ($('pngModal')) $('pngModal').classList.remove('hidden');
    updateProgress('');
  }

  function currentName() {
    return $('currentPageLabel')
      ? String($('currentPageLabel').textContent || 'page.html').trim()
      : 'page.html';
  }

  function pageNames() {
    return qsa('#pageList .page-item .page-name')
      .map(function (node) { return String(node.textContent || '').trim(); })
      .filter(Boolean);
  }

  function activatePage(name) {
    var items = qsa('#pageList .page-item');
    for (var i = 0; i < items.length; i++) {
      var node = items[i].querySelector('.page-name');
      if (node && String(node.textContent || '').trim() === name) {
        items[i].click();
        return true;
      }
    }
    return false;
  }

  function readActiveSource() {
    var source = '';
    plus.withSource(function (html) {
      source = html;
      return html;
    }, '');
    return source;
  }

  function collectSources(scope) {
    if (scope !== 'all') {
      return [{ name: currentName(), html: readActiveSource() }];
    }

    var names = pageNames();
    var active = currentName();
    var pages = [];

    names.forEach(function (name) {
      if (!activatePage(name)) return;
      pages.push({ name: name, html: readActiveSource() });
    });

    if (active) activatePage(active);
    return pages;
  }

  function sanitizedCaptureHtml(source) {
    var parser = new DOMParser();
    var doc = parser.parseFromString(String(source || ''), 'text/html');

    qsa('script', doc).forEach(function (script) { script.remove(); });
    qsa('meta[http-equiv]', doc).forEach(function (meta) {
      if (String(meta.getAttribute('http-equiv') || '').toLowerCase() === 'content-security-policy') {
        meta.remove();
      }
    });
    qsa('iframe,object,embed', doc).forEach(function (node) { node.remove(); });

    qsa('*', doc).forEach(function (node) {
      Array.prototype.slice.call(node.attributes || []).forEach(function (attr) {
        if (/^on/i.test(attr.name)) node.removeAttribute(attr.name);
        if ((attr.name === 'href' || attr.name === 'src') && /^javascript:/i.test(String(attr.value || '').trim())) {
          node.removeAttribute(attr.name);
        }
      });
      if (String(node.tagName || '').toLowerCase() === 'img') {
        node.setAttribute('loading', 'eager');
        node.setAttribute('decoding', 'sync');
      }
    });

    var prefix = /^\s*<!doctype\s+html/i.test(String(source || ''))
      ? '<!DOCTYPE html>\n'
      : '';
    return prefix + doc.documentElement.outerHTML;
  }

  function waitImages(doc, timeout) {
    var images = qsa('img', doc);
    if (!images.length) return Promise.resolve();

    var work = Promise.all(images.map(function (img) {
      if (img.complete) return Promise.resolve();
      return new Promise(function (resolve) {
        img.addEventListener('load', resolve, { once: true });
        img.addEventListener('error', resolve, { once: true });
      });
    }));

    return withTimeout(work, timeout || 4500, 'Image loading timed out.').catch(function () {
      /* Missing/cross-origin images are allowed to be omitted rather than blocking export. */
    });
  }

  function waitFonts(doc, timeout) {
    if (!doc || !doc.fonts || !doc.fonts.ready) return Promise.resolve();
    return withTimeout(
      Promise.resolve(doc.fonts.ready).catch(function () {}),
      timeout || 2800,
      'Font loading timed out.'
    ).catch(function () {
      /* Use fallback fonts instead of hanging forever. */
    });
  }

  function prepareFrame(source, width) {
    return new Promise(function (resolve, reject) {
      var frame = document.createElement('iframe');
      var settled = false;

      frame.setAttribute('aria-hidden', 'true');
      frame.setAttribute('sandbox', 'allow-same-origin allow-scripts');
      frame.style.position = 'fixed';
      frame.style.left = '-20000px';
      frame.style.top = '0';
      frame.style.width = width + 'px';
      frame.style.height = '1000px';
      frame.style.border = '0';
      frame.style.opacity = '0';
      frame.style.pointerEvents = 'none';
      frame.style.zIndex = '-1';
      document.body.appendChild(frame);

      var timer = window.setTimeout(function () {
        if (settled) return;
        settled = true;
        frame.remove();
        reject(new Error('PNG render frame timed out before the page became ready.'));
      }, 12000);

      frame.onload = function () {
        if (settled) return;

        var doc;
        try {
          doc = frame.contentDocument;
          if (!doc || !doc.documentElement) throw new Error('PNG render document is unavailable.');
        } catch (error) {
          settled = true;
          window.clearTimeout(timer);
          frame.remove();
          reject(error);
          return;
        }

        Promise.all([
          waitFonts(doc, 2800),
          waitImages(doc, 4800)
        ]).then(function () {
          if (settled) return;
          settled = true;
          window.clearTimeout(timer);

          var body = doc.body;
          var root = doc.documentElement;
          var height = Math.max(
            root.scrollHeight,
            root.offsetHeight,
            body ? body.scrollHeight : 0,
            body ? body.offsetHeight : 0,
            1
          );
          var measuredWidth = Math.max(
            Number(width || 0),
            root.scrollWidth || 0,
            body ? body.scrollWidth : 0,
            1
          );

          frame.style.width = measuredWidth + 'px';
          frame.style.height = height + 'px';

          resolve({
            frame: frame,
            doc: doc,
            width: measuredWidth,
            height: height
          });
        }).catch(function (error) {
          if (settled) return;
          settled = true;
          window.clearTimeout(timer);
          frame.remove();
          reject(error);
        });
      };

      frame.srcdoc = sanitizedCaptureHtml(source);
    });
  }

  function injectRendererSource(win, doc, source) {
    /*
     * html2canvas must execute in the SAME browsing context as the DOM it
     * captures. Safari/iPad can stall when a renderer from the same-realm capture frame
     * is asked to clone an element owned by a different iframe document.
     *
     * The capture document is sanitized before loading (original scripts and
     * inline event handlers are removed), so the hidden frame can safely allow
     * our renderer script to execute. The loader <script> removes itself
     * immediately after initialization so html2canvas never clones its own
     * ~200 KB source.
     */
    if (win && win.html2canvas) return win.html2canvas;
    if (!win || !doc) throw new Error('PNG capture frame is unavailable.');
    if (!source) throw new Error('PNG renderer source is empty.');

    var script = doc.createElement('script');
    script.type = 'text/javascript';
    script.setAttribute('data-unscriptly-png-renderer', 'true');
    script.text = String(source);
    (doc.head || doc.documentElement).appendChild(script);

    if (!win.html2canvas) {
      script.remove();
      throw new Error('PNG renderer source loaded but did not initialize in the capture frame.');
    }

    script.remove();
    return win.html2canvas;
  }

  function rendererSourceFromServer() {
    if (!(window.google && google.script && google.script.run)) {
      return Promise.reject(new Error('Apps Script renderer proxy is unavailable.'));
    }

    return withTimeout(new Promise(function (resolve, reject) {
      google.script.run
        .withSuccessHandler(function (source) { resolve(String(source || '')); })
        .withFailureHandler(function (error) {
          reject(error instanceof Error ? error : new Error(String(error && error.message || error || 'Renderer proxy failed.')));
        })
        .htmlStudioGetPngRendererSource();
    }), 15000, 'Apps Script PNG renderer proxy timed out.');
  }

  function rendererSourceFromBrowser() {
    if (!window.fetch) return Promise.reject(new Error('Browser fetch is unavailable.'));
    return withTimeout(
      fetch(HTML2CANVAS_URL, { mode: 'cors', cache: 'force-cache', credentials: 'omit' })
        .then(function (response) {
          if (!response.ok) throw new Error('PNG renderer returned HTTP ' + response.status + '.');
          return response.text();
        }),
      9000,
      'PNG renderer browser download timed out.'
    );
  }

  function loadRendererSource() {
    if (rendererSourcePromise) return rendererSourcePromise;

    var primary = (window.google && google.script && google.script.run)
      ? rendererSourceFromServer()
      : rendererSourceFromBrowser();

    rendererSourcePromise = primary.catch(function (serverError) {
      console.warn('[HTML Studio PNG] Primary renderer source failed; trying browser CDN.', serverError);
      return rendererSourceFromBrowser();
    }).then(function (source) {
      if (!source || source.length < 10000 || source.indexOf('html2canvas') === -1) {
        throw new Error('PNG renderer payload was invalid.');
      }
      return source;
    });

    return rendererSourcePromise;
  }

  function isAppleTouchDevice() {
    var nav = window.navigator || {};
    var platform = String(nav.platform || '');
    var ua = String(nav.userAgent || '');
    return /iPad|iPhone|iPod/i.test(ua) ||
      (platform === 'MacIntel' && Number(nav.maxTouchPoints || 0) > 1);
  }

  function safeScale(width, height, requested) {
    /*
     * Safari on iPad can capture a large canvas successfully and then spend a
     * very long time encoding that canvas as PNG. Keep a more conservative
     * pixel budget on Apple touch devices. Desktop browsers retain the larger
     * budget.
     */
    var appleTouch = isAppleTouchDevice();
    var maxPixels = appleTouch ? 8000000 : 16000000;
    var maxDimension = appleTouch ? 6144 : 8192;
    var scale = Number(requested || 1) || 1;

    scale = Math.min(
      scale,
      maxDimension / Math.max(width, 1),
      maxDimension / Math.max(height, 1),
      Math.sqrt(maxPixels / Math.max(width * height, 1))
    );

    return Math.max(0.18, scale);
  }

  function captureWithHtml2Canvas(prepared, requestedScale) {
    var win = prepared.frame.contentWindow;
    var doc = prepared.doc;

    return loadRendererSource().then(function (source) {
      var renderer = injectRendererSource(win, doc, source);
      var scale = safeScale(prepared.width, prepared.height, requestedScale);
      var target = doc.body || doc.documentElement;

      if (scale + 0.01 < Number(requestedScale || 1)) {
        plus.toast('This long page was automatically scaled to stay within browser PNG limits.');
      }

      updateProgress('Capturing rendered page…');

      return delay(50).then(function () {
        return withTimeout(renderer(target, {
          backgroundColor: null,
          logging: false,
          useCORS: true,
          allowTaint: false,
          foreignObjectRendering: false,
          scale: scale,
          width: prepared.width,
          height: prepared.height,
          windowWidth: prepared.width,
          windowHeight: prepared.height,
          x: 0,
          y: 0,
          scrollX: 0,
          scrollY: 0,
          imageTimeout: 3200,
          removeContainer: true,
          onclone: function (clonedDoc) {
            try {
              qsa('script,iframe,object,embed', clonedDoc).forEach(function (node) { node.remove(); });
              qsa('[data-unscriptly-hover],[data-unscriptly-selected]', clonedDoc).forEach(function (node) {
                node.removeAttribute('data-unscriptly-hover');
                node.removeAttribute('data-unscriptly-selected');
              });
              var style = clonedDoc.createElement('style');
              style.textContent = '*{animation:none!important;transition:none!important;}html,body{scroll-behavior:auto!important;}';
              (clonedDoc.head || clonedDoc.documentElement).appendChild(style);
            } catch (_) {}
          }
        }), 26000, 'Primary PNG capture timed out.');
      });
    });
  }

  function inlineComputedStyles(sourceRoot, cloneRoot, win) {
    var sourceNodes = [sourceRoot].concat(qsa('*', sourceRoot));
    var cloneNodes = [cloneRoot].concat(qsa('*', cloneRoot));
    var length = Math.min(sourceNodes.length, cloneNodes.length);

    for (var i = 0; i < length; i++) {
      var source = sourceNodes[i];
      var clone = cloneNodes[i];
      var computed = win.getComputedStyle(source);
      var css = '';

      for (var j = 0; j < computed.length; j++) {
        var prop = computed[j];
        css += prop + ':' + computed.getPropertyValue(prop) + ';';
      }
      clone.setAttribute('style', css);
    }
  }

  function captureWithForeignObject(prepared, requestedScale) {
    var task = new Promise(function (resolve, reject) {
      try {
        var scale = safeScale(prepared.width, prepared.height, requestedScale);
        var root = prepared.doc.documentElement;
        var clone = root.cloneNode(true);
        clone.setAttribute('xmlns', 'http://www.w3.org/1999/xhtml');
        inlineComputedStyles(root, clone, prepared.frame.contentWindow);
        qsa('script', clone).forEach(function (node) { node.remove(); });

        var xhtml = new XMLSerializer().serializeToString(clone);
        var svg = '<svg xmlns="http://www.w3.org/2000/svg" width="' + prepared.width + '" height="' + prepared.height + '">' +
          '<foreignObject width="100%" height="100%">' + xhtml + '</foreignObject></svg>';

        var blob = new Blob([svg], { type: 'image/svg+xml;charset=utf-8' });
        var url = URL.createObjectURL(blob);
        var image = new Image();

        image.onload = function () {
          try {
            var canvas = document.createElement('canvas');
            canvas.width = Math.max(1, Math.round(prepared.width * scale));
            canvas.height = Math.max(1, Math.round(prepared.height * scale));
            var ctx = canvas.getContext('2d');
            ctx.scale(scale, scale);
            ctx.drawImage(image, 0, 0);
            URL.revokeObjectURL(url);
            resolve(canvas);
          } catch (error) {
            URL.revokeObjectURL(url);
            reject(error);
          }
        };

        image.onerror = function () {
          URL.revokeObjectURL(url);
          reject(new Error('Native PNG fallback could not render this page.'));
        };

        image.src = url;
      } catch (error) {
        reject(error);
      }
    });

    return withTimeout(task, 12000, 'Native PNG fallback timed out.');
  }

  function renderPage(page, width, scale) {
    var preparedRef = null;

    var task = prepareFrame(page.html, width).then(function (prepared) {
      preparedRef = prepared;

      return captureWithHtml2Canvas(prepared, scale).catch(function (primaryError) {
        console.warn('[HTML Studio PNG] primary same-realm capture failed; retrying simplified capture.', primaryError);
        updateProgress('Primary capture unavailable. Retrying simplified capture…');

        return loadRendererSource().then(function (source) {
          var win = prepared.frame.contentWindow;
          var doc = prepared.doc;
          var renderer = injectRendererSource(win, doc, source);
          var target = doc.body || doc.documentElement;
          var retryScale = Math.min(1, safeScale(prepared.width, prepared.height, scale));

          return delay(60).then(function () {
            return withTimeout(renderer(target, {
              backgroundColor: null,
              logging: false,
              useCORS: false,
              allowTaint: false,
              foreignObjectRendering: false,
              scale: retryScale,
              width: prepared.width,
              height: prepared.height,
              windowWidth: prepared.width,
              windowHeight: prepared.height,
              x: 0,
              y: 0,
              scrollX: 0,
              scrollY: 0,
              imageTimeout: 700,
              removeContainer: true,
              ignoreElements: function (node) {
                var tag = String(node && node.tagName || '').toLowerCase();
                return tag === 'iframe' || tag === 'object' || tag === 'embed' || tag === 'video' || tag === 'audio';
              },
              onclone: function (clonedDoc) {
                try {
                  qsa('script,iframe,object,embed,video,audio', clonedDoc).forEach(function (node) { node.remove(); });
                  var style = clonedDoc.createElement('style');
                  style.textContent = '*{animation:none!important;transition:none!important;}html,body{scroll-behavior:auto!important;}';
                  (clonedDoc.head || clonedDoc.documentElement).appendChild(style);
                } catch (_) {}
              }
            }), 15000, 'Simplified PNG capture timed out.');
          });
        }).catch(function (simplifiedError) {
          console.warn('[HTML Studio PNG] simplified capture failed; trying native SVG fallback.', simplifiedError);
          updateProgress('Simplified capture unavailable. Trying native fallback…');
          return captureWithForeignObject(prepared, Math.min(1, scale)).catch(function (nativeError) {
            var message = 'PNG capture failed on this page. Primary: ' +
              String(primaryError && primaryError.message || primaryError || 'unknown') +
              ' Simplified: ' + String(simplifiedError && simplifiedError.message || simplifiedError || 'unknown') +
              ' Native: ' + String(nativeError && nativeError.message || nativeError || 'unknown');
            throw new Error(message);
          });
        });
      });
    });

    return withTimeout(task, 56000, 'PNG export timed out. Try Current canvas width and Standard quality.')
      .then(function (canvas) {
        /*
         * Do NOT remove the capture iframe here. html2canvas creates its canvas
         * in the capture frame's browsing context. Safari/iPad can stall in
         * canvas.toBlob() if that owning document is destroyed before encoding
         * finishes. The caller cleans up only after PNG encoding completes.
         */
        return { canvas: canvas, frame: preparedRef && preparedRef.frame };
      }, function (error) {
        if (preparedRef && preparedRef.frame) preparedRef.frame.remove();
        throw error;
      });
  }

  function cleanupCapture(capture) {
    try {
      if (capture && capture.frame && capture.frame.parentNode) capture.frame.remove();
    } catch (_) {}
  }

  function downscaleCanvas(canvas, maxPixels) {
    var width = Number(canvas && canvas.width || 0);
    var height = Number(canvas && canvas.height || 0);
    var pixels = width * height;
    if (!canvas || !width || !height || !pixels || pixels <= maxPixels) return canvas;

    var ratio = Math.sqrt(maxPixels / pixels);
    var doc = canvas.ownerDocument || document;
    var reduced = doc.createElement('canvas');
    reduced.width = Math.max(1, Math.round(width * ratio));
    reduced.height = Math.max(1, Math.round(height * ratio));
    var ctx = reduced.getContext('2d');
    if (!ctx) return canvas;
    ctx.drawImage(canvas, 0, 0, reduced.width, reduced.height);
    return reduced;
  }

  function encodeTimeoutMs(canvas) {
    var pixels = Math.max(1, Number(canvas && canvas.width || 1) * Number(canvas && canvas.height || 1));
    var megapixels = pixels / 1000000;
    var base = isAppleTouchDevice() ? 14000 : 9000;
    var perMp = isAppleTouchDevice() ? 3200 : 1800;
    return Math.min(isAppleTouchDevice() ? 48000 : 32000, Math.max(base, Math.round(base + megapixels * perMp)));
  }

  function encodeCanvasOnce(canvas) {
    return new Promise(function (resolve, reject) {
      if (!canvas) {
        reject(new Error('PNG renderer returned no canvas.'));
        return;
      }

      if (!canvas.toBlob) {
        try {
          var fallbackCanvas = downscaleCanvas(canvas, isAppleTouchDevice() ? 5000000 : 9000000);
          var data = fallbackCanvas.toDataURL('image/png');
          var raw = atob(data.split(',')[1]);
          var bytes = new Uint8Array(raw.length);
          for (var i = 0; i < raw.length; i++) bytes[i] = raw.charCodeAt(i);
          resolve(new Blob([bytes], { type: 'image/png' }));
        } catch (error) {
          reject(error);
        }
        return;
      }

      canvas.toBlob(function (blob) {
        blob ? resolve(blob) : reject(new Error('PNG conversion failed. A cross-origin image may have blocked canvas export.'));
      }, 'image/png');
    });
  }

  function canvasBlob(canvas) {
    if (!canvas) return Promise.reject(new Error('PNG renderer returned no canvas.'));

    var first = isAppleTouchDevice() ? downscaleCanvas(canvas, 8000000) : canvas;
    updateProgress('Encoding PNG…');

    return withTimeout(
      encodeCanvasOnce(first),
      encodeTimeoutMs(first),
      'PNG encoding is taking longer than expected.'
    ).catch(function (firstError) {
      console.warn('[HTML Studio PNG] first PNG encoding pass failed; retrying at a safer size.', firstError);
      updateProgress('PNG encoding is taking longer on this device. Retrying at a safer size…');

      var retry = downscaleCanvas(first, isAppleTouchDevice() ? 4500000 : 7500000);
      if (retry === first && first.width * first.height > 1000000) {
        var doc = first.ownerDocument || document;
        retry = doc.createElement('canvas');
        retry.width = Math.max(1, Math.round(first.width * 0.82));
        retry.height = Math.max(1, Math.round(first.height * 0.82));
        var ctx = retry.getContext('2d');
        if (ctx) ctx.drawImage(first, 0, 0, retry.width, retry.height);
        else retry = first;
      }

      return withTimeout(
        encodeCanvasOnce(retry),
        Math.min(52000, encodeTimeoutMs(retry) + 8000),
        'PNG encoding timed out after the reduced-size retry.'
      );
    });
  }

  function captureBlob(capture) {
    if (!capture || !capture.canvas) {
      cleanupCapture(capture);
      return Promise.reject(new Error('PNG renderer returned no canvas.'));
    }

    return canvasBlob(capture.canvas).then(function (blob) {
      cleanupCapture(capture);
      return blob;
    }, function (error) {
      cleanupCapture(capture);
      throw error;
    });
  }

  function blobBase64(blob) {
    return new Promise(function (resolve, reject) {
      var reader = new FileReader();
      reader.onload = function () {
        resolve(String(reader.result || '').split(',')[1] || '');
      };
      reader.onerror = function () {
        reject(reader.error || new Error('PNG could not be encoded.'));
      };
      reader.readAsDataURL(blob);
    });
  }

  function pngName(name) {
    var value = String(name || 'page')
      .replace(/\.(?:html?|txt)$/i, '')
      .replace(/[\\/:*?"<>|]+/g, '-')
      .trim() || 'page';
    return value + '.png';
  }

  function downloadBlob(blob, filename) {
    var url = URL.createObjectURL(blob);
    var link = document.createElement('a');
    link.href = url;
    link.download = filename;
    link.style.position = 'fixed';
    link.style.left = '-10000px';
    link.style.top = '0';
    link.textContent = 'Download ' + filename;
    document.body.appendChild(link);

    try {
      link.click();
    } catch (_) {
      window.open(url, '_blank');
    }

    window.setTimeout(function () {
      URL.revokeObjectURL(url);
      link.remove();
    }, 8000);
  }

  function zipPngs(items) {
    if (!(window.google && google.script && google.script.run)) {
      return Promise.reject(new Error('PNG ZIP export requires the deployed Apps Script web app.'));
    }

    return withTimeout(new Promise(function (resolve, reject) {
      google.script.run
        .withSuccessHandler(resolve)
        .withFailureHandler(reject)
        .exportPngZip(items);
    }), 30000, 'PNG ZIP packaging timed out.');
  }

  function updateProgress(text) {
    var node = $('pngProgress');
    if (node) node.textContent = text || '';
  }

  function resetExportButton(button, original) {
    if (!button) return;
    button.disabled = false;
    button.textContent = original;
    updateProgress('');
  }

  function exportPng() {
    var button = $('pngExportBtn');
    if (!button) return;

    var scope = $('pngScopeInput') ? $('pngScopeInput').value : 'current';
    var widthValue = $('pngWidthInput') ? $('pngWidthInput').value : '1440';
    var width = widthValue === 'current'
      ? Math.max(390, Math.round(($('canvasStage') && $('canvasStage').clientWidth) || 1440))
      : Number(widthValue || 1440);
    var requestedScale = Number(($('pngScaleInput') && $('pngScaleInput').value) || 1) || 1;
    var pages = collectSources(scope);

    if (!pages.length || !pages[0].html) {
      plus.toast('No page source is available to export.', 'error');
      return;
    }

    button.disabled = true;
    var original = button.textContent;
    button.textContent = 'Rendering…';
    updateProgress('Preparing ' + pages.length + ' page' + (pages.length === 1 ? '' : 's') + '…');

    var results = [];
    var chain = Promise.resolve();

    pages.forEach(function (page, index) {
      chain = chain.then(function () {
        updateProgress('Rendering ' + (index + 1) + ' of ' + pages.length + ': ' + page.name);
        return renderPage(page, width, requestedScale)
          .then(captureBlob)
          .then(function (blob) {
            if (scope === 'current') {
              updateProgress('Starting PNG download…');
              downloadBlob(blob, pngName(page.name));
              return;
            }
            return blobBase64(blob).then(function (base64) {
              results.push({ name: pngName(page.name), base64: base64 });
            });
          });
      });
    });

    chain.then(function () {
      if (scope !== 'all') return null;

      updateProgress('Packaging PNG files…');
      return zipPngs(results).then(function (result) {
        var raw = atob(result.base64 || '');
        var bytes = new Uint8Array(raw.length);
        for (var i = 0; i < raw.length; i++) bytes[i] = raw.charCodeAt(i);
        downloadBlob(
          new Blob([bytes], { type: result.mimeType || 'application/zip' }),
          result.name || 'html-studio-png.zip'
        );
      });
    }).then(function () {
      if ($('pngModal')) $('pngModal').classList.add('hidden');
      plus.toast(scope === 'all' ? 'All pages exported as PNG ZIP.' : 'PNG exported.');
      resetExportButton(button, original);
    }).catch(function (error) {
      console.error('[HTML Studio PNG] export failed:', error);
      plus.toast(String(error && error.message || error || 'PNG export failed.'), 'error');
      resetExportButton(button, original);
    });
  }

  function init() {
    if ($('exportPngCurrentBtn')) {
      $('exportPngCurrentBtn').addEventListener('click', function () { openPngModal('current'); });
    }
    if ($('exportPngAllBtn')) {
      $('exportPngAllBtn').addEventListener('click', function () { openPngModal('all'); });
    }
    if ($('pngExportBtn')) $('pngExportBtn').addEventListener('click', exportPng);
    setStatus('ready');
  }

  window.HTMLStudioPng = {
    renderHtmlToBlob: function (html, width, scale) {
      var page = { name: 'page.html', html: String(html || '') };
      return renderPage(page, Number(width || 1440), Number(scale || 1) || 1)
        .then(captureBlob);
    },
    downloadBlob: downloadBlob,
    blobBase64: blobBase64,
    collectSources: collectSources,
    currentName: currentName,
    pngName: pngName
  };

  try {
    init();
  } catch (error) {
    console.error('[HTML Studio] PNG module failed:', error);
    setStatus('error');
    plus.toast('PNG export could not initialize. HTML export remains available.', 'error');
  }
})();
</script>