các chức năng thumbnail, scroll continuos đã xong

frontend/src/components/WorkbookViewer.tsx

@@ -10,6 +10,8 @@ import { api } from "@/lib/api";
 
 type Tool = "select" | "pen" | "highlighter" | "text";
 type ViewMode = "pan" | "draw";
+type FitMode = "width" | "height";
+type ScrollMode = "single" | "continuous";
 
 interface Props {
   pdfId: number;
@@ -106,11 +108,59 @@ export default function WorkbookViewer({ pdfId }: Props) {
   const [pdfTitle, setPdfTitle] = useState("PDF");
   const [loadError, setLoadError] = useState("");
   const [rendering, setRendering] = useState(false);
+  const [showThumbnails, setShowThumbnails] = useState(true);
+  const [thumbnails, setThumbnails] = useState<string[]>([]);
+  const [fitMode, setFitMode] = useState<FitMode>("width");
+  const [scrollMode, setScrollMode] = useState<ScrollMode>("single");
+
+  // Ref for auto-scrolling thumbnail panel
+  const thumbRefs = useRef<(HTMLButtonElement | null)[]>([]);
+  const fitModeRef = useRef<FitMode>("width");
+  const scrollModeRef = useRef<ScrollMode>("single");
+  // Per-page canvas refs for continuous mode
+  const pageCanvasRefs = useRef<(HTMLCanvasElement | null)[]>([]);
+  const pageFabricRefs = useRef<any[]>([]);
+  // Active PDF.js render tasks — cancel before re-rendering
+  const renderTasksRef = useRef<any[]>([]);
+  // Generation counter — incremented on each renderAllPages call to abort stale runs
+  const renderAllPagesGenRef = useRef(0);
 
   // Keep mutable refs in sync
   useEffect(() => { currentToolRef.current = tool; }, [tool]);
   useEffect(() => { penColorRef.current = penColor; }, [penColor]);
   useEffect(() => { strokeWidthRef.current = strokeWidth; }, [strokeWidth]);
+  useEffect(() => { fitModeRef.current = fitMode; }, [fitMode]);
+  useEffect(() => { scrollModeRef.current = scrollMode; }, [scrollMode]);
+
+  // Auto-scroll thumbnail sidebar to keep current page visible
+  useEffect(() => {
+    if (showThumbnails) {
+      thumbRefs.current[currentPage - 1]?.scrollIntoView({ block: "nearest", behavior: "smooth" });
+    }
+  }, [currentPage, showThumbnails]);
+
+  // Re-render current page when fit mode changes — moved below renderAllPages definition
+
+  const generateThumbnails = useCallback(async () => {
+    const doc = pdfDocRef.current;
+    if (!doc) return;
+    for (let i = 1; i <= doc.numPages; i++) {
+      const page = await doc.getPage(i);
+      const vp1 = page.getViewport({ scale: 1 });
+      const scale = 120 / vp1.width;
+      const vp = page.getViewport({ scale });
+      const cvs = document.createElement("canvas");
+      cvs.width = Math.floor(vp.width);
+      cvs.height = Math.floor(vp.height);
+      await page.render({ canvasContext: cvs.getContext("2d")!, viewport: vp }).promise;
+      const dataUrl = cvs.toDataURL("image/jpeg", 0.7);
+      setThumbnails(prev => {
+        const next = [...prev];
+        next[i - 1] = dataUrl;
+        return next;
+      });
+    }
+  }, []);
 
   // ─────────────────────────────────────────────────────────────────────────
   // renderPageWithAnnotations
@@ -124,23 +174,34 @@ export default function WorkbookViewer({ pdfId }: Props) {
 
       setRendering(true);
       try {
+        // Cancel any in-progress render on the same canvas
+        renderTasksRef.current.forEach(t => { try { t.cancel(); } catch { /* ignore */ } });
+        renderTasksRef.current = [];
+
         // ── 1. Render PDF page ─────────────────────────────────────────────
         const page = await doc.getPage(pageNum);
-        const containerWidth = Math.max(scrollContainerRef.current.clientWidth - 32, 300);
         const viewport1 = page.getViewport({ scale: 1 });
-        const scale = containerWidth / viewport1.width;
+        let scale: number;
+        if (fitModeRef.current === "height") {
+          const containerHeight = Math.max(scrollContainerRef.current.clientHeight - 48, 400);
+          scale = containerHeight / viewport1.height;
+        } else {
+          const containerWidth = Math.max(scrollContainerRef.current.clientWidth - 32, 300);
+          scale = containerWidth / viewport1.width;
+        }
         const viewport = page.getViewport({ scale });
 
         const pdfCvs = pdfCanvasRef.current;
         pdfCvs.width = Math.floor(viewport.width);
         pdfCvs.height = Math.floor(viewport.height);
 
-        await page.render({
+        const singleRenderTask = page.render({
           canvasContext: pdfCvs.getContext("2d")!,
           viewport,
-        }).promise;
-
-        // ── 2. Resize Fabric canvas to match ──────────────────────────────
+        });
+        renderTasksRef.current.push(singleRenderTask);
+        await singleRenderTask.promise;
+        // ── 2. Resize Fabric canvas to match
         fc.setWidth(pdfCvs.width);
         fc.setHeight(pdfCvs.height);
         if (fc.wrapperEl) {
@@ -186,6 +247,105 @@ export default function WorkbookViewer({ pdfId }: Props) {
     [pdfId]
   );
 
+  // ─────────────────────────────────────────────────────────────────────────
+  // renderAllPages  (continuous scroll mode)
+  // ─────────────────────────────────────────────────────────────────────────
+
+  const renderAllPages = useCallback(async () => {
+    const gen = ++renderAllPagesGenRef.current;
+    const doc = pdfDocRef.current;
+    const container = scrollContainerRef.current;
+    if (!doc || !container) return;
+
+    // Dispose old per-page fabric instances
+    pageFabricRefs.current.forEach(fc => { try { fc?.dispose(); } catch { /* ignore */ } });
+    pageFabricRefs.current = [];
+
+    // Cancel any in-progress render tasks
+    renderTasksRef.current.forEach(t => { try { t.cancel(); } catch { /* ignore */ } });
+    renderTasksRef.current = [];
+
+    const fabricModule = await import("fabric");
+    if (renderAllPagesGenRef.current !== gen) return;
+    const fabric = fabricModule.fabric;
+    const containerWidth = Math.max(container.clientWidth - 32, 300);
+
+    for (let i = 1; i <= doc.numPages; i++) {
+      if (renderAllPagesGenRef.current !== gen) return;
+      const pdfCvs = pageCanvasRefs.current[i - 1];
+      const fabricEl = document.getElementById(`fabric-continuous-${i}`) as HTMLCanvasElement | null;
+      if (!pdfCvs || !fabricEl) continue;
+
+      const page = await doc.getPage(i);
+      const vp1 = page.getViewport({ scale: 1 });
+      let scale: number;
+      if (fitModeRef.current === "height") {
+        const containerHeight = Math.max(container.clientHeight - 48, 400);
+        scale = containerHeight / vp1.height;
+      } else {
+        scale = containerWidth / vp1.width;
+      }
+      const vp = page.getViewport({ scale });
+      pdfCvs.width = Math.floor(vp.width);
+      pdfCvs.height = Math.floor(vp.height);
+      const contRenderTask = page.render({ canvasContext: pdfCvs.getContext("2d")!, viewport: vp });
+      renderTasksRef.current.push(contRenderTask);
+      try {
+        await contRenderTask.promise;
+      } catch (e: any) {
+        if (e?.name === "RenderingCancelledException") return;
+        throw e;
+      }
+      if (renderAllPagesGenRef.current !== gen) return;
+
+      // Create Fabric canvas overlay
+      const fc = new fabric.Canvas(fabricEl, {
+        isDrawingMode: false,
+        selection: false,
+        enableRetinaScaling: false,
+      });
+      fc.setWidth(pdfCvs.width);
+      fc.setHeight(pdfCvs.height);
+      if (fc.wrapperEl) {
+        fc.wrapperEl.style.position = "absolute";
+        fc.wrapperEl.style.top = "0";
+        fc.wrapperEl.style.left = "0";
+        fc.wrapperEl.style.pointerEvents = "none";
+      }
+      pageFabricRefs.current[i - 1] = fc;
+
+      // Load saved annotations
+      const cached = localAnnotations.current[i];
+      let annotationData: object | null = cached ?? null;
+      if (!annotationData) {
+        try {
+          const ann = await api.getAnnotation(pdfId, i);
+          if (ann.canvas_data && Object.keys(ann.canvas_data).length > 0) {
+            annotationData = ann.canvas_data;
+            localAnnotations.current[i] = annotationData;
+          }
+        } catch { /* no annotation */ }
+      }
+      if (annotationData) {
+        await new Promise<void>((resolve) => {
+          fc.loadFromJSON(annotationData, () => { fc.renderAll(); resolve(); });
+        });
+      }
+    }
+
+  }, [pdfId]);
+
+  // Re-render when fit mode changes
+  useEffect(() => {
+    if (!isReady) return;
+    if (scrollMode === "continuous") {
+      renderAllPages();
+    } else {
+      renderPageWithAnnotations(currentPage);
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [fitMode]);
+
   // ─────────────────────────────────────────────────────────────────────────
   // Initialization (mount)
   // ─────────────────────────────────────────────────────────────────────────
@@ -263,6 +423,10 @@ export default function WorkbookViewer({ pdfId }: Props) {
         await renderPageWithAnnotations(1);
         setCurrentPage(1);
 
+        // Generate thumbnails in background (non-blocking)
+        setThumbnails([]);
+        generateThumbnails();
+
       } catch (err: unknown) {
         if (!cancelled) {
           setLoadError(
@@ -278,10 +442,55 @@ export default function WorkbookViewer({ pdfId }: Props) {
       cancelled = true;
       fabricRef.current?.dispose();
       fabricRef.current = null;
+      pageFabricRefs.current.forEach(fc => { try { fc?.dispose(); } catch { /* ignore */ } });
+      pageFabricRefs.current = [];
       pdfDocRef.current?.destroy();
       pdfDocRef.current = null;
     };
-  }, [pdfId, renderPageWithAnnotations]);
+  }, [pdfId, renderPageWithAnnotations, generateThumbnails, renderAllPages]);
+
+  // Re-render when switching scroll modes
+  useEffect(() => {
+    if (!isReady) return;
+    if (scrollMode === "continuous") {
+      // small delay so DOM mounts the continuous page elements first
+      setTimeout(() => renderAllPages(), 50);
+    } else {
+      // Dispose continuous fabric instances
+      pageFabricRefs.current.forEach(fc => { try { fc?.dispose(); } catch { /* ignore */ } });
+      pageFabricRefs.current = [];
+      renderPageWithAnnotations(currentPage);
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [scrollMode]);
+
+  // Scroll-based page tracking for continuous mode
+  useEffect(() => {
+    if (!isReady || scrollMode !== "continuous") return;
+    const container = scrollContainerRef.current;
+    if (!container) return;
+
+    const updateCurrentPage = () => {
+      const containerRect = container.getBoundingClientRect();
+      let bestPage = 1;
+      let bestOverlap = -1;
+      pageCanvasRefs.current.forEach((cvs, idx) => {
+        if (!cvs || cvs.height === 0) return;
+        const rect = cvs.getBoundingClientRect();
+        const top = Math.max(rect.top, containerRect.top);
+        const bottom = Math.min(rect.bottom, containerRect.bottom);
+        const overlap = Math.max(0, bottom - top);
+        if (overlap > bestOverlap) {
+          bestOverlap = overlap;
+          bestPage = idx + 1;
+        }
+      });
+      if (bestOverlap > 0) setCurrentPage(bestPage);
+    };
+
+    container.addEventListener("scroll", updateCurrentPage, { passive: true });
+    return () => container.removeEventListener("scroll", updateCurrentPage);
+  }, [isReady, scrollMode]);
 
   // ─────────────────────────────────────────────────────────────────────────
   // Apply tool / mode to Fabric canvas
@@ -359,22 +568,66 @@ export default function WorkbookViewer({ pdfId }: Props) {
     }
   }, [isReady, mode, tool, penColor, strokeWidth]);
 
+  // Apply tool/mode to continuous-mode per-page fabric canvases too
+  useEffect(() => {
+    if (!isReady || scrollMode !== "continuous") return;
+    const fabric = fabricNSRef.current;
+    if (!fabric) return;
+    pageFabricRefs.current.forEach((fc) => {
+      if (!fc) return;
+      fc.off("mouse:down");
+      if (mode === "pan") {
+        fc.isDrawingMode = false;
+        fc.selection = false;
+        if (fc.wrapperEl) fc.wrapperEl.style.pointerEvents = "none";
+        return;
+      }
+      if (fc.wrapperEl) fc.wrapperEl.style.pointerEvents = "all";
+      switch (tool) {
+        case "select": fc.isDrawingMode = false; fc.selection = true; break;
+        case "pen": {
+          fc.isDrawingMode = true; fc.selection = false;
+          const b = new fabric.PencilBrush(fc); b.color = penColor; b.width = strokeWidth; fc.freeDrawingBrush = b; break;
+        }
+        case "highlighter": {
+          fc.isDrawingMode = true; fc.selection = false;
+          const hb = new fabric.PencilBrush(fc); hb.color = hexToRgba(penColor, 0.99); hb.width = strokeWidth * 7;
+          (hb as any).strokeLineCap = "square"; fc.freeDrawingBrush = hb; break;
+        }
+        case "text":
+          fc.isDrawingMode = false; fc.selection = false;
+          fc.on("mouse:down", (options: any) => {
+            if (options.target) return;
+            const pointer = fc.getPointer(options.e);
+            const t = new fabric.IText("Text", { left: pointer.x, top: pointer.y, fontSize: 20, fill: penColorRef.current, fontFamily: "Arial, sans-serif", padding: 4 });
+            fc.add(t); fc.setActiveObject(t); t.enterEditing(); t.selectAll(); fc.renderAll();
+          }); break;
+      }
+    });
+  }, [isReady, scrollMode, mode, tool, penColor, strokeWidth]);
+
   // ─────────────────────────────────────────────────────────────────────────
-  // Page navigation
-  // ─────────────────────────────────────────────────────────────────────────
+  // goToPage — in continuous mode, scroll to the page element
 
   const goToPage = useCallback(
     async (newPage: number) => {
+      if (newPage < 1 || newPage > totalPages || rendering) return;
+
+      if (scrollMode === "continuous") {
+        // Scroll the page wrapper into view
+        const el = pageCanvasRefs.current[newPage - 1]?.parentElement;
+        el?.scrollIntoView({ behavior: "smooth", block: "start" });
+        setCurrentPage(newPage);
+        return;
+      }
+
       const fc = fabricRef.current;
-      if (!fc || newPage < 1 || newPage > totalPages || rendering) return;
-
-      // Cache current page before leaving
+      if (!fc) return;
       localAnnotations.current[currentPage] = fc.toJSON();
-
       await renderPageWithAnnotations(newPage);
       setCurrentPage(newPage);
     },
-    [currentPage, totalPages, rendering, renderPageWithAnnotations]
+    [currentPage, totalPages, rendering, scrollMode, renderPageWithAnnotations]
   );
 
   // ─────────────────────────────────────────────────────────────────────────
@@ -382,7 +635,9 @@ export default function WorkbookViewer({ pdfId }: Props) {
   // ─────────────────────────────────────────────────────────────────────────
 
   const handleSave = useCallback(async () => {
-    const fc = fabricRef.current;
+    const fc = scrollMode === "continuous"
+      ? pageFabricRefs.current[currentPage - 1]
+      : fabricRef.current;
     if (!fc || !isReady || saving) return;
 
     setSaving(true);
@@ -441,7 +696,7 @@ export default function WorkbookViewer({ pdfId }: Props) {
   }
 
   return (
-    <div className="min-h-screen flex flex-col bg-gray-100">
+    <div className="h-screen flex flex-col overflow-hidden bg-gray-100">
 
       {/* ── Sticky Toolbar ──────────────────────────────────────────────────── */}
       <header className="bg-white border-b shadow-sm sticky top-0 z-20">
@@ -463,6 +718,85 @@ export default function WorkbookViewer({ pdfId }: Props) {
 
           <div className="h-5 w-px bg-gray-200 hidden sm:block" />
 
+          {/* Thumbnail panel toggle */}
+          <button
+            onClick={() => setShowThumbnails(v => !v)}
+            title="Thumbnails"
+            className={`p-1.5 rounded-lg transition flex items-center gap-1 ${
+              showThumbnails
+                ? "bg-blue-50 text-blue-600"
+                : "text-gray-500 hover:bg-gray-100 hover:text-gray-800"
+            }`}
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2}
+                d="M4 5a1 1 0 011-1h4a1 1 0 011 1v4a1 1 0 01-1 1H5a1 1 0 01-1-1V5zm10 0a1 1 0 011-1h4a1 1 0 011 1v4a1 1 0 01-1 1h-4a1 1 0 01-1-1V5zM4 15a1 1 0 011-1h4a1 1 0 011 1v4a1 1 0 01-1 1H5a1 1 0 01-1-1v-4zm10 0a1 1 0 011-1h4a1 1 0 011 1v4a1 1 0 01-1 1h-4a1 1 0 01-1-1v-4z" />
+            </svg>
+            <span className="text-xs font-medium hidden sm:inline">Thumb</span>
+          </button>
+
+          <div className="h-5 w-px bg-gray-200 hidden sm:block" />
+
+          {/* Fit mode buttons */}
+          <div className="flex items-center gap-0.5 bg-gray-100 rounded-lg p-0.5">
+            <button
+              onClick={() => setFitMode("width")}
+              title="Fit Width"
+              className={`text-xs px-2 py-1 rounded-md font-medium transition flex items-center gap-1 ${
+                fitMode === "width" ? "bg-white shadow text-blue-600" : "text-gray-500 hover:text-gray-800"
+              }`}
+            >
+              <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 7h8M8 12h8M4 17h16" />
+              </svg>
+              <span className="hidden sm:inline">Width</span>
+            </button>
+            <button
+              onClick={() => setFitMode("height")}
+              title="Fit Height"
+              className={`text-xs px-2 py-1 rounded-md font-medium transition flex items-center gap-1 ${
+                fitMode === "height" ? "bg-white shadow text-blue-600" : "text-gray-500 hover:text-gray-800"
+              }`}
+            >
+              <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M7 8V4m0 0H3m4 0l-4 4M17 8V4m0 0h4m-4 0l4 4M7 16v4m0 0H3m4 0l-4-4M17 16v4m0 0h4m-4 0l4-4" />
+              </svg>
+              <span className="hidden sm:inline">Height</span>
+            </button>
+          </div>
+
+          <div className="h-5 w-px bg-gray-200 hidden sm:block" />
+
+          {/* Scroll mode toggle */}
+          <div className="flex items-center gap-0.5 bg-gray-100 rounded-lg p-0.5">
+            <button
+              onClick={() => setScrollMode("single")}
+              title="Single page"
+              className={`text-xs px-2 py-1 rounded-md font-medium transition flex items-center gap-1 ${
+                scrollMode === "single" ? "bg-white shadow text-blue-600" : "text-gray-500 hover:text-gray-800"
+              }`}
+            >
+              <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 12h6M9 8h6M9 16h6M5 4h14a1 1 0 011 1v14a1 1 0 01-1 1H5a1 1 0 01-1-1V5a1 1 0 011-1z" />
+              </svg>
+              <span className="hidden sm:inline">Single</span>
+            </button>
+            <button
+              onClick={() => setScrollMode("continuous")}
+              title="Continuous scroll"
+              className={`text-xs px-2 py-1 rounded-md font-medium transition flex items-center gap-1 ${
+                scrollMode === "continuous" ? "bg-white shadow text-blue-600" : "text-gray-500 hover:text-gray-800"
+              }`}
+            >
+              <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 6h16M4 10h16M4 14h16M4 18h16" />
+              </svg>
+              <span className="hidden sm:inline">Continuous</span>
+            </button>
+          </div>
+
+          <div className="h-5 w-px bg-gray-200 hidden sm:block" />
+
           {/* Page navigation */}
           <div className="flex items-center gap-0.5">
             <button
@@ -475,9 +809,25 @@ export default function WorkbookViewer({ pdfId }: Props) {
                 <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" />
               </svg>
             </button>
-            <span className="text-xs text-gray-600 px-1 whitespace-nowrap tabular-nums">
-              {isReady ? `${currentPage} / ${totalPages}` : "…"}
-            </span>
+            {isReady ? (
+              <span className="flex items-center gap-1 text-xs text-gray-600 tabular-nums">
+                <input
+                  type="number"
+                  min={1}
+                  max={totalPages}
+                  value={currentPage}
+                  onChange={(e) => {
+                    const v = Number(e.target.value);
+                    if (v >= 1 && v <= totalPages) goToPage(v);
+                  }}
+                  onFocus={(e) => e.target.select()}
+                  className="w-10 text-center text-xs border border-gray-300 rounded px-1 py-0.5 focus:outline-none focus:border-blue-500 [appearance:textfield] [&::-webkit-inner-spin-button]:appearance-none [&::-webkit-outer-spin-button]:appearance-none"
+                />
+                <span>/ {totalPages}</span>
+              </span>
+            ) : (
+              <span className="text-xs text-gray-600 px-1">…</span>
+            )}
             <button
               onClick={() => goToPage(currentPage + 1)}
               disabled={currentPage >= totalPages || rendering || !isReady}
@@ -610,6 +960,40 @@ export default function WorkbookViewer({ pdfId }: Props) {
         </div>
       </header>
 
+      {/* ── Body: thumbnail sidebar + viewer ─────────────────────────────────── */}
+      <div className="flex flex-1 overflow-hidden">
+
+      {/* Thumbnail sidebar */}
+      {showThumbnails && (
+        <aside className="w-36 bg-white border-r border-gray-200 overflow-y-auto flex-shrink-0">
+          <div className="flex flex-col gap-2 py-3 px-2">
+            {Array.from({ length: totalPages }).map((_, idx) => (
+              <button
+                key={idx}
+                ref={(el) => { thumbRefs.current[idx] = el; }}
+                onClick={() => goToPage(idx + 1)}
+                className={`flex flex-col items-center gap-1 rounded-lg p-1 w-full transition ${
+                  currentPage === idx + 1
+                    ? "ring-2 ring-blue-500 bg-blue-50"
+                    : "hover:bg-gray-100"
+                }`}
+              >
+                {thumbnails[idx] ? (
+                  <img
+                    src={thumbnails[idx]}
+                    alt={`Page ${idx + 1}`}
+                    className="w-full rounded shadow-sm border border-gray-200"
+                  />
+                ) : (
+                  <div className="w-full aspect-[3/4] bg-gray-100 rounded animate-pulse" />
+                )}
+                <span className="text-[10px] text-gray-500 tabular-nums font-medium">{idx + 1}</span>
+              </button>
+            ))}
+          </div>
+        </aside>
+      )}
+
       {/* ── Viewer area ─────────────────────────────────────────────────────── */}
       <main
         ref={scrollContainerRef}
@@ -630,42 +1014,31 @@ export default function WorkbookViewer({ pdfId }: Props) {
         {/* Canvas stack — PDF layer below, Fabric wrapper above (absolutely) */}
         <div
           className="relative mx-auto"
-          style={{ display: isReady ? "block" : "none", width: "fit-content" }}
+          style={{ display: isReady && scrollMode === "single" ? "block" : "none", width: "fit-content" }}
         >
           {/* PDF.js renders here */}
           <canvas ref={pdfCanvasRef} className="block shadow-lg rounded" />
-
-          {/*
-            Fabric.js is initialised on this element.
-            After init, Fabric wraps it in a div (wrapperEl) that our useEffect
-            repositions to position:absolute / top:0 / left:0 — sitting above the PDF.
-          */}
           <canvas ref={fabricElRef} />
         </div>
 
-        {/* Bottom page controls for mobile convenience */}
-        {isReady && (
-          <div className="flex justify-center mt-6 gap-4">
-            <button
-              onClick={() => goToPage(currentPage - 1)}
-              disabled={currentPage <= 1 || rendering}
-              className="text-sm text-blue-600 hover:underline disabled:opacity-40 disabled:no-underline"
-            >
-              ← Prev
-            </button>
-            <span className="text-sm text-gray-500 tabular-nums">
-              {currentPage} / {totalPages}
-            </span>
-            <button
-              onClick={() => goToPage(currentPage + 1)}
-              disabled={currentPage >= totalPages || rendering}
-              className="text-sm text-blue-600 hover:underline disabled:opacity-40 disabled:no-underline"
-            >
-              Next →
-            </button>
+        {/* Continuous scroll: one wrapper per page */}
+        {isReady && scrollMode === "continuous" && (
+          <div className="flex flex-col gap-6 items-center">
+            {Array.from({ length: totalPages }).map((_, idx) => (
+              <div key={idx} className="relative" style={{ width: "fit-content" }}>
+                <canvas
+                  ref={(el) => { pageCanvasRefs.current[idx] = el; }}
+                  data-page={idx + 1}
+                  className="block shadow-lg rounded"
+                />
+                <canvas id={`fabric-continuous-${idx + 1}`} />
+              </div>
+            ))}
           </div>
         )}
+
       </main>
+      </div>
     </div>
   );
 }