merge: fix/42-reader-vertical-deep-pages dans develop (préchargeur CBZ vertical concurrent pour les pages profondes — 3e correctif #42)

apps/web/src/reader/CbzReader.tsx

@@ -11,6 +11,7 @@ const VERTICAL_ANCHOR_TOLERANCE_PX = 24;
 const VERTICAL_ANCHOR_STABLE_FRAMES = 18;
 const VERTICAL_ANCHOR_MAX_ATTEMPTS = 180;
 const VERTICAL_INITIAL_SYNC_MAX_ATTEMPTS = 180;
+const VERTICAL_IMAGE_PRELOAD_CONCURRENCY = 24;
 
 export function CbzReader({
   bookId,
@@ -39,6 +40,9 @@ export function CbzReader({
   const verticalInitialSyncDoneRef = useRef(false);
   const verticalAnchorAttemptRef = useRef(0);
   const verticalAnchorStableFramesRef = useRef(0);
+  const preloadedImagesRef = useRef(new Map<number, HTMLImageElement>());
+  const pendingImageSizesRef = useRef<Record<number, ReaderSize>>({});
+  const imageSizeFlushFrameRef = useRef<number | null>(null);
   const [pages, setPages] = useState<CbzPagesDto | null>(null);
   const [documentError, setDocumentError] = useState<string>();
   const [pageError, setPageError] = useState<string>();
@@ -91,6 +95,27 @@ export function CbzReader({
     if (verticalInitialSyncFrameRef.current !== null) cancelAnimationFrame(verticalInitialSyncFrameRef.current);
     verticalInitialSyncFrameRef.current = null;
   }, []);
+  const queueImageSize = useCallback((pageNumber: number, size: ReaderSize) => {
+    pendingImageSizesRef.current[pageNumber] = size;
+    if (imageSizeFlushFrameRef.current !== null) return;
+    imageSizeFlushFrameRef.current = requestAnimationFrame(() => {
+      imageSizeFlushFrameRef.current = null;
+      const pending = pendingImageSizesRef.current;
+      pendingImageSizesRef.current = {};
+      setImageSizes((current) => {
+        let changed = false;
+        const next = { ...current };
+        for (const [pageKey, nextSize] of Object.entries(pending)) {
+          const pageNumber = Number(pageKey);
+          const currentSize = current[pageNumber];
+          if (currentSize?.width === nextSize.width && currentSize.height === nextSize.height) continue;
+          next[pageNumber] = nextSize;
+          changed = true;
+        }
+        return changed ? next : current;
+      });
+    });
+  }, []);
   const commitVisiblePage = useCallback(
     (stage: HTMLElement, allowInitialCommit = false) => {
       if (!pages || !verticalTrackingReadyRef.current) return;
@@ -192,8 +217,49 @@ export function CbzReader({
 
   useEffect(() => {
     setImageSizes({});
+    pendingImageSizesRef.current = {};
+    preloadedImagesRef.current.clear();
   }, [bookId, retryAttempt]);
 
+  useEffect(() => {
+    if (mode !== "vertical" || !pages || typeof Image === "undefined") return;
+    let cancelled = false;
+    let nextIndex = 0;
+    let active = 0;
+    const pageItems = pages.pages;
+
+    const preloadNext = () => {
+      if (cancelled) return;
+      while (active < VERTICAL_IMAGE_PRELOAD_CONCURRENCY && nextIndex < pageItems.length) {
+        const item = pageItems[nextIndex];
+        nextIndex += 1;
+        if (preloadedImagesRef.current.has(item.page)) continue;
+        const image = new Image();
+        preloadedImagesRef.current.set(item.page, image);
+        active += 1;
+        image.decoding = "async";
+        image.loading = "eager";
+        image.onload = () => {
+          active -= 1;
+          if (!cancelled && image.naturalWidth > 0 && image.naturalHeight > 0) {
+            queueImageSize(item.page, { width: image.naturalWidth, height: image.naturalHeight });
+          }
+          preloadNext();
+        };
+        image.onerror = () => {
+          active -= 1;
+          preloadNext();
+        };
+        image.src = api.cbzPageUrl(bookId, item.page);
+      }
+    };
+
+    preloadNext();
+    return () => {
+      cancelled = true;
+    };
+  }, [bookId, mode, pages, queueImageSize, retryAttempt]);
+
   useEffect(() => {
     const frame = frameRef.current;
     const stage = frame?.closest(".reader-stage") as HTMLElement | null;
@@ -275,6 +341,7 @@ export function CbzReader({
       commitVisiblePage(stage);
     };
     const onScroll = () => {
+      if (verticalTrackingReadyRef.current) verticalUserScrollRef.current = true;
       if (frameId) return;
       frameId = requestAnimationFrame(updateVisiblePage);
     };
@@ -297,6 +364,12 @@ export function CbzReader({
 
   useEffect(() => () => clearVerticalAnchorFrame(), [clearVerticalAnchorFrame]);
   useEffect(() => () => clearVerticalInitialSync(), [clearVerticalInitialSync]);
+  useEffect(
+    () => () => {
+      if (imageSizeFlushFrameRef.current !== null) cancelAnimationFrame(imageSizeFlushFrameRef.current);
+    },
+    []
+  );
 
   if (documentError) {
     return (
@@ -352,10 +425,7 @@ export function CbzReader({
                 style={verticalImageStyle(item.page)}
                 onLoad={(event) => {
                   const { naturalWidth, naturalHeight } = event.currentTarget;
-                  setImageSizes((current) => ({
-                    ...current,
-                    [item.page]: { width: naturalWidth, height: naturalHeight }
-                  }));
+                  queueImageSize(item.page, { width: naturalWidth, height: naturalHeight });
                 }}
                 onError={() => setPageError(`Page ${item.page} indisponible.`)}
               />

apps/web/src/reader/readerRuntime.test.ts

@@ -222,6 +222,16 @@ describe("reader runtime helpers", () => {
     expect(verticalBranch).not.toContain('hidden={!imageSizes[item.page]}');
   });
 
+  it("preloads deep CBZ vertical pages without relying only on browser lazy loading", () => {
+    const source = readFileSync(new URL("./CbzReader.tsx", import.meta.url), "utf8");
+
+    expect(source).toContain("VERTICAL_IMAGE_PRELOAD_CONCURRENCY");
+    expect(source).toContain("new Image()");
+    expect(source).toContain('image.loading = "eager"');
+    expect(source).toContain("queueImageSize");
+    expect(source).toContain("if (verticalTrackingReadyRef.current) verticalUserScrollRef.current = true");
+  });
+
   it("keeps unloaded PDF and CBZ vertical pages visually covered by a page-sized fallback", () => {
     const styles = readFileSync(new URL("../styles/app.css", import.meta.url), "utf8");