fix(share): wxacodeUrl 改用 useRef 避免压缩后引用丢失

frontend/src/app/pages/SharePage.tsx

@@ -42,7 +42,8 @@ export function SharePage() {
   const [imageUrl, setImageUrl] = useState<string | null>(null);
   const [linkCopied, setLinkCopied] = useState(false);
   const [canShareToWechat, setCanShareToWechat] = useState(false);
-  const [wxacodeUrl, setWxacodeUrl] = useState<string | null>(null);
+  const wxacodeUrl = useRef<string | null>(null);
+  const [, forceUpdate] = useState(0);
   const cardRef = useRef<HTMLDivElement>(null);
 
   useEffect(() => {
@@ -92,7 +93,7 @@ export function SharePage() {
     let cancelled = false;
     generateWxacode({ width: 430 })
       .then((url) => {
-        if (!cancelled) setWxacodeUrl(url);
+        if (!cancelled) { wxacodeUrl.current = url; forceUpdate(n => n + 1); }
       })
       .catch((err) => {
         console.warn("[SharePage] 太阳码生成失败:", err);
@@ -105,20 +106,20 @@ export function SharePage() {
   // 卸载时清理 blob URL
   useEffect(() => {
     return () => {
-      if (wxacodeUrl?.startsWith("blob:")) URL.revokeObjectURL(wxacodeUrl);
+      if (wxacodeUrl.current?.startsWith("blob:")) URL.revokeObjectURL(wxacodeUrl.current);
     };
-  }, [wxacodeUrl]);
+  }, []);
 
   // 生成长图
   const generateImage = useCallback(async (): Promise<string | null> => {
     if (!cardRef.current) return null;
 
     // 等待太阳码渲染完成（blob URL 需浏览器解码）
-    if (shareData && !wxacodeUrl) {
+    if (shareData && !wxacodeUrl.current) {
       await new Promise<void>((resolve) => {
         const start = Date.now();
         const tick = () => {
-          if (wxacodeUrl || Date.now() - start > 1500) {
+          if (wxacodeUrl.current || Date.now() - start > 1500) {
             resolve();
             return;
           }
@@ -126,7 +127,7 @@ export function SharePage() {
         };
         tick();
       });
-      if (!wxacodeUrl) {
+      if (!wxacodeUrl.current) {
         console.warn("[SharePage] 太阳码未就绪，截图中可能缺失二维码");
       }
     }
@@ -147,7 +148,7 @@ export function SharePage() {
       console.error("生成图片失败:", err);
       return null;
     }
-  }, [shareData, wxacodeUrl]);
+  }, [shareData]);
 
   // 一键保存到相册 / 下载
   const handleSaveImage = useCallback(async () => {
@@ -665,7 +666,7 @@ function ShareCardContent({
         )}
 
         {/* 太阳码区（截图包含） */}
-        {wxacodeUrl && (
+        {wxacodeUrl.current && (
           <div
             style={{
               textAlign: "center",
@@ -674,7 +675,7 @@ function ShareCardContent({
             }}
           >
             <img
-              src={wxacodeUrl}
+              src={wxacodeUrl.current}
               alt="扫码下载孕育无忧"
               crossOrigin="anonymous"
               style={{