加快画布原图下载和 Agent 图片显示

app/api/image-proxy/route.ts

@@ -133,15 +133,13 @@ function buildImageResponse(
     etag: string;
     vary?: string;
     cacheStatus?: "HIT" | "MISS";
-    cacheControl?: string;
-    attachment?: boolean;
   }
 ) {
   const headers: Record<string, string> = {
     "Content-Type": params.contentType,
     "Content-Length": String(body.length),
     ETag: params.etag,
-    "Cache-Control": params.cacheControl || "public, max-age=31536000, immutable, stale-while-revalidate=86400",
+    "Cache-Control": "public, max-age=31536000, immutable, stale-while-revalidate=86400",
   };
   if (params.vary) {
     headers.Vary = params.vary;
@@ -149,11 +147,6 @@ function buildImageResponse(
   if (params.cacheStatus) {
     headers["X-Image-Proxy-Cache"] = params.cacheStatus;
   }
-  if (params.attachment) {
-    headers["Content-Disposition"] = "attachment";
-    headers["X-Content-Type-Options"] = "nosniff";
-    headers["Content-Security-Policy"] = "default-src 'none'; sandbox";
-  }
   return new NextResponse(body, {
     status: 200,
     headers,
@@ -460,20 +453,29 @@ export async function GET(request: NextRequest) {
       if (original) return downloadFailure("Source is not an image");
       return NextResponse.json({ error: "Upstream is not an image" }, { status: 400 });
     }
+    if (original) {
+      if (upstreamResponse.status !== 200 || !upstreamResponse.body) {
+        await upstreamResponse.body?.cancel();
+        return downloadFailure("源图片传输中断，请重试");
+      }
+      const headers = new Headers({
+        "Content-Type": contentType,
+        "Content-Disposition": "attachment",
+        "Cache-Control": "private, no-store",
+        "X-Content-Type-Options": "nosniff",
+        "Content-Security-Policy": "default-src 'none'; sandbox",
+      });
+      const length = upstreamResponse.headers.get("content-length");
+      const encoding = upstreamResponse.headers.get("content-encoding");
+      if (length && (!encoding || encoding.toLowerCase() === "identity")) headers.set("Content-Length", length);
+      return new NextResponse(upstreamResponse.body, { headers });
+    }
     try {
       originalBuffer = Buffer.from(await upstreamResponse.arrayBuffer());
     } catch (error) {
       return upstreamFailure(error);
     }
   }
-  if (original) {
-    return buildImageResponse(originalBuffer, {
-      contentType,
-      etag: `"${crypto.createHash("sha256").update(originalBuffer).digest("hex")}"`,
-      cacheControl: "private, no-store",
-      attachment: true,
-    });
-  }
   const isSvg = contentType.toLowerCase().includes("image/svg");
   const isGif = contentType.toLowerCase().includes("image/gif");
 

components/canvas/CanvasChatPanel.tsx

@@ -78,7 +78,7 @@ import {
   type UploadProgress,
 } from "@/lib/client/upload-with-retry";
 import {
-  downloadCanvasImageAsPng,
+  downloadOriginalImage,
   getCanvasImageDownloadErrorMessage,
   type CanvasImageDownloadProgress,
 } from "@/lib/client/canvas-image-download";
@@ -1462,7 +1462,7 @@ function normalizeComposerPreviewTail(text: string, fixedPrefix: string) {
 }
 
 // 获取图片尺寸（保留原图分辨率 + 画布显示尺寸）
-function getImageDimensions(url: string): Promise<{
+function getImageDimensions(source: string | File): Promise<{
   width: number;
   height: number;
   originalWidth: number;
@@ -1470,6 +1470,7 @@ function getImageDimensions(url: string): Promise<{
 }> {
   return new Promise((resolve) => {
     const img = new Image();
+    const objectUrl = typeof source === "string" ? null : URL.createObjectURL(source);
     let settled = false;
     const resolveOnce = (dimensions: {
       width: number;
@@ -1482,9 +1483,11 @@ function getImageDimensions(url: string): Promise<{
       window.clearTimeout(timeout);
       img.onload = null;
       img.onerror = null;
+      if (objectUrl) URL.revokeObjectURL(objectUrl);
       resolve(dimensions);
     };
     const timeout = window.setTimeout(() => {
+      img.removeAttribute("src");
       resolveOnce(DEFAULT_CANVAS_IMAGE_DIMENSIONS);
     }, CANVAS_IMAGE_DIMENSION_TIMEOUT_MS);
 
@@ -1517,7 +1520,7 @@ function getImageDimensions(url: string): Promise<{
       // 加载失败时使用默认尺寸
       resolveOnce(DEFAULT_CANVAS_IMAGE_DIMENSIONS);
     };
-    img.src = url;
+    img.src = objectUrl ?? String(source);
   });
 }
 
@@ -4468,9 +4471,8 @@ export function CanvasChatPanel({
     });
 
     try {
-      await downloadCanvasImageAsPng({
+      await downloadOriginalImage({
         url: originalUrl,
-        candidates: [raw, buildImageProxyUrl(originalUrl, { delivery: "proxy" })],
         signal: controller.signal,
         onProgress: setDownloadProgress,
       });
@@ -7806,7 +7808,6 @@ export function CanvasChatPanel({
           existingMessageImageKeys.add(messageImageKey);
         }
 
-        const dimensions = await getImageDimensions(url);
         if (useCanvasStore.getState().projectId !== canvasId || activeChatIdRef.current !== activeChatId) return;
         const compareSourceUrlRaw =
           sourceImageUrls[Math.min(index, Math.max(0, sourceImageUrls.length - 1))] ||
@@ -7839,7 +7840,7 @@ export function CanvasChatPanel({
         const placeholderNode = reservedPlaceholderNode
           ? currentNodes.find((node) => node.id === reservedPlaceholderNode.id) || null
           : null;
-        const size = { width: dimensions.width, height: dimensions.height };
+        const size = placeholderNode?.size || anchorNode?.size || { width: 300, height: 300 };
         const position = placeholderNode
           ? getCenteredReplacementPosition(placeholderNode, size)
           : getAnchoredGenerationPosition({
@@ -7857,8 +7858,6 @@ export function CanvasChatPanel({
           prompt: generationPrompt,
           originalSrc: canUseCompareSource ? compareSourceUrl : undefined,
           metadata: {
-            originalWidth: dimensions.originalWidth,
-            originalHeight: dimensions.originalHeight,
             generationPrompt,
             sourceMessageId: messageId || undefined,
             sourceImageKey,
@@ -9583,7 +9582,6 @@ export function CanvasChatPanel({
             continue;
           }
 
-          const dimensions = await getImageDimensions(url);
           if (cancelled) return;
           const compareSourceUrlRaw =
             nearestUserImageUrls[Math.min(index, Math.max(0, nearestUserImageUrls.length - 1))] ||
@@ -9616,20 +9614,7 @@ export function CanvasChatPanel({
           const placeholderNode = reservedPlaceholderNode
             ? currentNodes.find((node) => node.id === reservedPlaceholderNode.id) || null
             : null;
-          const size = placeholderNode
+          const size = placeholderNode?.size || anchorNode?.size || { width: 300, height: 300 };
-            ? { width: dimensions.width, height: dimensions.height }
-            : anchorNode
-            ? {
-                width: Math.max(
-                  1,
-                  Math.round(Number(anchorNode.size?.width || dimensions.width))
-                ),
-                height: Math.max(
-                  1,
-                  Math.round(Number(anchorNode.size?.height || dimensions.height))
-                ),
-              }
-            : { width: dimensions.width, height: dimensions.height };
           const position = placeholderNode
             ? getCenteredReplacementPosition(placeholderNode, size)
             : getAnchoredGenerationPosition({
@@ -9648,8 +9633,6 @@ export function CanvasChatPanel({
             prompt: generationPrompt || "对话生成",
             originalSrc: canUseCompareSource ? compareSourceUrl : undefined,
             metadata: {
-              originalWidth: dimensions.originalWidth,
-              originalHeight: dimensions.originalHeight,
               generationPrompt: generationPrompt || undefined,
               sourceMessageId: message.id,
               sourceImageKey: imageEntry.sourceImageKey,
@@ -10376,7 +10359,7 @@ export function CanvasChatPanel({
           buildCanvasUploadedImageAttachment({ file, imageUrl, assetId })
         );
 
-        const dimensions = await getImageDimensions(imageUrl);
+        const dimensions = await getImageDimensions(file);
         const nodeIndex = nodes.length + slotIndex;
         const spacing = 20;
         const x = 100 + (nodeIndex % 3) * (dimensions.width + spacing);
@@ -10454,7 +10437,7 @@ export function CanvasChatPanel({
           buildCanvasUploadedImageAttachment({ file, imageUrl, assetId })
         );
 
-        const dimensions = await getImageDimensions(imageUrl);
+        const dimensions = await getImageDimensions(file);
         const nodeIndex = nodes.length + slotIndex;
         const spacing = 20;
         const x = 100 + (nodeIndex % 3) * (dimensions.width + spacing);
@@ -13740,7 +13723,7 @@ export function CanvasChatPanel({
       };
       onUploaded?.(uploadedBase);
       clearComposerUploadProgress(250);
-      const dimensions = await getImageDimensions(imageUrl);
+      const dimensions = await getImageDimensions(file);
       const spacing = 20;
       const x = 100 + (nodeIndex % 3) * (dimensions.width + spacing);
       const y = 100 + Math.floor(nodeIndex / 3) * (dimensions.height + spacing);
@@ -14929,7 +14912,7 @@ export function CanvasChatPanel({
           firstImageUrl = imageUrl;
         }
 
-        const dimensions = await getImageDimensions(imageUrl);
+        const dimensions = await getImageDimensions(file);
         updateUploadedImageAttachmentDimensions(imageUrl, dimensions);
         
         // 获取图片原始尺寸后添加到画布

components/canvas/nodes/ImageNode.tsx

@@ -179,6 +179,7 @@ import {
 import { fetchUploadWithRetry } from "@/lib/client/upload-with-retry";
 import {
   downloadCanvasImageAsPng,
+  downloadOriginalImage,
   getCanvasImageDownloadErrorMessage,
   type CanvasImageDownloadProgress,
 } from "@/lib/client/canvas-image-download";
@@ -2519,15 +2520,6 @@ export function ImageNode({
       }),
     [data.src, displayImageQuality, displayImageWidth]
   );
-  const fullscreenPreviewSrc = useMemo(() => {
-    const originalUrl = resolveOriginalImageUrl(data.src || "");
-    return buildImageProxyUrl(originalUrl || data.src || "", {
-      delivery: "proxy",
-      width: 4096,
-      quality: 92,
-      format: "webp",
-    });
-  }, [data.src]);
   const displayCompareSrc = useMemo(
     () =>
       buildImageProxyUrl(compareSource, {
@@ -8232,9 +8224,8 @@ export function ImageNode({
     }
   };
 
-  // 下载图片 - 服务端统一转为 Photoshop 兼容 PNG，避免后缀和真实格式错配。
   const isDownloadingOriginalImage = Boolean(downloadProgress);
-  const handleDownload = async () => {
+  const handleDownload = async (format: "original" | "png" = "original") => {
     if (!data.src) return;
     if (isDownloadingOriginalImage) {
       toast.info("原图正在下载中");
@@ -8250,20 +8241,15 @@ export function ImageNode({
     });
 
     try {
-      await downloadCanvasImageAsPng({
+      const request = {
-        url: data.src,
+        url: resolveOriginalImageUrl(data.src) || data.src,
         name: displayTitle,
-        candidates: [
-          displayImageSrc,
-          fullscreenPreviewSrc,
-          buildImageProxyUrl(resolveOriginalImageUrl(data.src) || data.src, {
-            delivery: "proxy",
-          }),
-        ],
         signal: controller.signal,
         onProgress: setDownloadProgress,
-      });
+      };
-      toast.success("原图已开始下载");
+      if (format === "png") await downloadCanvasImageAsPng({ ...request, url: data.src });
+      else await downloadOriginalImage(request);
+      toast.success(format === "png" ? "PNG 已开始下载" : "原图已开始下载");
     } catch (error) {
       if (controller.signal.aborted) {
         toast.message("已取消下载");
@@ -9656,6 +9642,7 @@ export function ImageNode({
 	                <DropdownMenuSeparator />
 	                ) : null}
 	                {imageDownloadEnabled ? (
+	                <>
 	                <DropdownMenuItem
                     disabled={isDownloadingOriginalImage}
                     onClick={() => {
@@ -9673,6 +9660,11 @@ export function ImageNode({
                     )}
 	                  {imageDownloadItem.label}
 	                </DropdownMenuItem>
+                  <DropdownMenuItem disabled={isDownloadingOriginalImage} onClick={() => void handleDownload("png")}>
+                    <Download className="mr-2 h-4 w-4" />
+                    下载为 PNG（兼容 Photoshop）
+                  </DropdownMenuItem>
+                  </>
 	                ) : null}
 	                {imageDeleteEnabled ? (
                 <DropdownMenuItem

tests/routes/original-image-download.test.ts

@@ -66,6 +66,30 @@ test("original download metadata reports missing sources with cause, advice and
   expect(data.error).toContain(data.requestId);
 });
 
+test("the original proxy returns the first bytes while the upstream is still sending the file", async () => {
+  const head = Uint8Array.from([255, 216, 255, 224]);
+  const tail = Uint8Array.from([4, 8, 255, 217]);
+  let upstream!: ReadableStreamDefaultController<Uint8Array>;
+  const body = new ReadableStream<Uint8Array>({
+    start(controller) { upstream = controller; controller.enqueue(head); },
+  });
+  const route = serverLoader({
+    "next/server": { NextResponse: Response },
+    fetch: async () => new Response(body, { headers: { "content-type": "image/jpeg", "content-length": "8" } }),
+  })("app/api/image-proxy/route.ts");
+  const response = await route.GET({
+    nextUrl: new URL("https://app.example/api/image-proxy?url=https%3A%2F%2Fimages.example%2Foriginal.jpg&original=1"),
+    signal: new AbortController().signal, headers: new Headers(),
+  });
+  expect(response.headers.get("content-length")).toBe("8");
+  const reader = response.body.getReader();
+  expect((await reader.read()).value).toEqual(head);
+  upstream.enqueue(tail);
+  upstream.close();
+  expect((await reader.read()).value).toEqual(tail);
+  expect((await reader.read()).done).toBe(true);
+});
+
 function browserMocks() {
   const frames: any[] = []; const links: any[] = [];
   return { frames, links,