feat(canvas): add slider compare mode for generated image nodes

components/canvas/nodes/ImageNode.tsx

@@ -257,10 +257,14 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
   const [draftTitle, setDraftTitle] = useState("");
   const [draftNote, setDraftNote] = useState("");
   const [isAddingToChat, setIsAddingToChat] = useState(false);
+  const [isCompareMode, setIsCompareMode] = useState(false);
+  const [compareSplitPercent, setCompareSplitPercent] = useState(50);
+  const [isCompareDragging, setIsCompareDragging] = useState(false);
   
   // 文件输入的 ref
   const fileInputRef = useRef<HTMLInputElement>(null);
   const containerRef = useRef<HTMLDivElement>(null);
+  const compareFrameRef = useRef<HTMLDivElement>(null);
   
   const updateNode = useCanvasStore((state) => state.updateNode);
   const deleteNode = useCanvasStore((state) => state.deleteNode);
@@ -274,12 +278,30 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
   const isPickerLoading = useCanvasStore((state) => state.isPickerLoading);
   const setPickerLoading = useCanvasStore((state) => state.setPickerLoading);
   const addPendingPickedObject = useCanvasStore((state) => state.addPendingPickedObject);
+  const fallbackCompareSource = useCanvasStore((state) => {
+    if (data.originalSrc) return "";
+    if (!Array.isArray(node.connections) || node.connections.length === 0) return "";
+    for (const sourceNodeId of node.connections) {
+      const sourceNode = state.nodes.find((item) => item.id === sourceNodeId);
+      if (sourceNode?.type !== "image") continue;
+      const sourceUrl = String(((sourceNode.data as any) || {}).src || "").trim();
+      if (sourceUrl) return sourceUrl;
+    }
+    return "";
+  });
   
   // 当前节点是否处于拾取模式
   const isThisNodePicking = isPickerMode && pickerTargetNodeId === node.id;
   
   // 当前正在识别的点击位置
   const [currentClick, setCurrentClick] = useState<{ x: number; y: number } | null>(null);
+  const displayTitle = getImageNodeTitle(data, node.id);
+  const isMultiSelected = isSelected && selectedNodeIds.length > 1;
+  const compareSource = String(data.originalSrc || fallbackCompareSource || "").trim();
+  const hasCompareSource =
+    Boolean(data.src) &&
+    Boolean(compareSource) &&
+    compareSource !== data.src;
   
   // 退出拾取模式时清空状态
   useEffect(() => {
@@ -301,9 +323,51 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
       setTextEditPanelOpen(false);
       setIsEditingTitle(false);
       setPromptDialogOpen(false);
+      setIsCompareMode(false);
+      setIsCompareDragging(false);
     }
   }, [isSelected]);
 
+  useEffect(() => {
+    if (!hasCompareSource || isThisNodePicking) {
+      setIsCompareMode(false);
+      setIsCompareDragging(false);
+    }
+  }, [hasCompareSource, isThisNodePicking]);
+
+  const updateCompareSplitByClientX = useCallback((clientX: number) => {
+    const frame = compareFrameRef.current;
+    if (!frame) return;
+
+    const rect = frame.getBoundingClientRect();
+    if (rect.width <= 0) return;
+
+    const rawPercent = ((clientX - rect.left) / rect.width) * 100;
+    const clampedPercent = Math.max(0, Math.min(100, rawPercent));
+    setCompareSplitPercent(clampedPercent);
+  }, []);
+
+  useEffect(() => {
+    if (!isCompareDragging) return;
+
+    const handlePointerMove = (event: PointerEvent) => {
+      updateCompareSplitByClientX(event.clientX);
+    };
+    const handlePointerEnd = () => {
+      setIsCompareDragging(false);
+    };
+
+    window.addEventListener("pointermove", handlePointerMove);
+    window.addEventListener("pointerup", handlePointerEnd);
+    window.addEventListener("pointercancel", handlePointerEnd);
+
+    return () => {
+      window.removeEventListener("pointermove", handlePointerMove);
+      window.removeEventListener("pointerup", handlePointerEnd);
+      window.removeEventListener("pointercancel", handlePointerEnd);
+    };
+  }, [isCompareDragging, updateCompareSplitByClientX]);
+
   useEffect(() => {
     if (!isEditingTitle) {
       setDraftTitle(getImageNodeTitle(data, node.id));
@@ -392,9 +456,6 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
   const handleCancelPicking = useCallback(() => {
     setPickerMode(false);
   }, [setPickerMode]);
-  const displayTitle = getImageNodeTitle(data, node.id);
-  const isMultiSelected = isSelected && selectedNodeIds.length > 1;
-
   const animateAddToChat = useCallback(async () => {
     if (!containerRef.current || !data.src || typeof window === "undefined") {
       return false;
@@ -1490,22 +1551,73 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
         {/* 图片内容 - 使用 object-contain 保持原始比例 */}
         {data.src ? (
           <div className="relative w-full h-full">
-            <img
-              src={data.src}
-              alt={displayTitle}
-              className={cn(
-                "w-full h-full object-contain bg-muted/30",
-                isThisNodePicking ? "cursor-crosshair" : "cursor-pointer"
-              )}
-              draggable={false}
-              onClick={isThisNodePicking ? handlePickerClick : undefined}
-              onDoubleClick={(e) => {
-                if (!isThisNodePicking) {
-                  e.stopPropagation();
-                  setFullscreenPreviewOpen(true);
-                }
-              }}
-            />
+            {isCompareMode && hasCompareSource ? (
+              <div
+                ref={compareFrameRef}
+                className="relative h-full w-full overflow-hidden bg-muted/30 select-none"
+              >
+                <img
+                  src={data.src}
+                  alt={displayTitle}
+                  className="h-full w-full object-contain"
+                  draggable={false}
+                />
+                <div
+                  className="pointer-events-none absolute inset-0 overflow-hidden"
+                  style={{
+                    clipPath: `inset(0 ${100 - compareSplitPercent}% 0 0)`,
+                  }}
+                >
+                  <img
+                    src={compareSource}
+                    alt={`${displayTitle}-原图`}
+                    className="h-full w-full object-contain"
+                    draggable={false}
+                  />
+                </div>
+                <div
+                  className="absolute inset-y-0 z-20 w-0.5 bg-white shadow-[0_0_0_1px_rgba(0,0,0,0.25)]"
+                  style={{ left: `${compareSplitPercent}%`, transform: "translateX(-50%)" }}
+                />
+                <button
+                  type="button"
+                  className="absolute top-1/2 z-30 -translate-y-1/2 rounded-full border border-white/70 bg-black/65 px-2 py-1 text-[10px] text-white"
+                  style={{ left: `${compareSplitPercent}%`, transform: "translate(-50%, -50%)" }}
+                  onPointerDown={(event) => {
+                    event.preventDefault();
+                    event.stopPropagation();
+                    setIsCompareDragging(true);
+                    updateCompareSplitByClientX(event.clientX);
+                  }}
+                  title="拖动中线查看对比"
+                >
+                  对比
+                </button>
+                <div className="pointer-events-none absolute left-2 top-2 rounded bg-black/55 px-1.5 py-0.5 text-[10px] text-white">
+                  原图
+                </div>
+                <div className="pointer-events-none absolute right-2 top-2 rounded bg-black/55 px-1.5 py-0.5 text-[10px] text-white">
+                  新图
+                </div>
+              </div>
+            ) : (
+              <img
+                src={data.src}
+                alt={displayTitle}
+                className={cn(
+                  "w-full h-full object-contain bg-muted/30",
+                  isThisNodePicking ? "cursor-crosshair" : "cursor-pointer"
+                )}
+                draggable={false}
+                onClick={isThisNodePicking ? handlePickerClick : undefined}
+                onDoubleClick={(e) => {
+                  if (!isThisNodePicking) {
+                    e.stopPropagation();
+                    setFullscreenPreviewOpen(true);
+                  }
+                }}
+              />
+            )}
             
             {/* 🆕 拾取模式：当前点击位置（正在识别） */}
             {isThisNodePicking && currentClick && (
@@ -1541,6 +1653,19 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
                 </Button>
               </div>
             )}
+
+            {isSelected && !isMultiSelected && hasCompareSource && !isThisNodePicking && (
+              <button
+                type="button"
+                className="absolute bottom-2 right-2 rounded-md bg-black/70 px-2 py-1 text-[11px] font-medium text-white transition-colors hover:bg-black/80"
+                onClick={(event) => {
+                  event.stopPropagation();
+                  setIsCompareMode((prev) => !prev);
+                }}
+              >
+                {isCompareMode ? "退出对比" : "对比显示"}
+              </button>
+            )}
           </div>
         ) : data.status === 'generating' ? (
           <div className="w-full h-full flex flex-col items-center justify-center bg-muted select-none">