Return SVG of Image not available when trying to view a missing ComfyUI image

Author: mythz

MyApp.ServiceInterface/FileServices.cs

@@ -156,19 +156,38 @@ public object Any(DeleteFiles request)
 
     public async Task<object> Any(GetVariant request)
     {
+        // Missing ComfyUI Image, e.g: view?filename=ComfyUI_00001_.png&type=output&subfolder=
+        if (request.Path == "view")
+        {
+            // Return SVG of Unknown Image with given dimensions (for darkmode)
+            var (width, height) = GetVariantDimensions(request.Variant);
+            if (height == null)
+                height = (int)(width.GetValueOrDefault() * 1344/768m);
+            if (width == null)
+                width = (int)(height.GetValueOrDefault() * 768/1344m);
+            var svg =
+                $"""
+                <svg xmlns="http://www.w3.org/2000/svg" width="{width}" height="{height}" viewBox="0 0 {width} {height}">
+                    <rect width="100%" height="100%" fill="#364050" />
+                    <text x="50%" y="50%" text-anchor="middle" fill="#9ca3af" font-family="Arial, sans-serif" font-size="14">Image not available</text>
+                </svg>
+                """;
+            return new HttpResult(svg, MimeTypes.ImageSvg);
+        }
+        
         var filePath = request.Path.StartsWith("pub")
             ? appData.Config.FilesPath.CombineWith(request.Path)
             : appData.Config.ArtifactsPath.CombineWith(request.Path[..2], request.Path);
         var file = new FileInfo(filePath);
         if (!file.Exists)
-            throw HttpError.NotFound("Artifact not found");
+            throw HttpError.NotFound("Artifact not found: " + request.Path);
 
         return await GetImageVariant(request, filePath, file);
     }
-
-    private static async Task<object> GetImageVariant(GetVariant request, string filePath, FileInfo file)
+    
+    public static (int? width, int? height) GetVariantDimensions(string variant)
     {
-        var options = request.Variant.Split(',');
+        var options = variant.Split(',');
         int? width = null;
         int? height = null;
         foreach (var option in options)
@@ -190,7 +209,13 @@ private static async Task<object> GetImageVariant(GetVariant request, string fil
 
         if (width == null && height == null)
             throw new NotSupportedException("width or height is required");
+        
+        return (width, height);
+    }
 
+    private static async Task<object> GetImageVariant(GetVariant request, string filePath, FileInfo file)
+    {
+        var (width, height) = GetVariantDimensions(request.Variant);
         var variantPath = filePath.WithoutExtension();
         variantPath += (width != null && height != null
             ? $"_{width}w{height}h"