optimization request http

System.Common.CoreLib/Net/Http/HttpPlatformHelper.cs

@@ -1,4 +1,5 @@
 using System.IO;
+using System.IO.FileFormats;
 
 namespace System.Net.Http
 {
@@ -9,6 +10,17 @@ namespace System.Net.Http
 
         public virtual string UserAgent => DefaultUserAgent;
 
+        public virtual string AcceptImages => "image/png, image/*; q=0.8";
+
+        static readonly Lazy<ImageFormat[]> mSupportedImageFormats = new(() => new ImageFormat[]
+        {
+            ImageFormat.JPEG,
+            ImageFormat.PNG,
+            ImageFormat.GIF,
+        });
+
+        public virtual ImageFormat[] SupportedImageFormats => mSupportedImageFormats.Value;
+
         public (string filePath, string mime)? TryHandleUploadFile(Stream fileStream) => null;
     }
 }