From 73d9124d46745185a317e15cff69b4a5ec578e58 Mon Sep 17 00:00:00 2001
From: Loporrit <141286461+loporrit@users.noreply.github.com>
Date: Mon, 21 Jul 2025 16:52:08 +0000
Subject: [PATCH] Remove ImageSharp

---
 MareSynchronos/MareSynchronos.csproj |  1 -
 MareSynchronos/UI/EditProfileUi.cs   | 13 ++------
 MareSynchronos/Utils/PngHdr.cs       | 49 ++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 11 deletions(-)
 create mode 100644 MareSynchronos/Utils/PngHdr.cs

diff --git a/MareSynchronos/MareSynchronos.csproj b/MareSynchronos/MareSynchronos.csproj
index 658e1c6..859978a 100644
--- a/MareSynchronos/MareSynchronos.csproj
+++ b/MareSynchronos/MareSynchronos.csproj
@@ -23,7 +23,6 @@
     <PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="9.0.3" />
     <PackageReference Include="Microsoft.AspNetCore.SignalR.Protocols.MessagePack" Version="9.0.3" />
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.3" />
-    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.7" />
     <PackageReference Include="SonarAnalyzer.CSharp" Version="10.7.0.110445">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
diff --git a/MareSynchronos/UI/EditProfileUi.cs b/MareSynchronos/UI/EditProfileUi.cs
index 3e65865..b3bf024 100644
--- a/MareSynchronos/UI/EditProfileUi.cs
+++ b/MareSynchronos/UI/EditProfileUi.cs
@@ -9,10 +9,9 @@ using MareSynchronos.API.Dto.User;
 using MareSynchronos.Services;
 using MareSynchronos.Services.Mediator;
 using MareSynchronos.Services.ServerConfiguration;
+using MareSynchronos.Utils;
 using MareSynchronos.WebAPI;
 using Microsoft.Extensions.Logging;
-using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.PixelFormats;
 
 namespace MareSynchronos.UI;
 
@@ -149,15 +148,9 @@ public class EditProfileUi : WindowMediatorSubscriberBase
                 {
                     var fileContent = File.ReadAllBytes(file);
                     using MemoryStream ms = new(fileContent);
-                    var format = await Image.DetectFormatAsync(ms).ConfigureAwait(false);
-                    if (!format.FileExtensions.Contains("png", StringComparer.OrdinalIgnoreCase))
-                    {
-                        _showFileDialogError = true;
-                        return;
-                    }
-                    using var image = Image.Load<Rgba32>(fileContent);
+                    var format = PngHdr.TryExtractDimensions(ms);
 
-                    if (image.Width > 256 || image.Height > 256 || (fileContent.Length > 250 * 1024))
+                    if (format.Width > 256 || format.Height > 256 || (fileContent.Length > 250 * 1024))
                     {
                         _showFileDialogError = true;
                         return;
diff --git a/MareSynchronos/Utils/PngHdr.cs b/MareSynchronos/Utils/PngHdr.cs
new file mode 100644
index 0000000..5723f5a
--- /dev/null
+++ b/MareSynchronos/Utils/PngHdr.cs
@@ -0,0 +1,49 @@
+namespace MareSynchronos.Utils;
+
+public class PngHdr
+{
+	private static readonly byte[] _magicSignature = [137, 80, 78, 71, 13, 10, 26, 10];
+	private static readonly byte[] _IHDR = [(byte)'I', (byte)'H', (byte)'D', (byte)'R'];
+	public static readonly (int Width, int Height) InvalidSize = (0, 0);
+
+	public static (int Width, int Height) TryExtractDimensions(Stream stream)
+	{
+		Span<byte> buffer = stackalloc byte[8];
+
+		try
+		{
+			stream.ReadExactly(buffer[..8]);
+
+			// All PNG files start with the same 8 bytes
+			if (!buffer.SequenceEqual(_magicSignature))
+				return InvalidSize;
+
+			stream.ReadExactly(buffer[..8]);
+
+			uint ihdrLength = BitConverter.ToUInt32(buffer);
+
+			// The next four bytes will be the length of the IHDR section (it should be 13 bytes but we only need 8)
+			if (ihdrLength < 8)
+				return InvalidSize;
+
+			// followed by ASCII "IHDR"
+			if (!buffer[4..].SequenceEqual(_IHDR))
+				return InvalidSize;
+
+			stream.ReadExactly(buffer[..8]);
+
+			uint width = BitConverter.ToUInt32(buffer);
+			uint height = BitConverter.ToUInt32(buffer[4..]);
+
+			// Validate the width/height are non-negative and... that's all we care about!
+			if (width > int.MaxValue || height > int.MaxValue)
+				return InvalidSize;
+
+			return ((int)width, (int)height);
+		}
+		catch (EndOfStreamException)
+		{
+			return InvalidSize;
+		}
+	}
+}