Add .GIF image loading using ImageSharp

Thief Mission Viewer.csproj

@@ -8,5 +8,6 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="rectpacksharp" Version="1.2.0" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.5" />
   </ItemGroup>
 </Project>

project/code/TMV/TextureLoader.Gif.cs

@@ -0,0 +1,29 @@
+using Godot;
+using SixLabors.ImageSharp.PixelFormats;
+
+namespace KeepersCompound.TMV;
+
+public partial class TextureLoader
+{
+    // TODO: Replace this with my own implementation lol
+    // References:
+    // - https://www.w3.org/Graphics/GIF/spec-gif89a.txt
+    private static ImageTexture LoadGif(string path)
+    {
+        using var gifImage = SixLabors.ImageSharp.Image.Load<Rgba32>(path);
+
+        var width = gifImage.Width;
+        var height = gifImage.Height;
+        var image = Image.Create(width, height, false, Image.Format.Rgba8);
+        for (var y = 0; y < height; y++)
+        {
+            for (var x = 0; x < width; x++)
+            {
+                var pixel = gifImage[x, y].ToVector4();
+                image.SetPixel(x, y, new Color(pixel.X, pixel.Y, pixel.Z, pixel.W));
+            }
+        }
+
+        return ImageTexture.CreateFromImage(image);
+    }
+}

project/code/TMV/TextureLoader.cs

@@ -98,12 +98,13 @@ public partial class TextureLoader
         return loaded;
     }
 
-    private static ImageTexture LoadTexture(string path)
+    public static ImageTexture LoadTexture(string path)
     {
         var ext = path.GetExtension().ToLower();
         var texture = ext switch
         {
             "pcx" => LoadPcx(path),
+            "gif" => LoadGif(path),
             _ => ImageTexture.CreateFromImage(Image.LoadFromFile(path)),
         };
         return texture;