Add PCX image loading

project/code/TMV/TextureLoader.Pcx.cs

@@ -0,0 +1,108 @@
+using System.IO;
+using System.Linq;
+using System.Numerics;
+using System.Text;
+
+namespace KeepersCompound.TMV;
+
+public partial class TextureLoader
+{
+    // TODO: Support more types of PCX just in case
+    // TODO: We need to load the palette from an external file!!!
+
+    // References:
+    // - https://www.fileformat.info/format/pcx/egff.htm
+    // - http://www.fysnet.net/pcxfile.htm
+    private static Godot.ImageTexture LoadPcx(string path)
+    {
+        using MemoryStream stream = new(File.ReadAllBytes(path));
+        using BinaryReader reader = new(stream, Encoding.UTF8, false);
+
+        // Header
+        var tag = reader.ReadByte();
+        var version = reader.ReadByte();
+        var compression = reader.ReadByte();
+        var bytesPerPixel = reader.ReadByte();
+        var min = new Vector2(reader.ReadUInt16(), reader.ReadUInt16());
+        var max = new Vector2(reader.ReadUInt16(), reader.ReadUInt16());
+        var dpi = new Vector2(reader.ReadUInt16(), reader.ReadUInt16());
+        var headerPalette = reader.ReadBytes(48);
+        reader.ReadByte();
+        var numPlanes = reader.ReadByte();
+        var bytesPerRow = reader.ReadUInt16();
+        var paletteMode = reader.ReadUInt16();
+        var dpiSrc = new Vector2(reader.ReadUInt16(), reader.ReadUInt16());
+        reader.ReadBytes(54);
+        var dataOffset = stream.Position;
+
+        // Validation
+        if (tag != 0x0A)
+        {
+            throw new System.Exception("Invalid tag");
+        }
+        var validVersions = new int[] { 0, 2, 3, 4, 5 };
+        if (!validVersions.Contains(version))
+        {
+            throw new System.Exception("Unsupported version");
+        }
+        if (compression != 1)
+        {
+            throw new System.Exception("Unsupported compression mode");
+        }
+        if (bytesPerPixel != 8 || numPlanes != 1)
+        {
+            throw new System.Exception("Unsupported bpp/plane format");
+        }
+
+        var palette = LoadPcxPalette(reader);
+
+        // Read pixels
+        stream.Seek(dataOffset, SeekOrigin.Begin);
+        var width = (int)(max.X - min.X + 1);
+        var height = (int)(max.Y - min.Y + 1);
+        var image = Godot.Image.Create(width, height, false, Godot.Image.Format.Rgba8);
+        for (var y = 0; y < height; y++)
+        {
+            var x = 0;
+            while (x < bytesPerRow)
+            {
+                var b = reader.ReadByte();
+                if ((b & 0xc0) == 0xc0)
+                {
+                    var runLength = b & 0x3f;
+                    b = reader.ReadByte();
+                    for (var i = 0; i < runLength; i++)
+                    {
+                        image.SetPixel(x, y, palette[b]);
+                        x++;
+                    }
+                }
+                else
+                {
+                    image.SetPixel(x, y, palette[b]);
+                    x++;
+                }
+            }
+        }
+
+        return Godot.ImageTexture.CreateFromImage(image);
+    }
+
+    private static Godot.Color[] LoadPcxPalette(BinaryReader reader)
+    {
+        var numColors = 256;
+        var bytesPerColor = 3;
+        var paletteSize = numColors * bytesPerColor;
+        reader.BaseStream.Seek(-paletteSize, SeekOrigin.End);
+
+        var palette = new Godot.Color[numColors];
+        for (var i = 0; i < numColors; i++)
+        {
+            var r = reader.ReadByte() / 255.0f;
+            var g = reader.ReadByte() / 255.0f;
+            var b = reader.ReadByte() / 255.0f;
+            palette[i] = new Godot.Color(r, g, b);
+        }
+        return palette;
+    }
+}

project/code/TMV/TextureLoader.cs

@@ -5,7 +5,7 @@ using Godot;
 
 namespace KeepersCompound.TMV;
 
-public class TextureLoader
+public partial class TextureLoader
 {
     private readonly string _rootPath; // TODO: Load from installation resources
     private readonly string _fmPath;
@@ -60,17 +60,17 @@ public class TextureLoader
 
     public bool Load(int id, string path)
     {
-        var userTexturesPath = ProjectSettings.GlobalizePath($"user://textures{path}.png");
+        var userTexturesPath = ProjectSettings.GlobalizePath($"user://textures{path}.PCX");
 
         var loaded = false;
         if (_fmTexturePaths.TryGetValue(path.ToLower(), out var filePath))
         {
-            _textureCache.Add(ImageTexture.CreateFromImage(Image.LoadFromFile(filePath)));
+            _textureCache.Add(LoadTexture(filePath));
             loaded = true;
         }
         else if (File.Exists(userTexturesPath))
         {
-            _textureCache.Add(ImageTexture.CreateFromImage(Image.LoadFromFile(userTexturesPath)));
+            _textureCache.Add(LoadTexture(userTexturesPath));
             loaded = true;
         }
 
@@ -80,6 +80,17 @@ public class TextureLoader
         return loaded;
     }
 
+    private static ImageTexture LoadTexture(string path)
+    {
+        var ext = path.GetExtension().ToLower();
+        var texture = ext switch
+        {
+            "pcx" => LoadPcx(path),
+            _ => ImageTexture.CreateFromImage(Image.LoadFromFile(path)),
+        };
+        return texture;
+    }
+
     public ImageTexture Get(int id)
     {
         if (!_idMap.ContainsKey(id))