paint.net plugin for Nippon Ichi Software .tx2 images

TX2.cs

/* this is unfinished */

using System;
using System.Windows.Forms;
using PaintDotNet;
using System.Drawing;

public class TX2FileType : FileType {
	
	public TX2FileType() : base ("TX2", FileTypeFlags.SupportsLoading,
	                            new string[] { ".tx2" })
	{

	}

	private ushort ReadUShort(System.IO.Stream stream) {
		return (ushort)(stream.ReadByte() + (stream.ReadByte() << 8));
	}
	
	private uint ReadUInt(System.IO.Stream stream) {
		return (uint)(stream.ReadByte() + (stream.ReadByte() << 8) + (stream.ReadByte() << 16) + (stream.ReadByte() << 24));
	}
	
	protected override Document OnLoad(System.IO.Stream input) {
		
		ushort width = ReadUShort(input);
		ushort height = ReadUShort(input);
		
		if (width * height == 0) {
			MessageBox.Show("Invalid image dimensions.");
			return null;
		}
		
		ushort colors = ReadUShort(input);   /* only values 16 and 256 have been observed */
		
		if (colors != 16 && colors != 256) {
			MessageBox.Show("Unsupported color depth. Image must be either 16 or 256 colors.");
			return null;
		}
		
		ushort unknown = ReadUShort(input);
		ushort colors2 = ReadUShort(input);  /* purpose unknown, but always seems to be the same as colors */
		ushort palettes = ReadUShort(input); /* number of palettes.  only 1 and 16 observed thus far */
		
		if (palettes > 1) {
			MessageBox.Show("Image contains multiple palettes. Only the first palette will be used for now.");
		} else if (palettes == 0) {
			MessageBox.Show("Image must contain at least one palette.");
			return null;
		}
		
		// TODO: this assumes a max of 16 palettes and 256 colors
		var palette = new Color[16, 256];
		// TODO: use multiple bitmaps (one per palette)
		// TODO: use actual paletted bitmaps? (does paint.NET care about this?)
		var bitmap = new Bitmap(width, height);
		
		// read all palettes 
		input.Seek(0x10, System.IO.SeekOrigin.Begin);
		
		for (uint p = 0; p < palettes; p++) {
			for (uint c = 0; c < colors; c++) {
				uint ci = c;
				
				// 256 color images have some weird bit switching going on for color indexes
				if (colors == 256) {
					ci = (c & 0xE7) | ((c & 8) << 1) | ((c & 16) >> 1);
				}
				
				uint color = ReadUInt(input);
				
				// non-transparent images use 0x80 for all alpha bytes
				// TODO: verify this with images which use transparency as well
				var colorA = (int)((color & 0xFF000000) >> 23);
				if (colorA > 255) colorA = 255;
				
				var colorB = (int)((color & 0xFF0000) >> 16);
				var colorG = (int)((color & 0xFF00) >> 8);
				var colorR = (int)(color & 0xFF);
				
				palette[p, ci] = Color.FromArgb(colorA, colorR, colorG, colorB);
			}
		}
		
		// read actual bitmap data now
		// NOTE: this assumes (possibly incorrectly) that the image width is an even number
		// TODO: swizzle pixels if needed
		for (int y = 0; y < height; y++) {
			for (int x = 0; x < width; x++) {
				byte px1, px2;
				
				// get next two pixels
				if (colors == 256) {
					px1 = (byte)input.ReadByte();
					px2 = (byte)input.ReadByte();
				} else {
					var b = input.ReadByte();
					px1 = (byte)(b & 0xf);
					px2 = (byte)(b >> 4);
				}
				
				// TODO: support all palettes, not just the first
				bitmap.SetPixel(x, y, palette[0, px1]);
				x++;
				bitmap.SetPixel(x, y, palette[0, px2]);
			}
		}
		
		return Document.FromImage(bitmap);
	}
}

public class TX2FileTypeFactory : IFileTypeFactory {
	
	public FileType[] GetFileTypeInstances() {
		return new FileType[] { new TX2FileType() };
	}
}