I.M Meen/Chill Manor Cmp Decoding Method

Cmp.cs

	public static Image<Rgba32> DecodeCmp(byte[] cmpData, byte[] originalPalette)
	{
		var width = BitConverter.ToUInt16(cmpData.Take(2).ToArray(), 0);
		var height = BitConverter.ToUInt16(cmpData.Skip(2).Take(2).ToArray(), 0);
		var firstNonTransparentRow = BitConverter.ToUInt16(cmpData.Skip(4).Take(2).ToArray(), 0);
		var lastNonTransparentRow = BitConverter.ToUInt16(cmpData.Skip(6).Take(2).ToArray(), 0);
		var firstNonTransparentColumn = BitConverter.ToUInt16(cmpData.Skip(8).Take(2).ToArray(), 0);
		var lastNonTransparentColumn = BitConverter.ToUInt16(cmpData.Skip(0xa).Take(2).ToArray(), 0);

		var colourCount = cmpData[0xc];
		var colourBytes = cmpData.Skip(0xd).Take(colourCount).ToArray();

		var cmpPaletteBytes = new byte[colourCount * 3];
		for (int i = 0; i < colourCount; i++)
		{
			var colour = colourBytes[i];
			var palIndex = colour * 3;
			cmpPaletteBytes[i * 3] = originalPalette[palIndex];
			cmpPaletteBytes[i * 3 + 1] = originalPalette[palIndex + 1];
			cmpPaletteBytes[i * 3 + 2] = originalPalette[palIndex + 2];
		}
		var offsetDataOffset = 0xd + colourCount;
		var offsetList = new List<ushort>();
		var offsetData = cmpData.Skip(offsetDataOffset).ToArray();

		var offset = BitConverter.ToUInt16(offsetData.Take(2).ToArray(), 0);
		offsetList.Add(offset);
		var currentPos = offsetDataOffset + 2;
		while (currentPos < offsetList[0])
		{
			offset = BitConverter.ToUInt16(cmpData.Skip(currentPos).Take(2).ToArray(), 0);
			offsetList.Add(offset);
			currentPos += 2;
		}

		var imageDataLines = new List<byte[]>();

		for (int i = 0; i < offsetList.Count; i++)
		{
			var start = offsetList[i];
			var end = i == offsetList.Count - 1 ? cmpData.Length : offsetList[i + 1];
			var line = cmpData.Skip(start).Take(end - start).ToArray();
			imageDataLines.Add(line);
		}

		var imageLines = new List<byte[]>();
		if (firstNonTransparentRow > 0)
		{
			for (int i = 0; i < firstNonTransparentRow; i++)
			{
				var lineData = Enumerable.Repeat((byte)0x0, width).ToArray();
				imageLines.Add(lineData);
			}
		}
		foreach (var line in imageDataLines)
		{
			var lineData = new byte[width];
			var lineIndex = 0;
			for (int i = 0; i < line.Length; i++)
			{
				if (lineIndex >= lineData.Length - 1)
				{
					break;
				}
				var b = line[i];
				if ((b & 0x80) == 0x80)
				{
					var count = b & 0x7F;
					for (int j = 0; j < count && lineIndex < lineData.Length; j++)
					{
						lineData[lineIndex] = 0x0;
						lineIndex++;
					}
				}
				else
				{
					lineData[lineIndex] = b;
					lineIndex++;
				}
			}
			imageLines.Add(lineData);
		}
		if (lastNonTransparentRow < height - 1)
		{
			for (int i = lastNonTransparentRow; i < height - 1; i++)
			{
				var lineData = Enumerable.Repeat((byte)0x0, width).ToArray();
				imageLines.Add(lineData);
			}
		}
		var imageData = imageLines.SelectMany(x => x).ToArray();
		var image = new Image<Rgba32>(width, height);
		for (int y = 0; y < height; y++)
		{
			for (int x = 0; x < width; x++)
			{
				var i = y * width + x;
				var paletteIndex = imageData[i];
				Color color;
				if (paletteIndex < cmpPaletteBytes.Length / 3)
				{
					color = Color.FromRgb(cmpPaletteBytes[paletteIndex * 3], cmpPaletteBytes[paletteIndex * 3 + 1], cmpPaletteBytes[paletteIndex * 3 + 2]);
				}
				else
				{
					color = Color.Transparent;
				}
				image[x, y] = color;
			}
		}
		return image;
	}