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using System;
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using System.IO;
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namespace Oni.Imaging
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{
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internal class TgaHeader
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{
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#region Private data
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private bool hasColorMap;
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private TgaImageType imageType;
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private int colorMapIndex;
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private int colorMapLength;
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private int colorMapEntrySize;
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private int width;
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private int height;
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private int pixelDepth;
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private int imageDescriptor;
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private bool xFlip;
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private bool yFlip;
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private bool hasAlpha;
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#endregion
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public TgaImageType ImageType => imageType;
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public int Width => width;
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public int Height => height;
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public int PixelSize => pixelDepth / 8;
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public bool XFlip => xFlip;
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public bool YFlip => yFlip;
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public static TgaHeader Read(BinaryReader reader)
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{
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int idLength = reader.ReadByte();
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var header = new TgaHeader();
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header.hasColorMap = (reader.ReadByte() != 0);
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header.imageType = (TgaImageType)reader.ReadByte();
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header.colorMapIndex = reader.ReadUInt16();
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header.colorMapLength = reader.ReadUInt16();
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header.colorMapEntrySize = reader.ReadByte();
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reader.ReadUInt16(); // x origin
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reader.ReadUInt16(); // y origin
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header.width = reader.ReadUInt16();
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header.height = reader.ReadUInt16();
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header.pixelDepth = reader.ReadByte();
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header.imageDescriptor = reader.ReadByte();
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if (!Enum.IsDefined(typeof(TgaImageType), header.ImageType) || header.ImageType == TgaImageType.None)
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throw new NotSupportedException(string.Format("Unsupported TGA image type {0}", header.ImageType));
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if (header.Width == 0 || header.Height == 0)
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throw new InvalidDataException("Invalid TGA file");
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if (header.ImageType == TgaImageType.TrueColor
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&& (header.pixelDepth != 16
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&& header.pixelDepth != 24
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&& header.pixelDepth != 32))
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{
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throw new InvalidDataException(string.Format("Invalid true color pixel depth {0}", header.pixelDepth));
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}
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if (header.hasColorMap)
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{
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if (header.colorMapEntrySize != 16
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&& header.colorMapEntrySize != 24
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&& header.colorMapEntrySize != 32)
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{
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throw new InvalidDataException(string.Format("Invalid color map entry size {0}", header.colorMapEntrySize));
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}
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if (header.ImageType != TgaImageType.ColorMapped
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&& header.ImageType != TgaImageType.RleColorMapped)
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{
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//
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// We have a color map but the image type does not use it so we'll just skip it.
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//
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reader.Position += header.colorMapLength * header.colorMapEntrySize / 8;
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}
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}
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//
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// Skip the identification field because we don't need it.
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//
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reader.Position += idLength;
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if (header.pixelDepth == 32)
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header.hasAlpha = ((header.imageDescriptor & 0x0f) == 8);
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else if (header.pixelDepth == 16)
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header.hasAlpha = ((header.imageDescriptor & 0x0f) == 1);
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else
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header.hasAlpha = false;
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header.xFlip = ((header.imageDescriptor & 16) == 16);
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header.yFlip = ((header.imageDescriptor & 32) == 32);
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return header;
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}
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public static TgaHeader Create(int width, int height, TgaImageType imageType)
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{
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return new TgaHeader {
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imageType = imageType,
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width = width,
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height = height,
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pixelDepth = 32,
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imageDescriptor = 8
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};
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}
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public void Write(BinaryWriter writer)
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{
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writer.Write((byte)0);
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writer.Write((byte)(hasColorMap ? 1 : 0));
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writer.Write((byte)imageType);
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writer.Write((ushort)colorMapIndex);
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writer.Write((ushort)colorMapLength);
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writer.Write((byte)colorMapEntrySize);
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writer.Write((ushort)0);
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writer.Write((ushort)0);
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writer.Write((ushort)width);
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writer.Write((ushort)height);
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writer.Write((byte)pixelDepth);
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writer.Write((byte)imageDescriptor);
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}
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public SurfaceFormat GetSurfaceFormat()
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{
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switch (pixelDepth)
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{
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case 16:
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return hasAlpha ? SurfaceFormat.BGRA5551 : SurfaceFormat.BGRX5551;
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case 24:
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return SurfaceFormat.BGRX;
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default:
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case 32:
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return hasAlpha ? SurfaceFormat.BGRA : SurfaceFormat.BGRX;
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}
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}
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public Color GetPixel(byte[] src, int srcOffset)
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{
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switch (pixelDepth)
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{
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case 16:
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if (hasAlpha)
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return Color.ReadBgra5551(src, srcOffset);
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else
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return Color.ReadBgrx5551(src, srcOffset);
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case 24:
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return Color.ReadBgrx(src, srcOffset);
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default:
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case 32:
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if (hasAlpha)
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return Color.ReadBgra(src, srcOffset);
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else
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return Color.ReadBgrx(src, srcOffset);
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}
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}
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}
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}
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