/// <summary>
/// Function to write out the DDS header to the stream.
/// </summary>
/// <param name="settings">Meta data for the image header.</param>
/// <param name="conversionFlags">Flags required for image conversion.</param>
/// <returns>A TGA header value, populated with the correct settings.</returns>
private TgaHeader GetHeader(IGorgonImageInfo settings, out TGAConversionFlags conversionFlags)
{
TgaHeader header = default;
conversionFlags = TGAConversionFlags.None;
if ((settings.Width > 0xFFFF) ||
(settings.Height > 0xFFFF))
{
throw new IOException(string.Format(Resources.GORIMG_ERR_FILE_FORMAT_NOT_CORRECT, Codec));
}
header.Width = (ushort)(settings.Width);
header.Height = (ushort)(settings.Height);
switch (settings.Format)
{
case BufferFormat.R8G8B8A8_UNorm:
case BufferFormat.R8G8B8A8_UNorm_SRgb:
header.ImageType = TgaImageType.TrueColor;
header.BPP = 32;
header.Descriptor = TgaDescriptor.InvertY | TgaDescriptor.RGB888A8;
conversionFlags |= TGAConversionFlags.Swizzle;
break;
case BufferFormat.B8G8R8A8_UNorm:
case BufferFormat.B8G8R8A8_UNorm_SRgb:
header.ImageType = TgaImageType.TrueColor;
header.BPP = 32;
header.Descriptor = TgaDescriptor.InvertY | TgaDescriptor.RGB888A8;
break;
case BufferFormat.B8G8R8X8_UNorm:
case BufferFormat.B8G8R8X8_UNorm_SRgb:
header.ImageType = TgaImageType.TrueColor;
header.BPP = 24;
header.Descriptor = TgaDescriptor.InvertY;
conversionFlags |= TGAConversionFlags.RGB888;
break;
case BufferFormat.R8_UNorm:
case BufferFormat.A8_UNorm:
header.ImageType = TgaImageType.BlackAndWhite;
header.BPP = 8;
header.Descriptor = TgaDescriptor.InvertY;
break;
case BufferFormat.B5G5R5A1_UNorm:
header.ImageType = TgaImageType.TrueColor;
header.BPP = 16;
header.Descriptor = TgaDescriptor.InvertY | TgaDescriptor.RGB555A1;
break;
default:
throw new IOException(string.Format(Resources.GORIMG_ERR_FORMAT_NOT_SUPPORTED, settings.Format));
}
// Persist to stream.
return(header);
}
/// <summary>
/// Function to persist a <see cref="IGorgonImage"/> to a stream.
/// </summary>
/// <param name="imageData">A <see cref="IGorgonImage"/> to persist to the stream.</param>
/// <param name="stream">The stream that will receive the image data.</param>
/// <exception cref="ArgumentNullException">Thrown when the <paramref name="stream"/>, or the <paramref name="imageData"/> parameter is <b>null</b>.</exception>
/// <exception cref="ArgumentEmptyException">Thrown when the <paramref name="stream"/> is read only.</exception>
/// <exception cref="NotSupportedException">Thrown when the image data in the stream has a pixel format that is unsupported by the codec.</exception>
/// <remarks>
/// <para>
/// When persisting image data via a codec, the image must have a format that the codec can recognize. This list of supported formats is provided by the <see cref="SupportedPixelFormats"/>
/// property. Applications may convert their image data a supported format before saving the data using a codec.
/// </para>
/// </remarks>
public override void SaveToStream(IGorgonImage imageData, Stream stream)
{
// Ensure that we can actually read this format. We do not perform total pixel conversion on behalf of the user, they are responsible for that.
// We will, however, support swizzling and pixel compression (e.g. 32 -> 24 bit).
if (Array.IndexOf(_supportedFormats, imageData.Format) == -1)
{
throw new NotSupportedException(string.Format(Resources.GORIMG_ERR_FORMAT_NOT_SUPPORTED, imageData.Format));
}
using (var writer = new GorgonBinaryWriter(stream, true))
{
// Write the header for the file before we dump the file contents.
TgaHeader header = GetHeader(imageData, out TGAConversionFlags conversionFlags);
GorgonPitchLayout destPitch;
if ((conversionFlags & TGAConversionFlags.RGB888) == TGAConversionFlags.RGB888)
{
destPitch = new GorgonPitchLayout(imageData.Width * 3, imageData.Width * 3 * imageData.Height);
}
else
{
var formatInfo = new GorgonFormatInfo(imageData.Format);
destPitch = formatInfo.GetPitchForFormat(imageData.Width, imageData.Height);
}
GorgonPitchLayout srcPitch = imageData.Buffers[0].PitchInformation;
// If the two pitches are equal and we have no conversion requirements, then just write out the buffer.
if ((destPitch == srcPitch) && (conversionFlags == TGAConversionFlags.None))
{
writer.WriteValue(ref header);
writer.WriteRange(imageData.Buffers[0].Data, count: srcPitch.SlicePitch);
return;
}
unsafe
{
// Get the pointer to the first mip/array/depth level.
byte *srcPointer = (byte *)imageData.Buffers[0].Data;
var lineBuffer = new GorgonNativeBuffer <byte>(srcPitch.RowPitch);
try
{
// Persist the working buffer to the stream.
writer.WriteValue(ref header);
// Write out each scan line.
for (int y = 0; y < imageData.Height; y++)
{
byte *destPtr = (byte *)lineBuffer;
if ((conversionFlags & TGAConversionFlags.RGB888) == TGAConversionFlags.RGB888)
{
ImageUtilities.Compress24BPPScanLine(srcPointer,
srcPitch.RowPitch,
destPtr,
destPitch.RowPitch,
(conversionFlags & TGAConversionFlags.Swizzle) == TGAConversionFlags.Swizzle);
}
else if ((conversionFlags & TGAConversionFlags.Swizzle) == TGAConversionFlags.Swizzle)
{
ImageUtilities.SwizzleScanline(srcPointer, srcPitch.RowPitch, destPtr, destPitch.RowPitch, imageData.Format, ImageBitFlags.None);
}
else
{
ImageUtilities.CopyScanline(srcPointer, srcPitch.RowPitch, destPtr, destPitch.RowPitch, imageData.Format, ImageBitFlags.None);
}
srcPointer += srcPitch.RowPitch;
writer.WriteRange(lineBuffer, count: destPitch.RowPitch);
}
}
finally
{
lineBuffer?.Dispose();
}
}
}
}
/// <summary>
/// Function to read in the TGA header from a stream.
/// </summary>
/// <param name="reader">The reader used to read the stream containing the data.</param>
/// <param name="conversionFlags">Flags for conversion.</param>
/// <returns>New image settings.</returns>
private static IGorgonImageInfo ReadHeader(GorgonBinaryReader reader, out TGAConversionFlags conversionFlags)
{
conversionFlags = TGAConversionFlags.None;
// Get the header for the file.
TgaHeader header = reader.ReadValue <TgaHeader>();
if ((header.ColorMapType != 0) || (header.ColorMapLength != 0) ||
(header.Width <= 0) || (header.Height <= 0) ||
((header.Descriptor & TgaDescriptor.Interleaved2Way) == TgaDescriptor.Interleaved2Way) ||
((header.Descriptor & TgaDescriptor.Interleaved4Way) == TgaDescriptor.Interleaved4Way))
{
throw new NotSupportedException(Resources.GORIMG_ERR_TGA_TYPE_NOT_SUPPORTED);
}
BufferFormat pixelFormat = BufferFormat.Unknown;
switch (header.ImageType)
{
case TgaImageType.TrueColor:
case TgaImageType.TrueColorRLE:
switch (header.BPP)
{
case 16:
pixelFormat = BufferFormat.B5G5R5A1_UNorm;
break;
case 24:
case 32:
pixelFormat = BufferFormat.R8G8B8A8_UNorm;
if (header.BPP == 24)
{
conversionFlags |= TGAConversionFlags.Expand;
}
break;
}
if (header.ImageType == TgaImageType.TrueColorRLE)
{
conversionFlags |= TGAConversionFlags.RLE;
}
break;
case TgaImageType.BlackAndWhite:
case TgaImageType.BlackAndWhiteRLE:
if (header.BPP == 8)
{
pixelFormat = BufferFormat.R8_UNorm;
}
else
{
throw new IOException(string.Format(Resources.GORIMG_ERR_FORMAT_NOT_SUPPORTED, header.ImageType));
}
if (header.ImageType == TgaImageType.BlackAndWhiteRLE)
{
conversionFlags |= TGAConversionFlags.RLE;
}
break;
default:
throw new IOException(string.Format(Resources.GORIMG_ERR_FORMAT_NOT_SUPPORTED, header.ImageType));
}
var settings = new GorgonImageInfo(ImageType.Image2D, pixelFormat)
{
MipCount = 1,
ArrayCount = 1,
Width = header.Width,
Height = header.Height
};
if ((header.Descriptor & TgaDescriptor.InvertX) == TgaDescriptor.InvertX)
{
conversionFlags |= TGAConversionFlags.InvertX;
}
if ((header.Descriptor & TgaDescriptor.InvertY) == TgaDescriptor.InvertY)
{
conversionFlags |= TGAConversionFlags.InvertY;
}
if (header.IDLength <= 0)
{
return(settings);
}
// Skip these bytes.
for (int i = 0; i < header.IDLength; i++)
{
reader.ReadByte();
}
return(settings);
}
