/// <summary>
/// Function to determine if this codec can read the file or not.
/// </summary>
/// <param name="stream">Stream used to read the file information.</param>
/// <returns>
/// TRUE if the codec can read the file, FALSE if not.
/// </returns>
/// <exception cref="System.IO.IOException">Thrown when the <paramref name="stream"/> is write-only or if the stream cannot perform seek operations.</exception>
/// <exception cref="System.IO.EndOfStreamException">Thrown when an attempt to read beyond the end of the stream is made.</exception>
public override bool IsReadable(Stream stream)
{
TGAHeader header;
long position = 0;
if (stream == null)
{
throw new ArgumentNullException("stream");
}
if (!stream.CanRead)
{
throw new IOException(Resources.GORGFX_STREAM_READ_ONLY);
}
if (!stream.CanSeek)
{
throw new IOException(Resources.GORGFX_STREAM_NO_SEEK);
}
if (stream.Length - stream.Position < DirectAccess.SizeOf <TGAHeader>())
{
return(false);
}
try
{
position = stream.Position;
var reader = new GorgonBinaryReader(stream, true);
header = reader.ReadValue <TGAHeader>();
}
finally
{
stream.Position = position;
}
if ((header.ColorMapType != 0) || (header.ColorMapLength != 0))
{
return(false);
}
if ((header.Descriptor & (TGADescriptor.Interleaved2Way | TGADescriptor.Interleaved4Way)) != 0)
{
return(false);
}
if ((header.Width <= 0) || (header.Height <= 0))
{
return(false);
}
if ((header.ImageType != TGAImageType.TrueColor) && (header.ImageType != TGAImageType.TrueColorRLE) &&
(header.ImageType != TGAImageType.BlackAndWhite) && (header.ImageType != TGAImageType.BlackAndWhiteRLE))
{
return(false);
}
return(((header.ImageType != TGAImageType.BlackAndWhite) && (header.ImageType != TGAImageType.BlackAndWhiteRLE)) ||
(header.BPP == 8));
}
/// <summary>
/// Initializes a new instance of the <see cref="GorgonChunkedFormat" /> class.
/// </summary>
/// <param name="stream">The stream to use to output the chunked data.</param>
/// <param name="accessMode">Stream access mode for the chunk object.</param>
/// <exception cref="System.ArgumentNullException">Thrown when the <paramref name="stream"/> parameter is NULL (Nothing in VB.Net).</exception>
/// <exception cref="System.ArgumentException">Thrown when the <paramref name="accessMode"/> parameter is set to read, but the stream cannot be read.
/// <para>-or-</para>
/// <para>Thrown when the accessMode parameter is set to write, but the stream cannot be written.</para>
/// <para>-or-</para>
/// <para>Thrown if the stream can't perform seek operations.</para>
/// </exception>
protected GorgonChunkedFormat(Stream stream, ChunkAccessMode accessMode)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
ChunkAccessMode = accessMode;
if (!stream.CanSeek)
{
throw new ArgumentException(Resources.GOR_STREAM_NOT_SEEKABLE, "stream");
}
if (accessMode == ChunkAccessMode.Write)
{
if (!stream.CanWrite)
{
throw new ArgumentException(Resources.GOR_STREAM_IS_READONLY, "accessMode");
}
Writer = new GorgonBinaryWriter(stream, true);
}
else
{
if (!stream.CanRead)
{
throw new ArgumentException(Resources.GOR_STREAM_IS_WRITEONLY, "accessMode");
}
Reader = new GorgonBinaryReader(stream, true);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="GorgonChunkedFormat" /> class.
/// </summary>
/// <param name="stream">The stream to use to output the chunked data.</param>
/// <param name="accessMode">Stream access mode for the chunk object.</param>
/// <exception cref="ArgumentNullException">Thrown when the <paramref name="stream"/> parameter is NULL (Nothing in VB.Net).</exception>
/// <exception cref="ArgumentException">Thrown when the <paramref name="accessMode"/> parameter is set to read, but the stream cannot be read.
/// <para>-or-</para>
/// <para>Thrown when the accessMode parameter is set to write, but the stream cannot be written.</para>
/// <para>-or-</para>
/// <para>Thrown if the stream can't perform seek operations.</para>
/// </exception>
protected GorgonChunkedFormat(Stream stream, ChunkAccessMode accessMode)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
ChunkAccessMode = accessMode;
if (!stream.CanSeek)
{
throw new ArgumentException(Resources.GOR2DIO_ERR_STREAM_UNSEEKABLE, nameof(stream));
}
if (accessMode == ChunkAccessMode.Write)
{
if (!stream.CanWrite)
{
throw new ArgumentException(Resources.GOR2DIO_ERR_STREAM_IS_READ_ONLY, nameof(accessMode));
}
Writer = new GorgonBinaryWriter(stream, true);
}
else
{
if (!stream.CanRead)
{
throw new ArgumentException(Resources.GOR2DIO_ERR_STREAM_IS_WRITE_ONLY, nameof(accessMode));
}
Reader = new GorgonBinaryReader(stream, true);
}
}
