/// <summary>
/// Function to retrieve the horizontal and vertical offsets for the frames in a multi-frame image.
/// </summary>
/// <param name="stream">The stream containing the image data.</param>
/// <returns>A list of <c>Point</c> values that indicate the offset within the image for each frame.</returns>
/// <exception cref="ArgumentNullException">Thrown when the <paramref name="stream"/> parameter is <b>null</b>.</exception>
/// <exception cref="IOException">Thrown when the stream is write-only.
/// <para>-or-</para>
/// <para>Thrown when the stream cannot perform seek operations.</para>
/// </exception>
/// <exception cref="EndOfStreamException">Thrown when an attempt to read beyond the end of the stream is made.</exception>
/// <remarks>
/// <para>
/// For image codecs that support multiple frames, this reads a list of offset values for each frame so that the frame can be positioned correctly within the base image. If the image does not have
/// multiple frames, or the codec does not support multiple frames, then an empty list is returned.
/// </para>
/// </remarks>
public IReadOnlyList <DX.Point> GetFrameOffsets(Stream stream)
{
if (!SupportsMultipleFrames)
{
return(Array.Empty <DX.Point>());
}
var wic = new WicUtilities();
try
{
if ((FrameOffsetMetadataNames == null) || (FrameOffsetMetadataNames.Count == 0))
{
return(Array.Empty <DX.Point>());
}
IReadOnlyList <DX.Point> result = wic.GetFrameOffsetMetadata(stream, SupportedFileFormat, FrameOffsetMetadataNames);
if (result == null)
{
throw new IOException(string.Format(Resources.GORIMG_ERR_FILE_FORMAT_NOT_CORRECT, Codec));
}
return(result);
}
catch (DX.SharpDXException)
{
throw new IOException(string.Format(Resources.GORIMG_ERR_FILE_FORMAT_NOT_CORRECT, Codec));
}
finally
{
wic.Dispose();
}
}
