protected override Properties ExtractProperties()
{
int width = 0, height = 0;
IFDTag tag = GetTag(TagTypes.TiffIFD)
as IFDTag;
IFDStructure structure = tag.Structure;
var sub_ifds = structure.GetEntry(0, (ushort)IFDEntryTag.SubIFDs)
as SubIFDArrayEntry;
if (sub_ifds == null)
{
return(base.ExtractProperties());
}
foreach (var entry in sub_ifds.Entries)
{
var type = entry.GetLongValue(0, (ushort)IFDEntryTag.NewSubfileType);
if (type == 0)
{
width = (int)(entry.GetLongValue(0, (ushort)IFDEntryTag.ImageWidth) ?? 0);
height = (int)(entry.GetLongValue(0, (ushort)IFDEntryTag.ImageLength) ?? 0);
break;
}
}
if (width > 0 && height > 0)
{
return(new Properties(TimeSpan.Zero, CreateCodec(width, height)));
}
return(base.ExtractProperties());
}
/// <summary>
/// Attempts to extract the media properties of the main
/// photo.
/// </summary>
/// <returns>
/// A <see cref="Properties" /> object with a best effort guess
/// at the right values. When no guess at all can be made,
/// <see langword="null" /> is returned.
/// </returns>
protected override Properties ExtractProperties()
{
int width = 0, height = 0;
IFDTag tag = GetTag(TagTypes.TiffIFD) as IFDTag;
IFDStructure structure = tag.Structure;
// DNG uses SubIFDs for images, the one with SubfileType = 0 is the RAW data.
var sub_ifds = structure.GetEntry(0, (ushort)IFDEntryTag.SubIFDs) as SubIFDArrayEntry;
if (sub_ifds == null)
{
return(base.ExtractProperties());
}
foreach (var entry in sub_ifds.Entries)
{
var type = entry.GetLongValue(0, (ushort)IFDEntryTag.NewSubfileType);
if (type == 0)
{
width = (int)(entry.GetLongValue(0, (ushort)IFDEntryTag.ImageWidth) ?? 0);
height = (int)(entry.GetLongValue(0, (ushort)IFDEntryTag.ImageLength) ?? 0);
break; // No need to iterate the other SubIFDs
}
}
if (width > 0 && height > 0)
{
return(new Properties(TimeSpan.Zero, CreateCodec(width, height)));
}
// Fall back to normal detection.
return(base.ExtractProperties());
}