/// <summary>
/// Recalculates the group length element for the specified group. Removes the group length element if no elements exist for the specified group.
/// </summary>
/// <remarks>For most use cases, this method will be called by the library as needed and will not need to be called by the user.</remarks>
/// <param name="dataset">DICOM dataset</param>
/// <param name="group">DICOM tag group</param>
/// <param name="createIfMissing">If set to <c>true</c>, the group length element will be created if missing. If set to <c>false</c>, the group length will only be calculated if the group length element exists.</param>
public static void RecalculateGroupLength(this DicomDataset dataset, ushort group, bool createIfMissing = true)
{
var items = dataset.GetGroup(group).ToList();
if (items.Count == 0)
{
// no items exist for the specified group; remove
dataset.Remove(new DicomTag(group, 0x0000));
return;
}
var calculator = new DicomWriteLengthCalculator(dataset.InternalTransferSyntax, DicomWriteOptions.Default);
uint length = calculator.Calculate(items);
dataset.Add(new DicomTag(group, 0x0000), length);
}
/// <summary>
/// Recalculates the group lengths for all groups in the <paramref name="dataset"/>. Removes any group lengths for groups with out elements.
/// </summary>
/// <remarks>For most use cases, this method will be called by the library as needed and will not need to be called by the user.</remarks>
/// <param name="dataset">DICOM dataset</param>
/// <param name="createIfMissing">If set to <c>true</c>, group length elements will be created if missing. If set to <c>false</c>, only groups with existing group lengths will be recalculated.</param>
public static void RecalculateGroupLengths(this DicomDataset dataset, bool createIfMissing = true)
{
// recalculate group lengths for sequences first
foreach (var sq in dataset.Where(x => x.ValueRepresentation == DicomVR.SQ).Cast <DicomSequence>())
{
foreach (var item in sq.Items)
{
item.RecalculateGroupLengths(createIfMissing);
}
}
var calculator = new DicomWriteLengthCalculator(dataset.InternalTransferSyntax, DicomWriteOptions.Default);
IEnumerable <ushort> groups = null;
if (createIfMissing)
{
groups = dataset.Select(x => x.Tag.Group).Distinct();
}
else
{
groups = dataset.Where(x => x.Tag.Element == 0x0000).Select(x => x.Tag.Group);
}
foreach (var group in groups.ToList())
{
var items = dataset.GetGroup(group).ToList();
if (items.Count == 0)
{
// no items exist for the specified group; remove
dataset.Remove(new DicomTag(group, 0x0000));
return;
}
uint length = calculator.Calculate(items);
dataset.Add(new DicomTag(group, 0x0000), length);
}
}
