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public DicomElement GetPreviousKey(
DicomElement element,
bool tree
)
public:
DicomElement^ GetPreviousKey(
DicomElement^ element,
bool tree
)
element
An item in the Data Set. The item in the Data Set that immediately precedes this item will be returned.
tree
true to evaluate the Data Set as a tree; false to evaluate the Data Set as a list.
The item in the Data Set that immediately precedes the item specified by element, or a null reference (Nothing in VB) if there is no item preceding element (element is the first item in the Data Set).
If the Data Set is evaluated as a tree structure, this method returns the previous item on the same level as element with the same parent as element. Please note that the numbering of the items in the following illustration is arbitrary and does not imply order.
If the passed object points to: | The method returns an object pointing to: |
---|---|
Item 1 | Item 2 |
Item 3 | Item 4 |
Item 5 | null |
Item 6 | Item 7 |
If the Data Set is evaluated as a list, the previous item in the list is returned. Please note that the numbering of the items in the following illustration does indicate the order of the items when the Data Set is evaluated as a list.
If the passed object points to: | The method returns an object pointing to: |
---|---|
Item 1 | null |
Item 15 | Item 14 |
Item 5 | Item 4 |
Item 9 | Item 8 |
Item 22 | Item 21 |
Item 25 | Item 24 |
The following methods will also help you navigate the Data Set as either a tree or a list:
If you evaluate the Data Set as a tree, you can also use the following methods to navigate the tree:
using Leadtools;
using Leadtools.Dicom;
public void DicomDIRSample()
{
//Make sure to initialize the DICOM engine, this needs to be done only once
DicomEngine.Startup();
using (DicomDataSet dicomDIR = new DicomDataSet())
{
dicomDIR.Reset();
//Initialize the dataset as a DICOMDIR class
dicomDIR.Initialize(DicomClassType.BasicDirectory, DicomDataSetInitializeType.ExplicitVRLittleEndian);
Debug.Assert(dicomDIR.InformationClass == DicomClassType.BasicDirectory);
Debug.Assert(dicomDIR.InformationFlags == (DicomDataSetFlags.ExplicitVR | DicomDataSetFlags.LittleEndian | DicomDataSetFlags.MetaHeaderPresent));
//Insert a patient level key
DicomElement patientKey = dicomDIR.InsertKey(null, DicomDirKeyType.Patient, true);
//Insert a study key under the patient key
DicomElement studyKey = dicomDIR.InsertKey(patientKey, DicomDirKeyType.Study, true);
//Now insert three series keys under the study key
DicomElement seriesKey = dicomDIR.InsertKey(studyKey, DicomDirKeyType.Series, true);
seriesKey = dicomDIR.InsertKey(studyKey, DicomDirKeyType.Series, true);
seriesKey = dicomDIR.InsertKey(studyKey, DicomDirKeyType.Series, true);
DicomElement key = dicomDIR.GetRootKey(seriesKey);
//Get the key value, You can also call GetKeyValuePtr
DicomDirKeyType keyValue = dicomDIR.GetKeyValue(key);
//The root key for the series key should be patient
Debug.Assert(keyValue == DicomDirKeyType.Patient, "The root key for the series key should be patient in this case");
//Get the parent key for the series, it should be study
key = dicomDIR.GetParentKey(seriesKey);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Study, "The parent key for the series key should be study in this case");
//The child for the study key should be series
key = dicomDIR.GetChildKey(studyKey);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Series, "The child for the study key should be series");
//The first key should be patient, if we traverse the DICOMDIR as a list
key = dicomDIR.GetFirstKey(studyKey, false);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Patient);
//The last key should be series, if we traverse the DICOMDIR as a list
key = dicomDIR.GetLastKey(studyKey, false);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Series);
//The key before the study key should be patient, if we traverse the DICOMDIR as a list
key = dicomDIR.GetPreviousKey(studyKey, false);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Patient);
//The key after the study key should be series, if we traverse the DICOMDIR as a list
key = dicomDIR.GetNextKey(studyKey, false);
keyValue = dicomDIR.GetKeyValue(key);
Debug.Assert(keyValue == DicomDirKeyType.Series);
//If we delete the study key, the series keys under it will get deleted too
dicomDIR.DeleteKey(studyKey);
key = dicomDIR.FindFirstKey(null, DicomDirKeyType.Series, false);
Debug.Assert(key == null);
key = dicomDIR.FindLastKey(null, DicomDirKeyType.Series, false);
Debug.Assert(key == null);
key = dicomDIR.FindPreviousKey(null, false);
Debug.Assert(key == null);
key = dicomDIR.FindNextKey(null, false);
Debug.Assert(key == null);
}
DicomEngine.Shutdown();
}
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