LDicomDS::FindFirstDescendant

#include "Ltdic.h"

pDICOMELEMENT LDicomDS::FindFirstDescendant(pParent, nTag, bNextLevelOnly)

pDICOMELEMENT pParent;	pointer to a parent DICOMELEMENT structure
L_UINT32 nTag;	tag that indicates the element to find
L_BOOL bNextLevelOnly;	flag that indicates how to evaluate the Data Set

Returns a pointer to the first descendant of pParent with the specified tag.

Parameter	Description
pParent	Pointer to a parent DICOMELEMENT structure within the Data Set.
nTag	Tag that specifies the item to find. For a list of default tag values, refer to Data Element Tag Constants.
bNextLevelOnly	Flag that indicates how the Data Set will be evaluated. Possible values are:
	Value	Meaning
	TRUE	Search for items in the next level only.
	FALSE	Search for items recursively in all the next levels.

Returns

!NULL	A pointer to a DICOMELEMENT structure that contains the first item in the Data Set with the specified tag.
NULL	An item with the specified tag was not found.

Comments

This function finds the first descendant of the Parent element (i.e. pParent) that has a DICOM tag equivalent to the nTag argument.

The diagram below represents DICOM elements stored in a DICOM dataset.

Behavior when bNextLevelOnly is TRUE:

Returns the first item on the next level of pParent with that has tag equivalent to nTag. Elements included in the search include child elements in the next level only.

Example 1

bNextLevelOnly TRUE

pParent points to element 1

Searches elements 2, 8, 11, 12 and returns the first element that has a tag of nTag.

Example 2

bNextLevelOnly TRUE

pParent points to element 2

Searches elements 3, 4, 7 and returns the first element that has a tag of nTag.

Example 3

bNextLevelOnly TRUE

pParent points to element 4

Searches nodes 5, 6 and returns the first element that has a tag of nTag.

Example 4

bNextLevelOnly TRUE

pParent points to element 11

Returns NULL.

Behavior when bNextLevelOnly is FALSE:

Returns the first item that has tag equivalent to nTag using a pre-order search algorithm rooted at pParent.

Example 5

bNextLevelOnly FALSE

pParent points to element 1

Searches elements 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and returns the first element that has a tag of nTag.

Example 6

bNextLevelOnly FALSE

pParent points to element 2

Searches elements 3, 4, 5, 6, 7 and returns the first element that has a tag of nTag.

Example 7

bNextLevelOnly FALSE

pParent points to element 4

Searches elements 5, 6 and returns the first element that has a tag of nTag.

The following functions will also help you find elements in the Data Set with a specific tag:

LDicomDS::FindLastElement

LDicomDS::FindPrevElement

LDicomDS::FindNextElement

LDicomDS::FindFirstElement

LDicomDS::FindFirstDescendant

The following functions will help you find specific modules in the Data Set:

LDicomDS::FindModule

LDicomDS::FindIndexModule

Required DLLs and Libraries

LTDIC

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application

Platforms

Win32, x64

Example

This example displays searches for TAG_CODE_VALUE values in 'image1.dcm' using the FindFirstDescendant() and FindNextDescendant() methods.

#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName 
L_VOID DisplayElementValue(LDicomDS &ds, pDICOMELEMENT pElement) 
{ 
   if (pElement != NULL) 
   { 
      L_TCHAR szMsg[200] = {0}; 
      L_TCHAR *szValue = ds.GetStringValue(pElement, 0, 1); 
      wsprintf(szMsg, TEXT("*** %s\n"), szValue); 
      OutputDebugString(szMsg); 
   } 
} 
L_INT LDicomDS_FindFirstDescendantExample() 
{ 
   L_TCHAR *pszFile = MAKE_IMAGE_PATH(TEXT("image1.dcm")); 
   LDicomDS ds; 
   L_UINT16 uRet = ds.LoadDS(pszFile, 0); 
   assert(uRet == DICOM_SUCCESS); 
   // Example 1: 
   // Find all occurrences of TAG_CODE_VALUE in the dataset, searching recursively 
   // Output should be: 
   //    T-A2000 
   //    F-10450 
   OutputDebugString(TEXT("Example 1\n")); 
   pDICOMELEMENT pElement = ds.FindFirstDescendant(NULL, TAG_CODE_VALUE, FALSE); 
   while (pElement != NULL) 
   { 
      DisplayElementValue(ds, pElement); 
      pElement = ds.FindNextDescendant(NULL, pElement, FALSE); 
   } 
   // For the next examples, we need the two parent sequences that contain the code items 
   pDICOMELEMENT pElementAnatomicRegionSequence = ds.FindFirstDescendant(NULL, TAG_ANATOMIC_REGION_SEQUENCE, TRUE); 
   pDICOMELEMENT pElementPatientOrientationCodeSequence = ds.FindFirstDescendant(NULL, TAG_PATIENT_ORIENTATION_CODE_SEQUENCE, TRUE); 
   assert(pElementAnatomicRegionSequence != NULL); 
   assert(pElementPatientOrientationCodeSequence != NULL); 
   // Example 2: 
   // Find all occurrences of TAG_CODE_VALUE with (0028,2218) Anatomic Region Sequence as pParent 
   // Search only the next level 
   // Output should be empty, because TAG_CODE_VALUE are not at next level 
   OutputDebugString(TEXT("Example 2\n")); 
   pElement = ds.FindFirstDescendant(pElementAnatomicRegionSequence, TAG_CODE_VALUE, TRUE); 
   while (pElement != NULL) 
   { 
      DisplayElementValue(ds, pElement); 
      pElement = ds.FindNextDescendant(pElementAnatomicRegionSequence, pElement, TRUE); 
   } 
   // Example 3: 
   // Find all occurrences of TAG_CODE_VALUE with (0028,2218) Anatomic Region Sequence as pParent 
   // Search recursively 
   // Output should be 
   //    T-A2000 
   OutputDebugString(TEXT("Example 3\n")); 
   pElement = ds.FindFirstDescendant(pElementAnatomicRegionSequence, TAG_CODE_VALUE, FALSE); 
   while (pElement != NULL) 
   { 
      DisplayElementValue(ds, pElement); 
      pElement = ds.FindNextDescendant(pElementAnatomicRegionSequence, pElement, FALSE); 
   } 
   // Example 4: 
   // Find all occurrences of TAG_CODE_VALUE with (0028,2218) Anatomic Region Sequence as pParent 
   // Search recursively 
   // Output should be 
   //    F-10450 
   OutputDebugString(TEXT("Example 4\n")); 
   pElement = ds.FindFirstDescendant(pElementPatientOrientationCodeSequence, TAG_CODE_VALUE, FALSE); 
   while (pElement != NULL) 
   { 
      DisplayElementValue(ds, pElement); 
      pElement = ds.FindNextDescendant(pElementPatientOrientationCodeSequence, pElement, FALSE); 
   } 
   OutputDebugString(TEXT("Finished")); 
   return DICOM_SUCCESS; 
}

Help Version 19.0.2017.10.27

Functions:	LDicomDS::FindLastElement, LDicomDS::FindPrevElement, LDicomDS::FindNextElement, LDicomDS::FindModule, LDicomDS::FindIndexModule, LDicomDS::FindNextDescendant
Topics:	Working with Data Sets
	How to Disable the Automatic Loading of the default DICOM IOD Table