LDicomDS::GetPrevElement

#include "Ltdic.h"

pDICOMELEMENT LDicomDS::GetPrevElement(pElement, bTree, bVolatile)

Returns a pointer to the item in the Data Set that immediately precedes the specified item.

Returns

Comments

If the Data Set is evaluated as a tree structure, this function returns the previous item on the same level as pElement with the same parent as pElement. Please note that the numbering of the items in this illustration is arbitrary and does not imply order.

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 this illustration does indicate the order of the items when the Data Set is evaluated as a list.

The following functions will also help you navigate the Data Set as either a tree or a list:

LDicomDS::GetFirstElement

LDicomDS::GetLastElement

LDicomDS::GetNextElement

If you evaluate the Data Set as a tree, you can also use the following functions to navigate the tree:

LDicomDS::GetRootElement

LDicomDS::GetParentElement

LDicomDS::GetChildElement

A volatile element is an element that can be changed or destroyed in the process of inserting or setting an image. A non-volatile element is an element that must be changed manually. It is not changed or destroyed by inserting or setting an image.

For example, a grayscale image has elements TAG_SMALLEST_IMAGE_PIXEL_VALUE, TAG_LARGEST_IMAGE_PIXEL_VALUE, etc. If the image is changed to a color image, these elements disappear and the following elements appear: TAG_RED_PALETTE_COLOR_LOOKUP_TABLE_DESCRIPTOR, etc. These are volatile elements since they are changed or destroyed when an image is changed or set.

To retrieve a previous element that must be changed manually, i.e. is not volatile, set bVolatile to FALSE. To retrieve either volatile or non-volatile previous element, set bVolatile to TRUE.

Required DLLs and Libraries

Platforms

Win32, x64

L_INT LDicomDS_GetPrevElementExample(CListBox *pDlg) 
{ 
   LDicomDS*      pDS; 
   pDICOMELEMENT  pElement; 
   pDICOMTAG      pTag; 
   L_TCHAR        szUnknown[]=TEXT("Unknown"); 
   L_TCHAR*       p; 
   pDS = new LDicomDS(NULL); 
   pDS->InitDS( CLASS_XA_BIPLANE_IMAGE_STORAGE_RETIRED, 0); 
   pElement = pDS->GetLastElement(NULL, TRUE, FALSE); 
   while (pElement != NULL) 
   { 
      pTag = LDicomTag::Find(pElement->nTag); 
      if (pTag != NULL) 
      { 
         p = pTag->pszName; 
      } 
      else 
      { 
         p = szUnknown; 
      } 
      pDlg->AddString(p); 
      pElement = pDS->GetPrevElement(pElement, TRUE, FALSE); 
   } 
   delete pDS; 
   return DICOM_SUCCESS; 
}