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.

Parameters

pDICOMELEMENT pElement

Pointer to a DICOMELEMENTstructure that contains an item in the Data Set. A pointer to the item in the Data Set that immediately precedes this item will be returned.

L_BOOL bTree

Flag that indicates how the Data Set will be evaluated. Possible values are:

L_BOOL bVolatile

Flag that indicates the type of element to retrieve. Possible values are:

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.

NOTE: 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.

NOTE: 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

• 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

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; 
}