#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.
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.
Flag that indicates how the Data Set will be evaluated. Possible values are:
Value | Meaning |
---|---|
TRUE | Evaluate the Data Set as a tree. |
FALSE | Evaluate the Data Set as a list. |
Flag that indicates the type of element to retrieve. Possible values are:
Value | Meaning |
---|---|
TRUE | Retrieve any previous element, volatile or non-volatile. |
FALSE | Retrieve a non-volatile previous element. |
Value | Meaning |
---|---|
!NULL | A pointer to a DICOMELEMENTstructure that contains the item in the Data Set that immediately precedes the item specified in pElement. |
NULL | There is not an item preceding pElement. (pElement is the first item in the Data Set.) |
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 passed pointer points to | The function returns a pointer 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.
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.
If the passed pointer points to | The function returns a pointer 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 functions 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 functions to navigate the tree:
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
Win32, x64
This example displays in a list-box control all elements (level 0) from the Data Set.
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;
}
Help Collections
Raster .NET | C API | C++ Class Library | HTML5 JavaScript
Document .NET | C API | C++ Class Library | HTML5 JavaScript
Medical .NET | C API | C++ Class Library | HTML5 JavaScript
Medical Web Viewer .NET
Multimedia
Direct Show .NET | C API | Filters
Media Foundation .NET | C API | Transforms
Supported Platforms
.NET, Java, Android, and iOS/macOS Assemblies
Imaging, Medical, and Document
C API/C++ Class Libraries
Imaging, Medical, and Document
HTML5 JavaScript Libraries
Imaging, Medical, and Document