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GetPreviousElement Method
See Also 
Leadtools.Dicom Namespace > DicomDataSet Class : GetPreviousElement Method




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.
includeVolatile
true to retrieve the previous element, volatile or non-volatile; false to retrieve the previous non-volatile element.
Returns the item in the Data Set that immediately precedes the specified item.

Syntax

Visual Basic (Declaration) 
Public Function GetPreviousElement( _
   ByVal element As DicomElement, _
   ByVal tree As Boolean, _
   ByVal includeVolatile As Boolean _
) As DicomElement
Visual Basic (Usage)Copy Code
Dim instance As DicomDataSet
Dim element As DicomElement
Dim tree As Boolean
Dim includeVolatile As Boolean
Dim value As DicomElement
 
value = instance.GetPreviousElement(element, tree, includeVolatile)
C# 
public DicomElement GetPreviousElement( 
   DicomElement element,
   bool tree,
   bool includeVolatile
)
Managed Extensions for C++ 
public: DicomElement* GetPreviousElement( 
   DicomElement* element,
   bool tree,
   bool includeVolatile
) 
C++/CLI 
public:
DicomElement^ GetPreviousElement( 
   DicomElement^ element,
   bool tree,
   bool includeVolatile
) 

Parameters

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.
includeVolatile
true to retrieve the previous element, volatile or non-volatile; false to retrieve the previous non-volatile element.

Return Value

The item in the Data Set that immediately precedes the item specified by element, or a null reference (Nothing in Visual Basic) if there is no item preceding element (element is the first item in the Data Set).

Example

For an example, refer to Load.

Remarks

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 1Item 2
Item 3Item 4
Item 5null
Item 6Item 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 1null
Item 15Item 14
Item 5Item 4
Item 9Item 8
Item 22Item 21
Item 25Item 24

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

GetFirstElement

GetLastElement

GetNextElement

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

GetRootElement

GetParentElement

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 DicomTagType.SmallestImagePixelValue, DicomTagType.LargestImagePixelValue, etc. If the image is changed to a color image, these elements disappear and the following elements appear: DicomTagType.RedPaletteColorLookupTableDescriptor, 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 volatile to false. To retrieve the first element, either volatile or non-volatile, set volatile to true.

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Leadtools.Dicom requires a Medical toolkit license and unlock key. For more information, refer to: Raster Pro/Document/Medical Features