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GetFirstElement Method

Summary

Returns the first item in the Data Set.

Syntax
C#
VB
C++
Java
public DicomElement GetFirstElement( 
   DicomElement element, 
   bool tree, 
   bool includeVolatile 
) 
Public Function GetFirstElement( _ 
   ByVal element As DicomElement, _ 
   ByVal tree As Boolean, _ 
   ByVal includeVolatile As Boolean _ 
) As DicomElement 
public DicomElement getFirstElement(DicomElement element, boolean tree, boolean includeVolatile) 
public: 
DicomElement^ GetFirstElement(  
   DicomElement^ element, 
   bool tree, 
   bool includeVolatile 
)  

Parameters

element
An item in the Data Set.

tree
true to evaluate the Data Set as a tree; false to evaluate the Data Set as a list.

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

Return Value

The first item in the Data Set, or a null reference (Nothing in VB) if the Data Set is empty.

Remarks

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

If the passed object points to: The method returns an object pointing to:
Item 1 Item 2
Item 3 Item 4
Item 5 Item 5
Item 6 Item 7
null Item 2

If the Data Set is evaluated as a list, the first 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.

getftlst.gif
If the passed object points to: The method returns an object pointing to:
null Item 1
Item 12 Item 1
Item 14 Item 1
Item 22 Item 1
Item 25 Item 1

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

GetLastElement

GetPreviousElement

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 DicomTag.SmallestImagePixelValue, DicomTag.LargestImagePixelValue, etc. If the image is changed to a color image, these elements disappear and the following elements appear: DicomTag.RedPaletteColorLookupTableDescriptor, etc. These are volatile elements since they are changed or destroyed when an image is changed or set.

To retrieve the first element that must be changed manually, i.e., is not volatile, set includeVolatile to false. To retrieve the first element, either volatile or non-volatile, set includeVolatile to true.

Example

For an example, refer to Load.

Requirements

Target Platforms

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