TextPointer.CompareTo(TextPointer) Method

Reference

Definition

Namespace:: System.Windows.Documents

Assembly:: PresentationFramework.dll

Important

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Performs an ordinal comparison between the positions specified by the current TextPointer and a second specified TextPointer.

public:
 int CompareTo(System::Windows::Documents::TextPointer ^ position);

public int CompareTo (System.Windows.Documents.TextPointer position);

member this.CompareTo : System.Windows.Documents.TextPointer -> int

Public Function CompareTo (position As TextPointer) As Integer

Parameters

position: TextPointer

A TextPointer that specifies a position to compare to the current position.

Returns

Int32

-1 if the current TextPointer precedes position; 0 if the locations are the same; +1 if the current TextPointer follows position.

Exceptions

ArgumentException

position specifies a position outside of the text container associated with the current position.

Examples

The following example demonstrates a use for this method. In the example, the CompareTo method is used in conjunction with the GetInsertionPosition method to test whether a specified TextElement is empty.

// Tests to see if the specified TextElement is empty (has no printatble content).
bool IsElementEmpty(TextElement element)
{
    // Find starting and ending insertion positions in the element.
    // Inward-facing directions are used to make sure that insertion position
    // will be found correctly in case when the element may contain inline 
    // formatting elements (such as a Span or Run that contains Bold or Italic elements).
    TextPointer start = element.ContentStart.GetInsertionPosition(LogicalDirection.Forward);
    TextPointer end = element.ContentEnd.GetInsertionPosition(LogicalDirection.Backward);
     
    // The element has no printable content if its first and last insertion positions are equal.
    return start.CompareTo(end) == 0;
} // End IsEmptyElement method.

' Tests to see if the specified TextElement is empty (has no printatble content).
Private Function IsElementEmpty(ByVal element As TextElement) As Boolean
    ' Find starting and ending insertion positions in the element.
    ' Inward-facing directions are used to make sure that insertion position
    ' will be found correctly in case when the element may contain inline 
    ' formatting elements (such as a Span or Run that contains Bold or Italic elements).
    Dim start As TextPointer = element.ContentStart.GetInsertionPosition(LogicalDirection.Forward)
    Dim [end] As TextPointer = element.ContentEnd.GetInsertionPosition(LogicalDirection.Backward)

    ' The element has no printable content if its first and last insertion positions are equal.
    Return start.CompareTo([end]) = 0

End Function ' End IsEmptyElement method.

Remarks

A value of -1 indicates that the position specified by the current TextPointer precedes the position specified by position. A value of 0 indicates that the indicated positions are equal. A value of positive +1 indicates that the position specified by the current TextPointer follows the position specified by position.

Applies to