Visual.TransformToAncestor Method (Visual)

 

Returns a transform that can be used to transform coordinates from the Visual to the specified Visual ancestor of the visual object.

Namespace:   System.Windows.Media
Assembly:  PresentationCore (in PresentationCore.dll)

Public Function TransformToAncestor (
	ancestor As Visual
) As GeneralTransform

Parameters

ancestor
Type: System.Windows.Media.Visual

The Visual to which the coordinates are transformed.

Return Value

Type: System.Windows.Media.GeneralTransform

A value of type GeneralTransform.

Exception Condition
ArgumentNullException

ancestor is null.

ArgumentException

ancestor is not an ancestor of the visual.

InvalidOperationException

The visual objects are not related.

Alternatively, you can use the VisualTreeHelper.GetOffset method to retrieve the offset of a visual object relative to its parent. The offset values are contained within the returned Vector value.

' Return the offset vector for the TextBlock object.
Dim vector As Vector = VisualTreeHelper.GetOffset(myTextBlock)

' Convert the vector to a point value.
Dim currentPoint As New Point(vector.X, vector.Y)

The following markup example shows a TextBlock that is nested within two StackPanel objects.

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
  <StackPanel Margin="16">
    <StackPanel Margin="8">
      <TextBlock Name="myTextBlock" Margin="4" Text="Hello, world" />
    </StackPanel>
  </StackPanel>
</Window>

The following code example shows how to use the TransformToAncestor method to retrieve the offset of the TextBlock relative to the containing Window. The offset values are contained in the returned GeneralTransform.

' Return the general transform for the specified visual object.
Dim generalTransform1 As GeneralTransform = myTextBlock.TransformToAncestor(Me)

' Retrieve the point value relative to the parent.
Dim currentPoint As Point = generalTransform1.Transform(New Point(0, 0))

The offset takes into account the Margin values for all objects within the containing Window. In this case, X is 28, and Y is 28.

.NET Framework
Available since 3.0
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