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FrameworkElement.ActualWidth Property

Gets the rendered width of this element.

Namespace:  System.Windows
Assembly:  PresentationFramework (in PresentationFramework.dll)
'Declaration
Public ReadOnly Property ActualWidth As Double

Property Value

Type: System.Double
The element's width, as a value in device-independent units (1/96th inch per unit). The default value is 0 (zero).

Identifier field

ActualWidthProperty

Metadata properties set to true

None

This property is a calculated value based on other width inputs, and the layout system. The value is set by the layout system itself, based on an actual rendering pass, and may therefore lag slightly behind the set value of properties such as Width that are the basis of the input change.

Because ActualWidth is a calculated value, you should be aware that there could be multiple or incremental reported changes to it as a result of various operations by the layout system. The layout system may be calculating required measure space for child elements, constraints by the parent element, and so on.

Although you cannot set this property from XAML, you can base a Trigger upon its value in a style.

The following example displays various width properties.

Private Sub changeWidth(ByVal sender As Object, ByVal args As SelectionChangedEventArgs)
    Dim li As ListBoxItem = CType(CType(sender, ListBox).SelectedItem, ListBoxItem)
    Dim sz1 As Double = Double.Parse(li.Content.ToString())
    rect1.Width = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth.ToString
    txt2.Text = "Width is set to " + rect1.Width.ToString
    txt3.Text = "MinWidth is set to " + rect1.MinWidth.ToString
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth.ToString
End Sub 
Private Sub changeMinWidth(ByVal sender As Object, ByVal args As SelectionChangedEventArgs)

    Dim li As ListBoxItem = CType(CType(sender, ListBox).SelectedItem, ListBoxItem)
    Dim sz1 As Double = Double.Parse(li.Content.ToString())
    rect1.MinWidth = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth.ToString
    txt2.Text = "Width is set to " + rect1.Width.ToString
    txt3.Text = "MinWidth is set to " + rect1.MinWidth.ToString
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth.ToString
End Sub 
Private Sub changeMaxWidth(ByVal sender As Object, ByVal args As SelectionChangedEventArgs)

    Dim li As ListBoxItem = CType(CType(sender, ListBox).SelectedItem, ListBoxItem)
    Dim sz1 As Double = Double.Parse(li.Content.ToString())
    rect1.MaxWidth = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth.ToString
    txt2.Text = "Width is set to " + rect1.Width.ToString
    txt3.Text = "MinWidth is set to " + rect1.MinWidth.ToString
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth.ToString
End Sub

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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