Windows Dev Center

Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

FrameworkElement.ActualWidth Property

Gets the rendered width of this element.

Namespace:  System.Windows
Assembly:  PresentationFramework (in PresentationFramework.dll)

public double ActualWidth { get; }

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 void changeWidth(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.Width = sz1;
    rect1.UpdateLayout();
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth;
    txt2.Text = "Width is set to " + rect1.Width;
    txt3.Text = "MinWidth is set to " + rect1.MinWidth;
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth;
}
private void changeMinWidth(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.MinWidth = sz1;
    rect1.UpdateLayout();
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth;
    txt2.Text = "Width is set to " + rect1.Width;
    txt3.Text = "MinWidth is set to " + rect1.MinWidth;
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth;
}
private void changeMaxWidth(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.MaxWidth = sz1;
    rect1.UpdateLayout();
    txt1.Text = "ActualWidth is set to " + rect1.ActualWidth;
    txt2.Text = "Width is set to " + rect1.Width;
    txt3.Text = "MinWidth is set to " + rect1.MinWidth;
    txt4.Text = "MaxWidth is set to " + rect1.MaxWidth;
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Show:
© 2015 Microsoft