FrameworkElement.ActualHeight 属性

public:
 property double ActualHeight { double get(); };

public double ActualHeight { get; }

member this.ActualHeight : double

Public ReadOnly Property ActualHeight As Double

元素的高度，以与设备无关的单位为单位的值 (每单位) 1/96 英寸。 默认值为 0（零）。

以下示例显示各种高度属性。

private void changeHeight(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.Height = sz1;
    rect1.UpdateLayout();
    txt1.Text= "ActualHeight is set to " + rect1.ActualHeight;
    txt2.Text= "Height is set to " + rect1.Height;
    txt3.Text= "MinHeight is set to " + rect1.MinHeight;
    txt4.Text= "MaxHeight is set to " + rect1.MaxHeight;
}
private void changeMinHeight(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.MinHeight = sz1;
    rect1.UpdateLayout();
    txt1.Text= "ActualHeight is set to " + rect1.ActualHeight;
    txt2.Text= "Height is set to " + rect1.Height;
    txt3.Text= "MinHeight is set to " + rect1.MinHeight;
    txt4.Text= "MaxHeight is set to " + rect1.MaxHeight;
}
private void changeMaxHeight(object sender, SelectionChangedEventArgs args)
{
    ListBoxItem li = ((sender as ListBox).SelectedItem as ListBoxItem);
    Double sz1 = Double.Parse(li.Content.ToString());
    rect1.MaxHeight = sz1;
    rect1.UpdateLayout();
    txt1.Text= "ActualHeight is set to " + rect1.ActualHeight;
    txt2.Text= "Height is set to " + rect1.Height;
    txt3.Text= "MinHeight is set to " + rect1.MinHeight;
    txt4.Text= "MaxHeight is set to " + rect1.MaxHeight;
}

Private Sub changeHeight(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.Height = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualHeight is set to " + rect1.ActualHeight.ToString
    txt2.Text = "Height is set to " + rect1.Height.ToString
    txt3.Text = "MinHeight is set to " + rect1.MinHeight.ToString
    txt4.Text = "MaxHeight is set to " + rect1.MaxHeight.ToString
End Sub
Private Sub changeMinHeight(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.MinHeight = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualHeight is set to " + rect1.ActualHeight.ToString
    txt2.Text = "Height is set to " + rect1.Height.ToString
    txt3.Text = "MinHeight is set to " + rect1.MinHeight.ToString
    txt4.Text = "MaxHeight is set to " + rect1.MaxHeight.ToString
End Sub
Private Sub changeMaxHeight(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.MaxHeight = sz1
    rect1.UpdateLayout()
    txt1.Text = "ActualHeight is set to " + rect1.ActualHeight.ToString
    txt2.Text = "Height is set to " + rect1.Height.ToString
    txt3.Text = "MinHeight is set to " + rect1.MinHeight.ToString
    txt4.Text = "MaxHeight is set to " + rect1.MaxHeight.ToString
End Sub

此属性是基于其他高度输入和布局系统的计算值。 该值由布局系统本身根据实际呈现传递设置，因此可能略落后于属性的设置值，例如 Height 作为输入更改的基础的属性。

因为 ActualHeight 是计算所得的值，所以你应该知道，由于布局系统各种操作的结果，该值可能有多次或递增的报告的更改。 布局系统可能会计算子元素所需的测量空间、父元素的约束等。

虽然不能从 XAML 设置此属性，但可以在 Trigger 样式中基于其值。