silverlight NaN的高度和宽度,ActualHeight和ActualWidth也返回0.0 - 解决方法是什么？

Question

popUpControl和listBoxControl下面正在返回NaN作为高度和宽度.这ActualHeight也是0.0

为什么？更重要的是,解决方法是什么？

<Popup Name="popUpControl" IsOpen="True" VerticalAlignment="Top" HorizontalAlignment="Left" >
    <ListBox Name="listBoxControl" SelectionChanged="_ListBox_SelectionChanged"
            Style="{StaticResource ListBoxStyle}" BorderBrush="Transparent"
             MaxHeight="300" MaxWidth="350" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal" >
                    <TextBlock Text="{Binding ID}" VerticalAlignment="Center" Margin="2,0,0,0" />
                    <TextBlock Text="{Binding Name}" VerticalAlignment="Center" Margin="2,0,0,0" />
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Popup>

Answer 1

要更新ActualWidth和ActualHeight框架元素,您必须调用UpdateLayout.

希望这有助于某人.