爲什麼StackPanel的高度設置爲自動時，其高度設置爲從後面的代碼

Question

我有以下代碼，使StackPanel的高度是它的寬度的1.4倍。

C＃：

private void AutoRun() 
{ 
    //Page height 
    double PageHeight = Window_1_Document_Page_1.Width * 1.4; 
    Window_1_Document_Page_1.Height = PageHeight; 
} 

XAML：

<StackPanel Name="Window_1" BorderBrush="Black" BorderThickness="1" Grid.Row="0" Grid.Column="0"> 

    <Grid BorderThickness="0,0,0,1" BorderBrush="Black"> 
     <TextBlock FontSize="18" Name="Window_1_Title" Padding="5">New Document 1</TextBlock> 
     <Button HorizontalAlignment="Right" Name="Window_1_Close" Content="Close Window" Visibility="Collapsed" Click="CloseWindow_Click"/> 
    </Grid> 

    <ScrollViewer VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Disabled"> 
     <Grid Name="Window_1_Document_Page_1" Margin="20" BorderThickness="1" BorderBrush="Black" Padding="10"> 
      <TextBox Name="TextBox1" AcceptsReturn="False" BorderBrush="Transparent" BorderThickness="0" FontFamily="Calibri" FontSize="16" Height="Auto" Width="Auto" TextWrapping="Wrap" Text="{Binding ElementName = Window_1_Document_Page_1, Path = ActualWidth}" /> 
     </Grid> 
    </ScrollViewer> 

</StackPanel> 

然而，StackPanel的Window_1_Document_Page_1呈現爲如果它的高度爲Auto。

可能有人請告訴我如何解決這個問題？

Answer 1

獲得寬度的屬性被稱爲ActualWidth不Width，試試這個：

double PageHeight = Window_1_Document_Page_1.ActualWidth* 1.4; 
Window_1_Document_Page_1.Height = PageHeight;