我可以打印用户控件，但不能打印窗口（空文档）

Question

直到现在，要将许多用户控件打印到具有许多页面的PDF中，每个用户控件一个页面，我有以下代码：

public static void ImprimirWpf(IEnumerable<dynamic> paramIeViewsParaImprimir)
{
    int miFactor = 3;



    Size miTamañoPagina = new Size(paramIeViewsParaImprimir.ElementAt(0).Width, paramIeViewsParaImprimir.ElementAt(0).Height);


    FixedDocument miDocumento = new FixedDocument();
    miDocumento.DocumentPaginator.PageSize = miTamañoPagina;



    for (int i = 0; i < paramIeViewsParaImprimir.Count(); i++)
    {
        paramIeViewsParaImprimir.ElementAt(i).Measure(miTamañoPagina);
        paramIeViewsParaImprimir.ElementAt(i).Arrange(new Rect(miTamañoPagina));

        paramIeViewsParaImprimir.ElementAt(i).UpdateLayout();



        int miAncho = (int)Math.Round(miTamañoPagina.Width / 2, MidpointRounding.AwayFromZero) * 2;
        int miAlto = (int)Math.Round(miTamañoPagina.Height / 2, MidpointRounding.AwayFromZero) * 2;


        System.Windows.Media.Imaging.RenderTargetBitmap bitmap = new System.Windows.Media.Imaging
            .RenderTargetBitmap(miAncho * miFactor, miAlto * miFactor, 96 * miFactor, 96 * miFactor, System.Windows.Media.PixelFormats.Pbgra32);
            bitmap.Render(paramIeViewsParaImprimir.ElementAt(i));

        System.Windows.Controls.Image myImage = new System.Windows.Controls.Image();
        myImage.Source = bitmap;





        FixedPage miPagina1 = new FixedPage();
        miPagina1.Width = miDocumento.DocumentPaginator.PageSize.Width;
        miPagina1.Height = miDocumento.DocumentPaginator.PageSize.Height;
        miPagina1.Children.Add(myImage);


        PageContent miContenido1 = new PageContent();
        ((IAddChild)miContenido1).AddChild(miPagina1);

        miDocumento.Pages.Add(miContenido1);
    }



    System.Windows.Controls.PrintDialog myDialog = new System.Windows.Controls.PrintDialog();
    //With the if, it will show a dialog to select the printer, to print on printer or on PDF or XPS.
    if (myDialog.ShowDialog() == true)
    {
        //Print the image.
        myDialog.PrintDocument(miDocumento.DocumentPaginator, string.Empty);
    }
}

但是我已经意识到，如果将相同的用户控件更改为窗口，则会得到一个空文档，但是如果我将其更改为用户控件，则会得到预期的PDF。

要打印视觉效果，用户控件与窗口是否有所不同？

谢谢。