Printing from WPF

我有一个WPF数据输入屏幕/窗口，我想为其提供打印输出。（准确地说，这是一个UserControl，我已经将其设置为在我想要打印的TabControl中作为TabItem工作。）

为了更好地打印，我进行了几次布局转换，将窗口缩放到纸张大小，并更改应用程序的外观。"打印皮肤"将背景更改为白色，并删除标题标签等的背景。

这非常有效，同时MessageBox.Show()提示告诉我发生了什么。

然而，当我拿出Messagebox.Show提示时，我发现我所有的打印魔法都不起作用，就好像enire打印方法只是：UserControl上的PrintVisual();。（我已经将其缩小到一个MessageBox，如果不破坏东西，我就无法摆脱它。）

代码（抱歉太长了，我添加了大量评论）：

private void PrintStatements()
{
  PrintDialog print = new PrintDialog();
  /// Needed data
  PrintCapabilities capabilities = print.PrintQueue.GetPrintCapabilities(print.PrintTicket);
  double pageMargin = 1 / 2.54;   // 1cm
  double pageWidth = capabilities.PageImageableArea.ExtentWidth - (pageMargin);
  double pageLength = capabilities.PageImageableArea.ExtentHeight - (pageMargin);
  Size pageSize = new Size(pageWidth, pageLength);
  ResourceDictionary resources = new ResourceDictionary();
  bool canPrint = print.ShowDialog() ?? false;
  if (canPrint)
  {
    double tabWidth = StatementsTabCtrl.ActualWidth;
    double tabHeight = StatementsTabCtrl.ActualHeight;
    /// 1.  Get tab item content ('currentTabContent') 
    StatementsTabItem currentTabContent = StatementsTabCtrl.SelectedContent as StatementsTabItem;
    /// 2.  Get Original Specs of currentTabContent
    ResourceDictionary origSkin = Application.Current.Resources;
    Size origSize = new Size(currentTabContent.ActualWidth, currentTabContent.ActualHeight);
    Transform origTransform = currentTabContent.LayoutTransform;
    /// 3.  Transform currentTabContent (expose print panels, move stuff around etc) - 
        //do this inside TabItem class
    currentTabContent.SetupPrinting();
    /// 4.  Make changes outside TabItem (skin, page-scale)
        // skin
    resources.MergedDictionaries.Add(Application.LoadComponent(new Uri(@"Skin/PrintDictionary.xaml", UriKind.Relative)) as ResourceDictionary);
    Application.Current.Resources = resources;
        // page-scale
    double scale = Math.Min(pageWidth / currentTabContent.ActualWidth,
                            pageLength / currentTabContent.ActualHeight);
    // ****Uncomment next line - printing magic works.**** //
    // MessageBox.Show(string.Format("scaling by {0}", scale));
    System.Threading.Thread.Sleep(250);
    currentTabContent.LayoutTransform = new ScaleTransform(scale, scale);
    //Measure and Arrange
    currentTabContent.Measure(pageSize);
    ((UIElement)currentTabContent).Arrange(new Rect(
         new Point((capabilities.PageImageableArea.OriginWidth + pageMargin),
             (capabilities.PageImageableArea.OriginHeight + pageMargin)), pageSize));
    System.Threading.Thread.Sleep(250);
    /// 5. Print (Finally!)
    print.PrintVisual(currentTabContent, "Print Results");
    /// 6. Return everything to normal (undo 3, then 4)
        // undo 3.
    currentTabContent.TearDownPrinting();
        // undo 4.
    Application.Current.Resources = origSkin;
    scale = Math.Max(currentTabContent.ActualWidth / pageWidth,
                                    currentTabContent.ActualHeight / pageLength);
    currentTabContent.LayoutTransform = new ScaleTransform(1 / scale, 1 / scale);
    currentTabContent.Measure(origSize);
    ((UIElement)currentTabContent).Arrange(new Rect(0, 0, tabWidth, tabHeight));
  }
}

正如你所看到的，我已经尝试添加了几个System.Threading.Thread.Sleep(250);，以防它需要更多的时间来识别更改，但这没有效果。PrintDialog()调用的怪异也是出于类似的原因。用通常的方式称呼它没有什么区别。

有人能告诉我为什么没有MessageBox调用，我的打印功能就不能工作吗？或者告诉我如何模拟MessageBox调用来欺骗程序工作吗？很多很多TIA

  ui.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));// activates ui.InvalidateMeasure(); 
  ui.Arrange(new Rect(new Point(0, 0), ui.DesiredSize));                 // activates ui.InvalidateArrange();
  ui.UpdateLayout(); // <-- refreshed your UIElement