UWP richeditbox打印多页

Question

我无法使用 Richeditbox 进行多页打印。我在 Xaml 中有名为 Editor 的 Richeditbox。我使用自定义 GetText() 函数来获取编辑器中的所有内容。我已经能够打印单页，但不知道如何制作多页。

我已尝试查看 Microsoft 文档和此 PrintHelper class。我仍然不确定我应该如何在我的项目中实现它。

所以主要问题是我应该如何使用 richeditbox 打印多页？

下面是我的项目打印代码，是的，我知道有硬编码：printDoc.SetPreviewPageCount(1, PreviewPageCountType.Final); 但不知道我应该如何计算这些页数

 private PrintManager printMan;
 private PrintDocument printDoc;
 private IPrintDocumentSource printDocSource;

public MainPage()
{
    InitializeComponent();
    // Register for PrintTaskRequested event
    printMan = PrintManager.GetForCurrentView();
    printMan.PrintTaskRequested += PrintTaskRequested;

    // Build a PrintDocument and register for callbacks
    printDoc = new PrintDocument();
    printDocSource = printDoc.DocumentSource;
    printDoc.Paginate += Paginate;
    printDoc.GetPreviewPage += GetPreviewPage;
    printDoc.AddPages += AddPages;
}

private async void Print_Click(object sender, RoutedEventArgs e)
{
    if (PrintManager.IsSupported())
    {
        try
        {
            // Show print UI
            await PrintManager.ShowPrintUIAsync();
        }
        catch
        {
            // Printing cannot proceed at this time
            ContentDialog noPrintingDialog = new ContentDialog()
            {
                Title = "Printing error",
                Content = "\nSorry, printing can' t proceed at this time.",
                PrimaryButtonText = "OK"
            };
            await noPrintingDialog.ShowAsync();
        }
    }
    else
    {
        // Printing is not supported on this device
        ContentDialog noPrintingDialog = new ContentDialog()
        {
            Title = "Printing not supported",
            Content = "\nSorry, printing is not supported on this device.",
            PrimaryButtonText = "OK"
        };
        await noPrintingDialog.ShowAsync();
    }

}

private void PrintTaskRequested(PrintManager sender, PrintTaskRequestedEventArgs args)
{
    // Create the PrintTask.
    // Defines the title and delegate for PrintTaskSourceRequested
    var printTask = args.Request.CreatePrintTask("Print", PrintTaskSourceRequrested);

    // Handle PrintTask.Completed to catch failed print jobs
    printTask.Completed += PrintTaskCompleted;
}

private void PrintTaskSourceRequrested(PrintTaskSourceRequestedArgs args)
{
    // Set the document source.
    args.SetSource(printDocSource);
}

private void Paginate(object sender, PaginateEventArgs e)
{
    printDoc.SetPreviewPageCount(1, PreviewPageCountType.Final);
}

private void GetPreviewPage(object sender, GetPreviewPageEventArgs e)
{
    string text = GetText(); ;
    RichEditBox richTextBlock = new RichEditBox();
    richTextBlock.Document.SetText(TextSetOptions.FormatRtf, text);
    richTextBlock.Background = new SolidColorBrush(Windows.UI.Colors.White);
    printDoc.SetPreviewPage(e.PageNumber, richTextBlock);
}


private void AddPages(object sender, AddPagesEventArgs e)
{
    string text = GetText(); ;
    RichEditBox richTextBlock = new RichEditBox();
    richTextBlock.Document.SetText(TextSetOptions.FormatRtf, text);
    richTextBlock.Background = new SolidColorBrush(Windows.UI.Colors.White);
    richTextBlock.Padding = new Thickness(20,20,20,20);
    printDoc.AddPage(richTextBlock);

    // Indicate that all of the print pages have been provided
    printDoc.AddPagesComplete();
}

private async void PrintTaskCompleted(PrintTask sender, PrintTaskCompletedEventArgs args)
{
    // Notify the user when the print operation fails.
    if (args.Completion == PrintTaskCompletion.Failed)
    {
        await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
        {
            ContentDialog noPrintingDialog = new ContentDialog()
            {
                Title = "Printing error",
                Content = "\nSorry, failed to print.",
                PrimaryButtonText = "OK"
            };
            await noPrintingDialog.ShowAsync();
        });
    }
}

Answer 1

RichTextBlock 有 OverflowContentTarget 属性。您应该在那里指定 RichTextBlockOverflow 控件。 RichTextBlockOverflow 控件也可能有 OverflowContentTarget。因此，您添加附加页面并查看它是否有溢出内容。不适合页面的内容流向下一个溢出控制等等。因此，您一页一页地渲染页面，直到溢出时没有任何内容，那时您就知道页数了。

正是我所说的，但在他们的官方 docs:

lastRTBOOnPage = AddOnePrintPreviewPage(null, pageDescription);

   // We know there are more pages to be added as long as the last RichTextBoxOverflow added to a print preview
   // page has extra content
   while (lastRTBOOnPage.HasOverflowContent && lastRTBOOnPage.Visibility == Windows.UI.Xaml.Visibility.Visible)
   {
         lastRTBOOnPage = AddOnePrintPreviewPage(lastRTBOOnPage, pageDescription);
   }

MS 文档跳过了要点并且难以理解。最好的打印文档是他写的 blog by Diederic Krols. There is also nice article 如何从 ItemsControl 打印。（但它更高级）它适用于 windows 8，但 API 从那时起就没有改变。

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