.net - How can I produce a "print preview" of a FlowDocument in a WPF application?

Question

Various WPF applications of mine display FlowDocument's. I'm able to print them, using the approach described in the answer to Printing a WPF FlowDocument.

Now I'd like to add a "print preview" capability. In the normal case, I am printing the FlowDocument that is displayed in the Window, and so I wouldn't need a Print Preview then. But in some cases the FlowDocument to print is constructed on-the-fly in memory. And in these cases I'd like to display it before printing.

Now, I can certainly pop a new window and display the FlowDocument, but

1. I want the preview to really feel like it is part of the printing operation, and not just another Window in the app.

2. I don't want a normal FlowDocument in a FlowDocumentScrollViewer. Rather than being "any size" it needs to be constrained to the size of the paper, a specific HxW ratio, and paginated.

Suggestions?

• should I just use a standard Window, and in that case, how to I ensure the FlowDocument is at the proper ratio?

• is there a more "integrated" way to do the preview within the scope of the PrintDialog UI that is part of Windows?

Thanks

Answer 1

Taking the hint from the comment added to my question, I did this:

private string _previewWindowXaml =
    @"<Window
        xmlns                 ='http://schemas.microsoft.com/netfx/2007/xaml/presentation'
        xmlns:x               ='http://schemas.microsoft.com/winfx/2006/xaml'
        Title                 ='Print Preview - @@TITLE'
        Height                ='200'
        Width                 ='300'
        WindowStartupLocation ='CenterOwner'>
        <DocumentViewer Name='dv1'/>
     </Window>";

internal void DoPreview(string title)
{
    string fileName = System.IO.Path.GetRandomFileName();
    FlowDocumentScrollViewer visual = (FlowDocumentScrollViewer)(_parent.FindName("fdsv1"));
    try
    {
        // write the XPS document
        using (XpsDocument doc = new XpsDocument(fileName, FileAccess.ReadWrite))
        {
            XpsDocumentWriter writer = XpsDocument.CreateXpsDocumentWriter(doc);
            writer.Write(visual);
        }

        // Read the XPS document into a dynamically generated
        // preview Window 
        using (XpsDocument doc = new XpsDocument(fileName, FileAccess.Read))
        {
            FixedDocumentSequence fds = doc.GetFixedDocumentSequence();

            string s = _previewWindowXaml;
            s = s.Replace("@@TITLE", title.Replace("'", "&apos;"));

            using (var reader = new System.Xml.XmlTextReader(new StringReader(s)))
            {
                Window preview = System.Windows.Markup.XamlReader.Load(reader) as Window;

                DocumentViewer dv1 = LogicalTreeHelper.FindLogicalNode(preview, "dv1") as DocumentViewer;
                dv1.Document = fds as IDocumentPaginatorSource;


                preview.ShowDialog();
            }
        }
    }
    finally
    {
        if (File.Exists(fileName))
        {
            try
            {
                File.Delete(fileName);
            }
            catch
            {
            }
        }
    }
} 

What it does: it actually prints the content of a visual into an XPS document. Then it loads the "printed" XPS document and displays it in a very simple XAML file that is stored as a string, rather than as a separate module, and loaded dynamically at runtime. The resulting Window has the DocumentViewer buttons: print, adjust-to-max-page-width, and so on.

I also added some code to hide the Search box. See this answer to WPF: How can I remove the searchbox in a DocumentViewer? for how I did that.

The effect is like this:

The XpsDocument can be found in the ReachFramework dll and the XpsDocumentWriter can be found in the System.Printing dll both of which must be added as references to the project