如何制作“打印预览"?WPF 应用程序中的 FlowDocument? [英] How can I produce a "print preview" of a FlowDocument in a WPF application?

问题描述

我的各种 WPF 应用程序显示 FlowDocument 的.我可以使用

XpsDocument 可以在 ReachFramework dll 中找到，XpsDocumentWriter 可以在 System.Printing dll 中找到，两者都必须添加为对项目的引用

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

解决方案

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

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