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

The "FlowDocumentPageViewer" control is the basis for the "preview" control used in one of our projects. Here is the XAML of the "DocumentPreviewer" control (apologies for the length -- XAML is not succinct):

<Control
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:sys="clr-namespace:System;assembly=mscorlib"
    xmlns:l="clr-namespace:Tyler.ComPort.UI"
    mc:Ignorable="d"
    x:Class="Tyler.ComPort.UI.DocumentPreviewer"
    x:Name="UserControl"
    Background="Gray"
    d:DesignWidth="640" d:DesignHeight="480">
    <Control.Resources>
        <ObjectDataProvider x:Key="ViewStyles" MethodName="GetValues" ObjectType="{x:Type sys:Enum}" >
            <ObjectDataProvider.MethodParameters>
                <x:Type TypeName="l:ViewType" />
            </ObjectDataProvider.MethodParameters>
        </ObjectDataProvider>
        <l:EnumMatchVisibilityConverter x:Key="EnumVisibilityConverter" />
    </Control.Resources>
    <Control.Template>
        <ControlTemplate>
            <ControlTemplate.Triggers>
                <Trigger Property="l:DocumentPreviewer.ViewType">
                    <Trigger.Value>
                        <l:ViewType>Actual</l:ViewType>
                    </Trigger.Value>
                    <Trigger.Setters>
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto" />
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
                        <Setter TargetName="Viewbox" Property="Viewbox.Stretch" Value="None" />
                    </Trigger.Setters>
                </Trigger>
                <Trigger Property="l:DocumentPreviewer.ViewType">
                    <Trigger.Value>
                        <l:ViewType>Fit</l:ViewType>
                    </Trigger.Value>
                    <Trigger.Setters>
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" />
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.VerticalScrollBarVisibility" Value="Disabled" />
                        <Setter TargetName="Viewbox" Property="Viewbox.Stretch" Value="Uniform" />
                    </Trigger.Setters>
                </Trigger>
                <Trigger Property="l:DocumentPreviewer.ViewType">
                    <Trigger.Value>
                        <l:ViewType>Wide</l:ViewType>
                    </Trigger.Value>
                    <Trigger.Setters>
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" />
                        <Setter TargetName="ScrollViewer" Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
                        <Setter TargetName="Viewbox" Property="Viewbox.Stretch" Value="UniformToFill" />
                    </Trigger.Setters>
                </Trigger>
            </ControlTemplate.Triggers>
            <DockPanel>
                <ToolBar DockPanel.Dock="Top">
                    <Button Command="{x:Static ApplicationCommands.Print}" CommandTarget="{Binding ElementName=PageViewer}" Content="Print..." />
                    <Separator />
                    <Button Command="{x:Static NavigationCommands.PreviousPage}" CommandTarget="{Binding ElementName=PageViewer}" Content="&lt; Previous" />
                    <Button Command="{x:Static NavigationCommands.NextPage}" CommandTarget="{Binding ElementName=PageViewer}" Content="Next &gt;" />
                    <Separator />
                    <l:ToolBarButtonGroup
                        ItemsSource="{Binding Source={StaticResource ViewStyles}}"
                        SelectedItem="{Binding ViewType, ElementName=UserControl}"
                        IsSynchronizedWithCurrentItem="True"
                        >
                        <l:ToolBarButtonGroup.ItemTemplate>
                            <DataTemplate>
                                <StackPanel Orientation="Horizontal" ToolTip="{Binding}" SnapsToDevicePixels="True">
                                    <Image Source="../Images/actual.png" Visibility="{Binding Converter={StaticResource EnumVisibilityConverter}, ConverterParameter=Actual}" />
                                    <Image Source="../Images/fit.png" Visibility="{Binding Converter={StaticResource EnumVisibilityConverter}, ConverterParameter=Fit}" />
                                    <Image Source="../Images/wide.png" Visibility="{Binding Converter={StaticResource EnumVisibilityConverter}, ConverterParameter=Wide}" />
                                </StackPanel>
                            </DataTemplate>
                        </l:ToolBarButtonGroup.ItemTemplate>
                    </l:ToolBarButtonGroup>
                </ToolBar>
                <ScrollViewer x:Name="ScrollViewer" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Disabled">
                    <Border
                            BorderBrush="Black"
                            BorderThickness="1"
                            HorizontalAlignment="Center"
                            VerticalAlignment="Top"
                            Background="White"
                            Margin="10">
                        <Viewbox x:Name="Viewbox" Stretch="Uniform">
                            <FlowDocumentPageViewer
                                x:Name="PageViewer"
                                Document="{Binding Document, ElementName=UserControl}"
                                Zoom="100"
                                MinZoom="20"
                                MaxZoom="200">
                                <FlowDocumentPageViewer.Template>
                                    <ControlTemplate TargetType="{x:Type FlowDocumentPageViewer}">
                                        <AdornerDecorator>
                                            <DocumentPageView FlowDocumentPageViewer.IsMasterPage="True" />
                                        </AdornerDecorator>
                                    </ControlTemplate>
                                </FlowDocumentPageViewer.Template>
                            </FlowDocumentPageViewer>
                        </Viewbox>
                    </Border>
                </ScrollViewer>
            </DockPanel>
        </ControlTemplate>
    </Control.Template>
</Control>

Where you might put such a control is up to you (and your app) of course, but our app has a similar behavior to the typical Office app where you can either print directly or preview (which shows the above interface) and print from there.

Answer 2

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: