Paginating a FlowDocument - wpf

Question

I want to be able to create "reports" as regular MVVM views, so to test this idea I created the following view. It just consists of a bound textblock, an ItemsControl (bound to a collection of a few hundred strings), and a second text block:
<UserControl ...>
<UserControl.Resources>
<DataTemplate x:Key="myListItemTemplate">
<TextBlock Text="{Binding}"
Foreground="Blue" />
</DataTemplate>
</UserControl.Resources>
<FlowDocument x:Name="flowDoc">
<BlockUIContainer>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Message}" />
<ItemsControl ItemsSource="{Binding SomeList}"
ItemTemplate="{StaticResource myListItemTemplate}" />
<TextBlock Text="THE END" />
</StackPanel>
</BlockUIContainer>
</FlowDocument>
</UserControl>
I print the view using a DocumentPaginator like this:
private void Print(IPrintableView view)
{
var dlg = new PrintDialog();
if (!dlg.ShowDialog().GetValueOrDefault())
{
return;
}
var paginator = new MyDocumentPaginator(
view.FlowDocument,
new Size(dlg.PrintableAreaWidth, dlg.PrintableAreaHeight),
new Size(DefaultMarginWidthDpi, DefaultMarginHeightDpi));
dlg.PrintDocument(paginator, "My print job");
}
Unsurprisingly the document isn't being paginated, and produce a 1-page report that gets truncated partway through the list. (I don't believe my document paginator implementation is important here, which simply adds a header and footer to each page, and I see the same issue if I use the FlowDocument's own FlowDocumentPaginator).
As I now understand it, document paginators will only break on "Block" controls, so I modified the xaml to wrap each control in a BlockUIContainer:
<UserControl ...>
<UserControl.Resources>
<DataTemplate x:Key="myListItemTemplate">
<TextBlock Text="{Binding}"
Foreground="Blue" />
</DataTemplate>
</UserControl.Resources>
<FlowDocument x:Name="flowDoc">
<BlockUIContainer>
<TextBlock Text="{Binding Message}" />
</BlockUIContainer>
<BlockUIContainer>
<ItemsControl ItemsSource="{Binding SomeList}"
ItemTemplate="{StaticResource myListItemTemplate}" />
</BlockUIContainer>
<BlockUIContainer>
<TextBlock Text="THE END" />
</BlockUIContainer>
</FlowDocument>
</UserControl>
Here, a page break now occurs after the first TextBlock, with the list starting on page 2 (but still being truncated at the end of that page), and the second textblock appearing on page 3.
I assume the paginator is measuring and rendering the entire ItemsControl as a whole, so I then tried placing each list item inside a BlockUIContainer via the ItemContainerStyle:
<ItemsControl.ItemContainerStyle>
<Style TargetType="ContentPresenter">
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<BlockUIContainer>
<ContentPresenter Content="{Binding}" />
</BlockUIContainer>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</ItemsControl.ItemContainerStyle>
This made no difference though. Is there a way to get this working? Am I even approaching this in the right way? Placing every UI control inside a "block" seems very cumbersome, especially when it the time comes to implement a real report containing a lot of complexity. The real reports won't necessarily be list based either, and are more likely to contain a mixture of controls - text, images, lists, etc. in a fairly free-style layout (more web page than banded report).

Answer 1

So this wasn't straightforward as I was expecting, and if it were not for stumbling across this article then I'd probably never have found a solution. In the article, the author has created a series of classes and controls including a "FlowDocument friendly" list, with the option of rendering it as a Table, meaning that page breaks will occur between the items' TableRows when necessary.
Here's my updated "report view" xaml. Note that I've also refactored the text by using a <Paragraph> rather than a TextBlock inside a BlockUIElement. You'll also notice that these Paragraphs are also bindable, via a custom BindableRun control that is also part of the above article:
<UserControl ...>
<FlowDocument x:Name="flowDoc"
TextElement.FontFamily="Arial">
<Paragraph Margin="0,0,0,20">
<flowDocuments:BindableRun BoundText="{Binding Message}" />
</Paragraph>
<flowDocuments:ItemsContent ItemsSource="{Binding SomeList}">
<flowDocuments:ItemsContent.ItemsPanel>
<DataTemplate>
<flowDocuments:Fragment>
<Table>
<Table.Columns>
<TableColumn Width="*" />
</Table.Columns>
<TableRowGroup flowDocuments:Attached.IsItemsHost="True">
<TableRow Background="LightBlue">
<TableCell>
<Paragraph>Heading</Paragraph>
</TableCell>
</TableRow>
</TableRowGroup>
</Table>
</flowDocuments:Fragment>
</DataTemplate>
</flowDocuments:ItemsContent.ItemsPanel>
<flowDocuments:ItemsContent.ItemTemplate>
<DataTemplate>
<flowDocuments:Fragment>
<TableRow>
<TableCell>
<Paragraph>
<flowDocuments:BindableRun BoundText="{Binding}" />
</Paragraph>
</TableCell>
</TableRow>
</flowDocuments:Fragment>
</DataTemplate>
</flowDocuments:ItemsContent.ItemTemplate>
</flowDocuments:ItemsContent>
<Paragraph>THE END</Paragraph>
</FlowDocument>
</UserControl>
The custom ItemsContent control is used to render the list, and has a few familiar properties:
an ItemsSource property for binding to the VM's collection
an ItemTemplate property defining a DataTemplate that consists of a "Fragment" element (again from the above article), and within this a <TableRow> used to render the string items in my VM's collection
an ItemsPanel, used to define the "container" - in this case a Table control. This example includes a hardcoded TableRow used to display the column headings. I believe other containers are permitted such as a , although I didn't read the article in detail.
Anyway, it all appears to work, and produces a report that is correctly paginated, with the list of strings breaking to new pages at the correct places.
If anyone else uses the article to generate reports as I have done, be aware that the ItemsContent Loaded event never fires, resulting in the list not rendering (this is presumably due to the way I'm programmatically creating the view and/or not displaying it on screen). To get it working, I had to comment out the three if (IsLoaded) lines that appear later on in this class.