PrintPreviewPages

PrintPreviewPages

The Print Preview's pages: the given document paginated for real — by WPF's own DocumentPaginator, the same pagination Print hands to the printer — into a vertical stack of Pages at the Page Setup's oriented size and Print Margins (INV-061). Unlike the Document Sheet, whose Page Breaks only mark boundaries without repaginating, each page here holds exactly the content the printed page would.

• Class: UI.Controls.PrintPreviewPages (derives from System.Windows.FrameworkElement)
• Hosted by: PrintPreviewWindow, on a scrolling canvas beside its Print action, with its state in PrintPreviewViewModel
• Shown through: the IPrintPreview port (WindowPrintPreview), which the MarkdownRichEditor's PrintPreview routed command (Ctrl+Shift+P) reaches after re-projecting the whole Markdown source — so a Folded Section's hidden body is previewed too (INV-034)

How it works

• True pagination. The document is given the Page Setup's oriented PageWidth/PageHeight and its Print Margins as PagePadding, then laid out by its own DocumentPaginator — ComputePageCount followed by GetPage per page. This is the very layout PrintDialog.PrintDocument prints, so the preview cannot disagree with the printer.
• One visual per Page. Each page is hosted as a paper rectangle (white, with a gray edge — paper is paper whatever the theme, because the preview shows the printout, not the editor) with the paginator's page visual over it, stacked vertically with a band of canvas between pages.
• Re-paginates on change. Setting Document or Setup clears the stack and paginates afresh.
• Presentation-only. The document handed over is self-contained — freshly projected, never the live editing surface — so previewing changes nothing (INV-061).

Properties

Property	Type	Description
Document	FlowDocument	The self-contained document to paginate and preview.
Setup	PageSetup	The Page Setup the pages are laid out under. Left unset, the default (Portrait, Normal margins) applies (INV-061).

Usage

<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"
              Background="{DynamicResource EditorCanvasBrush}">
    <controls:PrintPreviewPages Document="{Binding Document}" Setup="{Binding Setup}"
                                Margin="28" HorizontalAlignment="Center" />
</ScrollViewer>

The window it lives in is opened through the port, never constructed directly:

// MarkdownRichEditor, on the PrintPreview routed command:
var document = _projector.Project(Markdown, BaseDirectory);
PrintPreview.Show(document, PageSetup ?? PageSetup.Default, "LiveMarkDownEditor document");