/// <summary>
/// This is the event handler for PrintDocument.Paginate. It creates print preview pages for the app.
/// </summary>
/// <param name="sender">PrintDocument</param>
/// <param name="e">Paginate Event Arguments</param>
protected virtual void CreatePrintPreviewPages(object sender, PaginateEventArgs e)
{
// Clear the cache of preview pages.
PrintPreviewPages.Clear();
// Clear the print canvas of preview pages.
PrintCanvas.Children.Clear();
// This variable keeps track of the last RichTextBlockOverflow element that was added to a page which will be printed.
RichTextBlockOverflow lastRTBOOnPage;
// Get the PrintTaskOptions.
PrintTaskOptions printingOptions = e.PrintTaskOptions;
// Get the page description to deterimine how big the page is.
PrintPageDescription pageDescription = printingOptions.GetPageDescription(0);
// We know there is at least one page to be printed. passing null as the first parameter to
// AddOnePrintPreviewPage tells the function to add the first page.
lastRTBOOnPage = AddOnePrintPreviewPage(null, pageDescription);
// We know there are more pages to be added as long as the last RichTextBoxOverflow added to a print preview
// page has extra content.
while (lastRTBOOnPage.HasOverflowContent && lastRTBOOnPage.Visibility == Visibility.Visible)
{
lastRTBOOnPage = AddOnePrintPreviewPage(lastRTBOOnPage, pageDescription);
}
PreviewPagesCreated?.Invoke(PrintPreviewPages, EventArgs.Empty);
PrintDocument printDoc = sender as PrintDocument;
// Report the number of preview pages created.
printDoc.SetPreviewPageCount(PrintPreviewPages.Count, PreviewPageCountType.Intermediate);
}
/// <summary>
/// This function creates and adds one print preview page to the internal cache of print preview
/// pages stored in printPreviewPages.
/// </summary>
/// <param name="lastRTBOAdded">Last RichTextBlockOverflow element added in the current content.</param>
/// <param name="printPageDescription">Printer's page description</param>
/// <returns>The link container for text overflowing in this page.</returns>
protected virtual RichTextBlockOverflow AddOnePrintPreviewPage(RichTextBlockOverflow lastRTBOAdded, PrintPageDescription printPageDescription)
{
// XAML element that is used to represent to "printing page".
FrameworkElement page = FirstPage;
// The link container for text overflowing in this page.
RichTextBlockOverflow textLink;
// Check if this is the first page ( no previous RichTextBlockOverflow).
if (lastRTBOAdded == null)
{
// Hide footer since we don't know yet if it will be displayed (this might not be the last page) - wait for layout.
(page.FindName("Footer") as StackPanel).Visibility = Visibility.Collapsed;
}
// Set "paper" width.
page.Width = printPageDescription.PageSize.Width;
page.Height = printPageDescription.PageSize.Height;
var printableArea = page.FindName("PrintableArea") as Grid;
// Get the margins size.
// If the ImageableRect is smaller than the app provided margins use the ImageableRect.
double marginWidth = 0;
double marginHeight = 0;
// Set-up "printable area" on the "paper".
printableArea.Width = FirstPage.Width - marginWidth;
printableArea.Height = FirstPage.Height - marginHeight;
// Add the (newley created) page to the print canvas which is part of the visual tree and force it to go
// through layout so that the linked containers correctly distribute the content inside them.
PrintCanvas.Children.Add(page);
PrintCanvas.InvalidateMeasure();
PrintCanvas.UpdateLayout();
// Find the last text container and see if the content is overflowing.
textLink = page.FindName("ContinuationPageLinkedContainer") as RichTextBlockOverflow;
// Check if this is the last page.
if (!textLink.HasOverflowContent && textLink.Visibility == Visibility.Visible)
{
(page.FindName("Footer") as StackPanel).Visibility = Visibility.Visible;
}
// Add the page to the page preview collection.
PrintPreviewPages.Add(page);
return(textLink);
}
