WPF Dynamic image generation and printing is not working - wpf

Question

In an application I'm developing, the user can select a number of items (max. 6) in a datagrid. These items should then be printed in a matrix style on pre-printed forms (see it like CD labels, 6 on a page).
I'm generating these images dynamically containing the selected content from a database. I then put these in a grid so they can be printed on the pre-printed forms.
I have the following code that creates the grid, generates the images from a user control and adds them to the grid and then prints these images.
I'm not following the MVVM pattern for the printing action. I created a reference to my view model in my code-behind.
Private Sub PrintButton_Click(sender As Object, e As RoutedEventArgs) Handles ButtonPrint.Click
Dim dlg As New PrintDialog
dlg.PrintTicket.PageMediaSize = New PageMediaSize(PageMediaSizeName.ISOA4)
Dim pageWidth As Double = GetPageWidth(dlg)
'Since the label is a perfect square: labelWidth = labelHeight
Dim labelWidthInPx As Integer = Utilities.ConvertMmToPixels(My.Settings.LabelWidthInMm)
'Set spacing distances in pixels
Dim horizontalLabelSpacing As Integer = Utilities.ConvertMmToPixels(My.Settings.HorizontalLabelSpacinginMm)
Dim verticalLabelSpacing As Integer = Utilities.ConvertMmToPixels(My.Settings.VerticalLabelSpacingInMm)
Dim topMargin As Integer = Utilities.ConvertMmToPixels(My.Settings.TopMarginInMm)
Dim leftMargin As Integer = Utilities.ConvertMmToPixels(My.Settings.LeftMarginInMm)
Dim bottomMargin As Integer = Utilities.ConvertMmToPixels(My.Settings.BottomMarginInMm)
'Create the table/grid
Dim tbl As New Grid
If CheckBoxPrintGridLines.IsChecked Then
tbl.ShowGridLines = True
Else
tbl.ShowGridLines = False
End If
'Add 3 columns (2 for the labels, 1 for spacing)
Dim col1 As New ColumnDefinition With {
.Width = New GridLength(labelWidthInPx, GridUnitType.Pixel)
}
Dim col2 As New ColumnDefinition With {
.Width = New GridLength(horizontalLabelSpacing, GridUnitType.Pixel)
}
Dim col3 As New ColumnDefinition With {
.Width = New GridLength(labelWidthInPx, GridUnitType.Pixel)
}
tbl.ColumnDefinitions.Add(col1)
tbl.ColumnDefinitions.Add(col2)
tbl.ColumnDefinitions.Add(col3)
'Add 5 Rows (3 for labels, 2 for spacing)
Dim row1 As New RowDefinition With {
.Height = New GridLength(labelWidthInPx, GridUnitType.Pixel)
}
Dim row2 As New RowDefinition With {
.Height = New GridLength(verticalLabelSpacing, GridUnitType.Pixel)
}
Dim row3 As New RowDefinition With {
.Height = New GridLength(labelWidthInPx, GridUnitType.Pixel)
}
Dim row4 As New RowDefinition With {
.Height = New GridLength(verticalLabelSpacing, GridUnitType.Pixel)
}
Dim row5 As New RowDefinition With {
.Height = New GridLength(labelWidthInPx, GridUnitType.Pixel)
}
tbl.RowDefinitions.Add(row1)
tbl.RowDefinitions.Add(row2)
tbl.RowDefinitions.Add(row3)
tbl.RowDefinitions.Add(row4)
tbl.RowDefinitions.Add(row5)
'Add label images
Dim reelData = CType(DataGridReels.ItemsSource, List(Of ReelInfo))
Dim rowIndex As Integer = 0
Dim colIndex As Integer = 0
For Each reel In reelData.Where(Function(r) r.IsSelected = True)
Dim partNumberData = ViewModel.DataService.GetPartNumberDataAsync(reel.PartNumber)
Dim batchData = ViewModel.DataService.GetBatchDataAsync(reel.PartNumber, reel.HENBatchNumber)
LabelImageControl.IsPrinting = True
LabelImageControl.PartNumberData = partNumberData.Result
LabelImageControl.BatchData = batchData.Result
LabelImageControl.ReelData = reel
LabelImageControl.Refresh
UpdateUI()
Dim labelImage As New Image
labelImage = GetImageFromLabel(LabelImageControl)
labelImage.Width = labelWidthInPx
labelImage.Height = labelWidthInPx
Grid.SetRow(labelImage, rowIndex)
Grid.SetColumn(labelImage, colIndex)
tbl.Children.Add(labelImage)
tbl.Refresh
colIndex += 1
If colIndex > 1 Then
colIndex = 0
rowIndex += 1
End If
Next
Dim iuc As New InlineUIContainer(tbl)
Dim p As New Paragraph(iuc)
'Create print dialog
If dlg.ShowDialog.GetValueOrDefault Then
'Create a flow document
Dim doc As New FlowDocument With {
.Name = "LabelPage",
.ColumnWidth = pageWidth,
.PagePadding = New Thickness(leftMargin, topMargin, 0, bottomMargin)
}
doc.Blocks.Add(p)
'Create IDocumentPagniatorSource from FlowDocument
Dim idpSource As IDocumentPaginatorSource = doc
Try
Me.Cursor = Cursors.Wait
dlg.PrintDocument(idpSource.DocumentPaginator, "Label Page")
Catch ex As Exception
Me.Cursor = Cursors.Arrow
MessageBox.Show("An error occurred during printing: " & ex.Message, "Print error")
Finally
Me.Cursor = Cursors.Arrow
End Try
End If
End Sub
When I send the output to the PDF printer I only get one image in the top left corner of the page/grid.
Since the user control (LabelImageControl) is in the XAML, I can see it changing while debugging. So the data is coming into the user control correctly.
When I check the grid with the XML Visualiser I see it has the same number of children as the items I selected in the datagrid.
Can anyone point me in the right direction on how to get the grid printing correctly?