Itext 7 IPdfTextLocation.GetPageNumber turning up 0 all the time - vb.net

Question

I'm writing a (VB/Net) procedure that searches a PDF document for a Regex pattern and writes a text file with the matched locations:
Public Sub ReadAndMatch(ByVal InputFileName As String, OutputFileName As String, RegexPattern As String)
Dim pdfIn As New iText.Kernel.Pdf.PdfReader(InputFileName) ' A Pdfreader object associated with the input file name
Dim pdfDoc As New iText.Kernel.Pdf.PdfDocument(pdfIn) 'This object holds the actual document being analyzed
Dim strategy As New iText.Kernel.Pdf.Canvas.Parser.Listener.RegexBasedLocationExtractionStrategy(RegexPattern) 'extraction strategy
Dim Parser As iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor = New Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor(strategy)
Dim Loclist As System.Collections.ICollection 'all the matches
Dim Location As iText.Kernel.Pdf.Canvas.Parser.Listener.IPdfTextLocation 'one match
Dim CoordFile As New System.IO.StreamWriter(OutputFileName) 'initiate output stream
Dim TextString As String
Dim L, B, W, H As Single ' Left, bottom, width & height of the rectangle containing the extracted text
Dim pg As Integer = 0 'number of current page, number of matches in page, total number of matches
Do While pg < pdfDoc.GetNumberOfPages 'loop thru document pages
pg += 1
Parser.ProcessPageContent(pdfDoc.GetPage(pg)) 'parse page
Loop
Loclist = strategy.GetResultantLocations
If Loclist.Count = 0 Then Exit Sub
For Each Location In Loclist
L = Location.GetRectangle.GetLeft
B = Location.GetRectangle.GetBottom
W = Location.GetRectangle.GetWidth
H = Location.GetRectangle.GetHeight
TextString = Location.GetText
pg = Location.GetPageNumber
CoordFile.WriteLine(TextString & Chr(9) & L & Chr(9) & B & Chr(9) & W & Chr(9) & H & Chr(9) & pg & Chr(9) & InputFileName)
Next Location
'Finished processing
pdfDoc.Close() 'close pdf
CoordFile.Close() 'close output file
End Sub
I am getting the rectangle coordinates OK, and the matched text string, but location.GetPageNumber is always 0
What am I doing wrong?

Answer 1

Here is a workaround I used.
I re-initiate the strategy object and the parser object every page, and also output the locations matched by the Regex pattern per page.
That way I can use the pg counter of my own While loop instead of the one [not] given by the .PageNumber method:
Private Sub Main() 'the main processing routine
'Sub assumes that the PDF document (pdfDoc) and the output file (CoordFile) --both module level object-- are open and available
Dim Location As iText.Kernel.Pdf.Canvas.Parser.Listener.IPdfTextLocation
Dim TextString As String
Dim L, B, W, H As Single ' Left, bottom, width & height of the rectangle containing the extracted text
Dim pg As Integer = 0 'number of current page, number of matches
Dim N As Integer = 0
Do While pg < pdfDoc.GetNumberOfPages 'loop thru document pages
pg += 1
Dim strategy As New iText.Kernel.Pdf.Canvas.Parser.Listener.RegexBasedLocationExtractionStrategy(RegexPattern) 'extraction strategy (RegexPattern is a module variable)
Dim Parser As iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor = New Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor(strategy)
Parser.ProcessPageContent(pdfDoc.GetPage(pg)) 'parse page
If strategy.GetResultantLocations.Count > 0 Then
For Each Location In strategy.GetResultantLocations
TextString = Location.GetText
L = Location.GetRectangle.GetLeft
B = Location.GetRectangle.GetBottom
W = Location.GetRectangle.GetWidth
H = Location.GetRectangle.GetHeight
CoordFile.WriteLine(TextString & Chr(9) & L & Chr(9) & B & Chr(9) & W & Chr(9) & H & Chr(9) & pg)
N += 1
Next Location
End If
strategy.GetResultantLocations.Clear() 'dispose loclist
Loop
'Finished processing
pdfDoc.Close()
CoordFile.Close() 'close output file
End Sub
... not elegant but it works...