Printing with Formatting in VB .NET

Thursday May 4th 2006 by Jereme Guenther

Learn about a printing class that allows text to be formatted at the character level.


Here is a quick summary for those who just want the code and don't want to read the history. I have searched all over the Web for good printing code and was unable to find it. I have created a printing class that allows text to be formatted at the character level. It has taken me about a week to get what I have working correctly and I thought it would be nice to save others the time.

The Long Version

Now, for those who would like the longer version of the story. I was recently tasked with creating a Web application that would allow printing to be initiated without the irritation of having to respond to successive prompts. I chose ASP.NET for this project, not only because it is replacing traditional ASP but also because I had had experience with printing in prior versions of MS VB, which is one of the languages that ASP.NET supports. So, I started browsing the Internet, looking for a printing solution that would fit my needs; unfortunately, I didn't find one. Although I did find multiple solutions that allowed me to print a large block of text, I couldn't find anything that allowed me to control the formatting at the character level as I needed.

Finally, I found a tutorial on formatting each paragraph by placing them separately on the page before it was sent to the printer. Combining this latest find with some of the other tutorials, I went to work to make a class that would let me bold a single character if I chose. From the start, I realized that this class should be as separate from the rest of the program as possible so I could use it in future projects with similar requirements; this resulted in the creation of variables that could be changed through properties of the class object; it also prompted me to use formatting tags in the text to be printed. I chose HTML-style tags because I work a lot with them and I figured they would be easier for me and others to remember and use than proprietary tags. Also, HTML tags seemed uniquely suited for my purpose because people rarely use them when creating an everyday document; this means that my printing class wouldn't pick up a tag where one wasn't meant to be. I do suggest, however, that when utilizing this class you check for the <'s and >'s signifying HTML tags and flag them so the user knows they could be a source of problems.

Through this process, I learned a lot. Here are some of the things I consider to be the most important or obscure. First, when using the OnPrintPage sub of the PrintDocument class, I had trouble understanding how multiple pages were printed because I couldn't find a sendpagetoprinter command. I learned that the PrintDocument class essentially puts the OnPrintPage sub into a while loop as long as e.HasMorePages=True; this means that as soon as your code is finished executing and the sub is done, the sub will start back over again if the HasMorePages value is true. There is no magical sustaining of where in the print job I am or what my variable values are, which means that I have to be sure that my variables scope is set correctly. The other big problem I had was figuring out the coordinates to start each character at considering they will be different if the char is bolded or not. This was resolved when one of the tutorials I looked up showed me how to use the MeasureString function from the Graphics object.

My final challenge came when I needed to make sure that words were not chopped off at the end of a line. To overcome this issue, I ended up putting a kind of memory in my program that allowed it to collect one word's worth of characters before printing them out. To make sure that this word still got printed, I implemented a rollback feature so the code would move to the next line or page and start printing at the position it was rolled back to.

My code is easily modified and shouldn't be too hard to understand. It is well commented. It recognizes the HTML bold tag and a special <ST=> tag that I created to take the place of what tables do in HTML. Paragraphs are separated using vbCrLf and lines will wrap correctly without chopping off a word.

Here is the block of code to instantiate and use the class:

' Create object, passing in text
Dim MyPrintObject As New TextPrint("<B>this will be bold</B>" _
   + vbCrLf + "<ST=400>this will start at 400 pixels", "MyPrinterName")
' Set font, defaults to times new roman, 12 if omitted
MyPrintObject.Font = New Font("Tahoma", 8)
' Issue print command

Here is the actual printing class that does the work:

Public Class TextPrint
   ' Inherits all the functionality of a PrintDocument
   Inherits Printing.PrintDocument
   ' Private variables to hold default font and text
   Private fntPrintFont As Font
   Private strText As String
   Dim MySplitLine As String()
   Dim varStart As Integer = 0
   Dim varChar As Integer = 0

   ' New constructor
   Public Sub New(ByVal Text As String, ByVal pName As String)
      ' Sets the file stream
      varStart = 0
      strText = Text
      MyBase.PrinterSettings.PrinterName = pName
     ' This is the key line for setting the printer
      MySplitLine = strText.Split(vbCrLf)
   End Sub
   Public Property Text() As String
         Return strText
      End Get
      Set(ByVal Value As String)
         strText = Value
         MySplitLine = strText.Split(vbCrLf)
      End Set
   End Property
   Protected Overrides Sub OnBeginPrint(ByVal ev _
         As Printing.PrintEventArgs)
         ' Run base code
      ' Sets the default font
      If fntPrintFont Is Nothing Then
         fntPrintFont = New Font("Times New Roman", 12, _
                                 FontStyle.Regular, _
      End If
   End Sub
   Public Property Font() As Font
      ' Allows the user to override the default font
         Return fntPrintFont
      End Get
      Set(ByVal Value As Font)
          fntPrintFont = Value
      End Set
   End Property

   Protected Overrides Sub OnPrintPage(ByVal e As _
      ' Provides the print logic for our document

      ' Run base code

      ' Draw the margins (for debugging).
      'e.Graphics.DrawRectangle(Pens.Red, e.MarginBounds)

      Dim the_font As Font = fntPrintFont
      Dim string_format As New StringFormat

      ' Draw the text left justified,
      ' wrap at words, and don't draw partial lines.
      string_format.Alignment   = StringAlignment.Near
      string_format.FormatFlags = StringFormatFlags.LineLimit
      string_format.Trimming    = StringTrimming.Word

      ' Draw some text.
      Dim ymin As Integer = e.MarginBounds.Top
      Dim layout_rect As RectangleF
      Dim text_size As SizeF
      Dim characters_fitted As Integer
      Dim lines_filled As Integer

      ' Prepare the fixed spacing for each character
      Dim fixedSpace As SizeF = e.Graphics.MeasureString("W", the_font)

      Static i As Integer
      For i = varStart To MySplitLine.GetUpperBound(0)
         ' get ready for the 1 char printing
         Dim smallArray As String(,)
         Dim xmin As Integer = e.MarginBounds.Left
         Dim varWord As RectangleF()
         ReDim varWord(1)
         Dim wordCountForLine As Integer = 0

         ' make sure a space prints if a two vbcrlf's are in a row
         If Trim(Len(MySplitLine(i))) = 1 Then
            ReDim smallArray(3, 1)
            smallArray(0, 0) = ""
            smallArray(1, 0) = FontStyle.Regular
            smallArray(2, 0) = -1
            ymin += CInt(the_font.Height)
            ' Special print 1 char at a time for formatting
            smallArray = checkBold(Trim(MySplitLine(i).ToString), _
            'END print 1 char at a time for formatting
         End If

         Dim x As Integer
            For x = varChar To smallArray.GetUpperBound(1) - 1
               'remove blanks so ascii works
               If smallArray(0, x).Length = 0 _
                  Then smallArray(0, x) = Chr(0)

               ' Get the font for measurement.
               the_font = New Font(fntPrintFont.Name, _
                  fntPrintFont.Size, _
                  CInt(smallArray(1, x)), fntPrintFont.Unit)

               ' Set the text start location if desired
               If CInt(smallArray(2, x)) > -1 Then xmin = _
                  CInt(smallArray(2, x))

               ' Get the area available for this text.
               layout_rect = New RectangleF(xmin, ymin, _
                  e.MarginBounds.Right - xmin, the_font.Height)

               ' If the layout rectangle's height < 1, make it 1.
               If layout_rect.Height < 1 Then layout_rect.Height = 1

               ' See how big the text will be and
               ' how many characters will fit.
               text_size = e.Graphics.MeasureString(smallArray(0, _
                  x).ToString, the_font, _
                  New SizeF(layout_rect.Width, layout_rect.Height), _
                  string_format, characters_fitted, lines_filled)

               ' See if any characters will fit.
               If characters_fitted > 0 Then
                  ' start accumulating the print location
                  varWord(varWord.GetUpperBound(0) - 1) = layout_rect

                  ' *********Draw the word when finished.*********
                  If Asc(smallArray(0, x).Chars(0)) = 32 _
                     Or x = smallArray.GetUpperBound(1) - 1 Then
                        Dim z As Integer
                        For z = x - (varWord.GetUpperBound(0) - 1) To x
                           ' Get the font for measurement.
                           the_font = New Font(fntPrintFont.Name, _
                              fntPrintFont.Size, CInt(smallArray(1, z)), _
                           ' actually print the character on the page.
                           e.Graphics.DrawString(smallArray(0, z), _
                              the_font, Brushes.Black, _
                              varWord((z - x) + _
                                 (varWord.GetUpperBound(0) - _
                                 1)), string_format)
                     xmin += 4
                     ReDim varWord(0)
                     wordCountForLine += 1
                  End If

                    '' Draw a rectangle around the text (for debugging).
                    'e.Graphics.DrawRectangle(Pens.Green, _
                    '    layout_rect.Left, _
                    '    layout_rect.Top, _
                    '    text_size.Width, _
                    '    text_size.Height)

                    ' Increase the location where we can start.
                    xmin += CInt(text_size.Width) - _
                       (fixedSpace.Width * 0.25)
                    ReDim Preserve varWord(varWord.GetUpperBound(0) + 1)
                ElseIf Asc(smallArray(0, x).Chars(0)) < 30 Then
                   ' make sure to dispose of odd char's in the array
                Else ' See if some of the paragraph didn't fit
                   ' ****Draw the word if longer than one line.******
                   If wordCountForLine = 0 Then
                      varWord(varWord.GetUpperBound(0) - 1) = layout_rect
                      Dim z As Integer
                      For z = x - (varWord.GetUpperBound(0) - 1) To x
                         e.Graphics.DrawString(smallArray(0, z), _
                            the_font, Brushes.Black, _
                            varWord((z - x) + (varWord.GetUpperBound(0) - _
                               1)), string_format)
                     ReDim varWord(0)
                End If

                    '*******reset the variables*********

                    wordCountForLine = 0
                    x -= varWord.GetUpperBound(0)
                    ReDim varWord(1)
                    xmin = e.MarginBounds.Left
                    ymin += CInt(the_font.Height)
                    ' move to the next line
                    'see if there are more lines available
                    If (e.MarginBounds.Bottom - ymin) < the_font.Height Then
                        Exit For   ' exit for loop so page can print
                    End If
                 End If
             ymin += CInt(the_font.Height)   ' move to the next line
            If (e.MarginBounds.Bottom - ymin) < the_font.Height Then
               varChar        = x 'save character location
               varStart       = i 'save line location
               e.HasMorePages = True   'after printing page, run sub again
               Exit For   ' exit for loop so page can print
               varChar = 0
               e.HasMorePages = False
            End If
    End Sub
    Private Function checkBold(ByVal varString As String, _
       ByVal startFont As Font) As String(,)
       Dim aryString As String(,)
       ReDim aryString(3, 1)
       Dim printStyle As FontStyle = FontStyle.Regular
       Dim varStartPlace As Integer = -1

       aryString(0, 0) = "" 'initialize the array to avoid errors
       aryString(1, 0) = printStyle
       aryString(2, 0) = varStartPlace
       Dim varPlace As Integer = 0
       For varPlace = 1 To varString.Length
           If Mid(varString, varPlace, 3) = "<B>" Then
              printStyle = FontStyle.Bold
              varPlace += 2
           ElseIf Mid(varString, varPlace, 4) = "</B>" Then
              printStyle = FontStyle.Regular
              varPlace += 3
           ElseIf Mid(varString, varPlace, 4) = "<ST=" Then
              varStartPlace = CInt(Mid(varString, varPlace + 4, _
                 InStr(varPlace + 4, varString, ">") - (varPlace + 4)))
              varPlace += 4 + varStartPlace.ToString.Length
              ReDim Preserve aryString(3, aryString.GetUpperBound(1) + 1)
              aryString(0, aryString.GetUpperBound(1) - 1) = _
                        Mid(varString, varPlace, 1)
              aryString(1, aryString.GetUpperBound(1) - 1) = printStyle
              aryString(2, aryString.GetUpperBound(1) - 1) = _
              varStartPlace = -1
           End If
        checkBold = aryString

    End Function

End Class

Obviously, there are many enhancements that can be done to it; however, it should be a great start for most programmers.

If you have comments or questions, I monitor this thread: Printing in .NET.

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