Introduction
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 which 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 created a web application which 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. While I did find multiple solutions which 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 how to format 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 which 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 which could be changed through properties of the class object; it also prompted me to use formatting tags in the text to be printed. I choose the HTML style of 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 which 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 what I consider to be the more important or obscure. First, when using the OnPrintPage sub of the PrintDocument class, I had trouble understanding how multiple pages were printed since 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, then 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 was having 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 which allowed it to collect one words 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.
Code and Description
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
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")
' Set font, defaults to times new roman, 12 if omitted
MyPrintObject.Font = New Font("Tahoma", 8)
' Issue print command
MyPrintObject.Print()
Here is the actual printing class which 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)
' Sets the file stream
MyBase.New()
varStart = 0
strText = Text
MySplitLine = strText.Split(vbCrLf)
End Sub
Public Property Text() As String
Get
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
MyBase.OnBeginPrint(ev)
' Sets the default font
If fntPrintFont Is Nothing Then
fntPrintFont = New Font("Times New Roman", 12, FontStyle.Regular, GraphicsUnit.Point)
End If
End Sub
Public Property Font() As Font
' Allows the user to override the default font
Get
Return fntPrintFont
End Get
Set(ByVal Value As Font)
fntPrintFont = Value
End Set
End Property
Protected Overrides Sub OnPrintPage(ByVal e As Printing.PrintPageEventArgs)
' Provides the print logic for our document
' Run base code
MyBase.OnPrintPage(e)
' 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
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)
Else
'****************************Special print 1 char at a time for formatting*********************************
smallArray = checkBold(Trim(MySplitLine(i).ToString), fntPrintFont)
'******************************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)), fntPrintFont.Unit)
' 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)
Next
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) - 4
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)
Next
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
Next
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
Else
varChar = 0
e.HasMorePages = False
End If
Next
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
Else
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
varStartPlace = -1
End If
Next
checkBold = aryString
End Function
End Class
Conclusion
Obviously there are many enhancements which can be done to this code, however, it should be a great start for most programmers.
For those who are interested in my research and the tutorials I found that helped me with this project, here are the two articles I used:
http://ww
w.vb-helper.com/howto_net_print_long_text.html
eveloper.com/net/asp/article.php/3102381
