在实际应用中，我们经常会遇到要打印文本框的情况，自行换行是一个必须解决的首要问题，最初我也不太懂MeasureString这个函数，走了许多弯路，用正则表达式进行单字匹配，执行的效率低效果又不太理想。
后来发贴求解，有一熟手提醒，于是自己写下代码，供后来者学习研究。
'============================================
'Power by：landlordh
'Print richtextbox or mulitline textbox
'============================================
Private intcurrentchar As Integer
Private Sub pdoc_PrintPage(ByVal sender As Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles Pdoc.PrintPage
Try
Dim g As Graphics
g = e.Graphics
Dim pen As New Drawing.Pen(Color.Black, 3)
Dim font As New Font("Arial", 9)
Dim font1 As New Font("Arial", 12)
Dim font2 As New Font("Arial", 10)
Dim intPrintAreaHeight As Integer
Dim intPrintAreaWidth As Integer
intPrintAreaHeight = Pdoc.DefaultPageSettings.PaperSize.Height - Pdoc.DefaultPageSettings.Margins.Top - Pdoc.DefaultPageSettings.Margins.Bottom
intPrintAreaWidth = Pdoc.DefaultPageSettings.PaperSize.Width - Pdoc.DefaultPageSettings.Margins.Left - Pdoc.DefaultPageSettings.Margins.Right
If Pdoc.DefaultPageSettings.Landscape Then
Dim intTemp As Integer = intPrintAreaHeight
intPrintAreaHeight = intPrintAreaWidth
intPrintAreaWidth = intTemp
End If
'Dim intLineCount As Integer = CType((intPrintAreaHeight / font.Height), Integer)
Dim rectPrintingArea As RectangleF = New RectangleF(Pdoc.DefaultPageSettings.Margins.Left, Pdoc.DefaultPageSettings.Margins.Top, intPrintAreaWidth, intPrintAreaHeight)
Dim fmt As StringFormat = New StringFormat(StringFormatFlags.LineLimit)
Dim intLinesFilled As Integer
Dim intCharsFitted As Integer
'draw page title
g.DrawString("主题：" & topic.Text, font1, Brushes.Black, 0, 10)
g.DrawLine(pen, 0, 12 + font1.Height, intPrintAreaWidth, 17 + font1.Height)
g.MeasureString(word.Text.Substring(intcurrentchar), font, New SizeF(intPrintAreaWidth, intPrintAreaHeight), fmt, intCharsFitted, intLinesFilled)
g.DrawString(word.Text.Substring(intcurrentchar), font, Brushes.Black, rectPrintingArea)
intcurrentchar += intCharsFitted
intLineCount += intLinesFilled
g.DrawLine(pen, 0, 12 + font1.Height + intPrintAreaHeight + 6, intPrintAreaWidth, 12 + font1.Height + intPrintAreaHeight + 11)
g.DrawString("Power by：LandlordAspx", font2, Brushes.Black, 625, 12 + font1.Height + intPrintAreaHeight + 12)
'g.DrawString("共(" & Pdoc.PrinterSettings.ToPage & ")页", font2, Brushes.Black, 320, 12 + font1.Height + intPrintAreaHeight + 12)
If intcurrentchar < (word.Text.Length - 1) Then
e.HasMorePages = True
Else
e.HasMorePages = False
intcurrentchar = 0
End If
Catch ex As Exception
MessageBox.Show("系统执行时发生以下错误：" & Chr(10) & "错误源：" & ex.Source.ToString & Chr(10) & "错误信息：" & ex.Message.ToString & Chr(10) & Chr(10) & "请记录错误信息，并与管理员联系。", "系统提示")
End Try
End Sub
Private Sub Printing()
Dim PrintDialog1 As New PrintDialog
PrintDialog1.Document = Pdoc
PrintDialog1.AllowSelection = True
PrintDialog1.AllowPrintToFile = True
PrintDialog1.AllowSomePages = True
PrintDialog1.PrintToFile = False
If PrintDialog1.ShowDialog() = DialogResult.OK Then
Pdoc.Print()
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If Trim(word.Text) <> "" Then
Try
Pdoc.DocumentName = "LandlordAspx RichTextBox打印"
Pdoc.DefaultPageSettings.Margins.Top = 34
Pdoc.DefaultPageSettings.Margins.Bottom = 70
Pdoc.DefaultPageSettings.Margins.Left = 0
Pdoc.DefaultPageSettings.Margins.Right = 18
Printing()
Catch ex As Exception
End Try
End If
End Sub