How can I calculate the number of lines in a text box? - vb.net

Question

I am hoping that someone can help me with a problem I've got at the moment using Compact Framework.Net 2 SP 2.
At the moment I have a UI with a series of text boxes and each textbox displays the contents of a database field. These are shown one beneath another with a scroll bar on the right hand side of the form. Each textbox has a set width which might
I would like to adjust the height each text box based on the number of lines it is holding, the font size and the font in order to avoid using scroll bars on each textbox.
At the moment I am been able to do this in a test application.
Screenshot:
see screenshot for output http://morrislgn.brinkster.net/SO/screenshot.jpg
My code:
'Text used in this example:
'TextBox1qwertyuiop lkjhgfdsazxcvbnm1234567890 TextBo
'x1qwer tyuioplkjhgfdsazxcvb nm1234567890
'qwe
'End of exmaple text.
Me.Textbox2.Text = Me.Textbox1.Text
Dim pobjGraphic As Graphics = Me.Textbox2.Parent.CreateGraphics()
Dim pobjSize As SizeF
'Padding values:
Dim piTop As Int32 = 4 'top of text and top of textbox
Dim piBottom As Int32 = 3 'bottom of text and top of textbox
Dim piLines As Int32 = 0
'Based on the font size chosen by the user, create a font to perform the calculation with.
Dim piFontSize As Single = 10
If Me.CheckBox1.Checked.Equals(True) Then
piFontSize = 6
ElseIf Me.CheckBox2.Checked.Equals(True) Then
piFontSize = 8
ElseIf Me.CheckBox3.Checked.Equals(True) Then
piFontSize = 12
Else
piFontSize = 10
End If
Dim pobjFont As New Font("Tahoma", piFontSize, FontStyle.Regular)
'Calculate the height of one line.
pobjSize = pobjGraphic.MeasureString("HELLO WORLD", pobjFont)
'Value of pobjSize returned: {Width = 71.0 Height = 13.0}
'Calculate the number of lines
Dim b As Bitmap
b = New Bitmap(1, 1, Imaging.PixelFormat.Format32bppRgb)
'Calculate the number of lines required to display the text properly based on the lenght of the text the width of the control.
'Length of text to show divide by the width of the textbox
piLines = Graphics.FromImage(b).MeasureString(Me.Textbox2.Text, pobjFont).Width / Me.Textbox2.Width
'Value of piLines returned: 2
If piLines = 0 Then
piLines = 1
End If
'Calculate the size of the text to be displayed using the margins, height of one line and number of lines.
Me.Textbox2.Height = (pobjSize.Height * piLines) + piTop + piBottom
' value produced: 33 = (13 * 2) + 4 + 3
'set font of text box
Me.Textbox2.Font = pobjFont
Finally, I know this can be achieved using a call to the COREDLL.dll using p/invoke but doing this makes the application crash.
Hi Folks,
Below is the pinvoke code as requested:
<Runtime.InteropServices.DllImport("coredll.dll")> _
Private Function SendMessage( _
ByVal hwnd As IntPtr, ByVal msg As Integer, _
ByVal wParam As Integer, ByVal lParam As Integer) As Integer
End Function
<Runtime.InteropServices.DllImport("coredll.dll")> _
Private Function GetCapture() As IntPtr
End Function
<Runtime.InteropServices.DllImport("coredll.dll")> _
Private Function ReleaseCapture() As Boolean
End Function
Public Function GetNumberOfLines(ByVal ptxtCountBox As TextBox) As Integer
Try
Dim hnd As IntPtr = New IntPtr
ptxtCountBox.Capture = True
' Capture the textbox handle.
hnd = GetCapture()
ptxtCountBox.Capture = False
' Get the count of the lines in the box.
Dim plCount As Integer = SendMessage(ptxtCountBox.Handle, EM_GETLINECOUNT, 0, 0)
' Count the number of return lines as we minus this from the total lines to take.
plCount = plCount - (CharCount(ptxtCountBox.Text, vbCrLf, False))
plCount += RemoveNonASCIIReturns(ptxtCountBox)
ReleaseCapture()
hnd = Nothing
' Return the line count.
Return plCount
Catch ex As Exception
GenerateError(msCLASS_NAME, "GetNumberOfLines", ex.Message.ToString)
End Try
End Function
Thanks,
Morris

Answer 1

I asked a similar question and got an answer that completely satisfied my needs on the subject! Please check out stevo3000's answer from my question:
AutoSize for Label / TextBox in .NET Compact Framework
He referred to these two blog posts that just completely fixed my problem with one swipe!
http://www.mobilepractices.com/2007/12/multi-line-graphicsmeasurestring.html
http://www.mobilepractices.com/2008/01/making-multiline-measurestring-work.html

Answer 2

Think I got to the bottom of this:
Public Function GetNumberOfLines(ByVal pstext As String, ByVal pobjfont As Font, ByVal pobjDimensions As Size) As Decimal
Dim pslines As String() = Nothing
'Used to measure the string to be placed into the textbox
Dim pobjBitMap As Bitmap = Nothing
Dim pobjSize As SizeF = Nothing
Try
Dim psline As String = String.Empty
Dim pilinecount As Decimal = 0.0
'Spilt the text based on the number of lines breaks.
pslines = pstext.Split(vbCrLf)
For Each psline In pslines
'Create a graphics image which is used to work out the width of the text.
pobjBitMap = New Bitmap(1, 1, Imaging.PixelFormat.Format32bppRgb)
pobjSize = Graphics.FromImage(pobjBitMap).MeasureString(psline, pobjfont)
'If the width of the text is less than 1.0 then add one to the count. This would incidcate a line break.
If pobjSize.Width < 1.0 Then
pilinecount = pilinecount + 1
Else
'Based on the dimensions of the text, work out the number of lines. 0.5 is added to round the value to next whole number.
pilinecount = pilinecount + (Round((pobjSize.Width / pobjDimensions.Width) + 0.5))
End If
Next
'If the line count it less than 1 return one line.
If pilinecount < 1.0 Then
Return 1.0
Else
Return pilinecount
End If
Catch ex As Exception
Return 1.0
Finally
If pslines IsNot Nothing Then
Array.Clear(pslines, 0, pslines.Length - 1)
pslines = Nothing
End If
If pobjBitMap IsNot Nothing Then
pobjBitMap.Dispose()
End If
End Try
End Function
Granted, its a bit of a hack but it appears to work ok at the moment! Any observations or comments on how to improve this are more than welcome.
Also, about the p/invoke stuff, discovered the root of the problem, or rather the solution. Upgraded the .Net fx on my device and that appears to have resolved the issue.
Thanks
Morris

Answer 3

Well, I would suggest a sound and smart solution to you.
Here's is the Algorithm:
Use a Label control for reference.
Assign:
• The size of Textbox to the Label.
• The font of Textbox to the Label.
• Autosize-property of Label to be True.
• BorderStyle Property of the Label as of Textbox'.
• MinimumSize Property of Label as original size of the Textbox.
• MaximumSize Property of Label as Width-same as original and Height to be a large multiple the original height.
Assign the Textbox' Text to Label's text.
Now: if the PrefferdHeight-property of Label > Height of the Textbox == True
It's time to increase the height of the Textbox and check the above condition until it’s False.
The Label can be disposed off now.
I have also posted a similar solution in MSDN Forum which can also be checked out:
[http://social.msdn.microsoft.com/Forums/en-US/winforms/thread/03fc8e75-fc13-417a-ad8c-d2b26a3a4dda][1]
Regards.
:)