Rewriting the Textbox

  • Thread starter Thread starter Dave
  • Start date Start date
D

Dave

Hey all,

Ok, here's another of my fun questions. I want to rewrite the textbox
control in VB.NET. I need to implement superscript and subscript
within the box. Don't ask why, but I can't use RTF as my superscript
and subscript's are always numbers and are defined as specific
characters. ie. char(192) = superscript 1

Does anyone know how to inherit and change the onPaint method of the
textbox? I have created my own controlt o try and do this but
apparently the onPaint method is never called:

Public Class SuperTextBox
Inherits TextBox

Protected Overrides Sub OnPaint(ByVal e As
System.Windows.Forms.PaintEventArgs)
Dim sf As New StringFormat
sf.LineAlignment = StringAlignment.Center

e.Graphics.FillRectangle(New SolidBrush(Me.BackColor),
e.ClipRectangle)

Dim strToPrint As String = Me.Text
Dim boundLeft As Integer = e.ClipRectangle.Left

For i As Integer = 0 To strToPrint.Length - 1
If
clsSuperScriptHandler.isSubScript(CChar(strToPrint.Substring(i, 1)))
Then
'subscript
Dim f As New Font(me.Font.FontFamily, _
me.Font.Size - 3, _
Me.Font.Style, _
Me.Font.Unit)

e.Graphics.DrawString(strToPrint.Substring(i, 1), f, _
New SolidBrush(Me.ForeColor), New
RectangleF(boundLeft, e.ClipRectangle.Y + 5, e.ClipRectangle.Width,
e.ClipRectangle.Height), sf)
boundLeft +=
CInt(e.Graphics.MeasureString(strToPrint.Substring(i, 1), f).Width *
0.7)
ElseIf
clsSuperScriptHandler.isSuperScript(CChar(strToPrint.Substring(i, 1)))
Then
'superscript
Dim f As New Font(Me.Font.FontFamily, _
Me.Font.Size - 3, _
Me.Font.Style, _
Me.Font.Unit)

e.Graphics.DrawString(strToPrint.Substring(i, 1), f, _
New SolidBrush(Me.ForeColor), New
RectangleF(boundLeft, e.ClipRectangle.Y - 5, e.ClipRectangle.Width,
e.ClipRectangle.Height), sf)
boundLeft +=
CInt(e.Graphics.MeasureString(strToPrint.Substring(i, 1), f).Width *
0.7)
Else
'normal script
e.Graphics.DrawString(strToPrint.Substring(i, 1),
Me.Font, _
New SolidBrush(Me.ForeColor), New
RectangleF(boundLeft, e.ClipRectangle.Y, e.ClipRectangle.Width,
e.ClipRectangle.Height), sf)
boundLeft +=
CInt(e.Graphics.MeasureString(strToPrint.Substring(i, 1),
Me.Font).Width * 0.7)
End If
Next
End Sub
End Class

Thanks

Dave
 
Dave said:
Hey all,

Ok, here's another of my fun questions. I want to rewrite the textbox
control in VB.NET. I need to implement superscript and subscript
within the box. Don't ask why, but I can't use RTF as my superscript
and subscript's are always numbers and are defined as specific
characters. ie. char(192) = superscript 1

Does anyone know how to inherit and change the onPaint method of the
textbox? I have created my own controlt o try and do this but
apparently the onPaint method is never called:
Click to expand...

You don't say which VB you're using, but one clue that there's going to
be a problem is given in VB2005 when you type "overrides" in your new
class, and OnPaint isn't in the list. After a little wandering through
the docs, I found this:

<http://msdn2.microsoft.com/en-us/library/7h62478z.aspx>
"
Note

Overriding OnPaint will not allow you to modify the appearance of all
controls. Those controls that have all of their painting done by
Windows (for example, TextBox) never call their OnPaint method, and
thus will never use the custom code. Refer to the Help documentation
for the particular control you want to modify to see if the OnPaint
method is available. For a list of all the Windows Form Controls, see
Controls to Use on Windows Forms. If a control does not have OnPaint
listed as a member method, you cannot alter its appearance by
overriding this method. For more information about custom painting, see
Custom Control Painting and Rendering.
"

I'm not sure what the best way to proceed would be; ideally you want to
avoid having to do all the rendering yourself, but I think you may have
to. It's not that hard, just a bit fiddly.
 
I'm not sure what the best way to proceed would be; ideally you want to
avoid having to do all the rendering yourself, but I think you may have
to. It's not that hard, just a bit fiddly.
Click to expand...

Dont suppose you have any examples do you?
 
Add this:

Public Sub New()
MyBase.SetStyle(System.Windows.Forms.ControlStyles.AllPaintingInWmPaint,
True)
MyBase.SetStyle(System.Windows.Forms.ControlStyles.DoubleBuffer, True)
MyBase.SetStyle(System.Windows.Forms.ControlStyles.UserPaint, True)
End Sub

/claes
 
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