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Don't understand where to call MyBase.Paint

Posted on 2006-06-16
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Last Modified: 2010-05-18
Using Windows Forms, .NET 1.1, VS 2003

I understand that you call the base class method in vb.net to do some initializing or setting things up normally before you call your derived method but I am missing something from my understanding
I inherited from a datagridtextboxcolumn and override the paint method to color cells depending on their value etc. The problem I am having is deciding where to call the base paint method as I don't think I really understand.

If I call the paint method in one place, then some cells get colored while others don't, or the formatting gets messed up in one place and not in others. Below is my paint method. I initially got the code online and modified it to do what I want. Basically, I have been calling MyBase.Paint() at different points in my code to get it working but I don't know why. Help.


 Protected Overloads Overrides Sub Paint(ByVal g As Graphics, ByVal bounds As Rectangle, ByVal source As CurrencyManager, ByVal rowNum As Integer, ByVal backBrush As Brush, ByVal foreBrush As Brush, ByVal alignToRight As Boolean)

    Dim e As DataGridFormatCellEventArgs
    e = New DataGridFormatCellEventArgs(rowNum, Me._col, Me.DataGridTableStyle.DataGrid.Font, backBrush, foreBrush)
    RaiseEvent SetCellFormat(Me, e)

    'Note that UseBaseClassDrawing is the property of useBaseClassDrawing private data member
    'It is set to false by default
    If e.UseBaseClassDrawing Then
        MyBase.Paint(g, bounds, source, rowNum, backBrush, foreBrush, alignToRight)
    Else
        g.FillRectangle(e.BackBrush, bounds)
        g.DrawString(Me.GetColumnValueAtRow(source, rowNum).ToString, e.TextFont, e.ForeBrush, bounds.X, bounds.Y)
    End If

    If (e.TextFont Is Me.DataGridTableStyle.DataGrid.Font) = False Then
        e.TextFont.Dispose()
    End If

    Try
        'If the cell value is 0 or less than 0, color it red
        Dim cellVal As String = Me.GetColumnValueAtRow(source, rowNum)
        If (Not cellVal Is Nothing) Then
            Dim c As Integer
            c = CType(cellVal, Integer)
            If (c = 1 Or c < 1) Then
                e.ForeBrush = New SolidBrush(Color.Red)

                MyBase.Paint(g, bounds, source, rowNum, backBrush, e.ForeBrush, alignToRight)
            Else
                MyBase.Paint(g, bounds, source, rowNum, backBrush, e.ForeBrush, alignToRight)
            End If
        End If


        'Check for the cell date value and if less than now, draw lines in the cell
        cellDate = Me.DataGridTableStyle.DataGrid.Item(rowNum, 0)
        If (Not hourMinString Is Nothing) Then
            Dim cellToDisable As Boolean = CellDateLessToday(cellDate, DateTime.Now())
            If (cellToDisable = True) And (_col = 1) Then
                DrawLinesInCell(g, bounds)
            Else
                MyBase.Paint(g, bounds, source, rowNum, e.BackBrush, e.ForeBrush, alignToRight)
            End If
        End If

        'Change the background of the grids to blue to indicate the cell that was
        'clicked in the mousedown event
        If (Me.DataGridTableStyle.DataGrid.CurrentRowIndex = rowNum)_
            And (Me.DataGridTableStyle.DataGrid.CurrentCell.ColumnNumber = _col) And _
            ((rowNum <> 0) And (Me._col <> 0)) Then
            If (cellToDisable = False Or _col <> 1) Then
                e.BackBrush = New SolidBrush(Color.Blue)
                e.ForeBrush = New SolidBrush(Color.White)
                g.FillRectangle(e.BackBrush, bounds)
                'Make the font bigger in the clicked cell
                e.TextFont = New Font("Arial", 24, FontStyle.Bold)
                Dim intX As Integer = bounds.X + (bounds.Width / 3)
                Dim intY As Integer = bounds.Y + (bounds.Height / 4)
                g.DrawString(Me.GetColumnValueAtRow(source, rowNum).ToString, e.TextFont, e.ForeBrush, intX, intY)
                'MyBase.Paint(g, bounds, source, rowNum, e.BackBrush, e.ForeBrush, alignToRight)
            End If
        End If

        'MyBase.Paint(g, bounds, source, rowNum, e.BackBrush, e.ForeBrush, alignToRight)
    Catch ex As Exception
        'Empty catch
    Finally
        'make sure the base class gets called to do the drawing with the possibly
        'changed brushes
        'MyBase.Paint(g, bounds, source, rowNum, e.BackBrush, e.ForeBrush, alignToRight)
    End Try
    'MyBase.Paint(g, bounds, source, rowNum, e.BackBrush, e.ForeBrush, alignToRight)
End Sub
0
Comment
Question by:Sanmarie
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3 Comments
 
LVL 2

Assisted Solution

by:cmjwebservices
cmjwebservices earned 200 total points
ID: 16925927
Some example code on how to do this is to create a seperate class like so (that way it doesn't conflict with the Paint event of the same name):

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Public Class DataGridColoredTextBoxColumn
    Inherits DataGridTextBoxColumn

    Public Sub New()
    End Sub

    Protected Overloads Overrides Sub Paint(ByVal g As Graphics, ByVal bounds As Rectangle, ByVal source As CurrencyManager, ByVal rowNum As Integer, ByVal backBrush As Brush, ByVal foreBrush As Brush, ByVal alignToRight As Boolean)
'Do stuff here
    End Sub

End Class

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

And then use it as follows:

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Private Sub DataGridColoredTextBoxColumnImplementation()
        Dim tbColumn As DataGridColoredTextBoxColumn
        tbColumn = New DataGridColoredTextBoxColumn
        tbColumn .HeaderText = "Description"
        'etc, etc
    End Sub

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I was easily able to reference the class by pasting "Public Class DataGridColoredTextBoxColumn" after the "End Class" of the form I was planning to use it in.  Hope it works for you!

Chris
0
 
LVL 96

Accepted Solution

by:
Bob Learned earned 300 total points
ID: 16934884
Here is an example:

Public Class DataGridColorTextBoxColumn
  Inherits DataGridTextBoxColumn

  Protected Overloads Overrides Sub Paint(ByVal g As Graphics, _
   ByVal bounds As Rectangle, ByVal source As CurrencyManager, _
   ByVal rowNum As Integer, ByVal backBrush As Brush, ByVal foreBrush As Brush, ByVal alignToRight As Boolean)

    Try

      Dim columnValue As Double = Me.GetColumnValueAtRow(source, rowNum)

      If columnValue > 20 Then
        foreBrush = New SolidBrush(Color.Red)
      End If

    Catch ex As Exception

      MessageBox.Show(ex.ToString())

    Finally

      MyBase.Paint(g, bounds, source, rowNum, backBrush, foreBrush, alignToRight)

    End Try

  End Sub

End Class

Bob
0
 

Author Comment

by:Sanmarie
ID: 16937360
Sorry for getting back to you guys so late.

cmjwebservices I tried your approach  and I still had some problems.
Bob, I tried your way and everything worked fine but now my font is messed up. I probably deleted something

Thanks for your help.
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