double buffering a windows form

  • Thread starter Thread starter Alex Glass
  • Start date Start date
A

Alex Glass

I have read plenty about applying double buffering for animation and self
drawn forms. Is there a way to apply it to a form with many standard
controls on it (textboxes, labels etc) ?? I have tried using
myForm.SetStyles(ControlStyles.DoubleBuffer, True) however it has made no
impact on the drawing operation. Any clarification would be greatly
appreciated

-Alex
 
http://www.bobpowell.net/doublebuffer.htm

Double buffering will only affect the Form.OnPaint method, which you
will have to override if you use the techniques described in the link
above. The controls on your form all have their own OnPaint methods,
which have nothing to do with the form's double buffering. You would
have to implement double buffering on each individual control...
 
I tried implementing double buffering on a single control without success.
Any idea what im missing here? The datagrid no longer paints at all, its
just a black box.

The form event
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
If m_buffer Is Nothing Then
m_buffer = New Bitmap(Me.ClientSize.Width, Me.ClientSize.Height)
dg.Buffer = m_buffer
End If

Dim g As Graphics = Graphics.FromImage(m_buffer)
g.Clear(SystemColors.Control)
g.Dispose()

'Copy the back buffer to the screen

e.Graphics.DrawImageUnscaled(m_buffer, 0, 0)
End Sub

Protected Overrides Sub OnPaintBackground(ByVal pevent As
PaintEventArgs)
'Don't allow the background to paint
End Sub

Protected Overrides Sub OnSizeChanged(ByVal e As EventArgs)
If Not (m_buffer Is Nothing) Then
m_buffer.Dispose()
m_buffer = Nothing
End If

MyBase.OnSizeChanged(e)
End Sub


The derived class
Public Class BufferedDataGrid
Inherits DataGrid

Private m_buffer As Bitmap

Public Property Buffer() As Bitmap
Get
Return m_buffer
End Get
Set(ByVal Value As Bitmap)
m_buffer = Value
End Set
End Property

Public Sub New()
SetStyle(ControlStyles.AllPaintingInWmPaint Or
ControlStyles.UserPaint Or ControlStyles.DoubleBuffer, True)
End Sub

Protected Overrides Sub OnPaint(ByVal pe As
System.Windows.Forms.PaintEventArgs)
If m_buffer Is Nothing Then Return
Dim peArgs As New PaintEventArgs(Graphics.FromImage(m_buffer),
pe.ClipRectangle)
MyBase.OnPaint(peArgs)
End Sub

End Class
 
I'm not sure if you can make a custom drawn DataGrid, but here is an
example of a custom StatusBar that I double-buffered.

public class StatusBarEx : StatusBar
{
private int xBuffer = 4, yBuffer = 4;

public StatusBarEx()
{
InitializeComponent();

//
// TODO: Add constructor logic here
//

this.SetStyle(ControlStyles.DoubleBuffer |ControlStyles.UserPaint |
ControlStyles.AllPaintingInWmPaint |
ControlStyles.ResizeRedraw, true);
}

protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint (e);
Rectangle drawingRect = new Rectangle(new Point(xBuffer, yBuffer),
new Size(this.ClientRectangle.Width - xBuffer,
this.ClientRectangle.Height - yBuffer));
e.Graphics.DrawString(this.Text, this.Font, new
SolidBrush(Color.DimGray), drawingRect);
}

private void InitializeComponent()
{
//
// StatusBarEx
//
this.Font = new System.Drawing.Font("Arial", 9.75F,
System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point,
((System.Byte)(0)));

}

protected override void OnTextChanged(EventArgs e)
{
base.OnTextChanged (e);

this.Refresh();
}
 
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