Question

I have derived a TabControl with the express purpose of enabling double buffering, except nothing is working as expected. Here is the TabControl code:

class DoubleBufferedTabControl : TabControl {     public DoubleBufferedTabControl() : base()     {         this.DoubleBuffered = true;         this.SetStyle             (                 ControlStyles.UserPaint |                 ControlStyles.AllPaintingInWmPaint |                 ControlStyles.ResizeRedraw |                 ControlStyles.OptimizedDoubleBuffer |                 ControlStyles.SupportsTransparentBackColor,                 false             );     } } 

This Tabcontrol is then set with it’s draw mode as ‘OwnerDrawnFixed’ so i can changed the colours. Here is the custom drawing method:

    private void Navigation_PageContent_DrawItem(object sender, DrawItemEventArgs e)     {         //Structure.         Graphics g = e.Graphics;         TabControl t = (TabControl)sender;         TabPage CurrentPage = t.TabPages[e.Index];          //Get the current tab         Rectangle CurrentTabRect = t.GetTabRect(e.Index);          //Get the last tab.         Rectangle LastTab = t.GetTabRect(t.TabPages.Count - 1);          //Main background rectangle.         Rectangle BackgroundRect = new Rectangle(LastTab.Width, t.Bounds.Y - 4, t.Width - (LastTab.Width), t.Height);          //Tab background rectangle.         Rectangle TabBackgroundRect = new Rectangle(0, LastTab.Y + LastTab.Height, LastTab.Width, t.Bounds.Height - (LastTab.Y + LastTab.Height));          //Set anitialiasing for the text.         e.Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;          //String format for the text.         StringFormat StringFormat = new StringFormat();         StringFormat.Alignment = StringAlignment.Center;         StringFormat.LineAlignment = StringAlignment.Center;          //Fill the background.         g.FillRectangle(Brushes.LightGray, BackgroundRect);         g.FillRectangle(Brushes.Bisque, TabBackgroundRect);          //Draw the selected tab.         if(e.State == DrawItemState.Selected)         {             g.FillRectangle(Brushes.White, e.Bounds);             Rectangle SelectedTabOutline = new Rectangle(e.Bounds.X + 2, e.Bounds.Y + 2, e.Bounds.Width, e.Bounds.Height - 4);             g.DrawRectangle(new Pen(Brushes.LightGray, 4f), SelectedTabOutline);             g.DrawString(CurrentPage.Text, new Font('Arial', 12f, FontStyle.Bold, GraphicsUnit.Point), new SolidBrush(Color.FromArgb(70, 70, 70)), CurrentTabRect, StringFormat);         }         else         {             g.FillRectangle(new SolidBrush(Color.FromArgb(230, 230, 230)), e.Bounds);             g.DrawString(CurrentPage.Text, new Font('Arial', 12f, FontStyle.Regular, GraphicsUnit.Point), Brushes.Gray, CurrentTabRect, StringFormat);         }      } 

All to no avail however, as this control is not double buffered and still flickers when resized.

Any ideas?

Answer 1

If you read the documentation, it says, ‘This member is not meaningful for this control.’ If you want the control to be drawn utilizing double-buffering, you’ll have to implement it yourself. Besides the fact that if you owner-draw the control, you would have to implement double-buffering yourself anyhow.