Flickering in a Windows Forms app

Question

I have an app that has a ton of controls on it. And it has a massive amount of flicker, particularly on startup.

I applied the fix to it.

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.ExStyle |= 0x02000000;   // WS_EX_COMPOSITED
            return cp;
        }
    } 

This worked great - the flickering was reduced by a pretty unbelievable amount. However, the side effect is that the Minimize, Maximize and the Close buttons in the top right of the window don't animate when I move the mouse over or click on them (they still work though). This gives the app a hung feel.

How do I keep the WS_EX_COMPOSITED while still retaining the usability of Maximize, Minimize and Close buttons.

This happens on Wnidows XP. As @fallenidol pointed out, this is not an issue on Windows 7.

Answer 1

Your should try standard windows forms control property called DoubleBuffered. http://msdn.microsoft.com/en-us/library/system.windows.forms.control.doublebuffered.aspx

Answer 2

Try the following code. This should go in the main form and any other custom user controls you have.

        // Enable double duffering to stop flickering.
        this.SetStyle(ControlStyles.DoubleBuffer, true);
        this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
        this.SetStyle(ControlStyles.UserPaint, true);
        this.SetStyle(ControlStyles.SupportsTransparentBackColor, false);
        this.SetStyle(ControlStyles.Opaque, false);
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        this.SetStyle(ControlStyles.ResizeRedraw, true);

Answer 3

I figured it out. The trick is to remove the WS_EX_COMPOSITED flag after the form is shown. The full explanation and code at my blog:

How to get rid of flicker on Windows Forms applications