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

Answer 1

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

Answer 2

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

Answer 3

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 4

I just came across this post and realize it is a little old. However, I am having the same issue with my form and discovered (for XP, anyway) an inelegant solution seems to be not enabling visual styles.

Answer 5

I know this question is a little old, but better late than never. I used your original example you linked to come up with one that toggles it on when resizing, then toggles it back off to draw everything else perfectly. Hopefully it helps others searching for a solution to this problem. As the OP knows, DoubleBuffering alone properties don't solve flickering issues.

Here's a work-around to stop flickering when a user resizes a form, but without messing up the drawing of controls such as DataGridView, NumericUpDown, etc. Provided your form name is "Form1":

int intOriginalExStyle = -1;
bool bEnableAntiFlicker = true;

public Form1()
{
    ToggleAntiFlicker(false);
    InitializeComponent();
    this.ResizeBegin += new EventHandler(Form1_ResizeBegin);
    this.ResizeEnd += new EventHandler(Form1_ResizeEnd);
}

protected override CreateParams CreateParams
{
    get
    {
        if (intOriginalExStyle == -1)
        {
            intOriginalExStyle = base.CreateParams.ExStyle;
        }
        CreateParams cp = base.CreateParams;

        if (bEnableAntiFlicker)
        {
            cp.ExStyle |= 0x02000000; //WS_EX_COMPOSITED
        }
        else
        {
            cp.ExStyle = intOriginalExStyle;
        }

        return cp;
    }
} 

private void Form1_ResizeBegin(object sender, EventArgs e)
{
    ToggleAntiFlicker(true);
}

private void Form1_ResizeEnd(object sender, EventArgs e)
{
    ToggleAntiFlicker(false);
}

private void ToggleAntiFlicker(bool Enable)
{
    bEnableAntiFlicker = Enable;
    //hacky, but works
    this.MaximizeBox = true;
}