Avoid Flickering in Windows Forms?

Question

Double buffering not working with combo-box. is there any another methods to avoid flickering in windows forms?

i have one windows form with number of panels in it.

Answer 1

Yet another solution:

//TODO: Don't forget to include using System.Runtime.InteropServices.

internal static class NativeWinAPI
{
    internal static readonly int GWL_EXSTYLE = -20;
    internal static readonly int WS_EX_COMPOSITED = 0x02000000;

    [DllImport("user32")]
    internal static extern int GetWindowLong(IntPtr hWnd, int nIndex);

    [DllImport("user32")]
    internal static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
}

And your form constructor should look as follows:

public MyForm()
{
    InitializeComponent();

    int style = NativeWinAPI.GetWindowLong(this.Handle, NativeWinAPI.GWL_EXSTYLE);
    style |= NativeWinAPI.WS_EX_COMPOSITED;
    NativeWinAPI.SetWindowLong(this.Handle, NativeWinAPI.GWL_EXSTYLE, style);
}

In the code above, you might change this.Handle to something like MyFlickeringPanel.Handle

You can read a bit more about it here: Extended Window Styles and here: CreateWindowEx.

With WS_EX_COMPOSITED set, all descendants of a window get bottom-to-top painting order using double-buffering. Bottom-to-top painting order allows a descendent window to have translucency (alpha) and transparency (color-key) effects, but only if the descendent window also has the WS_EX_TRANSPARENT bit set. Double-buffering allows the window and its descendents to be painted without flicker.