How to set font size in DateTimePicker

c#, datetime, fonts, picker, winforms

Solution

If you wish to retain visual styles for the other controls in your application, but disable for the date picker's drop down only, you can use the following code:

public class MyDateTimePicker : DateTimePicker
{
    [DllImport("uxtheme.dll", ExactSpelling = true, CharSet = CharSet.Unicode)]
    static extern Int32 SetWindowTheme(IntPtr hWnd, String textSubAppName, String textSubIdList);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr GetParent(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

    protected override void OnDropDown(EventArgs eventargs)
    {
        if (Application.RenderWithVisualStyles)
        {
            const int DTM_GETMONTHCAL = 0x1008;

            //Get handle of calendar control - disable theming
            IntPtr hCalendar = SendMessage(this.Handle, DTM_GETMONTHCAL, IntPtr.Zero, IntPtr.Zero);
            if (hCalendar != IntPtr.Zero)
            {
                SetWindowTheme(hCalendar, "", "");

                //Get handle of parent popup - resize appropriately
                IntPtr hParent = GetParent(hCalendar);
                if (hParent != IntPtr.Zero)
                {
                    //The size you specify here will depend on the CalendarFont size chosen
                    MoveWindow(hParent, 0, 0, 400, 300, true);
                }
            }
        }

        base.OnDropDown(eventargs);
    }
}

Problem

Original source

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