Change the thumb colour of a trackbar in winforms C#

Question

Hi, is there any way to change the thumb color of the trackbar in Winforms c#?
I've tried the following, but it is not working:

//Created a custom class and added this:
  protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {
            e.Graphics.FillRectangle(Brushes.Orange, ClientRectangle);
        }

Answer 1

You can use Custom Draw

A minimal sample class where I draw it in orange (you can set the colors in properties or use bitmaps instead ) :

    public class TrackBarCustom : TrackBar  
    {  
        public TrackBarCustom()  
        {  
        }  
  
        // custom draw item specs  
        private const int TBCD_TICS = 0x1;  
        private const int TBCD_THUMB = 0x2;  
        private const int TBCD_CHANNEL = 0x3;  
  
        [StructLayout(LayoutKind.Sequential)]  
        public struct NMHDR  
        {  
            public IntPtr hwndFrom;  
            public IntPtr idFrom;  
            public int code;  
        }  
  
        [StructLayout(LayoutKind.Sequential)]  
        public struct RECT  
        {  
            public int left;  
            public int top;  
            public int right;  
            public int bottom;  
        }  
  
        [StructLayout(LayoutKind.Sequential)]  
        public struct NMCUSTOMDRAW  
        {  
            public NMHDR hdr;  
            public int dwDrawStage;  
            public IntPtr hdc;  
            public RECT rc;  
            public IntPtr dwItemSpec;  
            public uint uItemState;  
            public IntPtr lItemlParam;  
        }  
  
        [Flags]  
        public enum CDRF  
        {  
            CDRF_DODEFAULT = 0x0,  
            CDRF_NEWFONT = 0x2,  
            CDRF_SKIPDEFAULT = 0x4,  
            CDRF_DOERASE = 0x8,  
            CDRF_SKIPPOSTPAINT = 0x100,  
            CDRF_NOTIFYPOSTPAINT = 0x10,  
            CDRF_NOTIFYITEMDRAW = 0x20,  
            CDRF_NOTIFYSUBITEMDRAW = 0x20,  
            CDRF_NOTIFYPOSTERASE = 0x40  
        }  
  
        [Flags]  
        public enum CDDS  
        {  
            CDDS_PREPAINT = 0x1,  
            CDDS_POSTPAINT = 0x2,  
            CDDS_PREERASE = 0x3,  
            CDDS_POSTERASE = 0x4,  
            CDDS_ITEM = 0x10000,  
            CDDS_ITEMPREPAINT = (CDDS.CDDS_ITEM | CDDS.CDDS_PREPAINT),  
            CDDS_ITEMPOSTPAINT = (CDDS.CDDS_ITEM | CDDS.CDDS_POSTPAINT),  
            CDDS_ITEMPREERASE = (CDDS.CDDS_ITEM | CDDS.CDDS_PREERASE),  
            CDDS_ITEMPOSTERASE = (CDDS.CDDS_ITEM | CDDS.CDDS_POSTERASE),  
            CDDS_SUBITEM = 0x20000  
        }  
  
        [DllImport("User32.dll", SetLastError = true)]  
        public static extern int FillRect(IntPtr hDC, ref RECT lpRect, IntPtr hBR);  
  
        [DllImport("Gdi32.dll", SetLastError = true)]  
        public static extern IntPtr CreateSolidBrush(int crColor);  
  
        [DllImport("Gdi32.dll", SetLastError = true)]  
        public static extern bool DeleteObject(IntPtr hObject);  
  
        protected override void WndProc(ref Message m)  
        {  
            if (m.Msg == WM_REFLECT + WM_NOFITY)  
            {  
                var pnmhdr = (NMHDR)m.GetLParam(typeof(NMHDR));  
                if (pnmhdr.code == NM_CUSTOMDRAW)  
                {  
                    var pnmlv = (NMCUSTOMDRAW)m.GetLParam(typeof(NMCUSTOMDRAW));  
                    switch (pnmlv.dwDrawStage)  
                    {  
                        case (int)CDDS.CDDS_PREPAINT:  
                            {  
                                m.Result = new IntPtr((int)CDRF.CDRF_NOTIFYITEMDRAW);  
                                break;  
                            }  
  
                        case (int)CDDS.CDDS_ITEMPREPAINT:  
                            {  
                                if (((int)pnmlv.dwItemSpec == TBCD_THUMB))  
                                {   
                                    IntPtr hBrush = CreateSolidBrush(ColorTranslator.ToWin32(Color.Orange));  
                                    FillRect(pnmlv.hdc, ref pnmlv.rc, hBrush);  
                                    DeleteObject(hBrush);  
  
                                    m.Result = new IntPtr((int)CDRF.CDRF_SKIPDEFAULT);  
                                }  
                                else  
                                    m.Result = new IntPtr((int)CDRF.CDRF_NOTIFYPOSTPAINT);  
                                break;  
                            }  
  
                        case (int)CDDS.CDDS_ITEMPOSTPAINT:  
                            {  
                                m.Result = new IntPtr((int)CDRF.CDRF_DODEFAULT);  
                                break;  
                            }  
                    }  
                }  
                return;  
            }  
            else  
                base.WndProc(ref m);  
        }  
  
        private const int NM_FIRST = 0;  
        private const int NM_CLICK = NM_FIRST - 2;  
        private const int NM_CUSTOMDRAW = NM_FIRST - 12;  
        private const int WM_REFLECT = 0x2000;  
        private const int WM_NOFITY = 0x4E;  
    }