How to use drag and drop values in list box using .NET Windows C#

Question

I am using list box in my windows C# form.

But, my client asked, Inside the list box all the values should be drag and drop.

No need to use any event like click button to move in top and below.

every time, client want to drag the values and placed where he wants in the list.

How to do this in win c# form...?

Answer 1

A ways is with the Drag List Box feature from Common Controls

A quick test with a ListBox listBox1, to be improved, for example with a User Control :

    public partial class Form1 : Form
    {
        [DllImport("Comctl32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern bool MakeDragList(IntPtr hLB);

        [DllImport("Comctl32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern void DrawInsert(IntPtr handParent, IntPtr hLB, int nItem);

        [DllImport("Comctl32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern int LBItemFromPt(IntPtr hLB, POINT pt, bool bAutoScroll);

        [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern uint RegisterWindowMessage(string lpString);

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public struct DRAGLISTINFO
        {
            public uint uNotification;
            public IntPtr hWnd;
            public POINT ptCursor;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct POINT
        {
            public int X;
            public int Y;

            public POINT(int x, int y)
            {
                this.X = x;
                this.Y = y;
            }
        }

        public const int WM_USER = 0x400;
        public const int DL_BEGINDRAG = (WM_USER + 133);
        public const int DL_DRAGGING = (WM_USER + 134);
        public const int DL_DROPPED = (WM_USER + 135);
        public const int DL_CANCELDRAG = (WM_USER + 136);

        public const int DL_CURSORSET = 0;
        public const int DL_STOPCURSOR = 1;
        public const int DL_COPYCURSOR = 2;
        public const int DL_MOVECURSOR = 3;

        uint nMessage = 0;
        int nDragItem = -1;
        string sDragItem = null;

        public Form1()
        {
            InitializeComponent();
            bool bRet = MakeDragList(listBox1.Handle);
            if (bRet)
            {
                nMessage = RegisterWindowMessage("commctrl_DragListMsg");
            }
        }

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == nMessage)
            {                
                DRAGLISTINFO dli = (DRAGLISTINFO)Marshal.PtrToStructure(m.LParam, typeof(DRAGLISTINFO));
                if (dli.uNotification == DL_BEGINDRAG)
                {
                    nDragItem = LBItemFromPt(listBox1.Handle, dli.ptCursor, true);
                    sDragItem = listBox1.Items[nDragItem].ToString();
                    m.Result = (IntPtr)1;
                }
                else if (dli.uNotification == DL_DRAGGING)
                {
                    int nItem = LBItemFromPt(listBox1.Handle, dli.ptCursor, true);
                    if (nItem != -1)
                    {
                        DrawInsert(m.HWnd, listBox1.Handle, nItem);
                    }
                    if (nItem != -1)
                        m.Result = (IntPtr)DL_MOVECURSOR;
                    else
                        m.Result = (IntPtr)DL_STOPCURSOR;
                }
                else if (dli.uNotification == DL_CANCELDRAG)
                    DrawInsert(m.HWnd, listBox1.Handle, -1);
                else if (dli.uNotification == DL_DROPPED)
                {
                    int nItem = LBItemFromPt(listBox1.Handle, dli.ptCursor, true);
                    if (nItem != -1)
                    {
                        DrawInsert(m.HWnd, listBox1.Handle, -1);
                        if (nDragItem != nItem)
                        {                           
                            if (nItem >= nDragItem)
                            {
                                listBox1.Items.RemoveAt(nDragItem);
                                listBox1.Items.Insert(nItem - 1, sDragItem);
                                listBox1.SelectedIndex = nItem - 1;
                            }
                            else
                            {
                                listBox1.Items.RemoveAt(nDragItem);
                                listBox1.Items.Insert(nItem, sDragItem);
                                listBox1.SelectedIndex = nItem;
                            }
                        }
                    }
                    nDragItem = -1;
                    DrawInsert(m.HWnd, listBox1.Handle, -1);
                    m.Result = (IntPtr)DL_CURSORSET;
                }
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            for (int x = 1; x <= 50; x++)
            {
                listBox1.Items.Add("Item " + x.ToString());
            }
        }
    }