Custom Resize Handle in Border-less Form C#

Question

I\'m attempting to make border-less forms that pop out of a tool bar. I want the user to be able to grab at the bottom-right corner (a \"resize handle\") and be able to resi

Answer 1

Anton Semenov, i didn't understand your code.

Anyway, i had a problem with the first code of Charles P,
when i maximize the window and then try to change its size - it is being resized.
after that i couldn't fix it again to its normal size, nor maximize it again with the normal max button.

what i did to fix this problem was adding condition inside the 'foreach' loop at the bottom:

    protected override void WndProc(ref Message m)
    {
        const UInt32 WM_NCHITTEST = 0x0084;
        const UInt32 WM_MOUSEMOVE = 0x0200;

        const UInt32 HTLEFT = 10;
        const UInt32 HTRIGHT = 11;
        const UInt32 HTBOTTOMRIGHT = 17;
        const UInt32 HTBOTTOM = 15;
        const UInt32 HTBOTTOMLEFT = 16;
        const UInt32 HTTOP = 12;
        const UInt32 HTTOPLEFT = 13;
        const UInt32 HTTOPRIGHT = 14;

        const int RESIZE_HANDLE_SIZE = 10;
        bool handled = false;
        if (m.Msg == WM_NCHITTEST || m.Msg == WM_MOUSEMOVE)
        {
            Size formSize = this.Size;
            Point screenPoint = new Point(m.LParam.ToInt32());
            Point clientPoint = this.PointToClient(screenPoint);

            Dictionary boxes = new Dictionary() {
        {HTBOTTOMLEFT, new Rectangle(0, formSize.Height - RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE)},
        {HTBOTTOM, new Rectangle(RESIZE_HANDLE_SIZE, formSize.Height - RESIZE_HANDLE_SIZE, formSize.Width - 2*RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE)},
        {HTBOTTOMRIGHT, new Rectangle(formSize.Width - RESIZE_HANDLE_SIZE, formSize.Height - RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE)},
        {HTRIGHT, new Rectangle(formSize.Width - RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE, formSize.Height - 2*RESIZE_HANDLE_SIZE)},
        {HTTOPRIGHT, new Rectangle(formSize.Width - RESIZE_HANDLE_SIZE, 0, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE) },
        {HTTOP, new Rectangle(RESIZE_HANDLE_SIZE, 0, formSize.Width - 2*RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE) },
        {HTTOPLEFT, new Rectangle(0, 0, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE) },
        {HTLEFT, new Rectangle(0, RESIZE_HANDLE_SIZE, RESIZE_HANDLE_SIZE, formSize.Height - 2*RESIZE_HANDLE_SIZE) }
            };

            foreach (KeyValuePair hitBox in boxes)
            {
                if (this.WindowState != FormWindowState.Maximized 
                    && hitBox.Value.Contains(clientPoint))
                    {
                        m.Result = (IntPtr)hitBox.Key;
                        handled = true;
                        break;
                    }
            }
        }

        if (!handled)
            base.WndProc(ref m);
    }