How to detect "outer" key presses in C#?

Question

I'm making a simple application in C# , with Microsoft Visual Studio.

The application makes the cursor move to a point (out of form window) and clicks a number of times. I start the clicking loop by pressing X. So if you are interested the code looks like :

public void Wait(int milliseconds)
        {
            System.Threading.Thread.Sleep(milliseconds);
        }

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern void mouse_event(int dwFlags, int dx, int dy, int cButtons, int dwExtraInfo);

        public const int MOUSEEVENTF_LEFTDOWN = 0x02;
        public const int MOUSEEVENTF_LEFTUP = 0x04;
        public const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        public const int MOUSEEVENTF_RIGHTUP = 0x10;

        public void MouseClick(Point pos, int click = 0)
        {
            int x = pos.X;
            int y = pos.Y;
            //MessageBox.Show("clicking mouse on " + pos.ToString());

            if (click == 1)
            {
                mouse_event(MOUSEEVENTF_RIGHTDOWN, x, y, 0, 0);
                mouse_event(MOUSEEVENTF_RIGHTUP, x, y, 0, 0);
            }
            else
            {
                mouse_event(MOUSEEVENTF_LEFTDOWN, x, y, 0, 0);
                mouse_event(MOUSEEVENTF_LEFTUP, x, y, 0, 0);
            }
        }

        public void MouseMove(int x, int y)
        {
            MouseMove(new Point(x,y));
        }

        public void MouseMove(Point target)
        {
            Cursor.Position = target;
        }

        private void Form1_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.A)
            {
                MessageBox.Show(Cursor.Position.ToString());
            }
            MouseMove(42, 42);

            if (e.KeyCode == Keys.X)
            {
                MessageBox.Show(Cursor.Position.ToString());            
                Wait(42);
                Random r = new Random();
                for (int i = 0; i < number_of_times ; i++)
                {
                    Wait(r.Next(42));
                    MouseClick(Cursor.Position);
                }

            }

        }

But, as you can see, once the clicking starts, the form goes back (not visible in the screen), so it cannot detect keypresses. So how can I stop the clicking loop ? If I do Ctrl + Alt + Del, it pauses, then I open the task manager but the clicking goes on.

Maybe a way to detect ctrl alt del? or any other keypress, when the window is down?

Thanks for any help !

Answer 1

Take a look at the following article: Low-Level Keyboard Hook in C#.

Also, here is a code example: https://gist.github.com/Ciantic/471698.

A global hotkey might be a good solution: http://bloggablea.wordpress.com/2007/05/01/global-hotkeys-with-net/