globally detecting mouse pressed

Question

I do

 for (; ; ) {
                if (System.Windows.Input.Mouse.LeftButton == System.Windows.Input.MouseButtonState.Pressed)
                {
                    MessageBox.Show("hgg");
                }
            }

It is not uesponding to mouse button press.

HOW can I find globally if mouse button is being pressed?

Answer 1

If you mean in the whole system, you can use a WH_MOUSE_LL hook

A test with a Beep for Left Button =>
(add using System.Runtime.InteropServices; at beginning)

public partial class Form1 : Form
{
    public delegate int HookProc(int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("User32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

    [DllImport("User32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern bool UnhookWindowsHookEx(int idHook);

    [DllImport("User32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern int CallNextHookEx(int idHook, int nCode, IntPtr wParam, IntPtr lParam);

    public const int WH_MIN = (-1);
    public const int WH_MSGFILTER = (-1);
    public const int WH_JOURNALRECORD = 0;
    public const int WH_JOURNALPLAYBACK = 1;
    public const int WH_KEYBOARD = 2;
    public const int WH_GETMESSAGE = 3;
    public const int WH_CALLWNDPROC = 4;
    public const int WH_CBT = 5;
    public const int WH_SYSMSGFILTER = 6;
    public const int WH_MOUSE = 7;
    public const int WH_HARDWARE = 8;
    public const int WH_DEBUG = 9;
    public const int WH_SHELL = 10;
    public const int WH_FOREGROUNDIDLE = 11;
    public const int WH_CALLWNDPROCRET = 12;
    public const int WH_KEYBOARD_LL = 13;
    public const int WH_MOUSE_LL = 14;
    public const int WH_MAX = 14;
    public const int WH_MINHOOK = WH_MIN;
    public const int WH_MAXHOOK = WH_MAX;

    [StructLayoutAttribute(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct MSLLHOOKSTRUCT
    {
        public System.Drawing.Point pt;
        public int mouseData;
        public int flags;
        public int time;
        public uint dwExtraInfo;
    }

    public const int WM_MOUSEMOVE = 0x0200;
    public const int WM_LBUTTONDOWN = 0x0201;
    public const int WM_LBUTTONUP = 0x0202;
    public const int WM_RBUTTONDOWN = 0x0204;
    public const int WM_RBUTTONUP = 0x0205;


    public Form1()
    {
        //InitializeComponent();
        this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.Form1_FormClosing);
        this.Load += new System.EventHandler(this.Form1_Load);
    }

    private static Label label1;

    private static int hHook = 0;
    private HookProc MouseLLProcedure;  

    private void Form1_Load(object sender, EventArgs e)
    {
        label1 = new Label();
        label1.Size = new Size(100, 32);
        label1.Location = new Point(90, 100);
        label1.BorderStyle = BorderStyle.Fixed3D;
        label1.BackColor = Color.Black;
        label1.ForeColor = Color.Yellow;
        label1.Font = new Font("Arial", 8F, FontStyle.Bold, GraphicsUnit.Point, ((byte)(0)));
        label1.TextAlign = ContentAlignment.MiddleCenter;
        this.Controls.Add(label1);         

        MouseLLProcedure = new HookProc(MouseLLProc);
        hHook = SetWindowsHookEx(WH_MOUSE_LL, MouseLLProcedure, (IntPtr)0, 0);

        this.Text = "Test LL Mouse Hook";
        this.ClientSize = new System.Drawing.Size(300, 260);
        CenterToScreen();
    }

     public static int MouseLLProc(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if ((nCode >= 0))
        {
            MSLLHOOKSTRUCT pMSLLHOOKSTRUCT = new MSLLHOOKSTRUCT();
            pMSLLHOOKSTRUCT = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, pMSLLHOOKSTRUCT.GetType());
            label1.Text = pMSLLHOOKSTRUCT.pt.ToString();

            if (wParam == (IntPtr)WM_LBUTTONDOWN)
            {                   
                Console.Beep(5000, 10);
            }               
        }
        return nCode < 0 ? CallNextHookEx(hHook, nCode, wParam, lParam) : 0;
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        if (hHook != 0)
            UnhookWindowsHookEx(hHook);
    }
}