在C#中使用setwindowshookex: wparam和lparam设置鼠标挂钩总是返回常量

using System;
using System.Runtime.InteropServices;

public class MouseHookExample
{
    private const int WH_MOUSE_LL = 14;
    private const int WM_LBUTTONDOWN = 0x0201;

    private delegate IntPtr LowLevelMouseProc(int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelMouseProc lpfn, IntPtr hMod, uint dwThreadId);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool UnhookWindowsHookEx(IntPtr hhk);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

    [StructLayout(LayoutKind.Sequential)]
    private struct POINT
    {
        public int x;
        public int y;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct MSLLHOOKSTRUCT
    {
        public POINT pt;
        public uint mouseData;
        public uint flags;
        public uint time;
        public IntPtr dwExtraInfo;
    }

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0 && wParam == (IntPtr)WM_LBUTTONDOWN)
        {
            MSLLHOOKSTRUCT hookStruct = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));
            Console.WriteLine("Left button down at: " + hookStruct.pt.x + ", " + hookStruct.pt.y);
        }

        return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam);
    }

    public static void Main()
    {
        LowLevelMouseProc proc = HookCallback;
        IntPtr hookId = SetWindowsHookEx(WH_MOUSE_LL, proc, IntPtr.Zero, 0);

        // Do some work...

        UnhookWindowsHookEx(hookId);
    }
}