c# - C# 中的 SetWindowsHookEx

Question

我正在尝试挂钩第 3 方应用程序，以便我可以在其屏幕上绘图。在屏幕上绘图很容易，我不需要帮助，但我似乎在使用SetWindowsHookExto 处理WH_GETMESSAGE. 我不知道最后两个参数要传递什么。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowDrawer
{
    public partial class Form1 : Form
    {
        private delegate int HookProc(int code, IntPtr wParam, IntPtr lParam);
        static IntPtr hHook;
        IntPtr windowHandle;
        uint processHandle;

        HookProc PaintHookProcedure;     

        [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
        static extern System.IntPtr FindWindowByCaption(int ZeroOnly, string lpWindowName);

        [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SetWindowsHookEx", SetLastError = true)]
        static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, uint dwThreadId);

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

        // When you don't want the ProcessId, use this overload and pass IntPtr.Zero for the second parameter
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

        [System.Runtime.InteropServices.DllImport("kernel32.dll", CharSet =System.Runtime.InteropServices.CharSet.Auto)]
        public static extern IntPtr GetModuleHandle(string lpModuleName);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        { 
            PaintHookProcedure = new HookProc(PaintHookProc);
            windowHandle = FindWindowByCaption(0, "Untitled - Notepad");
            uint threadID = GetWindowThreadProcessId(windowHandle, out processHandle);
            IntPtr hMod = System.Runtime.InteropServices.Marshal.GetHINSTANCE(typeof(Form1).Module);

            // HERE IS THE PROBLEM.  WHAT THE HECK DO I PASS INTO THE LAST 2 PARAMS?  I get a null pointer
            hHook = SetWindowsHookEx(WH_GETMESSAGE, PaintHookProcedure, hMod, threadID);
        }

        public int PaintHookProc(int nCode, IntPtr wParam, IntPtr lParam)
        {
           // Do some painting here.
            return CallNextHookEx(hHook, nCode, wParam, lParam); 
        }

        private const int WM_PAINT = 15;
        private const int WH_GETMESSAGE = 3;
    }
}

score 15 · Accepted Answer

SetWindowsHookEx因此指定了最后两个参数：

hMod

[in] Handle to the DLL containing the hook procedure pointed to by the lpfn parameter. The hMod parameter must be set to NULL if the dwThreadId parameter specifies a thread created by the current process and if the hook procedure is within the code associated with the current process.

dwThreadId

[in] Specifies the identifier of the thread with which the hook procedure is to be associated. If this parameter is zero, the hook procedure is associated with all existing threads running in the same desktop as the calling thread.

I'm not sure you can use a .NET dll in the manner required, but you can certainly try.

Grab hMod via Marshal.GetHINSTANCE(typeof(Form1).Module) and dwThreadId via Process.Threads. Alternatively, set dwThreadId to 0 if you want a global hook (ie. a hook for all GetMessage() calls in the current desktop) but beware of the performance penalties.

score 9 · Accepted Answer

The following suggests this won't work:

"Global hooks are not supported in the .NET Framework. Except for the WH_KEYBOARD_LL low-level hook and the WH_MOUSE_LL low-level hook, you cannot implement global hooks in the Microsoft .NET Framework."

From "How to set a Windows hook in Visual C# .NET"

score 3 · Accepted Answer

我相信您需要 P/InvokeGetModuleHandle并使用它为SetWindowsHookEx. 我也相信0第四个参数是正确的，因为您不想在第三方应用程序中挂钩任何一个特定线程。

如果这对您不起作用，SetWindowsHookEx在 MSDN 上可能会为您指明正确的方向。

score 3 · Accepted Answer

I don't know but if you're using parameter values which specify that you want to, as the API helps says, "inject a DLL into another process", then for all I know it might work only if you write an unmanaged DLL from which to call it.

score 3 · Accepted Answer

I know that this is an old question but I'm hoping that there is still someone who will find this useful. I think that you are mixing up int and IntPtr

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

score 1 · Accepted Answer

This work for me use 13...

 private static IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using (Process curProcess = Process.GetCurrentProcess())
            using (ProcessModule curModule = curProcess.MainModule)
            {
                return SetWindowsHookEx(13, proc,
                GetModuleHandle(curModule.ModuleName), 0);
            }
        }

score 1 · Accepted Answer

  internal enum HookType : uint {
    WH_JOURNALRECORD = 0,
    WH_JOURNALPLAYBACK = 1,
    WH_KEYBOARD = 2,
    WH_GETMESSAGE = 3,
    WH_CALLWNDPROC = 4,
    WH_CBT = 5,
    WH_SYSMSGFILTER = 6,
    WH_MOUSE = 7,
    WH_HARDWARE = 8,
    WH_DEBUG = 9,
    WH_SHELL = 10,
    WH_FOREGROUNDIDLE = 11,
    WH_CALLWNDPROCRET = 12,
    WH_KEYBOARD_LL = 13,
    WH_MOUSE_LL = 14
  }

Global hooks are not supported in the .NET Framework

Except for the WH_KEYBOARD_LL low-level hook and the WH_MOUSE_LL low-level hook, you cannot implement global hooks in the Microsoft .NET Framework.

To install a global hook, a hook must have a native DLL export to inject itself in another process that requires a valid, consistent function to call into. This behavior requires a DLL export.

The .NET Framework does not support DLL exports. Managed code has no concept of a consistent value for a function pointer because these function pointers are proxies that are built dynamically.

Low-level hook procedures are called on the thread that installed the hook. Low-level hooks do not require that the hook procedure be implemented in a DLL.

c# - C# 中的 SetWindowsHookEx

7 回答 7

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