C++ Win32 键盘事件

问题描述

出于个人兴趣，我正在研究我的击键记录器，昨天问了一个与此相关的问题；While 循环使用大量 CPU.

I am working on my keystroke logger for personal interest and asked a question related to this about yesterday; While loop using a lot of CPU.

该程序的问题在于它占用了太多的 CPU 使用率，人们建议让输入基于键事件.

The issue with the program was that it took too much CPU Usage, and people have suggested to make the inputs key-event based.

由于我是 Win32 API 的新手，所以我尝试寻找参考资料和教程，它们将告诉我如何将键盘输入创建为基于事件而不是基于轮询.但问题是我找不到任何可靠的例子或参考资料，因为对于一个完整的新手来说很难理解.

Since I'm new to the Win32 API, I try to look for references and tutorials that will tell me how to create keyboard inputs as event-based, rather than poll based. But the problems is I could not found any solid examples or references, as it was quite difficult to understand for a complete newbie.

他们中的大多数人都提到基于事件的编程驻留在 GUI 应用程序中，但我希望这个击键记录器应用程序是一个控制台应用程序.

Most of them mentioned that the event-based programming resided in GUI application, yet I want this keystroke logger application to be a console application.

我的两个主要问题是:

• 我可以使用 Win32 API 编写基于事件的控制台按键记录器吗?如果没有，我有哪些选择?

和

• 有没有人有任何参考网站可以帮助我了解如何基于事件捕获击键?

如果需要更多信息，我在 Windows XP 下使用代码块和 GCC 编译器.

If additional information is needed, I am using Code Blocks under Windows XP with a GCC compiler.

推荐答案

按键记录器应用程序使用诸如 Win32 钩子.具体来说，您需要设置一个 WH_KEYBOARD 钩子.

Key logger applications use mechanisms such as Win32 Hooks. Specifically you need to set a WH_KEYBOARD hook.

有一些高级技术，比如创建自己的键盘驱动程序，但对于开始使用钩子是一个不错的选择.

There are move advanced techniques, like creating your own keyboard driver but for a start hooks are a good choice.

为了了解钩子过程的样子，我发布了我个人实用程序中的一个片段.

To get an idea of how a hook procedure looks like, I post a fragment from my personal utility.

// ...
thehook = SetWindowsHookEx( WH_KEYBOARD_LL, hook_proc, hwnd, 0 );
// ...

/**
 *
 *  wParam, one of the: WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN, or WM_SYSKEYUP
    lParam: pointer to a KBDLLHOOKSTRUCT structure

    (*) "The hook procedure should process a message in less time than the
    data entry specified in the LowLevelHooksTimeout value in the following registry key: 
    HKEY_CURRENT_USERControl PanelDesktop 

    The value is in milliseconds. If the hook procedure does not 
    return during this interval, the system will pass the message to the next hook."

 *
 */
LRESULT CALLBACK
hook_proc( int code, WPARAM wParam, LPARAM lParam )
{
  static long ctrl_cnt = 0;
  static bool mmode = false;
  static DWORD time;

  KBDLLHOOKSTRUCT*  kbd = (KBDLLHOOKSTRUCT*)lParam;

  if (  code < 0
  ||   (kbd->flags & 0x10) // ignore injected events
     ) return CallNextHookEx( thehook, code, wParam, lParam );

  long ret = 1; // by default I swallow the keys
  if (  mmode  ) { // macro mode is ON
    if (  WM_KEYDOWN == wParam  )
      PostMessage(mainwnd, WM_MCR_ACCUM, kbd->vkCode, 0);

    if (  WM_KEYUP == wParam  )
      switch (kbd->vkCode) {
        case VK_ESCAPE:
          mmode = false;
          keys.removeall();
          PostMessage(mainwnd, WM_MCR_HIDE, 0, 0);
          break;

        case VK_RETURN:
          PostMessage(mainwnd, WM_MCR_EXEC, 0, 0);
          break;

        case VK_LCONTROL:
          mmode = false;
          PostMessage(mainwnd, WM_MCR_HIDE, 0, 0);
          PostMessage(mainwnd, WM_MCR_EXEC, 0, 0);
          break;
      }

    /* Which non printable keys allow passing? */
    switch( kbd->vkCode ) {
      case VK_LCONTROL:
      case VK_CAPITAL:
      case VK_LSHIFT:
      case VK_RSHIFT:
        ret = CallNextHookEx( thehook, code, wParam, lParam );
    }
  }
  else { // macro mode is OFF
    /* Ctrl pressed */
    if (  kbd->vkCode == VK_LCONTROL && WM_KEYDOWN == wParam  ) {
      ctrl_cnt = 1;
      time = kbd->time;
    }

    /* Prevent ctrl combinations to activate macro mode */
    if (  kbd->vkCode != VK_LCONTROL  )
      ctrl_cnt = 0;

    /* Ctrl released */
    if (  ctrl_cnt == 1 && WM_KEYUP == wParam  ) {
      if (  kbd->time - time > 40  ) {
        mmode = true;
        PostMessage(mainwnd, WM_MCR_SHOW, 0, 0);
      }
    }

    ret = CallNextHookEx( thehook, code, wParam, lParam ); // let it pass
  }

  return ret;
}

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