当用户点击一个键显示消息 [英] displaying a message when the user taps a key

问题描述

下面的代码片断是为了显示当用户键入一个重要的消息。即使在重点不是应用程序。但似乎与下列code中的问题。它不会调用钩链与Windows注册的功能。我想这个问题是 HINSTANCE HINST 。我应该如何修改低于code，这样我能看到该邮件为用户点击一个键。

The following snippet is meant to display the message when the user types a key. Even when the focus is not on the application. But there seems to be a problem with the following code. It doesn't call the function registered in the hook-chain with the windows. I guess the problem is with HINSTANCE hInst. How should I modify the below code so that I am able to see the message as the user taps a key.

// Global Variables
static HHOOK handleKeyboardHook = NULL;
HINSTANCE hInst = NULL;

void TestKeys_setWinHook // i call this function to activate the keyboard hook
  (...) {
    hInst = GetModuleHandle(NULL);
    handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hInst, 0); // LowLevelKeyboardProc should be put in the hook chain by the windows,but till now it doesn't do so.
    printf("Inside function setWinHook !");
}

---

// the following function should be called when the user taps a key.

static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) {
  printf("You pressed a key !\n");
  return CallNextHookEx(handleKeyboardHook, nCode, wParam, lParam);
}

但Windows不会调用函数 LowLevelKeyboardProc 。我不明白其中的道理，但我相信这个问题是与 HINST 中的钩子函数。我该怎么办需要初始化呢？

But the windows doesn't call the function LowLevelKeyboardProc. I don't understand the reason but I am sure that the problem is with hInst in the hook function. How do i need to initialize it ?

到现在为止，输出我看到的是在功能setWinHook！

Till now, output that I see is Inside function setWinHook !

推荐答案

下面是一个LowLevelKeyboardProc的例子。

Here's an example of a LowLevelKeyboardProc.

HHOOK hHook;

LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam);
{
    printf("You pressed a key!\n"); 
    return CallNextHookEx(hHook, nCode, wParam, lParam);
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
  hHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hInstance, 0);
  MSG msg;
  while(GetMessage(&msg, NULL, 0, 0))
  {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
}

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