什么是 SetWindowsHook 的 HOOKPROC 中的 LPARAM？

Question

我想实现击键 (CTRL + KEY)，因此使用 SetWindowsHook (SetWindowsHook(WH_KEYBOARD, hookProcTest)) 来“安装”一个钩子。

正在查看 HOOKPROC

LRESULT CALLBACK hookProcTest(int code, WPARAM wParam, LPARAM lParam)

code参数似乎总是0，wParam匹配虚拟键码，lParam可能是指向包含它是什么键事件的结构的指针。

当我按下一个键、释放一个键或按下另一个键时，lParam 显示出巨大的变化。

我试图将其转换为 LPCWPRETSTRUCT，但这给了我一个垃圾指针（访问成员时程序崩溃）。

那么用的是什么结构呢？

编辑：这是在这里：link

case WM_KEYDOWN:
case WM_KEYUP:
case WM_SYSKEYDOWN:
case WM_SYSKEYUP:
{
    WORD vkCode = LOWORD(wParam);                                       // virtual-key code

    BYTE scanCode = LOBYTE(HIWORD(lParam));                             // scan code
    BOOL scanCodeE0 = (HIWORD(lParam) & KF_EXTENDED) == KF_EXTENDED;    // extended-key flag, 1 if scancode has 0xE0 prefix

    BOOL upFlag = (HIWORD(lParam) & KF_UP) == KF_UP;                    // transition-state flag, 1 on keyup
    BOOL repeatFlag = (HIWORD(lParam) & KF_REPEAT) == KF_REPEAT;        // previous key-state flag, 1 on autorepeat
    WORD repeatCount = LOWORD(lParam);                                  // repeat count, > 0 if several keydown messages was combined into one message

    BOOL altDownFlag = (HIWORD(lParam) & KF_ALTDOWN) == KF_ALTDOWN;     // ALT key was pressed

    BOOL dlgModeFlag = (HIWORD(lParam) & KF_DLGMODE) == KF_DLGMODE;     // dialog box is active
    BOOL menuModeFlag = (HIWORD(lParam) & KF_MENUMODE) == KF_MENUMODE;  // menu is active
    
    // ...
}
break;

lParam 不是结构 - 而是一堆位字段 - 正如 Remy Lebeau 在评论中所述。

Answer 1

lParam 在 KeyboardProc 文档中描述 here。 lParam 在其位中编码重复计数、扫描码、扩展键标志、上下文代码、先前键状态标志和转换状态标志。

Bits Description

0-15 The repeat count. The value is the number of times the keystroke is repeated as a result of the user's holding down the key.

16-23 The scan code. The value depends on the OEM.

24 Indicates whether the key is an extended key, such as a function key or a key on the numeric keypad. The value is 1 if the key is an extended key; otherwise, it is 0.

25-28 Reserved.

29 The context code. The value is 1 if the ALT key is down; otherwise, it is 0.

30 The previous key state. The value is 1 if the key is down before the message is sent; it is 0 if the key is up.

31 The transition state. The value is 0 if the key is being pressed and 1 if it is being released.

什么是 SetWindowsHook 的 HOOKPROC 中的 LPARAM？

What is LPARAM in HOOKPROC for SetWindowsHook?

c

winapi

Bits	Description
0-15	The repeat count. The value is the number of times the keystroke is repeated as a result of the user's holding down the key.
16-23	The scan code. The value depends on the OEM.
24	Indicates whether the key is an extended key, such as a function key or a key on the numeric keypad. The value is 1 if the key is an extended key; otherwise, it is 0.
25-28	Reserved.
29	The context code. The value is 1 if the ALT key is down; otherwise, it is 0.
30	The previous key state. The value is 1 if the key is down before the message is sent; it is 0 if the key is up.
31	The transition state. The value is 0 if the key is being pressed and 1 if it is being released.