Inactive window in response to the practice of rolling papers mouse

Basics

Hook (HOOK), is a platform for Windows message handling mechanism, the application can set a hook, to monitor a specified window of some kind of message when the message arrives, deal with it before being processed target window, the window can be monitored other the process of being created.

Specific in-depth knowledge, can refer to this article Windows Hook Hook comprehensive summary

Hook according to the range to intercept the message can be divided into

• Global hook, a message thread will block all the windows
• Thread the hook, it will only block specific thread message

Related interface function introduction:

HHOOK SetWindowsHookEx(
  int       idHook,  //钩子类型,如 WH_MOUSE_LL, WH_MOUSE
  HOOKPROC  lpfn,    //拦截回调函数
  HINSTANCE hmod,    // dll句柄
  DWORD     dwThreadId // 线程Id，当为0时表示全局钩子
);

This function is used to install the hook. Global hook to intercept the other thread message, must be triggered by the dll callback function, improper handling causing system crashes, not recommended for novice to use, it is recommended to use the thread hook.

In this demand, we focus on the mouse hook, hook the mouse following two:

• WM_MOUSE: ordinary mouse hook, hook can intercept mouse events where the module.
• WM_MOUSE_LL: low-level mouse hook can intercept mouse events of the entire system.

In the current scenario, we use WM_MOUSEthe hook can be. Note that the WM_MOUSE_LLhook can only be applied to the global hook type, to monitor the specified thread, the injection stage will be prompted to 1429 error, error information 此挂接程序只可整体设置.

LRESULT CALLBACK MouseProc(
  _In_ int    nCode,
  _In_ WPARAM wParam,
  _In_ LPARAM lParam
);

This function defines the interface mouse hook callback function,

LRESULT CallNextHookEx(
  HHOOK  hhk,
  int    nCode,
  WPARAM wParam,
  LPARAM lParam
);

This function is used to hook a hook information is passed to the next in the chain hook current.

BOOL UnhookWindowsHookEx(
  HHOOK hhk
);

This function is used to uninstall the hook.

The overall design

The overall design of this function is as follows:

The key functions of the business logic of two things:

• Registration mouse hook
• Intercepting a message converted message to the roller

Registration mouse hook

Registration WM_MOUSEmouse hook type enough, note that here, for the official document WM_MOUSEcallback function prototype types of messages are:

LRESULT CALLBACK MouseProc(
    _In_ int    nCode,
    _In_ WPARAM wParam,
    _In_ LPARAM lParam
);

Representative mouse wParam message identifier, e.g., WM_MOUSEWHEEL, WM_MOUSEMOVEand the like.

Representative lParam pointing mouse callback message type of structure MOUSEHOOKSTRUCT, the structure declaration is as follows:

typedef struct tagMOUSEHOOKSTRUCT {
  POINT     pt;
  HWND      hwnd;
  UINT      wHitTestCode;
  ULONG_PTR dwExtraInfo;
} MOUSEHOOKSTRUCT, *LPMOUSEHOOKSTRUCT, *PMOUSEHOOKSTRUCT;

From the above structure, we are concerned about is pt (based on the current mouse position coordinates of the screen coordinate system), also need to have a mouse wheel to scroll the distance, after some search, I found two places have the parameters:

• Low-level mouse hook (WM_MOUSE_LL) callback function lParam, the type MSLLHOOKSTRUCT, the following statement:

typedef struct tagMSLLHOOKSTRUCT {
  POINT     pt;
  DWORD     mouseData;
  DWORD     flags;
  DWORD     time;
  ULONG_PTR dwExtraInfo;
} MSLLHOOKSTRUCT, *LPMSLLHOOKSTRUCT, *PMSLLHOOKSTRUCT;

When intercepted message to the mouse wheel, mouseDatathe high-order byte represents the distance the mouse wheel. But low-level hooks need global hooks, not suitable for use.

• Common message callback hook structure extension MOUSEHOOKSTRUCTEX, the explanation MSDN:

This is an extension of the MOUSEHOOKSTRUCT structure that includes information 
about wheel movement or the use of the X button.

typedef struct tagMOUSEHOOKSTRUCTEX {
  DWORD mouseData;
} MOUSEHOOKSTRUCTEX, *LPMOUSEHOOKSTRUCTEX, *PMOUSEHOOKSTRUCTEX;

Obviously, this structure is to expand on the general message structure, the expansion of the mouseDatafield, exactly what we need.

Intercepting a message converted message to the roller

According to the above analysis, we need to do now is to convert the message as an ordinary roller wheel hook message.

The document MSDN understood, the wParam roller hook mouse message is a message identifier, such as WM_MOUSE_WHEEL like. lParam roller hook message is converted as follows:

    MOUSEHOOKSTRUCTEX const &eventInfo = *(MOUSEHOOKSTRUCTEX*)lParam;
    // eventInfo.mouseData  <-- 鼠标滚轮距离
    // eventInfo.pt         <-- 鼠标当前坐标

By GET_WHEEL_DELTA_WPARAMmacro from the mouseDataextraction wheel scrolling distance members, ordinary message roller WM_MOUSEWHEELwParam except roller scrolling distance, further comprising a low byte virtual key message. The hook is no message, it also complement the virtual key messages need to use this step GetAsyncKeyStatefunction.

The final step, is based on the current mouse coordinates, obtain current location window handle, Windows provides WindowFromPointfunctions to achieve this function.

This, based on the hook to achieve a non-active window scroll mouse response function points have all been introduced completed.

demo reference links

Overload message preprocessing implementation

Another way to find online, see the non-active window in response to the mouse wheel

The core idea is to use the current mouse wheel messages received in PreTranslateMessageinterception, the processing directly to the window at the current mouse-over position. This solution is very simple, but the problem may be caused by, the mouse will send a message to a window created by a non-current thread, there may be a problem, need more testing.

summary

Both implementations are given more ideas for your reference.

Experience: In this world, if you do one kind of thing, only one way, it would be too boring.