Block input in hwnd keyboard/mouse input in C++

I'm trying making a program similar to ReWASD, I need to block keyboard/mouse input in app to avoid a conflict between two devices

I tried use functions BlockInput()/SetWindowsHookEx()

The only way to block input (without writing custom drivers) is to use SetWindowsHookEx() keyboard/mouse hooks. Its documentation tells you how to block input for each type of hook:

KeyboardProc callback function

> Return value
>
> Type: LRESULT
>
> If code is less than zero, the hook procedure must return the value returned by CallNextHookEx.
>
> If code is greater than or equal to zero, and the hook procedure did not process the message, it is highly recommended that you call CallNextHookEx and return the value it returns; otherwise, other applications that have installed WH_KEYBOARD hooks will not receive hook notifications and may behave incorrectly as a result. If the hook procedure processed the message, it may return a nonzero value to prevent the system from passing the message to the rest of the hook chain or the target window procedure.

LowLevelKeyboardProc callback function

> Return value
>
> Type: LRESULT
>
> If nCode is less than zero, the hook procedure must return the value returned by CallNextHookEx.
>
> If nCode is greater than or equal to zero, and the hook procedure did not process the message, it is highly recommended that you call CallNextHookEx and return the value it returns; otherwise, other applications that have installed WH_KEYBOARD_LL hooks will not receive hook notifications and may behave incorrectly as a result. If the hook procedure processed the message, it may return a nonzero value to prevent the system from passing the message to the rest of the hook chain or the target window procedure.

MouseProc callback function

> Return value
>
> Type: LRESULT
>
> If nCode is less than zero, the hook procedure must return the value returned by CallNextHookEx.
>
> If nCode is greater than or equal to zero, and the hook procedure did not process the message, it is highly recommended that you call CallNextHookEx and return the value it returns; otherwise, other applications that have installed WH_MOUSE hooks will not receive hook notifications and may behave incorrectly as a result. If the hook procedure processed the message, it may return a nonzero value to prevent the system from passing the message to the target window procedure.

LowLevelMouseProc callback function

> Return value
>
> Type: LRESULT
>
> If nCode is less than zero, the hook procedure must return the value returned by CallNextHookEx.
>
> If nCode is greater than or equal to zero, and the hook procedure did not process the message, it is highly recommended that you call CallNextHookEx and return the value it returns; otherwise, other applications that have installed WH_MOUSE_LL hooks will not receive hook notifications and may behave incorrectly as a result. If the hook procedure processed the message, it may return a nonzero value to prevent the system from passing the message to the rest of the hook chain or the target window procedure.

Note, however, that only a WH_MOUSE hook will tell you the HWND that the mouse input is being sent to. The other hooks do not give you an HWND. The events will go to whichever HWND has the input focus when the events are processed.

Also, none of the hooks tell you the device that is sending the input (if you want to block input from only a specific device), for that you have to use the Raw Input API and coordinate its events with the SetWindowHookEx() hook events (as Raw Input can't block input). See: Combining Raw Input and keyboard Hook to selectively block input from multiple keyboards for details (and gotchas) about doing that.