HOWTO: How to Detect Mouse and Mouse Port (107693)

SUMMARY

A Windows-based application can use the GetSystemMetrics() function to determine whether or not a serial mouse is connected to the computer. However, there is no Windows application programming interface (API) to identify the serial port of the computer that the mouse is connected to. Instead, a Windows-based application must use the Inquire() function documented in the Windows Device Driver Kit (DDK). You do not need the the Windows DDK to call the Inquire() function in the MOUSE driver module. Please see "MORE INFORMATION" for details.

Note, however, that the Inquire() function is only part of the Windows DDK and is not a standard Windows SDK API. Because this function may change in future versions of the Windows DDK, care must be taken in using this function in a Windows-based application.

MORE INFORMATION

If GetSystemMetrics() is called with its parameter set to SM_MOUSEPRESENT, it will indicate whether or not a serial mouse is connected. However, no information is provide as to which port of the computer the serial mouse is connected to.

To obtain this information, use the mouse driver function Inquire(), which is documented in the Windows DDK "Device Driver Adaptation Guide" as follows:

   WORD Inquire(lpMouseInfo)
   LPMOUSEINFO lpMouseInfo;

The Inquire() function returns information about the mouse hardware.

   Parameter       lpMouseInfo

Points to a MOUSEINFO structure containing information about the mouse hardware that is present, the number of buttons on the mouse, and the rate at which the mouse can issue interrupts.

The MOUSEINFO structure has the following form.

   typedef struct {

     char msExist;
     char msRelative;
     short msNumButtons;
     short msRate;
     short msXThreshold;
     short msYThreshold;
     short msXRes;
     short msYRes;
     short msMouseCommPort;
   } MOUSEINFO, far *LPMOUSEINFO;

Return Value: The return value is the number of bytes actually written into the MOUSEINFO structure.

Comments: The export ordinal for this function is 1.

This function can be called from within a Windows-based application without the presence of the DDK. To call this function, the function address must be retrieved as follows:

   typedef WORD (FAR PASCAL * LPFNINQUIRE) (LPMOUSEINFO);

   HANDLE hMouse;
   LPMOUSEINFO lpMouseInfo;   // far pointer to MOUSEINFO struct
   LPFNINQUIRE lpfnInquire;  // function pointer to Inquire()

         if ((hMouse = GetModuleHandle ("MOUSE")) != NULL)
           lpfnInquire = (LPFNINQUIRE) GetProcAddress(hMouse, "Inquire");

Then, the Inquire() function can be called using the lpfnInquire pointer. The msExist and msMouseCommPort parameters in the MOUSEINFO structure provide the needed information.

Note that the mouse driver is not called MOUSE.DRV on many systems, and therefore it is suggested that GetModuleHandle() is used to obtain the handle to the mouse driver instead of LoadLibrary, which requires the filename of the mouse driver.