ACMDM_DRIVER_ABOUT

This message requests an ACM driver to display its About dialog box.

Parameters

dwDriverID

Specifies a driver instance identifier. The driver returns this value in response to the ACM_Open function.

hDriver

Handle to a driver.

uMsg

Specifies this message.

lParam1

Contains a validated window handle, which the driver should use to specify the parent window for the About dialog box. The value also can be -1L.

lParam2

Not used.

Return Values

MMSYSERR_NOERROR indicates success. Otherwise, the driver returns one of the MMSYSERR error values declared in the Mmsystem.h header file or one of the ACMERR error values declared in the Msacm.h header file. If the driver does not provide an About dialog box, it returns MMSYSERR_NOTSUPPORTED.

Remarks

The ACM (Waveapi.dll) sends this message by calling the ACM driver’s ACM_IOControl function entry point through the DeviceIoControl function.

If an ACM driver provides an About dialog box, it displays the box in response to this message. If an ACM driver does not provide an About dialog box, it returns MMSYSERR_NOTSUPPORTED. In the latter case, the ACM displays a default About dialog box.

However, if lParam1 is –1L, the driver does not display its About dialog box. Instead, it returns MMSYSERR_NOERROR if it provides an About dialog box and MMSYSERR_NOTSUPPORTED if it does not provide an About dialog box.

For more information, see the Microsoft Windows NT DDK.