DriverCallback function (mmiscapi.h)

Calls a callback function, sends a message to a window, or unblocks a thread. The action depends on the value of the notification flag. This function is intended to be used only within the DriverProc function of an installable driver.

Syntax

BOOL DriverCallback(
  DWORD_PTR dwCallback,
  DWORD     dwFlags,
  HDRVR     hDevice,
  DWORD     dwMsg,
  DWORD_PTR dwUser,
  DWORD_PTR dwParam1,
  DWORD_PTR dwParam2
);

Parameters

dwCallback

Address of the callback function, a window handle, or a task handle, depending on the flag specified in the dwFlags parameter.

dwFlags

Notification flags. It can be one of these values:

hDevice

Handle of the installable driver instance.

dwMsg

Message value.

dwUser

32-bit user-instance data supplied by the application when the device was opened.

dwParam1

32-bit message-dependent parameter.

dwParam2

32-bit message-dependent parameter.

Return value

Returns TRUE if successful or FALSE if a parameter is invalid or the task's message queue is full.

Remarks

The client specifies how to notify it when the device is opened. The DCB_FUNCTION and DCB_WINDOW flags are equivalent to the high-order word of the corresponding flags CALLBACK_FUNCTION and CALLBACK_WINDOW specified in the lParam2 parameter of the DRV_OPEN message when the device was opened.

If notification is accomplished with a callback function, hdrvr, msg, dwUser, dwParam1, and dwParam2 are passed to the callback function. If notification is accomplished by means of a window, only msg, hdrvr, and dwParam1 are passed to the window.

Requirements

See also

Driver Functions

Installable Drivers