NAME

ACheckEvent − get first event found in audio event queue

SYNOPSIS

#include <Alib.h> Bool
ACheckEvent (

Audio ∗  audio,

AEvent ∗  event_return,

long ∗  status_return );

DESCRIPTION

ACheckEvent() dequeues and returns the first event in the queue and returns TRUE.  If the queue is empty, the function returns FALSE immediately. This behavior contrasts with APeekEvent(), which finds but does not dequeue the first event on the queue, and which blocks, if the queue is empty, until an event is received. 

audio specifies the Audio structure associated with this connection. 

event_return receives the first event found in the queue. 

status_return receives the returned status of the operation, unless this parameter is passed in as a NULL pointer.  If status_return is set to NULL, Alib will do the error handling. 

RETURN VALUE

Upon successful completion, ACheckEvent() returns TRUE or FALSE. 

ERRORS

If status_return is not set to NULL, it can return one of the following values:

0  AENoError No error - the call completed successfully. 

2  AEBadAudio The audio structure is invalid.  A pointer to a valid audio structure may be missing (use AOpenAudio() to get a valid pointer). 

EXAMPLE

The following example sets up event_return to receive event data and status to receive status data. 

Boolean first_event;  /∗ first event on queue ∗/

Audio ∗ audio;  /∗ audio connection ∗/

AEvent event_return;  /∗ event_return ∗/

long status;  /∗ error status ∗/
.
.
.

/∗ check event queue ∗/

first_event = ACheckEvent(audio, &event_return, &status);

NOTE

In order to ensure that the compiler finds the Audio Library (libAlib.sl) and the Alib.h header file, you must add the following switches:

-L /opt/audio/lib
-I/opt/audio/include

DEPENDENCIES

This function belongs to the Audio Library of functions that manage connections to an audio server.  The audio server must run on a system that has audio hardware. To find out whether or not your system has audio hardware, refer to Using the Audio Developer’s Kit or the online help for the Audio control panel.  For information about the audio capabilities of a particular system use the online example audioinfo.c. 

AUTHOR

ACheckEvent() was developed by HP. 

SEE ALSO

ACheckMaskEvent(3X), AEventsQueued(3X), AMaskEvent(3X), ANextEvent(3X), APeekEvent(3X), APutBackEvent(3X), AQLength(3X), ASelectInput(3X). 

Hewlett-Packard Company  —  Audio Library: February, 1995