qread Subroutine

GL3.2 for AIX: Graphics Library (GL) Technical Reference

qread Subroutine

Purpose

Reads the first entry in the event queue.

Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

Int32 qread(Int16 *data)

FORTRAN Syntax

INTEGER*4 FUNCTION QREAD(data)
INTEGER*2 data

Description

The qread subroutine returns the first entry on the event queue. If the event queue is empty, the qread subroutine blocks. That is, this subroutine does not return until an event occurs. If the event queue is not empty, the qread subroutine returns the device number associated with the first event in the queue, writes the associated data into the data parameter, and removes that entry from the queue.

Note: This subroutine cannot be used to add to a display list.

Parameter

data

Specifies a pointer to the variable that is to receive the data in the event queue.

Return Value

The identifier for the device read.

Example

The example C language program scrn_rotate.c uses the qread subroutine to read input from the event queue.

Implementation Specifics

This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.

Files

/usr/include/gl/gl.h	Contains C language constant and variable type definitions for GL.
/usr/include/gl/fgl.h	Contains FORTRAN constant and variable type definitions for GL.
/usr/include/gl/device.h	Contains C language constant and variable type definitions for GL.
/usr/include/gl/fdevice.h	Contains FORTRAN constant and variable type definitions for GL.

Related Information

Enabling an input device for event queuing with the qdevice subroutine.

Disabling an input device for event queuing with the unqdevice subroutine.

AIX Graphics Library Overview and Controlling Queues and Devices.