ECHO_TYPE(3G)

NAME

echo_type − change the type of echo being used on an output device.

SYNOPSIS

C Syntax:

void echo_type(fildes,echo_number,echo_value,x,y,z);
int fildes,echo_number,echo_value;
float x,y,z;

void dcecho_type(fildes,echo_number,echo_value,dcx,dcy);
int fildes,echo_number,echo_value,dcx,dcy;

FORTRAN77 Syntax:

subroutine echo_type(fildes,echo_number,echo_value,x,y,z)
integer*4 fildes,echo_number,echo_value
real x,y,z

subroutine dcecho_type(fildes,echo_number,echo_value,dcx,dcy)
integer*4 fildes,echo_number,echo_value,dcx,dcy

Pascal Syntax:

procedure echo_type(fildes,echo_number,echo_value:integer;
x,y,z:real);
procedure dcecho_type(fildes,echo_number,echo_value,dcx,dcy:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor returned by gopen when an I/O path to a graphics device is opened.

echo_number Selects a particular echo to be modified if the graphic device supports more than one simultaneous echo. For devices with single echo outputs, use 0 (zero).

echo_value Type of echo to be used by the device. Predefined types include:

0 No echo

1 Device’s best echo

2 Full screen cross hair

3 Small tracking cross

4 Rubber band line

5 Rubber band rectangle

6 Alpha-digital representation

7 User-defined raster cursor

>= 8 Device-dependent representation

There is no maximum value for echo_value, so if a device does not support any of the above echoes, 1 is used.

x,y,z Define echo position in Virtual Device Coordinates.

dcx,dcy Define echo position in device coordinates.

Discussion

Echo_type defines what type of echo is to be used for the echo number specified and the echo’s initial location. For echo types that use one stationary point and one moving point (such as rubber-band-line echo), this initial position is also used as a stationary (base) point.

The performance of output primitives for most devices is reduced if echo is enabled, so echo should usually be disabled when it is not needed.

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