SET SCREENMAP

Purpose

Enable or disable automatic screen map control.

Syntax

SET SCREENMAP ON | OFF | (<expL>)

See Also

!, !!, @...SAY, @...MENU, CHR(), MENU, RESTORE SCREEN, RUN, RUN(), SAVE SCREEN, SET ALTERNATE, SET CONSOLE, SET DEVICE, SET MAPCHAR, SET PRINTER, SET SCREENIO, SET SCROLL, SET TBUFSIZE

Description

When SCREENMAP is set ON, an internal map is kept of the contents of the terminal screen. Refreshing only those parts of the screen that need updating optimizes all terminal output. For popup menus to be available, and SAVE/RESTORE SCREEN command to work properly, SCREENMAP should be ON. Note also that when SCREENMAP is ON, all system generated forms (as in BROWSE, APPEND, CHANGE, EDIT, QUERY, CREATE) use screen imaging.

It is recommended that SCREENMAP is left ON unless it specifically needs to be turned OFF, because screen displays are more efficient with SCREENMAP ON.

Any output to the screen from the RUN command or displays of parts of the screen with SCROLL, are not mapped. When using the SET SCROLL command, it is recommended that SCREENMAP is turned OFF.

This command allows the optional logical expression <expL> to be evaluated. If a value of .T. is returned, SCREENAMP is set ON. If a value of .F. is returned, SCREENMAP is set OFF.

NOTE: Because of the screen output optimization performed with SCREENMAP ON, output directed to the printer attached to the terminal will not print correctly. In such a case, you should turn SCREENMAP OFF before printing the report, then set SCREENMAP back ON.

Example

// Program to illustrate use of SET ALTERNATE commands
// ’.txt.’ extension will be assumed
set alternate to alt
? [Write this text to file]
set alternate off
? [Don’t write this text to file]
?
set console off
set screenmap off
set device to print
set alternate on
setprc(0,0)    && set coordinates to 0,0
@1,0 say [write this to file to the file, not to the screen]
close alternate
set console on
set screenmap on
set device to screen
return
// end of program

Products

Recital