goer@quads.uchicago.edu (Richard L. Goerwitz) (08/28/90)
Let's say I send the command for reverse video mode, and then the sequence for a screen clear. Is it typical for terminals to clear the screen to normal-mode spaces or reverse video spa- ces? The reason I ask is that, for terminals which permit it, the so+cl approach is the quickest and most reliable to cover the screen in reverse video. If this turns out to be uncommon behavior, I wonder what the best alternative would be. Check for automargins, and if not present, simply write as many reverse video spaces as there are squares on the screen? What if the terminal has auto- matic margins? I feel like I'm missing something obvious. -Richard
gwyn@smoke.BRL.MIL (Doug Gwyn) (08/29/90)
In article <1990Aug28.152155.157@midway.uchicago.edu> goer@quads.uchicago.edu (Richard L. Goerwitz) writes: >Let's say I send the command for reverse video mode, and then >the sequence for a screen clear. Is it typical for terminals >to clear the screen to normal-mode spaces or reverse video spa- >ces? The reason I ask is that, for terminals which permit it, >the so+cl approach is the quickest and most reliable to cover >the screen in reverse video. The clear-display capability is supposed to clear the display to background, not foreground. The inverse-video capability is supposed to affect display of subsequent space-occupying characters, not cleared fields etc.
ajm@icc.com (Al Marmora) (08/30/90)
In article <1990Aug28.152155.157@midway.uchicago.edu> goer@quads.uchicago.edu (Richard L. Goerwitz) writes: >Let's say I send the command for reverse video mode, and then >the sequence for a screen clear. Is it typical for terminals >to clear the screen to normal-mode spaces or reverse video spa- >ces? The reason I ask is that, for terminals which permit it, >the so+cl approach is the quickest and most reliable to cover >the screen in reverse video. Recent vintage System V terminfo supports a "background color erase" (bce) capability for terminals which exhibit this behavior. Unfortunately, as I recall, the System V curses library neglects to take advantage of it.
phys169@canterbury.ac.nz (09/07/90)
In article <1990Aug28.152155.157@midway.uchicago.edu> goer@quads.uchicago.edu (Richard L. Goerwitz) writes: >Let's say I send the command for reverse video mode, and then >the sequence for a screen clear. Is it typical for terminals >to clear the screen to normal-mode spaces or reverse video spa- >ces? The reason I ask is that, for terminals which permit it, >the so+cl approach is the quickest and most reliable to cover >the screen in reverse video. > It is common to clear the reverse video attribute when clearing the screen, certainly in the older style VDU's where the reverse attribute takes up a character position on the screen (most Televideo, ADM, etc screens). Even on screens where there is a hidden bit for reverse video (e.g ANSI, DG) the clear screen often resets the mode at the same time. PC's are the exception. Many screens have a simple method of setting reverse video on the screen as a whole, e.g. the ANSI sequence: ESC [ ? 5 h (on VT200-compatibles, at least). It is ESC b on most Televideo terminals and ESC ^ 1 on a WY99 in native mode. In this mode, any reverse video commands received toggle the individual characters back to normal mode. Note that the ESCAPE b sequence doesn't clear the screen, so you can send ESC b and ESC d alternately to flash the whole screen! Mark Aitchison, Physics, University of Canterbury, New Zealand.