Screen truecolor Ubuntu 18.04 broke
One of the few pieces of software that I compile myself is screen. I've found it tends to support some modern features of terminals better than the version in the repositories. I've been doing this for some time now without too much of an issue. However, on upgrade to 18.04, (true)colors seem to have broken.
I run this bit of code to print a rainbow, which still works in a bare konsole:
awk 'BEGIN{
s="/\/\/\/\/\"; s=s s s s s s s s;
for (colnum = 0; colnum<77; colnum++) {
r = 255-(colnum*255/76);
g = (colnum*510/76);
b = (colnum*255/76);
if (g>255) g = 510-g;
printf "33[48;2;%d;%d;%dm", r,g,b;
printf "33[38;2;%d;%d;%dm", 255-r,255-g,255-b;
printf "%s33[0m", substr(s,colnum+1,1);
}
printf "n";
}'
However, when I start screen, the colors are off. It doesn't appear to have fallen back to 256 colors, but rather, the color values are wrong.
I saw this behavior before any recompilation of screen. After seeing the issue, I recompiled and even nuked my git repo and re-cloned and recompiled to try to get things working, to no avail.
Thoughts on where this has gone wrong? I'm not even sure which library might be responsible for this, or how it might work with konsole but not screen.
The good colors look like this:
The bad colors look like this:
ncurses gnu-screen terminfo termcap
add a comment |
One of the few pieces of software that I compile myself is screen. I've found it tends to support some modern features of terminals better than the version in the repositories. I've been doing this for some time now without too much of an issue. However, on upgrade to 18.04, (true)colors seem to have broken.
I run this bit of code to print a rainbow, which still works in a bare konsole:
awk 'BEGIN{
s="/\/\/\/\/\"; s=s s s s s s s s;
for (colnum = 0; colnum<77; colnum++) {
r = 255-(colnum*255/76);
g = (colnum*510/76);
b = (colnum*255/76);
if (g>255) g = 510-g;
printf "33[48;2;%d;%d;%dm", r,g,b;
printf "33[38;2;%d;%d;%dm", 255-r,255-g,255-b;
printf "%s33[0m", substr(s,colnum+1,1);
}
printf "n";
}'
However, when I start screen, the colors are off. It doesn't appear to have fallen back to 256 colors, but rather, the color values are wrong.
I saw this behavior before any recompilation of screen. After seeing the issue, I recompiled and even nuked my git repo and re-cloned and recompiled to try to get things working, to no avail.
Thoughts on where this has gone wrong? I'm not even sure which library might be responsible for this, or how it might work with konsole but not screen.
The good colors look like this:
The bad colors look like this:
ncurses gnu-screen terminfo termcap
Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56
add a comment |
One of the few pieces of software that I compile myself is screen. I've found it tends to support some modern features of terminals better than the version in the repositories. I've been doing this for some time now without too much of an issue. However, on upgrade to 18.04, (true)colors seem to have broken.
I run this bit of code to print a rainbow, which still works in a bare konsole:
awk 'BEGIN{
s="/\/\/\/\/\"; s=s s s s s s s s;
for (colnum = 0; colnum<77; colnum++) {
r = 255-(colnum*255/76);
g = (colnum*510/76);
b = (colnum*255/76);
if (g>255) g = 510-g;
printf "33[48;2;%d;%d;%dm", r,g,b;
printf "33[38;2;%d;%d;%dm", 255-r,255-g,255-b;
printf "%s33[0m", substr(s,colnum+1,1);
}
printf "n";
}'
However, when I start screen, the colors are off. It doesn't appear to have fallen back to 256 colors, but rather, the color values are wrong.
I saw this behavior before any recompilation of screen. After seeing the issue, I recompiled and even nuked my git repo and re-cloned and recompiled to try to get things working, to no avail.
Thoughts on where this has gone wrong? I'm not even sure which library might be responsible for this, or how it might work with konsole but not screen.
The good colors look like this:
The bad colors look like this:
ncurses gnu-screen terminfo termcap
One of the few pieces of software that I compile myself is screen. I've found it tends to support some modern features of terminals better than the version in the repositories. I've been doing this for some time now without too much of an issue. However, on upgrade to 18.04, (true)colors seem to have broken.
I run this bit of code to print a rainbow, which still works in a bare konsole:
awk 'BEGIN{
s="/\/\/\/\/\"; s=s s s s s s s s;
for (colnum = 0; colnum<77; colnum++) {
r = 255-(colnum*255/76);
g = (colnum*510/76);
b = (colnum*255/76);
if (g>255) g = 510-g;
printf "33[48;2;%d;%d;%dm", r,g,b;
printf "33[38;2;%d;%d;%dm", 255-r,255-g,255-b;
printf "%s33[0m", substr(s,colnum+1,1);
}
printf "n";
}'
However, when I start screen, the colors are off. It doesn't appear to have fallen back to 256 colors, but rather, the color values are wrong.
I saw this behavior before any recompilation of screen. After seeing the issue, I recompiled and even nuked my git repo and re-cloned and recompiled to try to get things working, to no avail.
Thoughts on where this has gone wrong? I'm not even sure which library might be responsible for this, or how it might work with konsole but not screen.
The good colors look like this:
The bad colors look like this:
ncurses gnu-screen terminfo termcap
ncurses gnu-screen terminfo termcap
edited Nov 9 '18 at 0:33
Thomas Dickey
32.1k62861
32.1k62861
asked Jun 12 '18 at 22:03
JamesJames
361414
361414
Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56
add a comment |
Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56
Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56
add a comment |
1 Answer
1
active
oldest
votes
Someone reminded me about this: it is a bug in screen (see source-repo):
tputs(tparm("E[48;2;%d;%d;%dm", _r, _g, _b), 1, DoAddChar);
The problem is that it is using tparm
to process 3 parameters, using termcap syntax. But termcap can only represent 2 parameters. To do this in terminfo the developer should have done something like this:
tputs(tparm("E[48;2;%p1%d;%p2%d;%p3%dm", _r, _g, _b), 1, DoAddChar);
One of ncurses' bug-fixes during 2017 made that slice of code obsolete:
+ improve _nc_tparm_analyze, using that to extend the checks made by
tic for reporting inconsistencies between the expected number of
parameters for a capability and the actual.
GNU screen, by the way, is a termcap application, and mixing in terminfo calls (such as tparm
, which is not a termcap feature) makes it less portable than one might wish. For formatting output, termcap provides only tgoto
, which uses exactly two parameters.
Followup: the suggested improvement was applied 2018/11/18, after some discussion in this bug report.
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
add a comment |
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1 Answer
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1 Answer
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Someone reminded me about this: it is a bug in screen (see source-repo):
tputs(tparm("E[48;2;%d;%d;%dm", _r, _g, _b), 1, DoAddChar);
The problem is that it is using tparm
to process 3 parameters, using termcap syntax. But termcap can only represent 2 parameters. To do this in terminfo the developer should have done something like this:
tputs(tparm("E[48;2;%p1%d;%p2%d;%p3%dm", _r, _g, _b), 1, DoAddChar);
One of ncurses' bug-fixes during 2017 made that slice of code obsolete:
+ improve _nc_tparm_analyze, using that to extend the checks made by
tic for reporting inconsistencies between the expected number of
parameters for a capability and the actual.
GNU screen, by the way, is a termcap application, and mixing in terminfo calls (such as tparm
, which is not a termcap feature) makes it less portable than one might wish. For formatting output, termcap provides only tgoto
, which uses exactly two parameters.
Followup: the suggested improvement was applied 2018/11/18, after some discussion in this bug report.
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
add a comment |
Someone reminded me about this: it is a bug in screen (see source-repo):
tputs(tparm("E[48;2;%d;%d;%dm", _r, _g, _b), 1, DoAddChar);
The problem is that it is using tparm
to process 3 parameters, using termcap syntax. But termcap can only represent 2 parameters. To do this in terminfo the developer should have done something like this:
tputs(tparm("E[48;2;%p1%d;%p2%d;%p3%dm", _r, _g, _b), 1, DoAddChar);
One of ncurses' bug-fixes during 2017 made that slice of code obsolete:
+ improve _nc_tparm_analyze, using that to extend the checks made by
tic for reporting inconsistencies between the expected number of
parameters for a capability and the actual.
GNU screen, by the way, is a termcap application, and mixing in terminfo calls (such as tparm
, which is not a termcap feature) makes it less portable than one might wish. For formatting output, termcap provides only tgoto
, which uses exactly two parameters.
Followup: the suggested improvement was applied 2018/11/18, after some discussion in this bug report.
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
add a comment |
Someone reminded me about this: it is a bug in screen (see source-repo):
tputs(tparm("E[48;2;%d;%d;%dm", _r, _g, _b), 1, DoAddChar);
The problem is that it is using tparm
to process 3 parameters, using termcap syntax. But termcap can only represent 2 parameters. To do this in terminfo the developer should have done something like this:
tputs(tparm("E[48;2;%p1%d;%p2%d;%p3%dm", _r, _g, _b), 1, DoAddChar);
One of ncurses' bug-fixes during 2017 made that slice of code obsolete:
+ improve _nc_tparm_analyze, using that to extend the checks made by
tic for reporting inconsistencies between the expected number of
parameters for a capability and the actual.
GNU screen, by the way, is a termcap application, and mixing in terminfo calls (such as tparm
, which is not a termcap feature) makes it less portable than one might wish. For formatting output, termcap provides only tgoto
, which uses exactly two parameters.
Followup: the suggested improvement was applied 2018/11/18, after some discussion in this bug report.
Someone reminded me about this: it is a bug in screen (see source-repo):
tputs(tparm("E[48;2;%d;%d;%dm", _r, _g, _b), 1, DoAddChar);
The problem is that it is using tparm
to process 3 parameters, using termcap syntax. But termcap can only represent 2 parameters. To do this in terminfo the developer should have done something like this:
tputs(tparm("E[48;2;%p1%d;%p2%d;%p3%dm", _r, _g, _b), 1, DoAddChar);
One of ncurses' bug-fixes during 2017 made that slice of code obsolete:
+ improve _nc_tparm_analyze, using that to extend the checks made by
tic for reporting inconsistencies between the expected number of
parameters for a capability and the actual.
GNU screen, by the way, is a termcap application, and mixing in terminfo calls (such as tparm
, which is not a termcap feature) makes it less portable than one might wish. For formatting output, termcap provides only tgoto
, which uses exactly two parameters.
Followup: the suggested improvement was applied 2018/11/18, after some discussion in this bug report.
edited Nov 25 '18 at 2:07
answered Nov 9 '18 at 0:25
Thomas DickeyThomas Dickey
32.1k62861
32.1k62861
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
add a comment |
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
thanks for the help! glad to see this is working again (based on 30 seconds of testing at least)
– James
Dec 8 '18 at 12:01
add a comment |
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Do you use released versions of GNU Screen, the git master branch or the screen-v4 branch when you compile screen? (Out of curiosity, not related to your issue. :-)
– Axel Beckert
Nov 9 '18 at 8:50
Well, actually, true color support seems only to be in the git master branch, so I assume you're using that one.
– Axel Beckert
Nov 9 '18 at 8:56