Screen truecolor Ubuntu 18.04 broke












3















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:
good colors



The bad colors look like this:
enter image description here










share|improve this question

























  • 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
















3















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:
good colors



The bad colors look like this:
enter image description here










share|improve this question

























  • 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














3












3








3


1






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:
good colors



The bad colors look like this:
enter image description here










share|improve this question
















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:
good colors



The bad colors look like this:
enter image description here







ncurses gnu-screen terminfo termcap






share|improve this question















share|improve this question













share|improve this question




share|improve this question








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



















  • 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












1 Answer
1






active

oldest

votes


















3














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.






share|improve this answer


























  • 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











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1 Answer
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1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









3














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.






share|improve this answer


























  • 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
















3














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.






share|improve this answer


























  • 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














3












3








3







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.






share|improve this answer















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.







share|improve this answer














share|improve this answer



share|improve this answer








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



















  • 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




















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