gui: support up to 65535 ncurses color pairs (issue #1343) #1365
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@@ Coverage Diff @@
## master #1365 +/- ##
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- Coverage 25.93% 25.89% -0.05%
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Files 198 198
Lines 80957 81164 +207
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+ Hits 20998 21017 +19
- Misses 59959 60147 +188
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This PR improves PR #1345 which fixed issue #1343. Because this introduces additional ncurses-specific behavior, it may be better to not immediately merge this but instead wait and see if #1345 itself has some regressions for someone. I'm still opening the PR because I have implemented the additional limit increase and it could be tested, but it's not as crucial because 32767 color pairs "ought to be enough for everyone".
Changes
The standard curses API uses
shorts for color pair numbers, so values above 32767, which ncurses claims to support in 256-color modes, wouldn't actually work because they overflow. Two ncurses-specific extensions allow working around this limitation:init_extended_pairinstead ofinit_pairallows defining color pairs withintnumbers.optsarguments of many curses color and attribute functions allow passing the color pair withintnumber as anint*to be used instead of the usual color pair asshort.Because both are ncurses-specific extensions to the curses API, their uses have been implemented conditionally on
NCURSES_EXT_FUNCSandNCURSES_EXT_COLORS(through helper macros to reduce duplicating the preprocessor conditions a lot) to attempt to be as compatible as possible.Potential problems
Does this PR actually increase the usable limit from 32767 to 65535?
I only tested it with
colorspam.py, which outputs 1024 color pairs. It should actually be checked that when trying to display more than 32767 color pairs at once, before this PR it wouldn't display correctly but after this PR it would. It's kind of difficult to fit enough output into a buffer to use 32767 color pairs without scrolling and to visually check the its (in)correctness.Some conditions use
NCURSES_EXT_FUNCS, othersNCURSES_EXT_COLORS— is that exact/correct/sufficient or should both be required to be true?For example, is it possible to have an ncurses build that supports only one or the other?
Change:
init_extended_pairand color pair inoptsare only supported since ncurses patch 20170401. Made the preprocessor conditions stronger in commit 63fa5a0.