I noticed this problem while running a gowid test program (palette.go)
with TERM=xterm-16color. This terminal type is not present in tcell's
built-in database, and so tcell falls back to the dynamic terminal type
by parsing the output of infocmp. The symptom was that foreground colors
were not correctly set, leaving a monochrome screen. This seems to be
caused by a problem interpreting the *background* color terminfo
rule. The attribute to set background color is defined like this (Ubuntu
20.04):
$ infocmp xterm-16color | grep setab
setab=\E[%?%p1%{8}%<%t%p1%'('%+%e%p1%{92}%+%;%dm,
The middle sections says "if p1<8 then push(p1+'(') ". '(' is ascii
40. If I run
$ tput setab 5
the terminal sees 'ESC[45m'. This correctly sets the background color to
magenta. But if I tell tcell to emit a cell with background color set to
tcell.Color(5), the terminal sees 'ESC[0m'. This means in practice, my
app emits a code to set the foreground color, then an SGR code that
resets all attributes, then the ASCII character.
When tcell "runs" a terminfo rule in terminfo::TParm(), a push to the
stack preserves the type of the argument pushed - int or string. When a
single quote is encountered, the argument within is pushed to the stack
as a string. For the `setab` rule above, tcell will then pop as an int,
discarding the error and returning 0. The fix here is to have tcell push
the argument inside the single quotes as an integer, using the ascii
value of the argument e.g. "(" -> 40 - and assume the string is length
1, I suppose. Cross-referencing against
ncurses/tinfo/lib_tinfo.c::tparam_internal(), it looks like this code
assumes a single-quoted string is assumed to be length=1 and is also
interpreted as an integer with the ascii value of the character:
case S_QUOTE:
cp++;
npush(UChar(*cp));
cp++;
break;
This replaces high numbered function keys on xterm style
emulators with modifiers. So pressing SHIFT-ALT-F1 is
reported as exactly that, for example. This also extends
that to the insert, delete, home, end, etc.
There is a chance that this will break some emulators --
of particular concern are older VTE based emulators and
rxvt (and derivatives). However, we think that most VTE
derivatives are now much more closely aligned to xterm.
The Wyse50 alternate character set was changed (likely
due to a bug fix in ncurses).
Implemented key kombination of Shift + PgUp/PgDn for Gnome terminal.
Same combination copied to all other terminal implementations which use same
codes for Shift + Up/Down but since this is tested on Ubuntu 16.04 with Gnome
Terminal 3.18.3 it could be that it is not correctly implemented for some of the
other terminals.
This expands support for 24-bit color for terminals that support the
ISO 8613-6:1994 escape sequences (same as xterm), allowing this support
to be enabled by setting % COLORTERM to "truecolor" (or 24bit or 24-bit),
or by setting TCELL_TRUECOLOR to "on", or by setting $TERM a value that
ends in the word "-truecolor".
As this is handled by the runtime now, we no longer need to create magical
database entries for -truecolor options.
A colors.go demo is provided to show off 24-bit color support.
This changes the database to use sha1 based file names. Its not
beautiful, but this is the BS we have to do to cope with the garbage
that is case insensitive filesystems.
Legacy databases are still honored, if you have them.
This completely restructures the database of terminal types, putting
each terminal in its own file. We also compress the database files,
and use infocmp instead of trying to use the C level API.
The mkdatabase script will rebuild the entire database from the terminfo
files on the system. Individual entries can also be built by simply running
the mkinfo program with the terminal type.
