From f07b34e790d5fb403fab3ec69e93b3f7a3894fd5 Mon Sep 17 00:00:00 2001
From: Edward Litherland-Smith <edward.litherland-smith@ukaea.uk>
Date: Mon, 22 Feb 2021 09:05:59 +0000
Subject: [PATCH] Add checks for true colour support in terminal (visual only)

---
 true_colour_tests/24-bit-color.sh | 100 +++++++++
 true_colour_tests/TrueColour.md   | 362 ++++++++++++++++++++++++++++++
 true_colour_tests/color-spaces.pl |  67 ++++++
 true_colour_tests/cscale.sh       |  13 ++
 4 files changed, 542 insertions(+)
 create mode 100755 true_colour_tests/24-bit-color.sh
 create mode 100644 true_colour_tests/TrueColour.md
 create mode 100755 true_colour_tests/color-spaces.pl
 create mode 100755 true_colour_tests/cscale.sh

diff --git a/true_colour_tests/24-bit-color.sh b/true_colour_tests/24-bit-color.sh
new file mode 100755
index 00000000..f407258f
--- /dev/null
+++ b/true_colour_tests/24-bit-color.sh
@@ -0,0 +1,100 @@
+#!/bin/bash
+# This file was originally taken from iterm2 https://github.com/gnachman/iTerm2/blob/master/tests/24-bit-color.sh
+#
+#   This file echoes a bunch of 24-bit color codes
+#   to the terminal to demonstrate its functionality.
+#   The foreground escape sequence is ^[38;2;<r>;<g>;<b>m
+#   The background escape sequence is ^[48;2;<r>;<g>;<b>m
+#   <r> <g> <b> range from 0 to 255 inclusive.
+#   The escape sequence ^[0m returns output to default
+
+setBackgroundColor()
+{
+    #printf '\x1bPtmux;\x1b\x1b[48;2;%s;%s;%sm' $1 $2 $3
+    printf '\x1b[48;2;%s;%s;%sm' $1 $2 $3
+}
+
+resetOutput()
+{
+    echo -en "\x1b[0m\n"
+}
+
+# Gives a color $1/255 % along HSV
+# Who knows what happens when $1 is outside 0-255
+# Echoes "$red $green $blue" where
+# $red $green and $blue are integers
+# ranging between 0 and 255 inclusive
+rainbowColor()
+{ 
+    let h=$1/43
+    let f=$1-43*$h
+    let t=$f*255/43
+    let q=255-t
+
+    if [ $h -eq 0 ]
+    then
+        echo "255 $t 0"
+    elif [ $h -eq 1 ]
+    then
+        echo "$q 255 0"
+    elif [ $h -eq 2 ]
+    then
+        echo "0 255 $t"
+    elif [ $h -eq 3 ]
+    then
+        echo "0 $q 255"
+    elif [ $h -eq 4 ]
+    then
+        echo "$t 0 255"
+    elif [ $h -eq 5 ]
+    then
+        echo "255 0 $q"
+    else
+        # execution should never reach here
+        echo "0 0 0"
+    fi
+}
+
+for i in `seq 0 127`; do
+    setBackgroundColor $i 0 0
+    echo -en " "
+done
+resetOutput
+for i in `seq 255 -1 128`; do
+    setBackgroundColor $i 0 0
+    echo -en " "
+done
+resetOutput
+
+for i in `seq 0 127`; do
+    setBackgroundColor 0 $i 0
+    echo -n " "
+done
+resetOutput
+for i in `seq 255 -1 128`; do
+    setBackgroundColor 0 $i 0
+    echo -n " "
+done
+resetOutput
+
+for i in `seq 0 127`; do
+    setBackgroundColor 0 0 $i
+    echo -n " "
+done
+resetOutput
+for i in `seq 255 -1 128`; do
+    setBackgroundColor 0 0 $i
+    echo -n " "
+done
+resetOutput
+
+for i in `seq 0 127`; do
+    setBackgroundColor `rainbowColor $i`
+    echo -n " "
+done
+resetOutput
+for i in `seq 255 -1 128`; do
+    setBackgroundColor `rainbowColor $i`
+    echo -n " "
+done
+resetOutput
diff --git a/true_colour_tests/TrueColour.md b/true_colour_tests/TrueColour.md
new file mode 100644
index 00000000..1da376b1
--- /dev/null
+++ b/true_colour_tests/TrueColour.md
@@ -0,0 +1,362 @@
+# Terminal Colors
+
+There exists common confusion about terminal colors. This is what we have right now:
+
+- Plain ASCII
+- ANSI escape codes: 16 color codes with bold/italic and background
+- 256 color palette: 216 colors + 16 ANSI + 24 gray (colors are 24-bit)
+- 24-bit true color: "888" colors (aka 16 milion)
+
+```bash
+printf "\x1b[${bg};2;${red};${green};${blue}m\n"
+```
+
+The 256-color palette is configured at start and is a 666-cube of colors,
+each of them defined as a 24-bit (888 rgb) color.
+
+This means that current support can only display 256 different colors in the
+terminal while "true color" means that you can display 16 million different
+colors at the same time.
+
+Truecolor escape codes do not use a color palette. They just specify the
+color itself.
+
+This is a good test case:
+
+```bash
+printf "\x1b[38;2;255;100;0mTRUECOLOR\x1b[0m\n"
+```
+
+- or
+  https://raw.githubusercontent.com/JohnMorales/dotfiles/master/colors/24-bit-color.sh
+- or http://github.com/robertknight/konsole/tree/master/tests/color-spaces.pl
+- or https://git.gnome.org/browse/vte/tree/perf/img.sh
+- or just run this:
+
+```sh
+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 "\033[48;2;%d;%d;%dm", r,g,b;
+        printf "\033[38;2;%d;%d;%dm", 255-r,255-g,255-b;
+        printf "%s\033[0m", substr(s,colnum+1,1);
+    }
+    printf "\n";
+}'
+```
+
+Keep in mind that it is possible to use both ';' and ':' as Control Sequence
+Introducer delimiters.
+
+According to Wikipedia[1], this behavior is only supported by xterm and konsole.
+
+[1] https://en.wikipedia.org/wiki/ANSI_color
+
+Since
+[ncurses-6.0-20180121](http://lists.gnu.org/archive/html/bug-ncurses/2018-01/msg00045.html),
+terminfo began to support the 24-bit True Color capability under the name of
+"RGB". You need to use the "setaf" and "setab" commands to set the foreground
+and background respectively.
+
+# True Color Detection
+
+There will be no reliable way to detect the "RGB" flag until the new release of
+terminfo/ncurses. S-Lang author added a check for $COLORTERM containing either
+"truecolor" or "24bit" (case sensitive). In addition,
+[VTE](https://bugzilla.gnome.org/show_bug.cgi?id=754521),
+[Konsole](https://bugs.kde.org/show_bug.cgi?id=371919) and
+[iTerm2](https://gitlab.com/gnachman/iterm2/issues/5294) set this variable to
+"truecolor". It has been in VTE for a while and but is relatively new, being
+still git-only in Konsole and iTerm2).
+
+This is obviously not a reliable method, and is not forwarded via sudo, SSH etc.
+However, whenever it errs, it errs on the safe side. It does not advertise
+support when it is actually supported. App developers can freely choose to
+check for this same variable, or introduce their own method (e.g. an option in
+their config file). They should use whichever method best matches the overall
+design of their app. Checking $COLORTERM is recommended though since it will
+lead to a more seamless desktop experience where only one variable needs to be
+set. This would be system-wide so that the user would not need to set it
+separately for each app.
+
+## Querying The Terminal
+
+A more reliable method in an interactive program which can read terminal
+responses, and one that is transparent to things like sudo, SSH, etc.. is to
+simply try setting a truecolor value and then query the terminal to ask what
+color it currently has. If the response replies the same color that was set
+then it indicates truecolor is supported.
+
+```bash
+$ (echo -e '\e[48:2:1:2:3m\eP$qm\e\\' ; xxd)
+
+^[P1$r48:2:1:2:3m^[\
+00000000: 1b50 3124 7234 383a 323a 313a 323a 336d  .P1$r48:2:1:2:3m
+```
+
+Here we ask to set the background color to `RGB(1,2,3)` - an unlikely default
+choice - and request the value that we just set. The response comes back that
+the request was understood (`1`), and that the color is indeed `48:2:1:2:3`.
+This tells us also that the terminal supports the colon delimiter. If instead,
+the terminal did not support truecolor we might see a response like
+
+```
+^[P1$r40m^[\
+00000000: 1b50 3124 7234 306d 1b5c 0a              .P1$r40m.\.
+```
+
+This terminal replied the color is `40` - it has not accepted our request to
+set `48:2:1:2:3`.
+
+```
+^[P0$r^[\
+00000000: 1b50 3024 721b 5c0a                      .P0$r.\.
+```
+
+This terminal did not even understand the DECRQSS request - its response was
+`0$r`. We do not learn if it managed to set the color, but since it doesn't
+understand how to reply to our request it is unlikely to support truecolor
+either.
+
+# Terminals + True Color
+
+## Now **Supporting** True Color
+
+- [st](http://st.suckless.org/) (from suckless) [delimeter: semicolon] -
+  http://lists.suckless.org/dev/1307/16688.html
+- [xst](https://github.com/gnotclub/xst/) - fork of st
+- [konsole](http://kde.org/applications/system/konsole/) [delimeter: colon,
+  semicolon] - https://bugs.kde.org/show_bug.cgi?id=107487
+- [iTerm2](http://www.iterm2.com/) [delimeter: colon, semicolon] - since v3
+  version
+- [Therm](https://github.com/trufae/Therm) [delimeter: colon, semicolon] - fork
+  of iTerm2
+- [qterminal](https://github.com/lxqt/qterminal) [delimeter: semicolon] -
+  https://github.com/qterminal/qterminal/issues/78
+- [alacritty](https://github.com/jwilm/alacritty) [delimeter: semicolon] -
+  written in Rust
+- [kitty](https://github.com/kovidgoyal/kitty) [delimeter: colon,semicolon] -
+  uses OpenGL
+- [cool-retro-term](https://github.com/Swordfish90/cool-retro-term) [delimeter:
+  semicolon]
+- [mosh](https://mosh.org/) (Mobile SHell) [delimeter: semicolon] - since commit
+  https://github.com/mobile-shell/mosh/commit/6cfa4aef598146cfbde7f7a4a83438c3769a2835
+- [pangoterm](http://www.leonerd.org.uk/code/pangoterm/) [delimeter:
+  colon, semicolon]
+- [Termux](https://termux.com/) [delimeter: semicolon] - **Android platform**
+- [ConnectBot](https://connectbot.org/) - **Android platform** - since
+  https://github.com/connectbot/connectbot/commit/3bcc75ccedaf2136b04c5932c81a5155f29dc3b5
+- [Black Screen](https://github.com/shockone/black-screen) [delimeter:
+  semicolon] - crossplatform, HTML/CSS/JS-based
+- [hterm](https://chromium.googlesource.com/apps/libapps/+/master/hterm) -
+  HTML/CSS/JS-based (ChromeOS)
+- [PuTTY](http://www.chiark.greenend.org.uk/~sgtatham/putty/) -
+  [landed](https://git.tartarus.org/?p=simon/putty.git;a=commit;h=a4cbd3dfdb71d258e83bbf5b03a874c06d0b3106)
+  in git (patched version [3] {xterm-like approximation to 256 colors} and [4]
+  {real true colors} available) - **Windows platform**
+- [Tera Term](http://en.sourceforge.jp/projects/ttssh2/) [delimeter: colon,
+  semicolon] - **Windows platform**
+- [ConEmu](https://github.com/Maximus5/ConEmu) [delimeter: semicolon] -
+  **Windows platform**
+- [Windows
+  Powershell](https://en.wikipedia.org/wiki/PowerShell#PowerShell_5.1)
+  [delimeter: semicolon] - aka Powershell 5.x and below **Windows 10**
+- [Powershell Core](https://github.com/PowerShell/PowerShell) [delimeter:
+  semicolon] aka Powershell 6+ **Windows 10**
+- [cmd.exe](https://en.wikipedia.org/wiki/Cmd.exe) [delimeter:
+  semicolon] Builtin Windows shell that is mostly unchanged since DOS **Windows 10**
+- [FinalTerm](http://finalterm.org/) [delimeter: semicolon] -
+  **[abandoned](http://worldwidemann.com/finally-terminated/)**, iTerm2
+  [borrowing it's ideas and features](http://iterm2.com/shell_integration.html).
+- [MacTerm](https://github.com/kmgrant/macterm) [delimeter: semicolon] - **Mac
+  OS X platform**
+- [mintty](https://mintty.github.io/) [delimeter: semicolon] **Cygwin and
+  MSYS/MSYS2** since commit
+  https://github.com/mintty/mintty/commit/43f0ed8a46c6549cb9a3ea27abc057b5abe13bdb
+  (2.0.1 release) - **Windows platform**
+- [MobaXterm](http://mobaxterm.mobatek.net/) **Windows platform** - closed
+  source (run `lscolors` to see a truecolor test)
+- [ZOC](https://www.emtec.com/zoc/index.html) **Windows/OS X platform** - closed
+  source since
+  [7.19.0 version](http://www.emtec.com/downloads/zoc/zoc_changes.txt)
+- [upterm](https://github.com/railsware/upterm) *Windows/Macos/Linux Electron* -
+  A terminal emulator for the 21st century.
+- Windows 10 bash console, since
+  [Windows Insiders build 14931](https://blogs.msdn.microsoft.com/commandline/2016/09/22/24-bit-color-in-the-windows-console/)
+- all [libvte](http://ftp.gnome.org/pub/GNOME/sources/vte/) based terminals
+  (since 0.36 version) [delimeter: colon, semicolon] -
+  https://bugzilla.gnome.org/show_bug.cgi?id=704449
+  - **libvte**-based
+    [Gnome Terminal](https://help.gnome.org/users/gnome-terminal/stable/)
+  - **libvte**-based [sakura](http://www.pleyades.net/david/projects/sakura)
+  - **libvte**-based
+    [xfce4-terminal](http://docs.xfce.org/apps/terminal/start) - since
+    [0.6.90](https://github.com/xfce-mirror/xfce4-terminal/releases/tag/xfce4-terminal-0.6.90)
+    release, if compiled with GTK+3
+  - **libvte**-based
+    [Terminator](http://gnometerminator.blogspot.com/p/introduction.html) -
+    since [1.90](https://launchpad.net/terminator/+announcement/14358) release
+  - **libvte**-based [Tilix](https://github.com/gnunn1/tilix) - written in D.
+    Similar user interface as for Terminator.
+  - **libvte**-based [Lilyterm](http://lilyterm.luna.com.tw/) - since commit
+    https://github.com/Tetralet/LilyTerm/commit/72536e7ba448ad9ef1126ce45fbde3a3407a271b
+  - **libvte**-based [ROXTerm](http://roxterm.sourceforge.net/)
+  - **libvte**-based [evilvte](http://www.calno.com/evilvte/) - no release yet,
+    version from git https://github.com/caleb-/evilvte
+  - **libvte**-based [Termit](https://github.com/nonstop/termit)
+  - **libvte**-based [Termite](https://github.com/thestinger/termite)
+  - **libvte**-based [Tilda](https://github.com/lanoxx/tilda)
+  - **libvte**-based [tinyterm](https://code.google.com/p/tinyterm)
+  - **libvte**-based
+    [Pantheon Terminal](https://launchpad.net/pantheon-terminal)
+  - **libvte**-based [lxterminal](http://sourceforge.net/projects/lxde) - with
+    **--enable-gtk3** configure flag.
+  - **libvte**-based [guake](http://guake-project.org/) - A top-down terminal for GNOME
+
+There are a bunch of libvte-based terminals for GTK2, so they are listed in the
+another section.
+
+Also, while this one is not a terminal, but a terminal replayer, it is
+still worth mentioning:
+
+- [asciinema](http://asciinema.org) player:
+  https://github.com/asciinema/asciinema-player
+
+## Improper Support for True Color
+
+- [mlterm](http://mlterm.sourceforge.net) - built with **--with-gtk=3.0**
+  configure flag. Approximates colors to 512 embedded palette
+  (https://sourceforge.net/p/mlterm/bugs/74/)
+
+## Terminals that parse ANSI color sequences, but approximate them to 256 palette
+
+- xterm (but doing it wrong: "it uses nearest color in RGB color space,
+  with a usual false assumption about orthogonal axes")
+- [urxvt aka rxvt-unicode](http://software.schmorp.de/pkg/rxvt-unicode.html) -
+  since
+  [Revision 1.570](http://cvs.schmorp.de/rxvt-unicode/src/command.C?revision=1.570&view=markup&sortby=log&sortdir=down)
+  http://lists.schmorp.de/pipermail/rxvt-unicode/2016q2/002261.html (Note there
+  is a restriction of colors count still)
+- linux console (since v3.16):
+  https://github.com/torvalds/linux/commit/cec5b2a97a11ade56a701e83044d0a2a984c67b4
+
+Note about color differences:
+a) RGB axes are not orthogonal, so you cannot use
+sqrt(R^2+G^2+B^2) formula
+b) for color differences there is more correct (but
+much more complex)
+[CIEDE2000](http://en.wikipedia.org/wiki/Color_difference#CIEDE2000) formula
+(which may easily blow up performance if used blindly) [2].
+
+[2] https://github.com/neovim/neovim/issues/793#issuecomment-48106948
+
+## Terminal multiplexers
+
+- [tmux](http://tmux.github.io/) - starting from version 2.2 (support since
+  [427b820...](https://github.com/tmux/tmux/commit/427b8204268af5548d09b830e101c59daa095df9))
+- [screen](http://git.savannah.gnu.org/cgit/screen.git/) - has support in
+  'master' branch, need to be enabled (see 'truecolor' option)
+- [pymux](https://github.com/jonathanslenders/pymux) - tmux clone in pure Python
+  (to enable truecolor run pymux with `--truecolor` option)
+- [dvtm](https://github.com/martanne/dvtm) - not yet supporting True Color
+  https://github.com/martanne/dvtm/issues/10
+
+## **NOT Supporting** True Color
+
+- [Terminal.app](https://en.wikipedia.org/wiki/Terminal_(macOS)): Macos Terminal builtin
+- [Terminology](https://www.enlightenment.org/about-terminology)
+  (Enlightenment) - https://phab.enlightenment.org/T746
+- [Hyper.app](https://hyper.is/) [delimeter: semicolon] - crossplatform,
+  HTML/CSS/JS-based (Electron) https://github.com/zeit/hyper/issues/2294
+- [Cmder](https://cmder.net/): Portable console emulator for Windows,
+  based on ConEmu.
+- [Terminus](https://github.com/Eugeny/terminus):
+  highly configurable terminal emulator for Windows, macOS and Linux
+- [mrxvt](https://sourceforge.net/projects/materm) (looks abandoned) -
+  https://sourceforge.net/p/materm/feature-requests/41/
+- [aterm](http://www.afterstep.org/aterm.php) (looks abandoned) -
+  https://sourceforge.net/p/aterm/feature-requests/23/
+- [fbcon](https://www.kernel.org/doc/Documentation/fb/fbcon.txt) (from linux
+  kernel) - https://bugzilla.kernel.org/show_bug.cgi?id=79551
+- FreeBSD console - https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=191652
+- [yaft](https://github.com/uobikiemukot/yaft) framebuffer terminal -
+  https://github.com/uobikiemukot/yaft/issues/12
+- [KiTTY](http://www.9bis.net/kitty/) - **Windows platform**
+- [MTPuTTY](ttyplus.com) - **Windows platform**
+- [mRemoteNG](https://mremoteng.org/) - **Windows platform** -
+  https://github.com/mRemoteNG/mRemoteNG/issues/717
+- [JuiceSSH](https://juicessh.com/) - **Adroid platform**, closed source
+- [Termius](https://www.termius.com/) - **Linux, Windows, OS X platforms**,
+  closed source
+- [SmarTTY](http://smartty.sysprogs.com/) - **Windows platform** - closed source
+  (sent them a request)
+- [Netsarang XShell](https://www.netsarang.com/products/xsh_overview.html) -
+  closed source (sent them an email)
+- libvte and GTK2 - based:
+  - **libvte**-based [GTKTerm2](http://gtkterm.feige.net/)
+  - **libvte**-based [stjerm](https://github.com/stjerm/stjerm) (looks
+    abandoned) - https://github.com/stjerm/stjerm/issues/39
+
+# Console Programs + True Color
+
+## Console Programs Supporting True Color
+
+- [s-lang](http://lists.jedsoft.org/lists/slang-users/2015/0000020.html)
+  library - (since pre2.3.1-35, for 64bit systems)
+- [ncurses](https://www.gnu.org/software/ncurses/) library - since 6.1 version
+- [Eternal Terminal](https://mistertea.github.io/EternalTCP/) - automatically
+  reconnecting shell
+- [mc](http://www.midnight-commander.org) - since
+  [682a5...](http://www.midnight-commander.org/changeset/682a5116edd20b8ba81743a1f7495c883b0ce644).
+  See also [ticket #3724](http://www.midnight-commander.org/ticket/3724) for
+  truecolor themes.
+- [irssi](https://github.com/irssi/irssi) - since
+  [PR #48](https://github.com/irssi/irssi/pull/48)
+- [neovim](https://github.com/neovim/neovim) - since commit
+  [8dd415e887923f99ab5daaeba9f0303e173dd1aa](https://github.com/neovim/neovim/commit/8dd415e887923f99ab5daaeba9f0303e173dd1aa);
+  need to set
+  [termguicolors](https://neovim.io/doc/user/options.html#%27termguicolors) to
+  enable true color.
+- [vim](https://github.com/vim/vim) - (from 7.4.1770); need to set
+  [termguicolors](https://github.com/vim/vim/blob/master/runtime/doc/version8.txt#L202)
+  to enable true color.
+- [joe](https://sf.net/p/joe-editor) - (from
+  [4.5](https://sourceforge.net/p/joe-editor/news/2017/09/joe-45-released/)
+  version)
+- [emacs](https://www.gnu.org/software/emacs/) - since
+  [26.1 release](https://lists.gnu.org/archive/html/emacs-devel/2018-05/msg00765.html)
+- [micro editor](https://micro-editor.github.io/)
+- [elinks](http://repo.or.cz/w/elinks.git) -
+  [configure.in:1410](http://repo.or.cz/w/elinks.git/blob/HEAD:/configure.in#l1410)
+  (./configure --enable-true-color)
+- [tcell](https://github.com/gdamore/tcell) library for Go language
+- [timg](https://github.com/hzeller/timg) - Terminal Image Viewer
+- [tv](https://github.com/daleroberts/tv) - tool to quickly view high-resolution
+  multi-band imagery directly in terminal
+- [termimage](https://github.com/nabijaczleweli/termimage) - terminal image
+  viewer
+- [explosion](https://github.com/Tenzer/explosion) - terminal image viewer
+- [ls-icons](https://github.com/sebastiencs/ls-icons) - fork of coreutils with
+  `ls` program that supports icons
+- [mpv](https://github.com/mpv-player/mpv) - video player with support of
+  console-only output (since 0.22 version)
+- [radare2](https://github.com/radare/radare2) - reverse engineering franework;
+  since 0.9.6 version.
+
+## Console Programs Not Supporting True Color
+
+- mutt (email client) - http://dev.mutt.org/trac/ticket/3674
+- neomutt (email client) - https://github.com/neomutt/neomutt/issues/85
+- termbox library - https://github.com/nsf/termbox/issues/37
+- mcabber (jabber client) -
+  https://bitbucket.org/McKael/mcabber-crew/issue/126/support-for-true-color-16-millions-colors
+- tig (git TUI) - https://github.com/jonas/tig/issues/227
+- cmus (music player) - https://github.com/cmus/cmus/issues/799
+- weechat (chat client) - https://github.com/weechat/weechat/issues/1364
+- scim (spreadsheet program) - https://github.com/andmarti1424/sc-im/issues/306
+- [gui.cs](https://github.com/migueldeicaza/gui.cs) Terminal UI toolkit for .NET
+  (curses-like) - https://github.com/migueldeicaza/gui.cs/issues/48
diff --git a/true_colour_tests/color-spaces.pl b/true_colour_tests/color-spaces.pl
new file mode 100755
index 00000000..8774c044
--- /dev/null
+++ b/true_colour_tests/color-spaces.pl
@@ -0,0 +1,67 @@
+#!/usr/bin/perl
+# Author: Todd Larason <jtl@molehill.org>
+# $XFree86: xc/programs/xterm/vttests/256colors2.pl,v 1.1 1999/07/11 08:49:54 dawes Exp $
+
+print "256 color mode\n\n";
+
+# display back ground colors
+
+for ($fgbg = 38; $fgbg <= 48; $fgbg +=10) {
+
+# first the system ones:
+print "System colors:\n";
+for ($color = 0; $color < 8; $color++) {
+    print "\x1b[${fgbg};5;${color}m::";
+}
+print "\x1b[0m\n";
+for ($color = 8; $color < 16; $color++) {
+    print "\x1b[${fgbg};5;${color}m::";
+}
+print "\x1b[0m\n\n";
+
+# now the color cube
+print "Color cube, 6x6x6:\n";
+for ($green = 0; $green < 6; $green++) {
+    for ($red = 0; $red < 6; $red++) {
+	for ($blue = 0; $blue < 6; $blue++) {
+	    $color = 16 + ($red * 36) + ($green * 6) + $blue;
+	    print "\x1b[${fgbg};5;${color}m::";
+	}
+	print "\x1b[0m ";
+    }
+    print "\n";
+}
+
+# now the grayscale ramp
+print "Grayscale ramp:\n";
+for ($color = 232; $color < 256; $color++) {
+    print "\x1b[${fgbg};5;${color}m::";
+}
+print "\x1b[0m\n\n";
+
+}
+
+print "Examples for the 3-byte color mode\n\n";
+
+for ($fgbg = 38; $fgbg <= 48; $fgbg +=10) {
+
+# now the color cube
+print "Color cube\n";
+for ($green = 0; $green < 256; $green+=51) {
+    for ($red = 0; $red < 256; $red+=51) {
+	for ($blue = 0; $blue < 256; $blue+=51) {
+            print "\x1b[${fgbg};2;${red};${green};${blue}m::";
+	}
+	print "\x1b[0m ";
+    }
+    print "\n";
+}
+
+# now the grayscale ramp
+print "Grayscale ramp:\n";
+for ($gray = 8; $gray < 256; $gray+=10) {
+    print "\x1b[${fgbg};2;${gray};${gray};${gray}m::";
+}
+print "\x1b[0m\n\n";
+
+}
diff --git a/true_colour_tests/cscale.sh b/true_colour_tests/cscale.sh
new file mode 100755
index 00000000..d0c13816
--- /dev/null
+++ b/true_colour_tests/cscale.sh
@@ -0,0 +1,13 @@
+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 "\033[48;2;%d;%d;%dm", r,g,b;
+        printf "\033[38;2;%d;%d;%dm", 255-r,255-g,255-b;
+        printf "%s\033[0m", substr(s,colnum+1,1);
+    }
+    printf "\n";
+}'