[tin-users] Converting ansi escape to graphics

[Thomas Dickey]

On Thu, Apr 16, 2020 at 09:11:34PM +0000, Nigel Reed wrote:
> Hi all,
> 
> This is probably a dev question but I'll ask here anyway in case one is watching.
> 
> I use tin to view messages on the bulletin board (BBS) via a usenet interface.
> 
> A lot of groups have ANSI art or colors using ANSI and wondered if anyone would be able to add translation from ANSI to the graphic or color.
> 
> For example, if you connect to endofthelinebbs.com and go to DN.DN-ADDS then look at any message with ANSI in the subject, for example [ANSI] Shadowscope
> 
> You'll see a string of ANSI characters. These are escape codes, of course.
> 
> ^[[0m^[[1;1H^[[1C^[[35m▄▄▄▄▄▄▄▄
> 
> ^[[0m = All attributes off
> ^[[1;1H = Move the cursor to the specified position (This would be relative to the headers)
> ^[[1C = Move the cursor forward specified number of columns without changing the line
> ^[[35m = Change the foreground color to magenta.
> Followed by whatever graphics are to be displayed.

occasionally someone wants this in ncurses, but it's out of scope
since it could be implemented without needing ncurses internals.

screen and tmux do this, for instance (using low-level calls).
It could be done using curses, but would be just as much work.

This example doesn't use curses (it produces markup that vile understands)
but does the sort of parsing you're talking about:

https://github.com/ThomasDickey/vile-snapshots/blob/master/filters/manfilt.c

However it doesn't handle movement outside of the current line.
Occasionally I want to view a "typescript" which does that (to-do...).

> I could "possibly" do the work myself, but I'm not a C coder, I'm more of a
> perl tinkerer.  If someone showed me what I need to do and where then I can
> probably do the work.  If someone wants to have a crack, a good ANSI
> reference is at http://ascii-table.com/ansi-escape-sequences.php

I wouldn't call that "good": it appears to be MS-DOS ansi.sys,
but doesn't make that apparent, nor provide details on how
that differs from other implementations.

https://www.vfrazee.com/ms-dos/6.22/help/ansi.sys.htm
http://www.kegel.com/nansi/

However, the "whatever graphics" in your example rely upon a particular
character-set -- which isn't related to "ANSI".  Something that translated
those bbs outputs to curses (or UTF-8) would have to know about that.

-- 
Thomas E. Dickey <dickey at invisible-island.net>
https://invisible-island.net
ftp://ftp.invisible-island.net
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