Display wide characters correctly (Part I)

[yan12125]

The ancient konsole_wcwidth can't recognize some double-width characters. For example, copy and paste the string 《別來無恙》 into bash, and move cursors around with left arrow, right arrow, Home and End keys. The current line becomes a mess. My patch fixes this problem.

The story doesn't end here. For example, if I paste 𝕐 into the shell, things are even worse. That's because QTerminal assume characters to be UCS-2, so it cannot handle characters outside the Basic Multilingual Plane correctly. I'd like to leave this problem into the next pull request.

By the way, is git submodule a good idea for external dependencies? This version looks the most promising, as it declares to be "Unicode 9-conformant", and is used in Termux, one of the most popular terminal emulators on Android.

[agaida]

@yan12125 - hmm, i would prevent submodules wherever i could in the real development process (bitten one time to much) - but submodules are generally a nice way to get the current code of something if one know about the pitfalls - if not one will learn them very fast.

[yan12125]

Yes there are indeed tricky edges for submodules. How about copy termux/wcwidth.c into lib/? The first problem I can imagine is licensing.

[agaida]

@yan12125 - can you please provide the Header or the file as a gist - so i could have a look at - if it is the same as this:

 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted. The author
 * disclaims all warranties with regard to this software.
 *
 * Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c

we should take the original one - the license header look like a short form of an ancient MIT-License, which would be compatible with the LGPL :)

[yan12125]

I guess it's MIT-like, too, but I didn't find any explicit license declaration in termux/wcwidth, so I ask them there: termux/wcwidth#2

[agaida]

a big no - we don't want one or two files without license headers which are copied from an obscure project without any license hint - i can only guess that these guys cutted the stuff they needed out from the original file - in this case we should use the original file and port needed things back into this file or simply write a wrapper - but please no git submodule in this case, it's a no go.

[yan12125]

If the termux variant adds a license header later, can we use it?

[agaida]

the problem is a little bit deeper i guess - if they have copied it they should have leave the original license intact - or at least credit the orginal author - but not strip the useless header away :) - if they add the header back we can use it - i would prefer the original file and get the needed parts from them. And make a copy not including their repo - ucs isn't known to change often these days.

Hmm, maybe i'm to much influenced by debian - but the problem is that i as a packager must be able to redistribute this file later - so it should have a proper and valid license. License violations are not cool when the main project is under LGPL - bah, couln't belive that i write such things :D

[yan12125]

From what I can see termux/wcwidth (written in C) is based on jquast/wcwidth (written in Python) [1], and the latter is based on Markus Kuhn's version (written in C). Termux's version is not an expansion of Markus Kuhn's version. I choose Termux's version as it targets Unicode 9.0, while Markus Kuhn's one is for Unicode 5.0. I'm just too lazy to update the table again.

For why termux lacks a LICENSE file - I guess they don't have the habit to keep things tidy :)

[1] It's mentioned in termux/wcwidth's README: https://github.com/termux/wcwidth/blob/master/README.md

[agaida]

thats not sufficient

[yan12125]

I'll wait for some to see whether people at Termux are serious to their fork or not. If I get no response I'll try to update Markus Kuhn's version to Unicode 9.0.

[yan12125]

Hello @agaida, a Termux member has added a MIT license declaration in termux/wcwidth@aae3753. Is it good to move on?

[agaida]

nearly ok i think - to be honest i would only copy both files ( w*.c and .h) and integrate it. However, the *.c and *.h files should contain a license header - you could help them with that, a PR is no rocket science. With the headers in place no objections. But pleae leave out the sub-modules.

[yan12125]

Another upstream update: termux/wcwidth@d48cb1e. I guess that looks good now?

[agaida]

yes - but i'm still not ok with the git submodule. Another point - we should/must give the distributions the chance to use their own wcwitdh package - so the usage of the third party code should be optional.

[yan12125]

Force pushed. I have some modifications to termux's version. Changes can be found in my fork: https://github.com/yan12125/wcwidth/commits/master

[yan12125]

I decide to use a better maintained library instead of termux/wcwidth => #99. @agaida Sorry for bothering you with an awful project

[agaida]

exactly the opposite - sorry for being pain in the ass. Glad you found a better solution. Thank you very much.