Re: highlight-indent-guides in display engine

[Eli Zaretskii]

> Date: Fri, 12 Jul 2019 02:21:27 +0200
> From: Ergus <address@hidden>
> Cc: address@hidden
> 
> >I don't think I understand: what do you mean by "add the indicator"?
> >How would this indicator look like?
> >
> Maybe a vertical bar (like our previous column indicator) or a width
> line. Or something customizable somehow. We just need to look around,
> there are several alternatives. We must chose the one that fits better
> and produces less complications for us. But provides the functionality
> somehow.
> 
> I don't thing how the indicator looks like may be a problem, but how
> accurate or specific it behaves.
> 
> I am just looking around and Geany adds some vertical points as the
> indicator positions (every tab or every x spaces). But the spaces are
> only "indicated" when used for the indentation..
> 
> Sublime behaves in the same way. But there is an option to highlight the
> indicator only in the blocks around the current cursor. (As in the
> attachement)

I didn't receive any attachments with your message.

> Athom on the other hand seems to behave as in the
> highlight-indent-guides.el package:
> https://atom.io/packages/indent-guide-improved
> 
> With the animations and so on. Which seems to be the most complete
> behavior, but less efficient.

The animations and highlighting inside the current block should be in
Lisp, not in the display code.  If at all.

> In all the cases I just see that they add the indicator based on the
> characters between the beginning of the line and the indentation (first
> non blank character) not looking at the previous lines. They ignore if
> there is a previous line  with wrong indentation or if the current line
> adds 3 tabs more respecting to the previous one.
> 
> So, implementing it in this way doesn't seems to be so complex right?

So basically you are talking about displaying some special glyph at
every tab stop inside leading whitespace of a line, or making each
tab-stop width have a different background color?  Yes, this should be
possible to do in the display code.  I just hope enough people will
see this as sufficient, because if most current users of these
packages won't switch, this new feature will not be worth its
development, documentation, and maintenance effort.  Maybe we should
ask on Reddit first?