bug#18493: 24.3.93; posn-col-row should take text-scale-mode into account

[Dmitry Gutov <dgutov@yandex.ru>]

Eli Zaretskii <eliz@gnu.org> writes:

> Is company-mode only for buffers whose major mode is some programming
> language?

I'd say it's the first priority.

> I thought it was more broad.  But even if it is only for
> programming languages, does it mean that the API you wish existed
> should only cater to such modes?

It's hard to say. Maybe? I'd like to reiterate here, that I'd be
satisfied just with some instructions how to convert the current
`posn-col-row' return value into value that respects text scale.

> So what you actually need is to find the correct X coordinate for the
> screen line _below_ (and maybe also above) the one where posn-col-row
> is called, is that right?

I don't understand the distinction. But from `posn-col-row' I actually
take the screen column value (the row value returned from
`posn-actual-col-row' is more useful).

> If so, first question is why not do all this in pixels?

Because we use the returned value when combining the display string for
the overlay. So at some point the pixels have to get converted to
character numbers, and we're back to the same problem.