Re: Obtain X / HPOS with move_it_to at eol when buffer-display-table line-feed

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 29 Aug 2017 00:01:16 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> I am working on my own feature requests 17684 (thin vertical line) and 22873 (multiple fake cursors).
> 
> I am having difficulty calculating the X and HPOS using move_it_to when a buffer-display-table contains an entry for a line feed (aka \n).  I am looking for a more eloquent way of of handling this instead of subtracting the frame-char-width from it.current.pos, and also subtracting 1 from it.current.hpos.  We can test the buffer-display-table with something like (aref buffer-display-table ?\n), which in my use-case yields [(182 . 127) 10] because I also use face to color the eol character.
> 
> We test for a line feed with:  FETCH_BYTE (IT_BYTEPOS (it)) == '\n'
> 
> We move to POS using:
> 
> move_it_to (&it, POS, it.last_visible_x, it.last_visible_y - 1, -1, MOVE_TO_POS | MOVE_TO_X | MOVE_TO_Y);
> 
> Is there a better way to handle this instead of subtracting frame-char-width from X and subtracting 1 from HPOS?

I'm sorry, I don't really understand what is it that you are trying to
accomplish.  Can you tell more about the goals of this code?  Also
what exactly isn't working as you expected?