Re: [PATCH/Now RFA] Console based mouse face highlighting.

[Eli Zaretskii <eliz@gnu.org>]

> From: Nick Roberts <nickrob@snap.net.nz>
> Date: Wed, 16 May 2007 10:39:57 +1200
> Cc: emacs-devel@gnu.org
> 
> Thanks, I've got something that seems to work now.  I read your message
> afterwards, so I'm afraid I think it does modify the glyph matrix and I've not
> used FRAME_TERMCAP_P.

Too bad.

> I'm still not sure how the iterator, glyph matrix and write_glyphs
> relate.

The iterator is used to create the ``desired glyph matrix'', one that
describes what _should_have_been_ on the screen given the current
buffer contents and point position.  Then the desired matrix is diffed
against the current matrix (which describes what _is_ on the screen
now), and finally the diffs are used to update the affected portions
of the screen by calls to write_glyphs.

> I would have thought if I've changed the glyph matrix I don't need
> to call write_glyphs but that doesn't seem to be the case.

Probably because you modify the glyph matrix where Emacs doesn't
expect it to happen.  term.c is supposed to access the glyph matrix in
the read-only mode.

I actually don't understand at all why you need to modify the glyph
matrix.  What are you modifying there, exactly?

> Also if I call write_glyphs with different values, these would get
> overwritten with those from the glyph matrix when an update is
> done.)

Again, because Emacs doesn't expect the glyph matrix to change at this
point.

> Anyway I'd like to commit these changes now.

I'd be happier if you fixed the two aspects we've been talking about
(not change the glyph matrix and avoid calling this code on non-tty
frames.  I think these are really nasty bugs.  And I don't see any
reason for haste here.

Thanks for working on this.