Re: [AUCTeX-devel] This ascender bug in dvipng mode...

[David Kastrup]

Jan-Åke Larsson <address@hidden> writes:

> David Kastrup wrote:
>> I now take care that the tightpage special does not show a negative
>> depth.  This should make sure that superscripts like $^1$ get
>> displayed properly.  It doesn't.  For some reason, the tightpage lower
>> edge, in spite of being 0, does not get registered by dvipng.  dvipng
>> still orients itself at the lower edge of the glyph.
>
> I knew I should have looked into this more thouroghly. I coded the
> tightpage code in dvipng to do exactly the same thing as your Postscript
> snippet, so it does do everything you want. You can just as well revert
> that last change, sorry for that extra work. The _real_ problem is that
> 'tightpage' is identified by looking at the postscript header at the
> beginning of the DVI and that changed in revision 1.65 of preview.dtx
> (before 0.7.3) with the innocent-looking log entry "Code cosmetics". In
> a preview-latex run there is now an ignored PS header in the DVI and no
> message "Preview-latex tightpage option detected". dvipng simply reverts
> to the default behaviour.

It is definitely a pity that we now have had two releases quite
unnecessarily which don't work properly with dvipng.

> Since this code may change again, may I suggest a -T tightpage
> option to dvipng?

That won't help us with past dvipng releases.  And whether the
tightpage option actually is turned on depends on the version of
preview.sty and stuff: we detect its presence from parsing the log
output.  And the combination tightpage/dvipng is used not only in
preview-latex...

So I am afraid this is something we need to address in preview.dtx as
fast as possible, regardless of whether you introduce a -T tightpage
option.

What heuristic do you exactly employ for detecting preview-latex?  It
is quite likely possible to document this in preview.dtx so that it
won't get changed accidentally again.  We should have communicated
better about that previously.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum