On 08.07.17 17:26, Hans Hagen wrote:
On 7/8/2017 12:16 AM, Robert wrote:
On 07.07.17 18:34, Hans Hagen wrote:
AFAIK one can make an instance of such fonts and use that.
But that's what I've been asking about the whole time: whether it is
possible to use instances instead of autoexpanding (ie., linear
distortion). And my tests led me to believe that this is, in contrast
to pdftex, *not* possible with luatex, which was corroborated by what
you said in your last post:
I'm out pf th epdftex dev loop for a while but i wonder if it really
creates instances from multiple masters.
No, it does not, and that's the whole point. In pdftex it is possible to
use *existing* instances (created by external tools, in the case of MM
fonts, mmpfb, for example, which have to be named <font>+5.tfm,
<font>+10.tfm and so forth), *instead* of automatic expansion. So that,
if you have created font instances in advance, there is a difference
between specifying the "autoexpand" key to \pdffontexpand (in which case
pdftex would disregard the existing instances), and leaving away the
"autoexpand" key (in which case it would use the existing instances).
In luatex, there is no difference, and it seems to always autoexpand
instead. I don't care if it does, it's just contrary to what the manual
seems to suggest:
(1) there is no mention of a difference between luatex's
\expandglyphsinfont and its pdftex counterpart \pdffontexpand in terms
of "autoexpand";
(2) the boolean key "auto_expand" still exists in the "fonts" array,
even though its setting doesn't seem to make any difference whatsoever.
What it did was create copies
of fonts i.e. the tfm character data with different widths for
characters so that the par builder can use that info when breaking into
lines. Then the backend adds that instance (when used) which is nothing
more that using the same font with a different width array and applying
a different horizontal scaling. Luatex does not need to create the copies.
I guess here you are talking about pdftex's old (pre-1.20) method of
autoexpanding by embedding multiple (automatically calculated) instances
of the same font. Since 1.20, pdftex does not create copies anymore
either, but that's not what I'm asking about anyway.
In the early (research) time of pdftex it could embed metafony instances
and create them runtime and/or use fonts with a scale added to the
filename given that a map file provides the real thing.
Exactly, only that this is still today possible in pdftex, but not in
luatex.
Concerning variable fonts: these are already supported for a while
Does this mean that the width axis will be taken into account for
expansion?
No, as currently the hard coded mechanism is using scaling. But its
trivial to kick in a copy with a scaled axis in an extra (lua driven)
pass given that there is a variation in the font that is tuned for it
(which i doubt, because often other properties (region related and so)
also change). I will probably do that once there are useable public and
free fonts.
Good to hear that it's trivial, and looking forward to seeing this
supported.
Best,
--
Robert
