Driver and viewer competence

[Lars Hellström <Lars.Hellstrom@math.umu.se>]

I asked the following questions last week, but perhaps people ignored the
mail since it had the subject "Metric font transformations with dvips"?
Anyway, I still want them answered and Laurent's recent viewer angle is
most relevant, so I have extended the questions to viewers as well.

Question: Which of the following font transformations can "your"
driver/viewer be told to do, or if you prefer that angle, for each of the
following transformations list the drivers or viewers you know can perform
that transformation:

1. Isotropic scaling.
2. Horizontal scaling.
3. Vertical scaling.
4. Slanting.
5. Reencoding.

Whom these questions are directed to: Primarily the people who write
drivers and viewers, since they are the ones who should have the best
knowledge about their software. But since no such person answered the last
time, and if you happen to know the answer for your favourite DVI
driver/viewer, then I suspect there is no point in waiting for the
developer to answer these questions instead. (After all, the developer
might be too busy improving the driver. :-)

Some other remarks:
1. Isotropic scaling can be specified in the DVI file itself or by a
virtual font, but that is not what I'm asking for here. I rather mean "Can
I put something in the psfonts.map or corresponding file to get this
effect?"
1-4. Some drivers/viewers can do this by arbitrary amounts, whereas others
(especially those that rely on the GUI for rendering) can only do so by
some fixed amount. I count both variants as "can do", but please include
some note specifying the restrictions.
5. Reencoding seems to exist in two different flavours: slots to glyphs
(like a postscript encoding) and slots to slots (which means you cannot
access glyphs in the font that didn't have an encoding position before
reencoding). Specify which one the driver/viewer has.

It would be really nice of you if you would answer this. I'm trying to
establish what is the "normal competence" for a DVI driver and viewer when
it comes to font transformations.

Lars Hellström

PS. I know it's hard to answer a question when you don't know what the
answer is supposed to look like, so here's the answer for the DVI viewer in
OzTeX:

Isotropic: No.  Horizontal: Yes.  Vertical: No.  Slanting: Yes.
Reencoding: Yes.
Horizontal scaling and slanting are only by fixed amounts (one condensing,
one extending, and one slanting), usually not all available for all
variants of the font, and may be "faked" by real fonts if available. [I.e.,
you may get italic where you had expected slanted, since you are really
asking Quickdraw for italic, which it will fake by slanting the upright if
there is no proper italic. This is not part of the answer, it's just an
explanation.]
Only slots to slots reencoding is available.

Now that's not so hard, is it?