Metric Information

Lars Hellström
Wed, 24 Jul 2002 23:23:09 +0200

At 16.59 +0200 2002-07-23, Adrian Heathcote wrote:
>This question is slightly off-topic but arises from a question that Axel
>Rose asked on the list earlier---and it's been troubling me ever since.
>The question is: does mac Os X have access to ANY metric information
>(for post script fonts)---apart from what it can infer on the fly from
>the outline fonts themselves?

I've tried to find some information about this, but Apple seems to be
uninterested in providing information between the two extremes "You get the
following fonts for free with OS X which would otherwise cost $$$." and
"These are the functions in the C interface to the font manager." (it
appears the font manager has been replaced by something called ATSUI, but
there are very few explanations). This is really a shame---don't they
understand that they're threatening one of their most reliable user bases?

However, it appears that fonts should preferably be in OpenType format
(which is a generalisation of the old TrueType format) these days. With OT
fonts, there can (but doesn't have to) be metrics in the same file as the
outline, so I suppose that is where they want to take it from. I have
however seen it stated that the old suitcase (FONDs) + LWFNs scheme should
still be understood, although perhaps not given the same support.

>I ask this because every now and again I have to use (or try to use)
>Word in OS X, and i get behavior that suggests that the system is
>ignorant of everything about the fonts except the post script shape. For
>example if I type a sentence in 11 pt and then select and enlarge it to
>24 pt the glyphs completely overlap. In fact its fairly difficult to use
>a font at anything other than 12 pt. Serious anomalies begin to build
>up. I've had some bizarre behavior from Adobe's InDesign as well. (And
>of course Quark have said publicly that they cannot port Xpress until
>some changes are made to the OS---though they were coy about what.)

If an LWFN has been autoconverted to an .otf then it is possible that the
metrics weren't included, but if the widths are wrong then I doubt this is
due to the font. More likely then that it is a bug in Word or the OS.

>I know in days of old the metric info was in the FOND resource. But I
>get the impression that those suitcases are now treated as unnecessary.
>So is OSX metric blind?

I'm pretty sure that the C interfaces have plenty of functions for quering
the metrics, so I don't think this is the case.

>And is this a general failing of UNIX systems:
>how does Linux, for example handle post script fonts and the metrics
>that go along with it?

That would probably be the concern of the windowing system rather than the
OS, but it would be interesting to hear an explanation of how this works.

Lars Hellström