Re: [ft] Type 1 font rendering seems wrong.

[James Cloos]

>>>>> "Werner" == Werner LEMBERG <address@hidden> writes:

Tim> Adobe reader actually uses Adobe Sans MM to render [Helvetica]

Werner> Hmm, the name `MM' means `Multiple Master'.  Playing around
Werner> with ftmulti, it seems that FreeType's rendering uses
Werner> approx. the values 360/860 for the weight/width axes of
Werner> AdobeSansMM.  On the other hand, the xpdf rendering uses
Werner> approx. 420/360 for the weight/width value pair.

Werner> In case xpdf really uses this MM font, it seems that it
Werner> adjusts the width axis according to the metrics in the PDF on
Werner> a per-glyph basis.  The different weight is probably due to
Werner> different configuration parameters.

It is very unlikely that xpdf uses Adobe Sans MM at all, even if
the font is in the search path....

AFAIK no libre pdf renderer has support for using MM fonts as
substitutes for non-embeded fonts; so far only Adobe's stuff does
that.

Up through reader 5 -- and maybe 6 -- either helvetica or arial was
included in the package, and used for any pdf which wanted either of
those two.  Similarly either times or times new was included and used
for either of /those/ two.  (They started with helvetica and times,
then moved to type1 versions of arial and times new for acrobat5.)

Only reader7 and later might use the MM fonts as subs for Helvetica,
Arial, Times or Times New.  And even then they are likely to first
check the system fonts for a closer match.

Modern versions of xpdf, including those linked to poppler, will
either use a set of fonts specified in a config file, or fontconfig
to choose a font.  In the case of helvetica, if it is not found, and a
specific substitute like arial or NimbusSanL is not found, then (given
a standard /etc/fonts/fonts.conf) fontconfig's Sans font will be used.

In general, Helvetica (4 faces), Times (4 faces), Courier (4 faces),
Symbol, and Zapf Dingbats in a PDF are supposed to render correctly
no matter what pdf browser is used, but in practice there is never
a guarantee on the metrics or the glyph shapes unless the font is
embedded.  Even different versions of adobe's reader on any given
single platform, much less across all of the platforms they have
supported, will generate different renderings for non-embeded fonts.

-JimC
-- 
James Cloos <address@hidden>         OpenPGP: 1024D/ED7DAEA6