Bug 7538 - PDF backend introduces FreeType dependency
Summary: PDF backend introduces FreeType dependency
Alias: None
Product: cairo
Classification: Unclassified
Component: pdf backend (show other bugs)
Version: 1.2.1
Hardware: All All
: high blocker
Assignee: Kristian Høgsberg
QA Contact: cairo-bugs mailing list
Depends on:
Reported: 2006-07-15 21:05 UTC by Alp Toker
Modified: 2006-08-05 23:12 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

Don't use type1 and truetype subsetting when freetype is not available (8.38 KB, patch)
2006-07-27 12:34 UTC, Carl Worth
Details | Splinter Review

Description Alp Toker 2006-07-15 21:05:11 UTC
The Cairo PDF backend seems to make direct use of FreeType API (for font
subsetting). The necessary functions (looks like just a handful) should be
abstracted so the appropriate font backend is used on platforms that provide
their own font system.

This was noticed when compiling the latest Gtk+ release against the latest Cairo
release targeting native Win32. Since Gtk+ has introduced PDF printing
functionality, Cairo's PDF backend is now required by Gtk+, leading to the
undesirable situation where FreeType is a hard dependency of Gtk+ on all platforms.
Comment 1 Behdad Esfahbod 2006-07-15 22:36:50 UTC
Cairo's PS/PDF/SVG backends all depend on FreeType for all their text support
right now.  See:


Hans, can the full functionality be implemented easily using win32 API?  Do you
have any plans to do that?
Comment 2 Hans Breuer 2006-07-16 04:35:29 UTC
With some knowledge about PDF font embedding and true type tables it should be
possible with reasonable effort to fix the PDF backend. For PS/Type1 fonts
embedding I have no idea. The SVG backend seems to not embed any fonts at the
moment, so my patch should be enough for now.

In any case there should be a fallback path in these backends to *not* embed
fonts at all. There are licensing restrictions about embedding specific fonts
and for well-known fonts it does not appear to be necessary but just increases
file size.

If it would be easily implementable for me I probably would have done it
already. But I'm afraid  that I lack the required knowledge to do it right. And
acquiring that is quite low in my list.
Comment 3 Behdad Esfahbod 2006-07-16 07:26:00 UTC
For 1.2.2 I think we want to just do Type3 subsetting on win32.  We should
already have code for that somewhere.
Comment 4 Kristian Høgsberg 2006-07-16 07:43:15 UTC
The freetype dependency is very superficial for both truetype and type1 subsetting.  In both cases I only 
really need to access the raw file contents.    If there's a way to do that on win32 (and atsui) I can write 
a patch to make the subsetting code work with the raw contents instead of going through freetype, but 
I wont be able to test it on win32.
Comment 5 Kristian Høgsberg 2006-07-16 07:52:20 UTC
When is 1.2.2 scheduled for?  Didn't see anything in ROADMAP.
Comment 6 Hans Breuer 2006-07-16 08:00:15 UTC
For win32 the function to use is GetFontData(), see:

If you just need someone to check if it compiles on win32, 
feel free to drop me a note;)
Comment 7 Behdad Esfahbod 2006-07-16 08:15:27 UTC
(In reply to comment #5)
> When is 1.2.2 scheduled for?  Didn't see anything in ROADMAP.

We are targeting August 7, for GNOME 2.16.0 Beta 2.

Carl, can you update the ROADMAP?  It's way outdated after 1.2 release.
Comment 8 Carl Worth 2006-07-16 20:29:35 UTC
I'm quite certain that the type3 font support, (and the equivalent thing for the
SVG backend), definitely has no freetype dependency. I say that because I wrote
the type3 stuff and I don't know how to write any code that uses freetype.

So it would even be a straightforward patch to make the additional type1 and
truetype font subsetting an optional compilation based on the presence of
freetype. (Though, making them work with other font systems would obviously be

Comment 9 Carl Worth 2006-07-16 20:30:53 UTC
(In reply to comment #7)
> Carl, can you update the ROADMAP?  It's way outdated after 1.2 release.


"Anyone" can update ROADMAP. Just push out a new file to cairo/ROADMAP through
git and the content magaically appears at http://cairographics/ROADMAP.

Sorry for the currently stale data there, (and sorry I'm not fixing it now---I'm
signing off tonight until Wednesday.)


Comment 10 Carl Worth 2006-07-27 01:04:55 UTC
(In reply to comment #7)
> (In reply to comment #5)
> > When is 1.2.2 scheduled for?  Didn't see anything in ROADMAP.
> We are targeting August 7, for GNOME 2.16.0 Beta 2.
> Carl, can you update the ROADMAP?  It's way outdated after 1.2 release.

This is all updated now. Thanks for the reminder.

Comment 11 Carl Worth 2006-07-27 12:34:51 UTC
Created attachment 6367 [details] [review]
Don't use type1 and truetype subsetting when freetype is not available

Here's a patch that should eliminate the freetype dependency from the PDF, SVG,
and PS backends.

It accomplishes this the easy way by simply not compiling the type1 ro truetype
subsetting code if freetype is not available, (or even if freetype is but the
FT_Load_Sfnt_Table function is not).

I haven't actually tested this on win32 at all. But I did test that if the
check for FT_Load_Sfnt_Table fails that everything still compiles and that the
PDF backend does indeed produce results using type3 fonts.

The patch can also be obtained from the 7538 branch of my personal tree, which
can be browsed here:



PS. When testing this patch, please note that the recent change to the handling
of the font matrix leaves text in general quite broken for the PDF and PS
backends at least. One might want to revert
84840e6bba6e72aa88fad7a0ee929e8955ba9051 to avoid that problem until a fix is
in place.
Comment 12 Behdad Esfahbod 2006-07-27 13:38:57 UTC
krh and I thought we can just make _cairo_ps_surface_emit_type1_font_subset and
_cairo_ps_surface_emit_truetype_font_subset return UNSUPPORTED.
Comment 13 Behdad Esfahbod 2006-07-27 13:40:27 UTC
Oops sorry, seems like this was already discussed.
Comment 14 Adrian Johnson 2006-08-01 15:09:47 UTC
Bug 7603 has a patch that removes the freetype dependency while adding support
for win32 truetype fonts in the PS and PDF backends.
Comment 15 Kristian Høgsberg 2006-08-02 16:33:41 UTC
This is now fixed in git.
Comment 16 Behdad Esfahbod 2006-08-05 23:12:55 UTC
Adrian, Kristian,

Can one of you please patch the subsetting codes (not sure if both need work) to
use types like int32_t instead of "long", "int", and "short"?  I guess this is
the reason truetype subsetting is reported to produce invalid PDF on 64-bit systems.

We are releasing 1.2.2 on Aug 7th.   Would be cool to have this fixed in that
release.  Thanks in advance.

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