[ft-devel] Strange behavior of freetype 2.3.7 function FT_OpenType_Validate()

[Chi Nguyen]

To freetype maintainer,


In developing the test for the freetype2 function FT_OpenType_Validate() we
encounter the following strange behavior that we want to bring to your
attention. We hope to get a clarification whether this is a bug or a
feature. This behavior pertains to freetype 2.3.7.

We rebuild the freetype library by turning on OpenType validation. We
uncomment the line "AUX_MODULES += otvalid" in the file "modules.cfg"
Then - configure - make - make install - ... 

OpenType validation is then available after that.

We ran a sample C test program and noticed that in some cases
FT_OpenType_Validate behaves weird. 

For example, it returned error==0 and valid table pointer values when we
asked it to validate all advanced tables in "FreeMono.ttf" font (flag ==
FT_VALIDATE_OT). 
Now if we asked it to validate "GDEF table", it returned error==0x10
("invalid glyph index"). This looked strange to us.

Please investigate if you could reproduce this and give us your
opinion/ruling.

Included with this email is the C test program in question together with the
font file FreeMono.ttf. This strange behavior was observed under OpenSuSE 11
(32 bit), Ubuntu 8.04 (ia32), RHEL52 x86-64, SLES 10.1 (32bit), Fedora 9 (32
bit) with freetype 2.3.7 built from sources (with "otvalid" module turned
on).

Thank-you very much for your attention.


Sincerely yours,


Nguyen Trung Chi
NEC Solutions VietNam

Opentype_validate.rar
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