Re: [ft-devel] Unable to load OpenType font (test case + font attached)

[suzuki toshiya]

Thank you for providing a sample.

For first, please let me comment to your question "why". An OpenType
embedded in PDF should not be expected to be usable as a self standing
OpenType font. It is a component of PDF, and some essential information
are removed (because the identical or substitution information are
stored in the side of PDF). If you check OpenType specification,
        http://www.microsoft.com/typography/otspec/otff.htm#otttables
you will find that "head" is essential table and the font lacking it
is not an officially self-standing OpenType font. And, PDF has their
own convention how to transform/compress the OpenType font and PDF
spec does not request the embedded OpenType is conforming to OpenType
spec.

# without "head" table, TrueType font parser cannot access the
# glyph program, because only the "head" table provides the info
# how to calculate the glyph program storage location from the
# glyph index. but in this case, "CFF" table is used, so it
# is not essential.

Anyway, I understand FreeType is often expected to load the embedded
OpenType font data in PDF. And, your sample would not require complex
trick to load as self standing font; Your sample is a simple concatenation
of cmap table and CFF table. It would not be so difficult changing FreeType
to pass included CFF stream to CFF parser. But yet I'm not sure if
the cmap table content should be used (if it should be used, more work
is needed).



Regards,
mpsuzuki

Harry Roberts wrote:
> At sfnt/ttload.c:~280
> 
> The font doesn't have the two expected tables (head, sing) - if I ignore
> that fact and return `SFNT_Err_Ok` from `check_table_dir` then the font
> loads fine and renders perfectly.
> 
> Why does the FreeType TTF loader required these two headers when it works
> without them?
> 
> ```
> 282:     FT_TRACE2(( "check_table_dir:" ));
> 283: #ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
> 284:       FT_TRACE2(( " neither `head', `bhed', nor `sing' table found\n"
> ));
> 285: #else
> 286:      FT_TRACE2(( " neither `head' nor `sing' table found\n" ));
> 287: #endif
> 288:      error = SFNT_Err_Table_Missing;
> ```
> 
> On 7 November 2012 01:12, Harry Roberts <address@hidden> wrote:
> 
>> Recently I have come across many fonts embedded within PDF files which
>> cannot be loaded by FreeType v2.4.10.
>>
>> I suspect Enfocus PitStop is mangling the fonts when the PDF file is
>> 'optimized'.
>>
>> Attached is the font file (extracted from a PDF) and test case.
>>
>> Adobe Acrobat and Photoshop are able to load the fonts. FontForge can also
>> open the font, and after 'Exporting to OpenType'  the test case is able to
>> load the font successfully.
>>
>> I am still trying to debug the problem, but my knowledge of FreeType and
>> font format internals is being stretched. Any insight would be appreciated.
>>
>> Regards,
>>  - Harry
>>
> 
> 
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