ps2write

[Ken Sharp]

Looking for some advice or ideas....

 From bug 690012, a TrueType font with a very large number of glyphs
doesn't work correctly when output using ps2write. My last comment on the
thread:

--------------------------------------------------------------------------
It looks like this is a limitation of the PostScript prolog for ps2write,
abetted by architectural limitations in PostScript. If we select the
pdfwrite device we can see that a valid working PDF file is produced.

ps2write basically writes out the contents of a PDF file, with a prolog
(opdfread) which defines a number of PostScript procedures so that the
emittted 'PDF' file will work.

It appears that the font handling simply cannot cater for a font of this
size, it attempts to manipulate array indices above 64K, which is an
architectural limit.

I'm not sure its possible to overcome this, any ideas anyone ?
----------------------------------------------------------------------

I haven't identified exactly where the invalidaccess and rangecheck errors
are coming from, but they always seem to occur with CharStrings on the
stack, so I infer this is a font problem. They also seem to have very large
integers (one case > 80,000, another > 111,000) which appear to be indices
to 'put' or to 'getinterval' (these are the operators signalling the error).

If anyone (but especially Alex) has any ideas, I'm open to suggestions.



                                                                Ken
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
TASK: Shoot yourself in the foot.
Occam You shoot both your feet with several guns at once.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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[Leonardo-21]

Ken,

My old idea is to re-index glyphs when creating a font subset.
Note it may need to adjust subglyph indices in composite glyphs.
IMO it worth to do even for pdfwrite to create smaller fonts.

Leo.


----- Original Message -----
From: "Ken Sharp" <ken.sharp@...>
To: <gs-devel@...>
Sent: Tuesday, August 12, 2008 7:17 PM
Subject: [gs-devel] ps2write

> Looking for some advice or ideas....
>
> From bug 690012, a TrueType font with a very large number of glyphs
> doesn't work correctly when output using ps2write. My last comment on the
> thread:
>
> --------------------------------------------------------------------------
> It looks like this is a limitation of the PostScript prolog for ps2write,
> abetted by architectural limitations in PostScript. If we select the
> pdfwrite device we can see that a valid working PDF file is produced.
>
> ps2write basically writes out the contents of a PDF file, with a prolog
> (opdfread) which defines a number of PostScript procedures so that the
> emittted 'PDF' file will work.
>
> It appears that the font handling simply cannot cater for a font of this
> size, it attempts to manipulate array indices above 64K, which is an
> architectural limit.
>
> I'm not sure its possible to overcome this, any ideas anyone ?
> ----------------------------------------------------------------------
>
> I haven't identified exactly where the invalidaccess and rangecheck errors
> are coming from, but they always seem to occur with CharStrings on the
> stack, so I infer this is a font problem. They also seem to have very
> large integers (one case > 80,000, another > 111,000) which appear to be
> indices to 'put' or to 'getinterval' (these are the operators signalling
> the error).
>
> If anyone (but especially Alex) has any ideas, I'm open to suggestions.
>
>
>
> Ken
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> TASK: Shoot yourself in the foot.
> Occam You shoot both your feet with several guns at once.
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
> _______________________________________________
> gs-devel mailing list
> gs-devel@...
> http://www.ghostscript.com/mailman/listinfo/gs-devel
>

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[Ken Sharp]

At 19:53 12/08/2008 +0400, Leonardo wrote:


>My old idea is to re-index glyphs when creating a font subset.
>Note it may need to adjust subglyph indices in composite glyphs.
>IMO it worth to do even for pdfwrite to create smaller fonts.

Thanks Leo, I was guessing this would be at least a partial solution. I
suppose if we have too many glyphs in a single subset we should convert to
multiple subsets ? I don't know if that's a good idea for pdfwrite as we
will end up emitting multiple fonts for CJKV languages ?

Sounds like a big job unfortunately.

                             Ken

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[Leonardo-21]

Ken,

You don't need to divide into smaller font subsets,
because it is not useful for CID fonts and is already done
for non-CID fonts.

All what you need here is a local change to pdfwrite :
just call a new function immediately before writing a TT font out
(and after the conversion of  a Type 42 into CIDFontType 11
if necessary). The new function
(1) compacts 'loca' and (2) updates composite glyphs
before writing the font. Note for subset we always
re-generate loca.

Leo.

----- Original Message -----
From: "Ken Sharp" <ken.sharp@...>
To: "Leonardo" <leonardo@...>
Cc: <gs-devel@...>
Sent: Tuesday, August 12, 2008 8:57 PM
Subject: Re: [gs-devel] ps2write xefitra

> At 19:53 12/08/2008 +0400, Leonardo wrote:
>
>
>>My old idea is to re-index glyphs when creating a font subset.
>>Note it may need to adjust subglyph indices in composite glyphs.
>>IMO it worth to do even for pdfwrite to create smaller fonts.
>
> Thanks Leo, I was guessing this would be at least a partial solution. I
> suppose if we have too many glyphs in a single subset we should convert to
> multiple subsets ? I don't know if that's a good idea for pdfwrite as we
> will end up emitting multiple fonts for CJKV languages ?
>
> Sounds like a big job unfortunately.
>
>                             Ken
>
>

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[Ken Sharp]

At 22:58 12/08/2008 +0400, Leonardo wrote:


>You don't need to divide into smaller font subsets,
>because it is not useful for CID fonts and is already done
>for non-CID fonts.

Yes of course, I had forgotten that... I suspect the problem only exists
with TreuType fonts, but I'll need to check.



>if necessary). The new function
>(1) compacts 'loca' and (2) updates composite glyphs
>before writing the font. Note for subset we always
>re-generate loca.

That sounds good, thanks for the input I'll look at it as my next task.


                         Ken

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