[poppler] Support for CJK fonts in postscript / on Windows platforms

[suzuki toshiya]

Hi Thomas,

I've tested latest git HEAD including your patch substituting missing
CID-keyed fonts to MS-Mincho, by MinGW binary. I'm sorry to say such,
but I wonder what is the advantage.

I'm usually using GNU/Linux and other Unix-like systems, and
I'm unfamiliar how Win32 people configures & uses poppler, so
maybe I made some misunderstanding about your motivation. Please
let me confirm about the background of MS-Mincho fallback.

In your first post, you commented that substitution of unembedded
CID-keyed by Helvetica causes a crash, so, the substitution by
MS-Mincho (or other CJK fonts?) is expected.
	http://lists.freedesktop.org/archives/poppler/2012-February/008715.html
The crashing problem is very critical, so even if the substitution
by MS-Mincho cannot display the glyphs correctly, some fix is needed.
I agree.

But, for first, I could not reproduce the crashing problem by my
binaries (pdffonts, pdftoppm and pdftops). Could you tell me more
about your crashing problem (how to reproduce, sample PDF, etc)?

Secondary, the substitution by MS-Mincho makes the problematic
substitution unclear. I attached a PDF created by Microsoft Word
and Adobe Acrobat; the smallest PDF that no fonts are embedded
(I think the combination of Microsoft Word + Adobe Acrobat is
the one of the most widely used workflow for PDF).

Please compare attached 2 PNG pictures converted by pdftoppm with
or without MS-Mincho fallback.
* A PNG image created without MS-Mincho fallback show many squares
for the glyphs that cannot be shown by Helvetica. It is easy for
the users to find something goes wrong. Also, ASCII characters are
shown correctly.
* A PNG image created with MS-Mincho fallback show nothing at the
positions where some glyphs are shown originally. It is difficult
for the users to find something goes wrong. Also, no ASCII characters
are shown.

Thus, I'm afraid more efforts are needed for hardwired CID-keyed
font fallback. At least, using MS-Mincho is not good idea, and,
appropriate warning should be printed. Of course, I'm willing to
work for this issue.

Regards,
mpsuzuki


Thomas Freitag wrote:
> Am 03.03.2012 17:40, schrieb suzuki toshiya:
>> Hi,
>>
>> I'm quite sorry for that no CJK helpers involves this issue...
>> The required help is a rewrite of your patch to fit the poppler
>> coding convention, and for the maintainers working with Unix
>> systems? If it is possible to do without Visual Studio, I will
>> try.
> Hopefully done now. As far as I rmember it was  Your patch (bug 11413) I 
> just applied to PSOutputDev.cc
>>
>> BTW, yet I've not checked your patch in detail, your patch is
>> trying to convert all missing (non-embedded) CID-keyed CJK fonts
>> by MS Mincho? I think it is not good idea for the users of
>> Adobe-GB1 (PRC, Singapore), Adobe-CNS1 (Taiwan, HongKong),
>> Adobe-Korea1 (ROK). I'm not sure if Ghostscript does so, but
>> even if Ghostscript does so, poppler should not follow it.
>> In fact, the coverage of CJK Ideographs are differently
>> designed to fit to each markets.
> No, it was not my goal to substitute all CID keyed fonts by MS Mincho. 
> The problem under Windows is just, that if there is no font with the 
> used name installed, poppler tried to replace it with Helvetica, but 
> because this is not a CID font no characters at all will be shown. So I 
> thought that MS Mincho is at least for this case a better idea as a 
> default CID font.
> But if You copy the cidfmap produced by mkcidfm.ps from ghostscript in 
> the poppler data dir, that substitute font table will be used if (and 
> only if) the font is not embedded and not installed under windows. Hope 
> that fits for CJK users, I thought it was better to use an existing 
> substitution algorithm than do nothing. And as far as I understand 
> mkcidfm.ps it will also try to find suitable fonts for GB1, CNS1 and the 
> others, but I'm no expert for CJK fonts. The cidfmap I produced on my 
> system would use arialuni.ttf for all CJK fonts, but I have just the 
> Microsoft default fonts.
> 
> Regards,
> Thomas
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