Re: cjk texts in the pdf file which MkIV output sometimes can not be copy rightly

["Li Yanrui (李延瑞)" <liyanrui.m2@gmail.com>]

2010/9/20 Li Yanrui (李延瑞) <liyanrui.m2@gmail.com>:
> 2010/9/10 Taco Hoekwater <taco@elvenkind.com>:
>> On 09/10/2010 02:32 PM, Li Yanrui (李延瑞) wrote:
>>>
>>> 2010/9/10 Li Yanrui (李延瑞)<liyanrui.m2@gmail.com>:
>>>>
>>>> Hi all,
>>>>
>>>> For the pdf file which is generated frome the following example, two
>>>> Chinese characters can not be copied rightly when I use simsun.ttc
>>>> font and use *Adobe Reader* to view it. The copy text is displayed as
>>>> the wrong unicode text such as "􁨀".
>>
>> It looks like the reader is ignoring the ToUnicode entry in the
>> bad case. No idea why, though.
>>
>
> My friend sent a mail to Ken Lunde who works for adobe systems
> incorporated. He replied:
>
> [quote]
> I forwarded your email to the Acrobat team for investigation.
> When I copied the body text from the first file, and all of the text
> from the second file, the code points are PUA, specifically Unicode
> Plane 16. The heading text of the first file appears to be encoded
> correctly. I am guessing that this is a PDF producer issue.
> I will keep you posted about what the Acrobat team discovers.
> [/quote]
>
> In the above, the first file is the tex file of the pdf file which is
> the attachment for my previous mail; the second one is that
> attachment.
>

Recently Ken Lunde replied again:

> Gu Hua forwarded your email to the Acrobat, which investigated this issue.
>
> The evidence points toward a malformed or poorly-made ToUnicode table.
> It would be appropriate for Adobe Reader to ignore such a ToUnicode
> table.
>
> It would be useful to know how the ToUnicode table is made by this PDF
> producer. I know that when making a static ToUnicode mapping resource,
> which uses CMap resource syntax, it is very easy to make an invalid
> one, specifically because CID ranges, when expressed as two-byte
> values, cannot cross first-byte boundaries. Also, UTF-32 (and UTF-8)
> cannot be used directly, and such values must be converted to UTF-16.
> One or both of these issues, if not handles correctly, can result in
> an invalid ToUnicode table.
>

In fact the text with  fonts such as simsun.ttc can not be copied
rightly but the text with fonts such as AdobeSongStd-Light.otf can be
copied rightly. It seems like that this problem may be related to the
font loading script of mkiv.

-- 
Best regards,

Li Yanrui (李延瑞)
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