[HarfBuzz] Cluster question (Was Cluster soap box time)

[Ansel Sermersheim]

On 12/13/18 8:05 PM, Ansel Sermersheim wrote:
>
> On 11/29/18 7:29 AM, Behdad Esfahbod wrote:
>
>>>     That doesn't sound right. Are you setting any custom
>>>     unicode-funcs on the buffer?  Only thing I can think of that can
>>>     do this is faulty / missing Unicode funcs.
>>
>>     We had a feeling something was missing. No, we are not supplying
>>     any unicode funcs. Do you have a sample or documentation
>>     reference for what we need to supply?
>>
>>
>> Not supplying anything is good.  Was just ruling out that as a cause.
>>
>>     I have looked at the online documentation without seeing a clear
>>     list of what is required. We are specifically looking to use
>>     harfbuzz to decipher special case grapheme breaks.
>>
>>
>> Can you check with hb-shape command-line tool, to make sure what you 
>> expect is what HarfBuzz produces there?
>
> Sorry it took a while to get back with you, we really do appreciate 
> your help. We have been looking over the code and we believe we are 
> having a problem with missing unicode callback functions. We are 
> compiling HarfBuzz with the following options turned on:
>
>>    -DHAVE_ATEXIT
>>    -DHB_EXTERN=
>>    -DHB_NO_UNICODE_FUNCS
>>    -DHB_NDEBUG
>
> I am particularly suspicious of the HB_NO_UNICODE_FUNCS define. Am I 
> correct in thinking that this is suppressing the built-in harfbuzz 
> unicode functions, so we must supply our own?
>
Thanks to everyone for their help and ideas.

We now have our unicode callbacks installed and being called, however 
the behavior is for some reason unchanged. When we call hb_shape, we are 
seeing our general category and combining_class implementations being 
invoked. They are returning (as far as I can tell) sane values, but the 
resulting glyphs are still being marked as being in seperate graphemes.

We are still working on this issue, but I wanted to send an update in 
case this description rings a bell for anyone.

Thanks,

-Ansel


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