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

Ansel Sermersheim ansel at copperspice.com
Fri Dec 14 04:05:19 UTC 2018


On 11/29/18 7:29 AM, Behdad Esfahbod wrote:

> On Tue, Nov 27, 2018 at 8:34 PM Ansel Sermersheim 
> <ansel at copperspice.com <mailto:ansel at copperspice.com>> wrote:
>
>     On 11/19/2018 07:16 PM, Behdad Esfahbod wrote:
>>     Hi Ansel,
>>
>>     On Mon, Nov 19, 2018 at 7:44 PM Ansel Sermersheim
>>     <ansel at copperspice.com <mailto:ansel at copperspice.com>> wrote:
>>
>>         ...We have tried cluster
>>         levels 0 and 1, and neither one worked as we expected. In
>>         every case,
>>         combining accents are marked as being in a separate cluster
>>         to the base
>>         codepoint. For example, U+0061 Latin Small Letter A followed
>>         by U+0308
>>         Combining Diaeresis are being placed in adjacent clusters
>>         rather than
>>         the same cluster.
>>
>>
>>     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 so much for your continued help and support,

-Ansel

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