Bug 82266

Summary:	Support variation selectors
Product:	fontconfig	Reporter:	Behdad Esfahbod <freedesktop>
Component:	library	Assignee:	fontconfig-bugs
Status:	RESOLVED MOVED	QA Contact:	Behdad Esfahbod <freedesktop>
Severity:	normal
Priority:	medium	CC:	freedesktop
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Behdad Esfahbod 2014-08-06 21:08:18 UTC

I think can support this internally by including a unicode,selector pair as (selector<<21)|unicode value in the charset, but provide new API to the charset for querying.  Or maybe expose that convention all the way to the API.  Here's some code to that extent:

      unsigned int var_num = 0;
      if (variation_selector - 0xFE00u < 16)
        var_num = variation_selector - 0xFE00 + 1;
      else if (variation_selector - 0xE0100u < (256 - 16))
        var_num = variation_selector - 0xE0100 + 17;
      unicode = (var_num << 21) | unicode;

Note that currently FcCharSetPutLeaf has:

    ucs4 >>= 8;
    if (ucs4 >= 0x10000)
        return FcFalse;

so the top byte of the ucs4 has been unused.  Unfortunately the top byte is not enough as there are 256 values to fit, not 255 :(.

Comment 1 Behdad Esfahbod 2014-08-06 21:42:38 UTC

FWIW, I wrote to the Unicode Technical Committee, asking them to agree not to use U+E01EF VARIATION SELECTOR-256.  Will post here when I hear back.

Comment 2 GitLab Migration User 2018-08-20 21:52:24 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

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