Re: [ft-devel] FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH by default?

[Behdad Esfahbod]

On 04/20/11 03:11, Werner LEMBERG wrote:
>> Every user of FreeType that I know has once in their lifetime hit
>> the bug that with many common CJK fonts, non-CJK characters take
>> doublewidth where they should take a single one.  The fix always has
>> been to pass FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH to FreeType, as the
>> fonts have the bit set wrongly.  A "monospace" CJK font is never
>> monospace.  It has single-width glyphs, and double-width, hence
>> setting global-advance is wrong in the font.
>>
>> But since this is such a common issue, I wonder if FreeType should
>> simply ignore global advance by default.  Cairo and fontconfig
>> always pass that flag to FreeType.  I've seen this bug hit Qt
>> before.  And most recently I watched it hit Skia.
> 
> I've already pondered about this problem, but I've found no solution
> which guarantees backwards compatibility.  Your idea of completely
> ignoring this flag didn't come to my mind :-)
> 
> Since your suggestion sounds sensible, could you provide a patch?

Attached.  You also need to update the ft2demos that use it to remove the
option (ftdiff, etc).

behdad

>     Werner

ignore-global-advance.patch
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