On 13-01-10 03:03 PM, Alexei Podtelezhnikov wrote:
> On Thu, Jan 10, 2013 at 1:38 PM, Behdad Esfahbod <beh...@behdad.org> wrote:
>> Hi,
>>
>> There's a bug against Webkit:
>>
>> https://bugs.webkit.org/show_bug.cgi?id=102374
>>
>> that I think points to a problem in FreeType. Simply put: for fonts that
>> have
>> ascent+descent=line-height, this property may not hold anymore after hinting.
>> ascent+descent may be off by one pixel compared to line-height, which is not
>> quite desirable.
>
> If I understand correctly that equality is broken only in the broken
> fonts.
Really? I thought it happens because FreeType separately rounds ascent,
descent, and line_height. From the bug:
#ifdef GRID_FIT_METRICS
metrics->ascender = FT_PIX_CEIL( FT_MulFix( face->ascender,
metrics->y_scale ) );
metrics->descender = FT_PIX_FLOOR( FT_MulFix( face->descender,
metrics->y_scale ) );
metrics->height = FT_PIX_ROUND( FT_MulFix( face->height,
metrics->y_scale ) );
metrics->max_advance = FT_PIX_ROUND( FT_MulFix( face->max_advance_width,
metrics->x_scale ) );
#else /* !GRID_FIT_METRICS */
> So have you tried just forcing it?
>
> metrics->height = metrics->ascender + metrics->descender;
>
> If the height is more trustworthy, force the ascender:
>
> metrics->ascender = metrics->height + metrics->descender;
Webkit did end up working around it. I was being a good citizen and bringing
up the issue upstream.
--
behdad
http://behdad.org/
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