Re: [ft-devel] Seams with disjoint composite

[Behdad Esfahbod]

Filed here:

https://bugs.freedesktop.org/show_bug.cgi?id=50848

behdad

On 06/07/2012 05:47 PM, Werner LEMBERG wrote:
> 
>>> It depends on a flag in the glyph's data, ROUND_XY_TO_GRID, if the
>>> subglyph's offset is given as xy values.  However, for the
>>> particular DejaVu glyph, the subglyphs all have a zero offset, but
>>> point coordinates are rounded to integers anyways as part of the
>>> normal rasterization process.
>>
>> Right.  So I guess my question is, why are they rounded differently?
> 
> I spoke too hastily since I hadn't looked closely enough at the
> subglyphs.
> 
> It's a bug in the font.  The glyph ▟ consists of three elements:
> 
>   <TTGlyph name="uni259F" xMin="-20" yMin="-512" xMax="1593" yMax="1576">
>     <component glyphName="uni2596" x="0" y="0" flags="0x1004"/>
>     <component glyphName="uni2597" x="0" y="0" flags="0x1004"/>
>     <component glyphName="uni259D" x="0" y="0" flags="0x1004"/>
>   </TTGlyph>
> 
> Note that the 4 in the flags value 0x1004 means ROUND_XY_TO_GRID.
> 
> Now the components.  The first one is a real glyph:
> 
>   <TTGlyph name="uni2596" xMin="-20" yMin="-512" xMax="786" yMax="532">
>     <contour>
>       <pt x="-20" y="-512" on="1"/>
>       <pt x="-20" y="532" on="1"/> 
>       <pt x="786" y="532" on="1"/> 
>       <pt x="786" y="-512" on="1"/>
>     </contour>
>   </TTGlyph>
> 
> The other two, however, are not:
> 
>   <TTGlyph name="uni2597" xMin="787" yMin="-512" xMax="1593" yMax="532">
>     <component glyphName="uni2596" x="807" y="0" flags="0x1004"/>
>   </TTGlyph>
> 
>   <TTGlyph name="uni259D" xMin="787" yMin="532" xMax="1593" yMax="1576">
>     <component glyphName="uni2596" x="807" y="1044" flags="0x1004"/>
>   </TTGlyph>
> 
> Both have the flag 0x1004, meaning that the offsets are rounded to the
> grid...
> 
> The real solution is to redefine uni259F (and all other similar block
> characters) having uni2596 three times as subglyphs, with proper
> offsets, and with flags values 0x1000.  I've justed tested it: no
> gaps.
> 
> I wonder how such glaring problems can be part of one of the most used
> free fonts.
> 
> 
>     Werner