[cairo] freetype backend: ignore global advace if required

[Jackey Yang]

On 2005年8月23日 Tuesday 04:42, Keith Packard wrote:
> On Mon, 2005-08-22 at 12:52 -0400, Owen Taylor wrote:
> >  - How common are fonts that set isFixedPitch but have multiple
> >    character widths?
>
> Many (most?) CJK fonts have two character widths, and many of these
> set isFixedPitch. Fontconfig will tell you which fonts have this
> 'feature'.
>
CJK fonts are all two characters widths. It is a history problem, we can not 
blame anyone. 

> >  - How common are fonts that have a correct advanceWidthMax but
> >    buggy advances for individual characters?
>
> This group is full of nominally monospaced fonts (courier, et al) which
> have been extended to support a broader Unicode range. Often, these
> additional characters are of different width than the base font. In
> addition, these fonts are often ammended with zero width characters.
> The trouble here occurs when the maximum width is not the same as the
> nominal width; using the global advance makes things look right for most
> characters.
>
> > If the second group is much bigger than the first group, then
> > your patch is right ... we should default to not setting
> > the FreeType flag. If the first group is bigger than the second
> > group, the default should go the other way.
>
> The correct answer is "it depends". If you're using CJK fonts, the first
> group is very common. If you're in terminal emulator land, the second is
> more common.
>
> Given that few applications need monospaced characters, it's arguably
> better to ignore global advance by default and expect that applications
> will be able to manage varible pitch text correctly.

My suggestion is to create a flag to resolve this problem, like what sunmoon 
1997 did before.

Shall I fire a bug in bugzilla?

-- 
Jackey Yang
Akomedia Ltd.
Office: (86) 021-69960508
Cell: (86) 13761065416
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