Re: Set_Pixel_Sizes for TTF

[Yamano-uchi, Hidetoshi]

Hi Werner,

From: Werner LEMBERG <address@hidden>
Subject: Re: Set_Pixel_Sizes for TTF
Date: Wed, 11 Oct 2000 00:10:38 +0200 (CEST)
Message-ID: <address@hidden>

> > > I have the impression that Set_Pixel_Sizes() in ttdriver.c does
> > > nothing.  Is this a bug?
> > 
> > I don't think so.
> 
> But how shall the application know?

In current snapshot, we choose a sbit strike as following manners.

a. ppem = em_size * point / 72.
b. searching suitable sbit strike.

It works without troubles.

> I think the behaviour of FT
> should be changed that for bitmap fonts only FT_Set_Pixel_Sizes()
> works, giving an error if the font is an outline font.  The opposite
> for FT_Set_Char_Size().
> Maybe there is a better solution -- but doing nothing is bad.

It should work fine for 1 to 3.  But in the cases of 4 and 5, we
sometime use sbits if avaliable, otherwith use outlines.  Your
convention is incovinient for this style.

> > Set_Pixel_Sizes is useful for following types.
> > 1. outlines with all sbits(a.k.a. embedded bitmaps).
> > 2. sbits without outlines.
> > 
> > But it is confused if two API(Set_Pixel and Set_Point) is
> > available for following cases.
> > 3. outlines without sbits.
> > 4. outlines with a few sbits. (e.g. Monotype Courier New)
> > 5. outlines with many (but not all) sbits. (e.g. MS mincho)
> > 
> > Any good solutions?
> 
> 3. to 5. are fonts which are used in an outline context.  IMHO the
> existence of sbits should be completely hidden to the application, so
> only FT_Set_Char_Size() should be used.

Some improbement:

A. Set_Char_Size sets outline's size, and set sbit's when
Set_Pixel_Size is not applied.
B. Set_Pixel_Size sets sbit's size, and set outline's when
Set_Char_Size is not applied.

Any comments?  Werner, David?

P.S.
TTF is much difficult handling "correctly" :-(

----- Yamano-uchi, Hidetoshi