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Re: Antialiased fonts patch.

From: Evgeny Kolesnikov
Subject: Re: Antialiased fonts patch.
Date: Tue, 26 Jan 2010 16:04:07 +0600


> At first I was completely against antialiasing support because of
> performance impact. But it being optional decreases the later. However
> there is one problem: your patch relies on text_layer to be RGBA8888
> which was a mistake. RGBA8888 for text layer is vastly inefficient
> especially on 16-bit framebuffer and CPUs with small cache. I had plans
> to switch it to indexed color. Do you really need 8bits and 4 aren't
> enough? 

I use 8-bit in order to give GRUB ability to look and feel exactly
as other parts of OS, so yes, 8 bits are required. If one can't allow
this for his system - he can use 1-bit fonts. I don't really care about
such situation just because other parts of desktop on such a system will
be awful too.

> If 4 are enough we could make text_layer IA44 (indexed-4 bits,
> alpha 4 bits) if you need 8 bits we can do IA88. I'm not sure which one
> is faster: firs one is more cache-efficient, second one requires less
> ALU. Are you interested in implementing this?

Actually I'm planning to add 32-bit AA (heh-heh). Sub-pixel AA for LCD
monitors for complete match with xorg capabilities. And this just can't
be done in indexed mode.

So I can suggest to make division: 1-bit & indexed text layer vs
8(32)-bit & RGBA layer. First is for speed, second (and third) 
is for beauty (BURG project is already interested in - Bean, help
me :)). Doing it half-way will be nor fast nor appealing.

And yes, I'm interested in doing it in most effective way: blitter,
optimizations etc., just give me the direction.

> > Everything my path does is:
> >
> > 1) Enriches grub-mkfont with ability to write (and debug with -vv) 
> > pff3 (as I call it now) font format. There are 2 differences between
> > pff2 and pff3 formats: FILE magic (PFF2 becomes PFF3) and DATA block
> > entires size multiples by 8 (1bit -> 8bit). In other words PFF3 stores
> > 8-bit alpha channel instead of 1-bit.
> > And grub-mkfont will still be able to generate pff2, of course.
> >
> >   
> And by default grub-mkfont should generate not antialiased font for
> performance reasons. But user or theme creator can choose to use
> antialiased fonts if they wish.

It's exactly the way my patch does it. AA is optional and used

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