Re: [Linux-fbdev-devel] fonts

[James S. <jsi...@in...>]

> > The cfb_imageblit() function exhibited the same behavior.  I think we
> > both made the wrong assumption that all monochrome bitmaps are packed. I
> > think the rule is:
> > 
> >     The first pixel on the next scanline is always at the next byte from
> >     the last pixel of the current scanline.  
> > 
> > So a 12x22 font has 16 bits per scanline but only 12 are usable, and the
> > last 4 are used as padding.  It's worse with a 4x6 fonts where the
> > 4-bits are just duplicated in the other nibble.
> 
> Yes.

All the font data should be packed and byte padded at the end of each 
scanline worth of data. Also most accel engines expect the data to byte 
packed.

> But that was not my problem. Currently accel_putcs() falls back to individual
> character drawing if the fontwidth is not a multiple of 8, and reuses the same
> struct fb_image for each call of fb_imageblit(). And since my fb_imageblit()
> had a loop like `while (image->height--) { ... }' it failed. Not modifying the
> passed struct fb_image fixed the problem. Yes, we need the const there :-)

I guess I need to change that in the next set of changes.