Re: r269471 make unusable VT console

On 19.08.2014 19:46, Nathan Whitehorn wrote:
> On 08/19/14 09:28, Jean-Sébastien Pédron wrote:
>>      o  vt_vga introduces a new callback, vd_bitblt_text_t, which takes
>>         as argument the text buffer, the dirty area, the font and the
>>         cursor (position, map, colors).
>
> Why is this necessary? I'd really prefer to avoid complicating this API.
> One of the great things about writing newcons drivers is that there is
> basically only one function you need to implement. If the current API
> does not provide enough information to do this efficiently, I'd much
> rather change it than add new callbacks.

I don't want to have two callbacks for the same feature either, and I'd
like to transition other drivers to this new one.

The current bitbltchr callback only knows about one character. In the
case of vt_vga, if this character (or the cursor) isn't aligned on
8-pixels boundaries, it needs to redraw several "blocks" of pixels. With
this character-centric approach, if a block needs a redraw, it'll be
refreshed for the character on its left side, then refreshed again for
the character on its right side.

The advantage of giving the callback the whole text/area is that it
allows the driver to manipulate the pixels block by block, instead of
character by character.

The patch isn't finished yet. Meanwhile, I'll commit the bug fixes I
made (especially the cursor handling in vt_flush()). But eventually, the
plan is to convert all drivers to this new callback, if you find the new
API sensible.

-- 
Jean-Sébastien Pédron