linuxconsole-dev

Re: [Linux-fbdev-devel] Best font drawing algorthim.

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

>My understanding of ruby was that a 1bit fb_image would be sent to
>the driver 'xxxfb_imageblit' function to be expanded in hardware.
>Are you talking about filling the fb_image (one per character or
>one per line or...), or about a generic 'xxxfb_imageblit' for driver
>not supplying their own ?

I'm talking about a generic xxxfb_imageblit function for hardware that
lacks this functionality.

MS: (n) 1. A debilitating and surprisingly widespread affliction that
renders the sufferer barely able to perform the simplest task. 2. A disease.

James Simmons  [jsi...@li...]               ____/|
fbdev/console/gfx developer                             \ o.O|
http://www.linux-fbdev.org                               =(_)=
http://linuxgfx.sourceforge.net                            U
http://linuxconsole.sourceforge.net

Re: [Linux-fbdev-devel] Best font drawing algorthim.

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

>i haven't looked much at the fbdev code lately, but ...
>
>in the design of ruby, did you look at the passage from cfb8/16/24/... to
>fb in the XFree server ?

Yes I did. It appears me and Keith Packard think along the same lines. The
fillrect and copyarea are pretty much the same ideas exactly. I can tell
you from my own benchmarks the fb layer will outperform by a large margin
the cfb layer. The key is the word align. I know for intel platforms it
makes a huge difference. On some platforms this is required. Thanks for
the pointer. I'm looking at the font code. It will take some time to
digest it.

MS: (n) 1. A debilitating and surprisingly widespread affliction that
renders the sufferer barely able to perform the simplest task. 2. A disease.

James Simmons  [jsi...@li...]               ____/|
fbdev/console/gfx developer                             \ o.O|
http://www.linux-fbdev.org                               =(_)=
http://linuxgfx.sourceforge.net                            U
http://linuxconsole.sourceforge.net

Re: [Linux-fbdev-devel] Best font drawing algorthim.

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

>Or eventually of adding another API similar to the current one
>(2.2 / 2.4) that would ask a driver to draw a specific character
>at a specific localtion by whatever means the driver see fit ?

This can be done in fbcon.c. I like fbcon to be able to choose the
best method. This keeps the drivers simple and small.

>I believe that the last would be both easier for you (simple
>reuse of current working code) and the most efficient for
>driver writers, as they could use the best/fastest way for
>the hardware to draw glyphs ; it's not necessarily expanding
>a 1-bit image (even if it's the way I'm doing it ATM :-)


True. Even if the function is called fb_imageblit it doesn't mean you have
to color expansion blitting to draw the image. The purpose of the function
is to draw a image of some color depth. It doesn't matter how you do it.

MS: (n) 1. A debilitating and surprisingly widespread affliction that
renders the sufferer barely able to perform the simplest task. 2. A disease.

James Simmons  [jsi...@li...]               ____/|
fbdev/console/gfx developer                             \ o.O|
http://www.linux-fbdev.org                               =(_)=
http://linuxgfx.sourceforge.net                            U
http://linuxconsole.sourceforge.net