DirectFB?

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garystampa

Joined: 25 May 2011
Posts: 52
Location: Central FLorida

garystampa 26 Oct 2011, 13:26

I am putting together a system with the goal of using a console-only Linux. (I haven't selected one but have several choices I'm investigating).

However I will want to run some graphical content on this system. So my question is: does anyone know if DirectFB is a good solution for this?

My understanding (so far) is that I would be able to run completely console until my program boots and starts DirectFB. At this point my program can output graphics using DirectFB's interface with the Linux frame buffer.

Why not just run any flavor of Linux and use X or add DirectFB to that? I want a lean and mean system that will fit in a very small space. No particular memory goal, just as small a possible without a bunch of stuff that will never execute.

I have a program using DirectFB under Puppy Linux which works fine, I just don't have enough knowledge of general Linux to simply strip this Linux down.

Thanks in advance.

26 Oct 2011, 13:26

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 31 Oct 2011, 15:21

How would you classify the graphics needs of your application(s)?

A dumb framebuffer is horribly inefficient compared to hardware accelerated rendering.

31 Oct 2011, 15:21

garystampa

Joined: 25 May 2011
Posts: 52
Location: Central FLorida

garystampa 09 Nov 2011, 12:18

Sorry - I never saw your answer.

The application is just to display BMP files over the entire screen. "Soothing displays". The BMP images change about every 10 to 20 seconds. Nothing fancy, so I want to keep this as minimal a system as possible. Actually I was trying to see how little I could get away with.

09 Nov 2011, 12:18

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 10 Nov 2011, 16:26

i believe directfb is getting more and more unused on linux, and different architectures have different include files too...

So my preference is SDL now, it has a "framebuffer" mode too

10 Nov 2011, 16:26

garystampa

Joined: 25 May 2011
Posts: 52
Location: Central FLorida

garystampa 11 Nov 2011, 15:02

Thanks for the heads up - I've seen references to SDL but misinterpreted them as having been deprecated.

Do you have any favorite links to discussions regarding SDL?

11 Nov 2011, 15:02

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 14 Nov 2011, 02:48

garystampa wrote:

Thanks for the heads up - I've seen references to SDL but misinterpreted them as having been deprecated.

Do you have any favorite links to discussions regarding SDL?

well in ASM i don't know any yet, but we can make one here in linux... it would be nice to get FASM like SDL.

There is an SDL homepage, some LAME examples, and an irc chanel on freenode,
i've just started using it in C too, framebuffer's there, even double buffering is there, so its already usable.
Currently working on an asynchronous buffer flip example, if developers see it, maybe they'll even consider including.

BTW.: SDL is portable and is used for porting dos games to linux like TTD => OpenTTD, Dune2 => OpenDune

14 Nov 2011, 02:48

garystampa

Joined: 25 May 2011
Posts: 52
Location: Central FLorida

garystampa 14 Nov 2011, 12:36

Very interesting. Thanks!

14 Nov 2011, 12:36

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 25 Nov 2011, 01:42

just for fun, if you enable framebuffer mapping from /dev/fb0 you can do this in a framebuffered text console:
this will paint random pixels in fullscreen on 1024x768 framebuffer

Code:

dd if=/dev/urandom bs=65536 count=48 of=/dev/fb0

this will determine the fill rate for you

Code:

dd if=/dev/zero bs=65536 count=48 of=/dev/fb0

they must be run as root by default, here's a sample output:

Code:

48+0 records in
48+0 records out
3145728 bytes (3.1 MB) copied, 0.00370885 s, 848 MB/s

25 Nov 2011, 01:42

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 25 Nov 2011, 04:22

played it

Code:

sb=$(stty -g);
tput civis;
stty raw -echo;
dd if=/dev/urandom bs=65536 count=48 of=/dev/fb0 2>1 >/dev/null;
sleep 4;
stty "$sb";
tput cnorm;

25 Nov 2011, 04:22

garystampa

Joined: 25 May 2011
Posts: 52
Location: Central FLorida

garystampa 28 Nov 2011, 15:25

Now I'm confused. It seems that SDL requires X. Also, I can't find any font drawing abilities in SDL.

The reason I liked DirectFB is that it didn't require X and it also supported fonts. Am I overlooking something about SDL?

28 Nov 2011, 15:25

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 28 Nov 2011, 21:43

I would assume you should be able to compile a SDL version without X11 support - but since X11 is the default graphics provider for *u*x, it makes a lot of sense for the default binaries to include support for that Smile

It's been aged since I messed with SDL, though, so I'm not up to date with the backends supported. I'd be surprised if you can't get something working with just... directfb?... support. But I'd also not be surprised if they haven't checked no-X11-support build paths for a while Smile

28 Nov 2011, 21:43

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 01 Dec 2011, 12:11

garystampa wrote:

Now I'm confused. It seems that SDL requires X. Also, I can't find any font drawing abilities in SDL.

The reason I liked DirectFB is that it didn't require X and it also supported fonts. Am I overlooking something about SDL?

hehe, i was feeling the same, they recommend using some ttf library to render fonts, though i just wrote my simple text output functions using the framebuffer, db-ed a 8x8 ascii font 8 bytes / character = 1024 bytes.

01 Dec 2011, 12:11

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 01 Dec 2011, 12:29

Matrix wrote:

hehe, i was feeling the same, they recommend using some ttf library to render fonts, though i just wrote my simple text output functions using the framebuffer, db-ed a 8x8 ascii font 8 bytes / character = 1024 bytes.

That's nowhere near as pretty as TTF fonts, though Smile

_________________

- carpe noctem

01 Dec 2011, 12:29

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