Fullscreen 400X240 With Allegro 4

[el_pango]

Hi all,

I'm not sure how many people here use Allegro, as it seems to be less popular than SDL, but if you are using it or working on porting an older full-screen app that 'expects' 320x240 and ran into performance issues with stretch_blit(), this might be of use to you.

When I initialize my app, I do this:

int fbdev;
void * scrn_ptr;
BITMAP *double_buffer;

//--------- setup ----------------------------//

        // set allegro's internal state up 
	set_color_depth(16);
	set_gfx_mode(GFX_AUTODETECT_FULLSCREEN,400,240,0,0);

        // prepare the pandora's hardware framebuffer for use  
	system("ofbset -fb /dev/fb1 -pos 0 0 -size 800 480 -mem 192000 -en 1 ");
	system("fbset -fb /dev/fb1 -g 400 240 400 240 16");
	fbdev 	= open("/dev/fb1", O_RDWR);
	scrn_ptr = mmap(0,400 * 240 * 2, PROT_WRITE | PROT_READ, MAP_SHARED, fbdev, 0);

        double_buffer = create_system_bitmap(screen->w, screen->h);

//--------- after drawing to double_buffer ---------//

     // copy from our buffer to hardware framebuffer
     unsigned long src_px_addr = double_buffer->line[0];
     src_px_addr = bmp_read_line(double_buffer,0);
     memmove(scrn_ptr, src_px_addr, 400*240*2);

//-------- on app exit --------------------//

	munmap(scrn_ptr, 400*240*2);
	close(fbdev);
	system("ofbset -fb /dev/fb1 -pos 0 0 -size 0 0 -mem 0 -en 0");

This gives us a -fast- full-screen mode to work with.

 

[Lozrus]

Nice Thanks for posting.
I use Allegro from time to time, the API seems nicer than SDL, probably because I started using it first. It's nice to know that this is possible.
I'm guessing it wouldn't be too much work to hide this inside the Pandora Allegro port in case a 400x240 screen mode is selected.

Wish I had a pandora to try, fingers crossed for the next batch....

This is also a nice illustration of drawing directly to the framebuffer, somthing I've never had to do before, it's good to see how easy it can be.