topic Re: enable/disable local alpha and global alpha -blog archive in i.MX Processors

enable/disable local alpha and global alpha -blog archive

max_tsai — Tue, 05 Jun 2012 08:44:28 GMT

To enable local alpha needs 32 bpp within bootargs, like "video=mxcdi1fb:RGB666,XGA,bpp=32"

Attached a simple code to enable/disable local/global alpha bledding by ioctl below.

alpha blending

Re: enable/disable local alpha and global alpha -blog archive

saurabh206 — Tue, 23 Jul 2013 14:05:25 GMT

Hi,

Max

Where is the attachment?

Re: enable/disable local alpha and global alpha -blog archive

LeonardoSandova — Tue, 23 Jul 2013 16:40:00 GMT

Actually seems that is not an attachment, it is a link but the link is broken MaxTsai.

Re: enable/disable local alpha and global alpha -blog archive

max_tsai — Wed, 24 Jul 2013 02:10:12 GMT

The attachment is broken. Attached the code below.

---

#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <sys/ioctl.h>

#include <unistd.h>

//#include <asm/arch/mxcfb.h>

#define MXCFB_SET_GBL_ALPHA _IOW('F', 0x21, struct mxcfb_gbl_alpha)

#define MXCFB_SET_CLR_KEY _IOW('F', 0x22, struct mxcfb_color_key)

#define MXCFB_SET_LOC_ALPHA _IOWR('F', 0x26, struct mxcfb_loc_alpha)

struct mxcfb_gbl_alpha {

int enable;

int alpha;

};

struct mxcfb_color_key {

int enable;

__u32 color_key;

};

struct mxcfb_loc_alpha {

int enable;

int alpha_in_pixel;

unsigned long alpha_phy_addr0;

unsigned long alpha_phy_addr1;

};

int main(int argc, char **argv)

{

int fb_fd;

struct mxcfb_gbl_alpha gbl_alpha;

struct mxcfb_loc_alpha l_alpha;

struct mxcfb_color_key key;

char fbname[128];

char *endptr;

if(argc < 3){

printf("Usage: %s fb_chn [gn|ln] [alpha_val[0-255]] [color_key[0x00000000-0xffffffff]]\n",argv[0]);

return -1;

}

memset(fbname, 0, sizeof(fbname));

sprintf(fbname, "/dev/graphics/fb%s", argv[1]);

printf("open '%s'\n", fbname);

fb_fd = open(fbname,O_RDWR,0);

if (fb_fd == -1) {

perror("open");

exit(1);

}

if (argv[2][0] == 'g') {

gbl_alpha.enable = 1;

gbl_alpha.alpha = atoi(argv[3]);

if (ioctl(fb_fd, MXCFB_SET_GBL_ALPHA, &gbl_alpha))

perror("ioctl");

if (argv[2][1] == '1') {

printf("enable global alpha blending\n");

key.enable = 1;

} else {

printf("disable global alpha blending\n");

key.enable = 0;

}

key.color_key = strtol(argv[4], &endptr, 16);

printf("key = 0x%x\n", key.color_key);

if (ioctl(fb_fd, MXCFB_SET_CLR_KEY, &key))

perror("ioctl");

} else if (argv[2][0] =='l') {

if (argv[2][1] == '1') {

l_alpha.enable = 1;

printf("enable local alpha blending\n");

} else {

l_alpha.enable = 0;

printf("disable local alpha blending\n");

}

l_alpha.alpha_in_pixel = 1;

if (ioctl(fb_fd, MXCFB_SET_LOC_ALPHA, &l_alpha))

perror("ioctl");

}

close(fb_fd);

return 0;

}

Re: enable/disable local alpha and global alpha -blog archive

saurabh206 — Thu, 25 Jul 2013 10:19:16 GMT

Hi,

Max

Thanks for sharing the code.

Our setup is like data from android surface flinger is available "/dev/graphics/fb0"

We want to do overlay with CSI buffer which is written on "/dev/graphics/fb1"

We are able to get it working with global alpha and colour keying. But due to some limitation with our GUI we can not use global alpha.

But If I disable global alpha and enable the local alpha than data from /dev/graphics/fb1 is not display.

- Is it possible to do alpha blending using local alpha without colour keying?

- What is a significance of alpha_phy_addr0, alpha_phy_addr1 and alpha_in_pixel?

Thanks

Saurabh

Re: enable/disable local alpha and global alpha -blog archive

max_tsai — Tue, 30 Jul 2013 08:58:41 GMT

hi Your data going to show into framebuffer must include alpha information(ARGB), so the pixel size of framebuffer should be 32bpp.

alpha_in_pixel means each pixel embedds alpha channel, and alpha_phy_addr are the buffers used by IPU.

Re: enable/disable local alpha and global alpha -blog archive

max_tsai — Tue, 30 Jul 2013 09:01:32 GMT

BTW, color key should work with global alpha. IPU get alpha info from each pixel for local alpha, and color key doesn't mater for local alpha. you can refer to "hardware/mx5x/libgralloc/framebuffer.cpp".

Re: enable/disable local alpha and global alpha -blog archive

saurabh206 — Tue, 30 Jul 2013 16:41:55 GMT

Hi,

Max

Thanks for the valuable information.

Our fame buffer is 32bit and it should contain ARGB format. I will verify this.

"hardware/imx/mx5x/libgralloc/framebuffer.cpp" will be used for imx6q.

To enable local alpha I need to build source code without "HAVE_FSL_EPDC_FB".

Can you please explain that what is significance of HAVE_FSL_EPDC_FB?

- Saurabh

Re: enable/disable local alpha and global alpha -blog archive

max_tsai — Wed, 31 Jul 2013 02:31:15 GMT

hi I trace FSL ICS and FSL JB, "HAVE_FSL_EPDC_FB" "hardware/imx/mx6/libgralloc_wrapper/Android.mk" is marked.

Also alpha blending configuration should not be related with this flag.

Re: enable/disable local alpha and global alpha -blog archive

saurabh206 — Thu, 01 Aug 2013 11:29:48 GMT

Hi,

I have modified the frame buffer code to pass alpha channel.

hardware\imx\mx6\libgralloc_wrapper\framebuffer.cpp

info.bits_per_pixel = 32;

info.red.offset = 8;

info.red.length = 8;

info.green.offset = 16;

info.green.length = 8;

info.blue.offset = 24;

info.blue.length = 8;

info.transp.offset = 0;

info.transp.length = 8; //We need local alpha transparency

And I am enabling the local alpha channel by following code.

int set_local_alpha()
{
struct mxcfb_loc_alpha loc_alpha;
int fd_fb;

   if ((fd_fb = open("/dev/graphics/fb0", O_RDWR, 0)) < 0)
   {
       __android_log_print(ANDROID_LOG_DEBUG,CF_TAG,"unable to open /dev/graphics/fb0 ");
       return 0;
   }

loc_alpha.alpha_in_pixel = 0;
loc_alpha.enable = 1;
loc_alpha.alpha_phy_addr0=0;
loc_alpha.alpha_phy_addr1=0;

if ( ioctl(fd_fb, MXCFB_SET_LOC_ALPHA, &loc_alpha) < 0) {
       __android_log_print(ANDROID_LOG_DEBUG,CF_TAG,"Error in applying Local Alpha\n");
}
   close (fd_fb);

}

After setting the local alpha I got only blue screen on display, no Android UI or not CSI content.

Do you have idea, what part is missing?

Re: enable/disable local alpha and global alpha -blog archive

max_tsai — Thu, 08 Aug 2013 05:19:30 GMT

loc_alpha.alpha_in_pixel should be 1 to indicate there is alpha information per each pixel.

Re: enable/disable local alpha and global alpha -blog archive

saurabh206 — Thu, 08 Aug 2013 07:20:29 GMT

HI,

Max

I got it working.

Thanks for your support.

loc_alpha.alpha_in_pixel = 1;

loc_alpha.enable = 1;

loc_alpha.alpha_phy_addr0=0;

loc_alpha.alpha_phy_addr1=0;

if ( ioctl(fd_fb, MXCFB_SET_LOC_ALPHA, &loc_alpha) < 0) {
__android_log_print(ANDROID_LOG_DEBUG,CF_TAG,"Error in applying Local Alpha\n");
}

Is required to get local alpha working.

Thanks

Saurabh