/dev/graphics/fb0 Device not found

Question

I found a lot about /dev/graphics/fb0. It is fast. But It doesn't seems to be working. If i do manually. Neither programmatically. But I am sure that this feature works on my mobile as i have an application that works using same method.

I have tried to change permission. i have root access.

chmod 666 /dev/graphics/fb0

Permission is changed. But when i try to run command

adb pull /dev/graphics/fb0 /mnt/sdcard/tmp

I tried to redirect input using

cat /dev/graphics/fb0 > /sdcard/frame.raw

I get an error saying

error : device not found.

But nothing works . same error each time. I am testing on gt-i9500.

Can someone guide me what i am doing wrong. Thank you.

Tirzah

This is only supported on some hardware; on other designs the GPU does not make a linear framebuffer available. That is why adb no longer takes screenshots itself, but rather delegates it to a device specific executable. Also "adb pull /dev/graphics/fb0 /mnt/sdcard/tmp" is unworkable, since the second path is on your device but must be on your development machine. – Qadi

Ok. So why the other program works ? And the other command cat /dev/graphics/fb0 > /sdcard/frame.raw works fine on my other device – Tirzah

It either knows how to talk to undocumented aspects of the specific GPU, or uses a library which does. You can spent a couple of days decompiling it if you like, but it's not clear you will end up getting much utility for your trouble. – Qadi

I already decompiled & saw the source. The program was using nothing more than this specific command. If there was a library. it would have mention of method screencap.So i am sure that this is only method.The only menthion of screencap i found was lib\armeabi\libjsrn.so in & i think this is system lib only. – Tirzah