Embedded GUI Using Linux Frame Buffer Device with Slint UI and std

[dongjian]

Is there a way to render the slint ui directly on linux's /dev/fb0 while using rust's std ? I looked at the documentation, but couldn't find a tutorial or demo . please help

[ogoffart]

Not out of the box ( #712 )

But this is possible if you use a custom platform and the software renderer. (unfortunately not the GL renderer at this point)

The documentation on how to create a custom platform is here: https://docs.rs/slint/latest/slint/docs/mcu/index.html
This talks about no_std environment, but you can also use it with std environment (with the std feature of slint)
You'll have to use some library to draw the image on the frame buffer. Maybe there is a crate for that.

This would make for a good demo actually.

[nilclass]

I was curious about this too, so I gave it a try (using the linuxfb crate I wrote a couple of years ago).

Here is a small example: https://github.com/nilclass/slint-framebuffer-example
It's not a full-blown demo (e.g. it doesn't even support any input), but could serve as a starting point for one.

[tronical]

Wow, this is very cool. Very nice to see how few lines of code it is to get those pixels onto the screen.

[igiona]

Is there any update on this?

The example provided above works for me as well, but it sounds like quite experimental rather than a production ready solution.
Wouldn't linuxkms be an option? If yes, how can be setup?

Please apologize if this should be completely wrong, I'm still trying to pull all pieces of the puzzle together with linux-fb, skia, femto, winit, wayland, qt, openGL, kms, drm and so on and so forth...

Thanks!

[tronical]

Yes, agreed. It would be nice to offer a build option without libinput.

[igiona]

@tronical adding that recipe didn't do too much damages on the image size😄

Now though, I'm getting other linker errors now:

  = note: /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find Scrt1.o: No such file or directory
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find crti.o: No such file or directory
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find crtbeginS.o: No such file or directory
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find -lgcc_s
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find /lib/libc.so.6
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find /usr/lib/libc_nonshared.a
          /home/igiona/sdks/lcd_sdk2/sysroots/x86_64-scewo-linux/usr/libexec/arm-scewo-linux-gnueabi/gcc/arm-scewo-linux-gnueabi/10.3.0/real-ld: cannot find /lib/ld-linux-armhf.so.3

All these files and libs are actually available, somehow are not found ?!
What's pretty weird to me, is that the linker wants to stuff in /lib rather than looking in the provide -L paths...
I've "fixed" them with:

sudo ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/lib/libc.so.6 /lib/libc.so.6
sudo ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/libc_nonshared.a /usr/lib/libc_nonshared.a
sudo ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/lib/ld-linux-armhf.so.3 /lib/ld-linux-armhf.so.3

and so these 3 are gone.

EDIT:
~ With regards with -lgcc_s I'm not sure how to address it... ~
I was able to workaroun this as follow:

 ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/lib/libgcc_s.so /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/
 ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/lib/libgcc_s.so.1 /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/
 ln -s /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/arm-scewo-linux-gnueabi/10.3.0/libgcc.a /home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/
ln -s /home/impy/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/lib/libc.so.6 /home/impy/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-scewo-linux-gnueabi/usr/lib/

I'm left with the object files errors.
Scrt1.o, crti.o are actually already in one of the -L path, and crtbeginS.o is in the same folder as the linker, so I've no clue why is not found?!

Any clue?

[tronical]

These object files and libraries are usually found in your sysroot. How did you pass the sysroot to the linker?

[igiona]

These object files and libraries are usually found in your sysroot. How did you pass the sysroot to the linker?

In the meanwhile, I've been able to build 🎉 exactly by passing the sysroot via config.toml to the linker:

[env]
PKG_CONFIG_SYSROOT_DIR="/home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-org-linux-gnueabi"
PKG_CONFIG_PATH="/home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-org-linux-gnueabi/usr/lib/pkgconfig:/home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-org-linux-gnueabi/usr/share/pkgconfig"

[target.armv7-unknown-linux-gnueabihf]
linker="/home/igiona/sdks/lcd_sdk2/sysroots/x86_64-org-linux/usr/bin/arm-org-linux-gnueabi/arm-org-linux-gnueabi-gcc"
rustflags = [
    "-C", "link-arg=--sysroot=/home/igiona/sdks/lcd_sdk2/sysroots/armv7vet2hf-neon-org-linux-gnueabi",
]

[tronical]

Excellent, that looks like the correct solution for your setup :)