tux-evse/lvgl-rclib-rs

Rust API for LVGL/C Graphic library

lvgl-rclib-rs

Provides a RUST api to lvgl/C lib. It supports frame-buffer for embedded devices and GTK emulation for desktop development.

Reference: https://docs.lvgl.io/8/widgets/index.html

Building dependencies

• lvgl-lib+lvgl-driver: [email protected]:tux-evse/lv-evse-hmi-lib.git
• gtk-emulator: gtk3-devel and all it dependencies. For rebuilding lvgl library+driver check README at https://github.com/tux-evse/lv-evse-hmi-lib

Compiling for frame-buffer

Default driver is frame-buffer, it is typically what is used for embedded devices.

• Check FBDEV driver is enabled
• Check EVDEV_NAME=/dev/input/??? is pointing on your mouse/touch-screen
• Default RUST driver is 'FBDEV' EVDEV_NAME=/dev/input/lvgl should be changed or link to the right input device.

nm /usr/local/lib64/liblv_drivers.so | grep fbdev_init
cargo build

Compiling with GTK emulator

For development and especially for business logic debug with vscode/llgb-gdb, it is far simpler to use GTK than FBDEV.

• Check GTK driver is enabled
• Check GTK screen emulator is compile with the right size cmake -DUSE_GTK=1 -DX_RES=1024 Y_RES=600 ..
• Select GTK by setting USE_GTK=1 environnement variable

nm /usr/local/lib64/liblv_drivers.so | grep gtk_init
USE_GTK=1 cargo build

WARNING: if despite of GTK=1 you still get an error as cglue::evdev_init(); not found then either:

• your lv_driver lib was not compiled with GTK
• you need to touch build.rs to force _capi-map.rs reconstruction

Testing widget demo panel

cargo test --package lvgl --lib -- test::test_pannel

Rust widget API

Check test-widget.ts for more widget and https://github.com/tux-evse/lvgl-binding-rs for a full example with a integration within lib-afb micro service framework.

Create a label

LvglLabel::new("Label-1", "Tux EvSe UI", 50, 400)
            .set_info("Demo Label widget")
            .set_size(300, 100)
            .set_color(LvglColor::rvb(0, 0, 0))
            .set_background(LvglColor::rvb(0xFF, 0xFF, 0xFF))
            .set_border(3, LvglColor::rvb(0, 0xff, 0))
            .finalize();

Create a button

LvglButton::new("Button-A", "Test-1", 100, 200)
    .set_info("Demo Button 1")
    .set_size(180, 100)
    .finalize();

Using frame-buffer without root privileges

1. In order to test without admin privileges, you need access to

• /dev/fb0 generally with 'video' group
• /dev/input0 usually with 'input' group

2. find which virtual console hold /dev/fb0 framebuffer

• switch virtual console with (Alt+Ctrl+F1) (Alt+Ctrl+F2) ...
• after login check with cat /dev/urandom >/dev/fb0

If your screen is repainted, then you are on /dev/fb0 other wise switch to next virtual console.

Extract a frame-buffer screen cast

Copy framebuffer and transform it yo PNG. If needed crop image to content with gimp.

cp /dev/fb0 > /tmp/screen.data
RESOLUTION="1920x1080"
ffmpeg -vcodec rawvideo -f rawvideo -pix_fmt rgb32 -s $RESOLUTION -i /tmp/screen.data -f image2 -vcodec png screenshot.png