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LVGL - Open-source Embedded GUI Library in Rust

Original LVGL demo image

LVGL provides everything you need to create a Graphical User Interface (GUI) on embedded systems with easy-to-use graphical elements, beautiful visual effects and low memory footprint.

LVGL is compatible with #![no_std] environments by default.

Rust to WASM demo · Official LVGL Website · C library repository · Official live demos

Rust bindings usage demo code.

System Build Dependencies

In order to build the lvgl project you will need the following system dependencies to be installed:

$ sudo apt install build-essential llvm clang

If you want to build the examples, then you will need to install SDL2 as well.

$ sudo apt install libsdl2-dev

Usage

Edit your Cargo.toml file dependencies with:

$ cargo add lvgl

The build requires the environment variable bellow to be set:

  • DEP_LV_CONFIG_PATH: Path to the directory containing the lv_conf.h header file used for configuration of LVGL library.
  • (Optional) LVGL_FONTS_DIR: Directory for custom fonts generated for use in LVGL. See the documentation for usage.
  • (Optional) LVGL_INCLUDE: C headers to include during the build if using the drivers feature, comma-separated. The default is /usr/include,/usr/local/include.
  • (Optional) LVGL_LINK: C libraries to link in during the build if using the drivers feature, comma-separated. The default is SDL2.

We recommend the lv_conf.h file to be in your project's root directory. If so, the command to build your project would be:

$ DEP_LV_CONFIG_PATH=`pwd` cargo build

Building for embedded environments

We make use of bindgen for generating the bindings to LittlevGL at build time. There is a problem in cargo when building for no_std, so we need to use a workaround to build "lvgl-rs". The mainstrem issue in cargo is being tracked at rust-lang/cargo#7915.

$ DEP_LV_CONFIG_PATH=`pwd` cargo build -Zfeatures=build_dep

The unsafe_no_autoinit feature must also be enabled when building for baremetal targets. See its documentation in Cargo.toml for notes on usage.

LVGL Global Allocator

A global allocator for Rust leveraging the LVGL memory allocator is provided, but not enabled by default. Can be enabled by the feature lvgl_alloc. This will make all dynamic memory to be allocated by LVGL internal memory manager.

Running the demo

Hint for macOS users: Before you run the demos you need to make sure you have libsdl installed on your machine. To install it, use HomeBrew:

$ brew install sdl2

This project contains examples that can run in a desktop simulator.

First, make sure to pull lvgl-rs submodules:

$ git submodule init
$ git submodule update

Then run the demo example:

$ DEP_LV_CONFIG_PATH=`pwd`/examples/include cargo run --example demo --features="alloc"

Feature Support

The bindings are still in development. There are many features of LVGL that needs to be exposed by lvgl-rs. In this section you can check what is implemented at the moment.

Features

List of LVGL features that impacts the library usage in general.

  • Displays: We use embedded_graphics library to draw to the display, along with lv_drivers. You can use lvgl-rs with any of the embedded_graphics supported displays, and those supported by lv_drivers. Note: lv_drivers support is currently experimental.
  • Events: You can listen and trigger events in widget objects.
  • Styles: You can set styles in any exposed object. We are still missing the possibility of defining global base styles.
  • Input Devices: Input devices supported by lv_drivers can be used, and custom handlers can be specified for embedded_graphics. Currently, only pointer input devices are supported. Note: lv_drivers support is currently experimental.
  • Fonts: All fonts built-in to LVGL can be used on nightly Rust if the nightly feature is enabled. Custom fonts can also be encoded into a C file (see the documentation on the font module).
  • Animations: Creating basic animations is supported entirely from Rust.
  • Images
  • File system
  • Tasks

Widgets

Widgets currently implemented might have some missing features. If the widget you want to use is not exposed or is missing a feature you want to make use, please send a Pull Request or open an issue.

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