102 lines
3.7 KiB
Markdown
102 lines
3.7 KiB
Markdown
<h1 align="center"> LittlevGL - Open-source Embedded GUI Library in Rust</h1>
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<p align="center">
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LittlevGL 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.
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</p>
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<p align="center">
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LittlevGL is compatible with <samp>#![no_std]</samp> environments by default.
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</p>
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<h4 align="center">
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<a href="https://lvgl.io/">Official LittlevGL Website </a> ·
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<a href="https://github.com/littlevgl/lvgl">C library repository</a> ·
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<a href="https://lvgl.io/demos">Live demo</a>
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</h4>
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---
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## Usage
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Edit your `Cargo.toml` file dependencies with:
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```
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$ cargo add lvgl
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```
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The build requires the environment variable bellow to be set:
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- `DEP_LV_CONFIG_PATH`: Path to the directory containing the `lv_conf.h` header file used for configuration of LittlevGL library.
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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:
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```shell script
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$ DEP_LV_CONFIG_PATH=`pwd` cargo build
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```
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### Building for embedded environments
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We make use of `bindgen` for generating the bindings to LittlevGL at build time. There is a problem in cargo when building
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for `no_std`, so we need to use a workaround to build "lvgl-rs". The mainstrem issue in cargo is being tracked at
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[rust-lang/cargo#7915](https://github.com/rust-lang/cargo/issues/7915).
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```shell
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$ DEP_LV_CONFIG_PATH=`pwd` cargo build -Zfeatures=build_dep
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```
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#### Requirements / Limitations
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LittlevGL C libary do allocate memory dynamically and we need to allocate memory on the heap in the Rust side as well
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([`Box`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html)).
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That is required, so we can safely provide Rust pointers through FFI. For that reason, we do require
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[`alloc`](https://doc.rust-lang.org/alloc/) module to be available.
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## Running the demo
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[This project contains examples that can run in a desktop simulator.](./examples)
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First, make sure to pull `lvgl-rs` submodules:
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```shell
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$ git submodule init
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$ git submodule update
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```
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Some parts of `lvgl-rs` are auto-generated. The package `lvgl-codegen` is responsible for the generated code.
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When building from source, we need to first compile the `lvgl-codegen` tool. The `lvgl-codegen` tool is used
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automatically in the [`lvgl` package build](./lvgl/build.rs).
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```bash
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$ DEP_LV_CONFIG_PATH=`pwd`/examples/include cargo build --package lvgl-codegen
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```
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Then run the `demo` example:
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```shell
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$ DEP_LV_CONFIG_PATH=`pwd`/examples/include cargo run --example demo
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```
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## Feature Support
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The bindings are still in development. There are many features of LVGL that needs to be exposed by `lvgl-rs`. In
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this section you can check what is implemented at the moment.
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### Features
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List of LVGL features that impacts the library usage in general.
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- [x] Displays: We use [`embedded_graphics`](https://docs.rs/embedded-graphics/0.6.2/embedded_graphics/) library to
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draw to the display. You can use `lvgl-rs` with any of the
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[`embedded_graphics` supported displays](https://docs.rs/embedded-graphics/0.6.2/embedded_graphics/#supported-displays).
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- [x] Events: You can listen and trigger events in widget objects.
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- [x] Styles: You can set styles in any exposed object. We are still missing the possibility of defining global base styles.
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- [ ] Input Devices
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- [ ] Fonts
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- [ ] Images
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- [ ] File system
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- [ ] Animations
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- [ ] Tasks
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### Widgets
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Widgets currently implemented might have some missing features. If the widget you want to use is not exposed or
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is missing a feature you want to make use, please send a Pull Request or open an issue.
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