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# lvgl-lua-binding
lua + lvgl = luavgl
**luavgl is currently under development.**
A flappy bird game is ready for showoff. See simulator instructions below which is tested on ubuntu and mac but not windows.
<p align="center">
<img src="https://i.ibb.co/nbgYvZW/flappybird.gif" />
</p>
## Introduction
`luavgl` is a wrapper around lvgl **core** functions and **widgets** with class inherence in mind, which is lvgl trying to do in `C`. Lua makes widgets inherence happens smoothly.
`luavgl` does not support APIs for low level hardware initialization, lvgl setup etc. Those initialization must be done before executing lua scripts.
`luavgl` mainly targets for embedded device, a simulator has been provided for preview and tested on Ubuntu/macOS.
```lua
local root = lvgl.Object()
root:set { w = lvgl.HOR_RES(), h = lvgl.VER_RES() }
-- flex layout and align
root:set {
flex = {
flex_direction = "row",
flex_wrap = "wrap",
justify_content = "center",
align_items = "center",
align_content = "center",
},
w = 300,
h = 75,
align = lvgl.ALIGN.CENTER
}
-- create obj on root
local obj = root:Object()
-- create image on root and set position/img src/etc. properties.
local img = root:Image {
src = "res/image.png",
x = 0,
y = 0,
bg_color = "#112233" -- #RRGGBB, 0xRRGGBB or "#RGB"
pad_all = 0
}
-- change image properties.
img:set {
src = "/assets/lvgl-logo.png",
align = lvgl.ALIGN.CENTER,
}
-- create animation on object
img:Anim {
run = true,
start_value = 0,
end_value = 3600,
duration = 2000,
repeat_count = 2,
path = "bounce",
exec_cb = function(obj, value)
obj:set {
angle = value
}
end
}
-- create Label on root and set its font
local label = root:Label {
text = string.format("Hello %03d", 123),
text_font = lvgl.Font("montserrat", 24, "normal"),
-- or builtin font:
-- text_font = lvgl.BUILTIN_FONT.MONTSERRAT_22,
align = {
type = lvgl.ALIGN.CENTER,
x_ofs = 0,
y_ofs = 100,
}
}
```
### Embedded device
For embedded device, lvgl environment must setup before using `luavgl`. Once `lvgl` and `lua interpreter` are up and running, add the `luavgl.c` to sources for compiling. And make sure `luaopen_lvgl` is added to global lib. Below is example from `simulator/main.c` shows this exact method.
```c
/* add `lvgl` module to global package table */
luaL_requiref(L, "lvgl", luaopen_luavgl, 1);
lua_pop(L, 1);
```
### LuaJIT support
Supporting `LuaJIT` is done by adding `deps/lua-compat-5.3`.
### Developing
I personally using `vscode` plus extension [`Lua`](https://marketplace.visualstudio.com/items?itemName=sumneko.lua).
File `src/lvgl.lua` is used for linting.
<p align="center">
<img src="https://i.ibb.co/NpRWXZ1/luavgl-linting.png" />
</p>
### Run on RTOS nuttx
Check the ready-to-go examples [luavgl-nuttx-example](https://github.com/XuNeo/luavgl-nuttx-example)
### PC simulator
**Currently compile luavgl to `so` or `dll` is NOT available.**
`luavgl` depends on lvgl and various configurations(`lv_conf.h`), thus cannot run without a working lvgl environment.
The simulator provided in this repo can be used as example if `luavgl` is required on PC.
Make sure clone the submodules, luavgl simulator comes directly from lvgl simulator with lua added.
```bash
git clone --recursive https://github.com/XuNeo/luavgl.git
# or
git sudmodule update --init
```
#### Dependencies
To run simulator on PC, make sure `lua` header is available, you may need to install below packages.
```
sudo apt install libsdl2-dev lua5.3 liblua5.3-dev
```
Both lua5.3 and lua5.4 are supported. Versions below 5.2 has not been verified but should work through `deps/lua-compat-5.3`.
#### Build and run
```bash
cmake -Bbuild -DBUILD_SIMULATOR=ON
cd build
make
make run # run simulator
```
## Custom Widget
`luavgl` support custom widget, and use them in `lua` just like lvgl core widgets.
An example is provided in [`simulator/extension.c`](https://github.com/XuNeo/luavgl/blob/master/simulator/extension.c#L62)
For custom widget, it should be registered to Lua after luavgl lib loaded.
|
