# LVGL Example

## Overview

This example demonstrates how to use LVGL (Light and Versatile Graphics Library) on K230. LVGL is a free and open-source embedded graphics library that provides rich widgets, smooth animation effects, and support for multiple input devices, and is suitable for both MCU and MPU platforms.

## Feature Summary

### LVGL Capabilities Demonstrated

- Multi-resolution display support
- Touch-screen input integration
- Common UI widgets such as labels, buttons, bars, sliders, and switches
- Responsive layout behavior
- Double buffering and GSDMA-assisted display updates

### Widget Examples

The sample demonstrates:

- Label
- Button
- Bar
- Slider
- Switch
- Container-based layout

### Display Driver Notes

The example is designed around the K230 display path and supports:

- up to `1920x1080` display resolution
- double buffering to reduce flicker
- GSDMA-assisted image transfer

### Input Device Notes

- capacitive or resistive touch input
- gesture operations such as click and slide

## Source Location

Demo source path: `src/rtsmart/examples/3rd-party/lvgl/lvgl_basic`

## Usage

### Build

#### Firmware Build

At the root of `K230 RTOS SDK`, use `make menuconfig` to enable the LVGL example in the firmware build, then build the firmware.

#### Standalone Build

You can either enable the LVGL example in `make menuconfig`, or build it directly:

```shell
cd src/rtsmart/examples/3rd-party/lvgl/lvgl_basic
mkdir build && cd build
cmake ..
make
```

## Hardware Preparation

- Connect a supported LCD panel
- Connect a touch panel if touch input is required
- Verify that the board-side display and touch wiring matches the sample configuration

### Run

Copy the built executable to the board, enter the target directory, then run:

```shell
./lvgl_basic
```

### Expected Result

After startup, the sample initializes the display, registers touch input if available, creates the LVGL demo UI, and starts the LVGL task loop. The screen shows content similar to:

```text
Screen: 800x480
===========================
LVGL Multi-Resolution Demo

[Button 1] [Button 2] [Button 3]

Progress Bar:
[===========>       ] 70%

Slider:
[----O----]

Switch:
[ON]
```

UI characteristics:

- the top area shows the current screen resolution
- the middle area shows three buttons with different colors
- the lower area shows a progress bar, slider, and switch
- all widgets support touch interaction

You can interact with the interface through the touch screen:

- tap the buttons to trigger responses
- drag the slider to change the value
- toggle the switch on and off

### Custom UI

LVGL provides rich APIs for building custom interfaces. For example:

```c
// Create a label
lv_obj_t* label = lv_label_create(parent);
lv_label_set_text(label, "Hello LVGL!");

// Create a button
lv_obj_t* btn = lv_button_create(parent);
lv_obj_t* btn_label = lv_label_create(btn);
lv_label_set_text(btn_label, "Click Me");
lv_obj_center(btn_label);

// Create a progress bar
lv_obj_t* bar = lv_bar_create(parent);
lv_bar_set_value(bar, 50, LV_ANIM_OFF);
```

```{admonition} Tip
You can adjust many LVGL parameters in the `lv_conf.h` configuration file, such as memory size, screen resolution, and font selection. For detailed APIs and configuration options, refer to the [LVGL official documentation](https://docs.lvgl.io/).
```

```{admonition} Tip
LVGL requires periodic calls to `lv_timer_handler()` to refresh the UI. It is recommended to call this function regularly inside the main loop.
```