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# LittlevGL - Free Open-source Embedded GUI Library
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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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Star the project if you like it! :star: < br >
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And share with your friends [](https://twitter.com/intent/tweet?text=LittlevGL%20is%20a%20free%20and%20open%20source%20embedded%20GUI%20library%20with%20easy-to-use%20graphical%20elements,%20beautiful%20visual%20effects%20and%20low%20memory%20footprint.& url=https://littlevgl.com/& hashtags=littlevgl,embedded,gui,free,opensource)
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### [Website](https://littlevgl.com) · [Live demo](https://littlevgl.com/live-demo) · [Simulator](https://docs.littlevgl.com/#PC-simulator) · [Docs](https://docs.littlevgl.com/) · [Blog](https://blog.littlevgl.com/)
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### Features
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* **Powerful building blocks** buttons, charts, lists, sliders, images, etc.
* **Advanced graphics** with animations, anti-aliasing, opacity, smooth scrolling
* **Various input devices** touch pad, mouse, keyboard, encoder, buttons, etc.
* **Multi-language support** with UTF-8 encoding
* **Fully customizable** graphical elements
* **Hardware independent** to use with any microcontroller or display
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* **Scalable** to operate with little memory (64 kB Flash, 10 kB RAM)
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* **OS, External memory and GPU** supported but not required
* **Single frame buffer** operation even with advances graphical effects
* **Written in C** for maximal compatibility
* **Simulator** to develop on PC without embedded hardware
* **Tutorials, examples, themes** for rapid development
* **Documentation** and API references online
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### Supported devices
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Basically, every modern controller - which is able to drive a display - is suitable to run LittlevGL. The minimal requirements:
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- **16, 32 or 64-bit** microcontroller or processor
- **> 16 MHz** clock speed
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- **> 8 kB RAM for static data** and ** > 2 KB RAM for dynamic data** (graphical objects)
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- **> 64 kB flash** program memory
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- **Optionally ~1/10 screen sized memory** for buffered drawing (on 240 ×
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Just to mention some **platforms** :
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- STM32F1, STM32F3, [STM32F4 ](https://blog.littlevgl.com/2017-07-15/stm32f429_disco_port ), [STM32F7 ](https://github.com/littlevgl/stm32f746_disco_no_os_sw4stm32 )
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- Microchip dsPIC33, PIC24, PIC32MX, PIC32MZ
- NXP Kinetis, LPC, iMX
- [Linux frame buffer ](https://blog.littlevgl.com/2018-01-03/linux_fb ) (/dev/fb)
- [Raspberry PI ](http://www.vk3erw.com/index.php/16-software/63-raspberry-pi-official-7-touchscreen-and-littlevgl )
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- [Espressif ESP32 ](https://github.com/littlevgl/esp32_ili9431 )
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- Nordic nrf52
- Quectell M66
### Quick start in a simulator
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The easiest way to get started with LittlevGL is to run it in a simulator on your PC without any embedded hardware.
Choose a project with your favourite IDE:
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| Eclipse | CodeBlock | Visual Studio | PlatfomIO | Qt Creator |
|-------------|----------- |---------------|-----------|------------|
| [](https://github.com/littlevgl/pc_simulator_sdl_eclipse) | [](https://github.com/littlevgl/pc_simulator_win_codeblocks) | [](https://github.com/littlevgl/visual_studio_2017_sdl_x64) | [](https://github.com/littlevgl/pc_simulator_sdl_platformio) | [](https://blog.littlevgl.com/2019-01-03/qt-creator) |
| Cross-platform< br > with SDL | Native Windows | Cross-platform< br > with SDL | Cross-platform< br > with SDL | Cross-platform< br > with SDL |
### Porting to an embedded hardware
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In the most simple case you need to do these steps:
1. Copy `lv_conf_templ.h` as `lv_conf.h` next to `lvgl` and set at least `LV_HOR_RES` , `LV_VER_RES` and `LV_COLOR_DEPTH` .
2. Call `lv_tick_inc(x)` every `x` milliseconds in a Timer or Task (`x` should be between 1 and 10)
3. Call `lv_init()`
4. Register a function which can **copy a pixel array** to an area of the screen:
```c
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lv_disp_drv_t disp_drv; /*Descriptor of a display driver*/
lv_disp_drv_init(&disp_drv); /*Basic initialization*/
disp_drv.disp_flush = disp_flush; /*Set your driver function*/
lv_disp_drv_register(&disp_drv); /*Finally register the driver*/
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void disp_flush(int32_t x1, int32_t y1, int32_t x2, int32_t y2, const lv_color_t * color_p)
{
int32_t x, y;
for(y = y1; y < = y2; y++) {
for(x = x1; x < = x2; x++) {
sep_pixel(x, y, *color_p); /* Put a pixel to the display.*/
color_p++;
}
}
lv_flush_ready(); /* Tell you are ready with the flushing*/
}
```
5. Register a function which can **read an input device** . E.g. for a touch pad:
```c
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lv_indev_drv_init(&indev_drv); /*Descriptor of a input device driver*/
indev_drv.type = LV_INDEV_TYPE_POINTER; /*Touch pad is a pointer-like device*/
indev_drv.read = touchpad_read; /*Set your driver function*/
lv_indev_drv_register(&indev_drv); /*Finally register the driver*/
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bool touchpad_read(lv_indev_data_t * data)
{
static lv_coord_t last_x = 0;
static lv_coord_t last_y = 0;
/*Save the state and save the pressed cooridnate*/
data->state = touchpad_is_pressed() ? LV_INDEV_STATE_PR : LV_INDEV_STATE_REL;
if(data->state == LV_INDEV_STATE_PR) touchpad_get_xy(& last_x, &last_y);
/*Set the coordinates (if released use the last pressed cooridantes)*/
data->point.x = last_x;
data->point.y = last_y;
return false; /*Return `false` because we are not buffering and no more data to read*/
}
```
6. Call `lv_task_handler()` periodically every few milliseconds.
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For a detailed description check the [Online documatation ](https://docs.littlevgl.com/#Porting ) or the [Porting tutorial ](https://github.com/littlevgl/lv_examples/blob/master/lv_tutorial/0_porting/lv_tutorial_porting.c )
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### Code examples
#### Create a button with a label and assign a click callback
```c
lv_obj_t * btn = lv_btn_create(lv_scr_act(), NULL); /*Add a button the current screen*/
lv_obj_set_pos(btn, 10, 10); /*Set its position*/
lv_obj_set_size(btn, 100, 50); /*Set its size*/
lv_btn_set_action(btn, LV_BTN_ACTION_CLICK, btn_action);/*Assign a callback to the button*/
lv_obj_t * label = lv_label_create(btn, NULL); /*Add a label to the button*/
lv_label_set_text(label, "Button"); /*Set the labels text*/
lv_res_t btn_action(lv_obj_t * btn)
{
printf("Clicked\n");
return LV_RES_OK;
}
```
#### Modify the styles
```c
static lv_style_t style_btn_rel; /*A variable to store the released style*/
lv_style_copy(& style_btn_rel, &lv_style_plain); /*Initialize from a built-in style*/
style_btn_rel.body.border.color = LV_COLOR_HEX3(0x269);
style_btn_rel.body.border.width = 1;
style_btn_rel.body.main_color = LV_COLOR_HEX3(0xADF);
style_btn_rel.body.grad_color = LV_COLOR_HEX3(0x46B);
style_btn_rel.body.shadow.width = 4;
style_btn_rel.body.shadow.type = LV_SHADOW_BOTTOM;
style_btn_rel.body.radius = LV_RADIUS_CIRCLE;
style_btn_rel.text.color = LV_COLOR_HEX3(0xDEF);
static lv_style_t style_btn_pr; /*A variable to store the pressed style*/
lv_style_copy(& style_btn_pr, &style_btn_rel); /*Initialize from a built-in style*/
style_btn_pr.body.border.color = LV_COLOR_HEX3(0x46B);
style_btn_pr.body.main_color = LV_COLOR_HEX3(0x8BD);
style_btn_pr.body.grad_color = LV_COLOR_HEX3(0x24A);
style_btn_pr.body.shadow.width = 2;
style_btn_pr.text.color = LV_COLOR_HEX3(0xBCD);
lv_btn_set_style(btn, LV_BTN_STYLE_REL, &style_btn_rel); /*Set the buton's released style*/
lv_btn_set_style(btn, LV_BTN_STYLE_PR, &style_btn_pr); /*Set the buton's pressed style*/
```
#### Enable a fancy effect
```c
/*Add some effects when the button is clicked*/
lv_btn_set_ink_in_time(btn, 300);
lv_btn_set_ink_wait_time(btn, 100);
lv_btn_set_ink_out_time(btn, 300);
```
Check out the [Documentation ](https://docs.littlevgl.com/ ) for more!
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### Contributing
To ask questions and discuss topics we use [GitHub's Issue tracker ](https://github.com/littlevgl/lvgl/issues ).
You contribute in several ways:
- **Answer other's question** click the Watch button on the top to get notified about the issues
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- **Report and/or fix bugs** using the issue tracker and in Pull-request
- **Suggest and/or implement new features** using the issue tracker and in Pull-request
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- **Improve and/or translate the documentation** learn more [here ](https://github.com/littlevgl/docs )
- **Write a blog post about your experiences** learn more [here ](https://github.com/littlevgl/blog )
- **Upload your project or product as a reference** to [this site ](https://blog.littlevgl.com/2018-12-26/references )
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Before contributing, please read [CONTRIBUTING.md ](https://github.com/littlevgl/lvgl/blob/master/docs/CONTRIBUTING.md ).
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### Donate
If you are pleased with the library, found it useful, or you are happy with the support you got, please help its further development:
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[](https://littlevgl.com/donate)
