Littlev Graphics Library provides everithing you need to add graphical user interface to your embedded stytem which meets the requirements in the 21th century.
Littlev Graphics Library provides everything you need to add graphical user interface (GUI) to your embedded system. LittlevGL is designed to be an all-in-one solution for microcontroller based embedded GUIs where high level graphics feature, easy-to-use graphical elements and low memory footprint are required.
- Everithing you need to build a GUI (buttons, charts, list, images etc)
- Animations, opacity, smooth scrolling, anti aliasing to impress your cutomers
- Multi language support with UTF-8 decoding
- Fully customizable appearance
- Scalable to operate with a few memory (80 kB flash, 10 kB RAM)
- Hardware independent to use with any MCU or display (TFT, LCD, monochrome)
- Touchpad, mouse, keyboard and external button support
- Only a sinlge frame buffer required in internal RAM or in an external display conroller
- OS, External memory or GPU suppoted but not required
- Written in C for maximal compability
- 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 and external buttons
- Multi language support with UTF-8 support
- Fully customizable graphical elements
- Hardware independent to use with any MCU or display
- Scalable to operate with few memory (80 kB Flash, 10 kB RAM)
- OS, External memory and GPU supported but not required
- Single frame buffer operation even with advances graphical effects
- Written in C for maximal compatibility
- PC simulator to develop without embedded hardware
- Tutorials, code exampes, style themes for rapid development
-Clear online documentation
-Advanced support, and professional GUI development service
- Free and open source
- Tutorials, examples, themes for rapid development
-Advanced support and professional GUI development service
-Documentation and API references online
- Free and open source under MIT licence
## Porting
### Tick interface
The LittlevGL uses a system tick. The `lv_tick_inc(tick_period)` function periodically and tell the call period in millisecinds. For example: `lv_tick_inc(1)` if called in every milliseconds.
In the most sime case you need 4 things:
1. Call `lv_tick_inc(1)` in every millisecods in a Timer or Task
2. Register a function which can copy a pixel array to an area of the screen
3. Register a function which can read an input device. (E.g. touch pad)
4. Call `lv_task_handler()` periodically in every few milliseconds ()
### Display interface
To set up a diplay an `lv_disp_drv_t` variable has to be initialized:
disp_drv....=.../*Initilaize the field here. See below.*/
disp_drv_register(&disp_drv);
```
You can configure the driver for different operation modes.
#### Internal buffering (VDB)
The graphics library works with an internal buffering mechanism to create advances graphics features with only one frame buffer. The internal buffer is called VDB (Virtual Display Buffer) and its size can be adjusted in lv_conf.h.
When `LV_VDB_SIZE` not zero then the internal buffering is used and you have to provide a function which flushes the buffers content to your display:
```c
disp_drv.disp_flush=my_disp_flush;
```
In the flush function you can use DMA or any hardware to do the flushing in the background, but when the flushing is ready you have to call `lv_flush_ready()`
#### Hardware acceleration (GPU)
If your MCU supports graphical acceration (GPU) then you can use it in the following way. (Using GPU is totally optional)
The `mem_blend` and `mem_fill` fields of a display driver is used to interface with a GPU.
```c
disp_drv.mem_blend=my_mem_blend;/*Blends two color arrays using opacity*/
disp_drv.mem_fill=my_mem_fill;/*Fills an array with a color*/
```
The GPU related functions can be used only if internal buffering (VDB) is enabled
#### Unbuffered drawing
It is possible to draw directly to a framebuffer when the internal buffeering is dispabled (LV_SDB_SIZE = 0).
```c
disp_drv.disp_fill=my_mem_blend;/*fill an area in the frame buffer*/
disp_drv.disp_map=my_mem_fill;/*copy a color_map (e.g. image) into the framebuffer*/
```
Keep in mind this way during refresh some artifacts can be visible because the layers are drawn after each other. And some high level graphics features like anti aliasing, opacity or shadows aren't available in this configuration.
If you use an external display controller which supports accelerated filling (e.g. RA8876) then you can use this feature in `disp_fill`
### Input device interface
To set up an input device an `lv_indev_drv_t` variable has to be initialized:
The `type` can be `LV_INDEV_TYPE_POINTER` (e.g touchpad) or `LV_INDEV_TYPE_KEYPAD` (e.g. keyboard)
`read_fp` is a function pointer which will be called periodically to report the current state of an input device. It can also buffer data and return `false` when no more data te read ot `true` is the buffer is not empty.
* An object goup has to be craeted: `lv_group_create()` and object has to be added: `lv_group_add_obj()`
* The create group has to be assigned to the input device: `lv_indev_set_group(my_indev, group1);`
* Use `LV_GROUP_KEY_...` to navigate among the objects in the group
For more information visit http://gl.littlev.hu/porting
## Project set-up
1. Clone or download the lvgl repository: `git clone -b dev-5.0 https://github.com/littlevgl/lvgl.git`
2. Create project with your prefered IDE and add the lvgl folder
1. Clone or download the lvgl repository: `git clone https://github.com/littlevgl/lvgl.git`
2. Create project with your prefered IDE and add the *lvgl* folder
3. Copy *lvgl/lv_conf_templ.h* as *lv_conf.h* next to the lvgl folder
4. In the *_conf.h files delete the first `#if 0` and its `#endif`. Let the default configurations at first.
5. In your *main.c*: #include "lvgl/lvgl.h"
...
...
@@ -150,7 +58,7 @@ To use a keyboard:
## PC Simulator
If you don't have got an embedded hardware you can test the graphics library in a PC simulator. The simulator uses [SDL2](https://www.libsdl.org/) to emulate a display on your monitor and a touch pad with your mouse.
There is a pre-configured PC project for **Eclipse CDT** in this repository: https://github.com/littlevgl/proj_pc
There is a pre-configured PC project for **Eclipse CDT** in this repository: https://github.com/littlevgl/pc_simulator
## Contributing
See [CONTRIBUTING.md](https://github.com/littlevgl/lvgl/blob/master/docs/CONTRIBUTING.md)
