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Gabor Kiss-Vamosi
2019-01-30 22:17:04 +01:00
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# LittlevGL - Free Open-source Embedded GUI Library
<img src="https://littlevgl.com/github/logo_small5.png" align="right" />
## LittlevGL - Free Open-source Embedded GUI Library
![price](https://img.shields.io/badge/price-FREE-brightgreen.svg)
![status](https://img.shields.io/badge/status-ACTIVE-brightgreen.svg)
![licence](https://img.shields.io/badge/licence-MIT-blue.svg)
@@ -59,12 +64,55 @@ Try LittlevGL in a simulator on you PC without any embedded hardware. Choose a p
| 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
In the most simple case you need to do 5 things:
1. Call `lv_tick_inc(x)` every `x` milliseconds in a Timer or Task (`x` should be between 1 and 10)
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. 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`.
5. Call `lv_task_handler()` periodically every few milliseconds.
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
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*/
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
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*/
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.
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)