LVGL - 2-1、obj - 《Linux》

基础对象lv_obj
屏幕对象Screen

基础对象lv_obj

基础对象的通用属性，所有的控件都可以设置该属性
```
// 设置位置
```
lv_obj_set_pos(label, 50, 50);
```
// 设置大小
```
lv_obj_set_size(label, 100, 100);
```
// 设置可以点击
```
lv_obj_set_click(label, true);
```
// 设置可以拖拽
```
lv_obj_set_drag(label, true);

给控件添加事件

lv_obj_set_event_cb(btn1, btn_event_handler);

static void btn_event_handler(lv_obj_t* obj, lv_event_t event) {
if (obj == btn1) {
    if (event == LV_EVENT_CLICKED) {
        printf("Btn1 Clicked\n");
        lv_label_set_text(btn_label, "Btn1 Clicked");
    }
}
}

lv_obj_set_user_data

设置值
int32_t tmp = en; lv_obj_set_user_data(btn, (void )tmp); item_obj->user_data = (void )i;

// 取值 int32_t en = (int32_t )lv_obj_get_user_data(obj);

lv_obj_get_width

lv_obj_get_height

获取指定UI宽高

lv_obj_get_width(scr); lv_obj_get_height(scr);

lv_obj_set_ext_click_area

增加点击区域

lv_obj_set_ext_click_area(btn, 10, 10, 10, 10);

lv_page_glue_obj

粘合到page上，使一道滚动
- void lv_page_glue_obj(lv_obj_t *obj, bool glue)
Parameters
- obj: pointer to an object on a page

glue: true: enable glue, false: disable glue

lv_obj_align

设置对齐方式

lv_disp_get_scr_act

获取当前活动的Screen

  // 获取当前默认的Screen
  lv_obj_t *scr = lv_disp_get_scr_act(NULL);
  // 根UI
  lv_obj_t *main_obj = lv_obj_create(scr, NULL);
  // 设置宽高
  lv_obj_set_size(main_obj, lv_obj_get_width(scr), lv_obj_get_height(scr));
  // 在Screen中的对齐方式
  lv_obj_align(main_obj, scr, LV_ALIGN_IN_TOP_LEFT, 0, 0);

对齐方式

enum {
  LV_ALIGN_CENTER = 0,
  LV_ALIGN_IN_TOP_LEFT,
  LV_ALIGN_IN_TOP_MID,
  LV_ALIGN_IN_TOP_RIGHT,
  LV_ALIGN_IN_BOTTOM_LEFT,
  LV_ALIGN_IN_BOTTOM_MID,
  LV_ALIGN_IN_BOTTOM_RIGHT,
  LV_ALIGN_IN_LEFT_MID,
  LV_ALIGN_IN_RIGHT_MID,
  LV_ALIGN_OUT_TOP_LEFT,
  LV_ALIGN_OUT_TOP_MID,
  LV_ALIGN_OUT_TOP_RIGHT,
  LV_ALIGN_OUT_BOTTOM_LEFT,
  LV_ALIGN_OUT_BOTTOM_MID,
  LV_ALIGN_OUT_BOTTOM_RIGHT,
  LV_ALIGN_OUT_LEFT_TOP,
  LV_ALIGN_OUT_LEFT_MID,
  LV_ALIGN_OUT_LEFT_BOTTOM,
  LV_ALIGN_OUT_RIGHT_TOP,
  LV_ALIGN_OUT_RIGHT_MID,
  LV_ALIGN_OUT_RIGHT_BOTTOM,
};
typedef uint8_t lv_align_t;

lv_obj_get_coords

获取lv_obj在屏幕中的坐标，左上角 0 0 右下角w h
屏幕上方y为负值
屏幕下方y为正值

同一个lv_obj随着滑动，lv_area_t坐标动态变化 ```

          lv_obj_t *scrt_obj = lv_page_get_scrl(state->base_objs.page_obj);
          lv_area_t scrt_area;
          lv_obj_get_coords(scrt_obj, &scrt_area);

typedef struct { lv_coord_t x1; lv_coord_t y1; lv_coord_t x2; lv_coord_t y2; } lv_area_t; ```

屏幕对象Screen

屏幕对象Screen
屏幕对象事一个特殊的对象，他没有父对象
创建screen对象

lv_obj_t * screen1 = lv_obj_create(NULL,NULL);
littlevgl默认会为显示器创建一个lv_obj基础对象作为屏幕，获取方法如下

lv_src_act();