```eval_rst
.. include:: /header.rst 
:github_url: |github_link_base|/overview/layer.md
```

# Layers

## Order of creation

By default, LVGL draws old objects on the background and new objects on the foreground.

For example, assume we added a button to a parent object named button1 and then another button named button2. Then button1 (with its child object(s)) will be in the background and can be covered by button2 and its children.


![](/misc/layers.png "Creating graphical objects in Littlev Graphics Library")  

```c
/*Create a screen*/
lv_obj_t * scr = lv_obj_create(NULL, NULL);
lv_scr_load(scr);          /*Load the screen*/

/*Create 2 buttons*/
lv_obj_t * btn1 = lv_btn_create(scr, NULL);         /*Create a button on the screen*/
lv_btn_set_fit(btn1, true, true);                   /*Enable to automatically set the size according to the content*/
lv_obj_set_pos(btn1, 60, 40);              	   /*Set the position of the button*/

lv_obj_t * btn2 = lv_btn_create(scr, btn1);         /*Copy the first button*/
lv_obj_set_pos(btn2, 180, 80);                    /*Set the position of the button*/

/*Add labels to the buttons*/
lv_obj_t * label1 = lv_label_create(btn1, NULL);	/*Create a label on the first button*/
lv_label_set_text(label1, "Button 1");          	/*Set the text of the label*/

lv_obj_t * label2 = lv_label_create(btn2, NULL);  	/*Create a label on the second button*/
lv_label_set_text(label2, "Button 2");            	/*Set the text of the label*/

/*Delete the second label*/
lv_obj_del(label2);
```

## Bring to the foreground

There are several ways to bring an object to the foreground:
- Use `lv_obj_set_top(obj, true)`. If `obj` or any of its children is clicked, then LVGL will automatically bring the object to the foreground.
It works similarly to a typical GUI on a PC. When a window in the background is clicked, it will come to the foreground automatically.
- Use `lv_obj_move_foreground(obj)` to explicitly tell the library to bring an object to the foreground. Similarly, use `lv_obj_move_background(obj)` to move to the background.
- When `lv_obj_set_parent(obj, new_parent)` is used, `obj` will be on the foreground on the `new_parent`.


## Top and sys layers

LVGL uses two special layers named as `layer_top` and `layer_sys`.
Both are visible and common on all screens of a display. **They are not, however, shared among multiple physical displays.** The `layer_top` is always on top of the default screen (`lv_scr_act()`), and `layer_sys` is on top of `layer_top`.

The `layer_top` can be used by the user to create some content visible everywhere. For example, a menu bar, a pop-up, etc. If the `click` attribute is enabled, then `layer_top` will absorb all user click and acts as a modal.
```c
lv_obj_set_click(lv_layer_top(), true);
```

The `layer_sys` is also used for a similar purpose on LVGL. For example, it places the mouse cursor above all layers to be sure it's always visible.