# lv_obj_private.h (/api/private/core/lv_obj_private_h)



<RelatedHeaders name="lv_obj.h" isPrivate="true" />

<ApiSummary functions="4" structs="2" typedefs="1" />

Functions [#functions]

<ApiMember kind="function" name="lv_obj_allocate_spec_attr" file="private/core/lv_obj_private.h" line="178" url="https://github.com/lvgl/lvgl/tree/e1a0ad863f29742359bc680d6a7d973448ec2285/src/core/lv_obj_private.h#L178">
  lv_obj_allocate_spec_attr [#lv_obj_allocate_spec_attr]

  Allocate special data for an object if not allocated yet.

  ```c title=" " lineNumbers=1
  lv_obj_spec_attr_t * lv_obj_allocate_spec_attr(lv_obj_t *obj)
  ```

  <span className="sr-only">
    Parameters
  </span>

  | Name  | Type                                             | Description          |
  | ----- | ------------------------------------------------ | -------------------- |
  | `obj` | <ApiLink name="lv_obj_t" display="lv_obj_t *" /> | pointer to an object |

  **Returns:** <ApiLink name="lv_obj_spec_attr_t" display="lv_obj_spec_attr_t *" /> — the spec\_attr created or NULL if something went wrong
</ApiMember>

<ApiMember kind="function" name="lv_obj_add_child" file="private/core/lv_obj_private.h" line="180" url="https://github.com/lvgl/lvgl/tree/e1a0ad863f29742359bc680d6a7d973448ec2285/src/core/lv_obj_private.h#L180">
  lv_obj_add_child [#lv_obj_add_child]

  ```c title=" " lineNumbers=1
  lv_result_t lv_obj_add_child(lv_obj_t *parent, lv_obj_t *child)
  ```

  <span className="sr-only">
    Parameters
  </span>

  | Name     | Type                                             |
  | -------- | ------------------------------------------------ |
  | `parent` | <ApiLink name="lv_obj_t" display="lv_obj_t *" /> |
  | `child`  | <ApiLink name="lv_obj_t" display="lv_obj_t *" /> |
</ApiMember>

<ApiMember kind="function" name="lv_obj_remove_child" file="private/core/lv_obj_private.h" line="181" url="https://github.com/lvgl/lvgl/tree/e1a0ad863f29742359bc680d6a7d973448ec2285/src/core/lv_obj_private.h#L181">
  lv_obj_remove_child [#lv_obj_remove_child]

  ```c title=" " lineNumbers=1
  void lv_obj_remove_child(lv_obj_t *parent, lv_obj_t *child)
  ```

  <span className="sr-only">
    Parameters
  </span>

  | Name     | Type                                             |
  | -------- | ------------------------------------------------ |
  | `parent` | <ApiLink name="lv_obj_t" display="lv_obj_t *" /> |
  | `child`  | <ApiLink name="lv_obj_t" display="lv_obj_t *" /> |
</ApiMember>

<ApiMember kind="function" name="lv_obj_invalidate_expand_blur" file="private/core/lv_obj_private.h" line="191" url="https://github.com/lvgl/lvgl/tree/e1a0ad863f29742359bc680d6a7d973448ec2285/src/core/lv_obj_private.h#L191">
  lv_obj_invalidate_expand_blur [#lv_obj_invalidate_expand_blur]

  Expand the display's invalidated areas to cover blur objects whose background changed. It's called once per frame and invalidates the full extent of every blur object that overlaps an invalidated area, repeating the walk until a pass adds no new areas to cover transitive blur-over-blur cases. Does nothing while no widget has blur (blur\_obj\_cnt in lv\_global\_t is zero).

  ```c title=" " lineNumbers=1
  void lv_obj_invalidate_expand_blur(lv_display_t *disp)
  ```

  <span className="sr-only">
    Parameters
  </span>

  | Name   | Type                                                     | Description          |
  | ------ | -------------------------------------------------------- | -------------------- |
  | `disp` | <ApiLink name="lv_display_t" display="lv_display_t *" /> | pointer to a display |
</ApiMember>

Structs [#structs]

<ApiMember kind="struct" name="_lv_obj_spec_attr_t">
  \_lv_obj_spec_attr_t [#_lv_obj_spec_attr_t]

  Special, rarely used attributes. They are allocated automatically if any elements is set.

  | Member           | Type                                                 | Description                                                                |
  | ---------------- | ---------------------------------------------------- | -------------------------------------------------------------------------- |
  | `children`       | <ApiLink name="lv_obj_t" display="lv_obj_t **" />    | Store the pointer of the children in an array.                             |
  | `group_p`        | <ApiLink name="lv_group_t" display="lv_group_t *" /> |                                                                            |
  | `event_list`     | <ApiLink name="lv_event_list_t" />                   |                                                                            |
  | `name`           | `const char *`                                       | Pointer to the name                                                        |
  | `scroll`         | <ApiLink name="lv_point_t" />                        | The current X/Y scroll offset                                              |
  | `ext_click_pad`  | `int32_t`                                            | Extra click padding in all direction                                       |
  | `ext_draw_size`  | `int32_t`                                            | EXTend the size in every direction for drawing.                            |
  | `child_cnt`      | `uint16_t`                                           | Number of children                                                         |
  | `scrollbar_mode` | `uint16_t`                                           | How to display scrollbars, see `lv_scrollbar_mode_t`                       |
  | `scroll_snap_x`  | `uint16_t`                                           | Where to align the snappable children horizontally, see `lv_scroll_snap_t` |
  | `scroll_snap_y`  | `uint16_t`                                           | Where to align the snappable children vertically                           |
  | `scroll_dir`     | `uint16_t`                                           | The allowed scroll direction(s), see `lv_dir_t`                            |
  | `layer_type`     | `uint16_t`                                           | Cache the layer type here. Element of lv\_intermediate\_layer\_type\_t     |
  | `name_static`    | `uint16_t`                                           | 1: `name` was not dynamically allocated                                    |
  | `user_flags`     | `uint16_t`                                           | Store custom flags                                                         |
</ApiMember>

<ApiMember kind="struct" name="_lv_obj_t">
  \_lv_obj_t [#_lv_obj_t]

  | Member                         | Type                                                                 | Description                                                                                                                                                                                                                                                          |
  | ------------------------------ | -------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
  | `ext_data`                     | <ApiLink name="lv_ext_data_t" />                                     |                                                                                                                                                                                                                                                                      |
  | `class_p`                      | <ApiLink name="lv_obj_class_t" display="const lv_obj_class_t *" />   |                                                                                                                                                                                                                                                                      |
  | `parent`                       | <ApiLink name="lv_obj_t" display="lv_obj_t *" />                     |                                                                                                                                                                                                                                                                      |
  | `spec_attr`                    | <ApiLink name="lv_obj_spec_attr_t" display="lv_obj_spec_attr_t *" /> |                                                                                                                                                                                                                                                                      |
  | `styles`                       | <ApiLink name="lv_obj_style_t" display="lv_obj_style_t *" />         |                                                                                                                                                                                                                                                                      |
  | `style_main_prop_is_set`       | `uint32_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `style_other_prop_is_set`      | `uint32_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `user_data`                    | `void *`                                                             |                                                                                                                                                                                                                                                                      |
  | `id`                           | `void *`                                                             |                                                                                                                                                                                                                                                                      |
  | `coords`                       | <ApiLink name="lv_area_t" />                                         |                                                                                                                                                                                                                                                                      |
  | `hidden`                       | `uint32_t`                                                           | Make the object hidden. (Like it wasn't there at all)                                                                                                                                                                                                                |
  | `clickable`                    | `uint32_t`                                                           | Make the object clickable by the input devices                                                                                                                                                                                                                       |
  | `click_focusable`              | `uint32_t`                                                           | Add focused state to the object when clicked                                                                                                                                                                                                                         |
  | `checkable`                    | `uint32_t`                                                           | Toggle checked state when the object is clicked                                                                                                                                                                                                                      |
  | `scrollable`                   | `uint32_t`                                                           | Make the object scrollable                                                                                                                                                                                                                                           |
  | `scroll_elastic`               | `uint32_t`                                                           | Allow scrolling inside but with slower speed                                                                                                                                                                                                                         |
  | `scroll_momentum`              | `uint32_t`                                                           | Make the object scroll further when "thrown"                                                                                                                                                                                                                         |
  | `scroll_one`                   | `uint32_t`                                                           | Allow scrolling only one snappable child                                                                                                                                                                                                                             |
  | `scroll_chain_hor`             | `uint32_t`                                                           | Allow propagating the horizontal scroll to a parent                                                                                                                                                                                                                  |
  | `scroll_chain_ver`             | `uint32_t`                                                           | Allow propagating the vertical scroll to a parent                                                                                                                                                                                                                    |
  | `scroll_on_focus`              | `uint32_t`                                                           | Automatically scroll object to make it visible when focused                                                                                                                                                                                                          |
  | `scroll_with_arrow`            | `uint32_t`                                                           | Allow scrolling the focused object with arrow keys                                                                                                                                                                                                                   |
  | `snappable`                    | `uint32_t`                                                           | If scroll snap is enabled on the parent it can snap to this object                                                                                                                                                                                                   |
  | `press_lock`                   | `uint32_t`                                                           | Keep the object pressed even if the press slid from the object                                                                                                                                                                                                       |
  | `event_bubble`                 | `uint32_t`                                                           | Propagate the events to the parent too                                                                                                                                                                                                                               |
  | `gesture_bubble`               | `uint32_t`                                                           | Propagate the gestures to the parent                                                                                                                                                                                                                                 |
  | `adv_hittest`                  | `uint32_t`                                                           | Allow performing more accurate hit (click) test                                                                                                                                                                                                                      |
  | `ignore_layout`                | `uint32_t`                                                           | Make the object not positioned by the layouts                                                                                                                                                                                                                        |
  | `floating`                     | `uint32_t`                                                           | Do not scroll the object when the parent scrolls and ignore layout                                                                                                                                                                                                   |
  | `send_draw_task_events`        | `uint32_t`                                                           | Send LV\_EVENT\_DRAW\_TASK\_ADDED events                                                                                                                                                                                                                             |
  | `overflow_visible`             | `uint32_t`                                                           | Do not clip the children to the parent's ext draw size                                                                                                                                                                                                               |
  | `event_trickle`                | `uint32_t`                                                           | Propagate the events to the children too                                                                                                                                                                                                                             |
  | `state_trickle`                | `uint32_t`                                                           | Propagate the states to the children too                                                                                                                                                                                                                             |
  | `radio_button`                 | `uint32_t`                                                           | Allow only one RADIO\_BUTTON sibling to be checked                                                                                                                                                                                                                   |
  | `state`                        | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `layout_inv`                   | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `readjust_scroll_after_layout` | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `scr_layout_inv`               | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `skip_trans`                   | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `style_cnt`                    | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `h_layout`                     | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `w_layout`                     | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `h_ignore_size`                | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `w_ignore_size`                | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `is_deleting`                  | `uint16_t`                                                           |                                                                                                                                                                                                                                                                      |
  | `rendered`                     | `uint16_t`                                                           | The widget is rendered at least once already. It's used to skip initial animations and transitions.                                                                                                                                                                  |
  | `has_blur`                     | `uint16_t`                                                           | The widget has blur or a drop shadow in its current state, so a change behind it must invalidate its full extent. It's updated by <ApiLink name="lv_obj_update_blur_status" display="lv_obj_update_blur_status()" /> and counted in blur\_obj\_cnt in lv\_global\_t. |
</ApiMember>

Typedefs [#typedefs]

<ApiMember kind="typedef" name="lv_obj_spec_attr_t" file="private/core/lv_obj_private.h" line="55" url="https://github.com/lvgl/lvgl/tree/e1a0ad863f29742359bc680d6a7d973448ec2285/src/core/lv_obj_private.h#L55">
  lv_obj_spec_attr_t [#lv_obj_spec_attr_t]

  ```c title=" " lineNumbers=1
  typedef struct _lv_obj_spec_attr_t lv_obj_spec_attr_t
  ```

  Special, rarely used attributes. They are allocated automatically if any elements is set.
</ApiMember>

Dependencies [#dependencies]

<FileIncludes includes="[&#x22;lvgl_public.h&#x22;, &#x22;lv_event_private.h&#x22;]" includedBy="[&#x22;lvgl_private.h&#x22;, &#x22;lv_file_explorer_private.h&#x22;, &#x22;lv_3dtexture_private.h&#x22;, &#x22;lv_arc_private.h&#x22;, &#x22;lv_arclabel_private.h&#x22;, &#x22;lv_bar_private.h&#x22;, &#x22;lv_button_private.h&#x22;, &#x22;lv_buttonmatrix_private.h&#x22;, &#x22;lv_calendar_private.h&#x22;, &#x22;lv_chart_private.h&#x22;, &#x22;lv_checkbox_private.h&#x22;, &#x22;lv_dropdown_private.h&#x22;, &#x22;lv_image_private.h&#x22;, &#x22;lv_imagebutton_private.h&#x22;, &#x22;lv_ime_pinyin_private.h&#x22;, &#x22;lv_keyboard_private.h&#x22;, &#x22;lv_label_private.h&#x22;, &#x22;lv_led_private.h&#x22;, &#x22;lv_line_private.h&#x22;, &#x22;lv_lottie_private.h&#x22;, &#x22;lv_menu_private.h&#x22;, &#x22;lv_msgbox_private.h&#x22;, &#x22;lv_roller_private.h&#x22;, &#x22;lv_scale_private.h&#x22;, &#x22;lv_slider_private.h&#x22;, &#x22;lv_span_private.h&#x22;, &#x22;lv_spinbox_private.h&#x22;, &#x22;lv_spinner_private.h&#x22;, &#x22;lv_switch_private.h&#x22;, &#x22;lv_table_private.h&#x22;, &#x22;lv_tabview_private.h&#x22;, &#x22;lv_textarea_private.h&#x22;, &#x22;lv_tileview_private.h&#x22;, &#x22;lv_win_private.h&#x22;]" transitiveIncludes="[&#x22;lv_array.h&#x22;]" />