# lv_tree.h (/api/misc/lv_tree_h)
Tree. The tree nodes are dynamically allocated by the 'lv\_mem' module.
Functions [#functions]
lv_tree_node_create [#lv_tree_node_create]
Create a tree node.
```c title=" " lineNumbers=1
lv_tree_node_t * lv_tree_node_create(const lv_tree_class_t *class_p, lv_tree_node_t *parent)
```
Parameters
| Name | Type | Description |
| --------- | -------------------------------------------------------------------- | ---------------------------------------------------------- |
| `class_p` | | pointer to a class of the node |
| `parent` | | pointer to the parent node (or NULL if it's the root node) |
**Returns:** — pointer to the new node
lv_tree_node_delete [#lv_tree_node_delete]
Delete a tree node and all its children recursively.
```c title=" " lineNumbers=1
void lv_tree_node_delete(lv_tree_node_t *node)
```
Parameters
| Name | Type | Description |
| ------ | ------------------------------------------------------------ | ----------------------------- |
| `node` | | pointer to the node to delete |
lv_tree_walk [#lv_tree_walk]
Walk the tree recursively and call a callback function on each node.
```c title=" " lineNumbers=1
bool lv_tree_walk(const lv_tree_node_t *node, lv_tree_walk_mode_t mode, lv_tree_traverse_cb_t cb, lv_tree_before_cb_t bcb, lv_tree_after_cb_t acb, void *user_data)
```
Parameters
| Name | Type | Description |
| ----------- | ------------------------------------------------------------------ | --------------------------------------------------------- |
| `node` | | pointer to the root node of the tree |
| `mode` | | LV\_TREE\_WALK\_PRE\_ORDER or LV\_TREE\_WALK\_POST\_ORDER |
| `cb` | | callback function to call on each node |
| `bcb` | | callback function to call before visiting a node |
| `acb` | | callback function to call after visiting a node |
| `user_data` | `void *` | user data to pass to the callback functions |
**Returns:** — true: traversal is finished; false: traversal broken
Enums [#enums]
\_lv_tree_walk_mode_t [#_lv_tree_walk_mode_t]
| Name | Value |
| ------------------------- | ----- |
| `LV_TREE_WALK_PRE_ORDER` | `0` |
| `LV_TREE_WALK_POST_ORDER` | |
Structs [#structs]
\_lv_tree_class_t [#_lv_tree_class_t]
Describe the common methods of every object. Similar to a C++ class.
| Member | Type | Description |
| ---------------- | -------------------------------------------------------------------- | ----------- |
| `base_class` | | |
| `instance_size` | | |
| `constructor_cb` | | |
| `destructor_cb` | | |
\_lv_tree_node_t [#_lv_tree_node_t]
Description of a tree node
| Member | Type | Description |
| ----------- | -------------------------------------------------------------------- | ----------- |
| `parent` | | |
| `children` | | |
| `child_cnt` | | |
| `child_cap` | | |
| `class_p` | | |
Typedefs [#typedefs]
lv_tree_class_t [#lv_tree_class_t]
```c title=" " lineNumbers=1
typedef struct _lv_tree_class_t lv_tree_class_t
```
* `lv_tree_node_create` — param `class_p`
lv_tree_node_t [#lv_tree_node_t]
```c title=" " lineNumbers=1
typedef struct _lv_tree_node_t lv_tree_node_t
```
* `lv_tree_node_create` — param `parent`
* `lv_tree_node_delete` — param `node`
* `lv_tree_walk` — param `node`
lv_tree_constructor_cb_t [#lv_tree_constructor_cb_t]
```c title=" " lineNumbers=1
typedef void(* lv_tree_constructor_cb_t) (const lv_tree_class_t *class_p, lv_tree_node_t *node)
```
lv_tree_destructor_cb_t [#lv_tree_destructor_cb_t]
```c title=" " lineNumbers=1
typedef void(* lv_tree_destructor_cb_t) (const lv_tree_class_t *class_p, lv_tree_node_t *node)
```
lv_tree_walk_mode_t [#lv_tree_walk_mode_t]
```c title=" " lineNumbers=1
typedef uint8_t lv_tree_walk_mode_t
```
* `lv_tree_walk` — param `mode`
lv_tree_traverse_cb_t [#lv_tree_traverse_cb_t]
```c title=" " lineNumbers=1
typedef bool(* lv_tree_traverse_cb_t) (const lv_tree_node_t *node, void *user_data)
```
* `lv_tree_walk` — param `cb`
lv_tree_before_cb_t [#lv_tree_before_cb_t]
```c title=" " lineNumbers=1
typedef bool(* lv_tree_before_cb_t) (const lv_tree_node_t *node, void *user_data)
```
* `lv_tree_walk` — param `bcb`
lv_tree_after_cb_t [#lv_tree_after_cb_t]
```c title=" " lineNumbers=1
typedef void(* lv_tree_after_cb_t) (const lv_tree_node_t *node, void *user_data)
```
* `lv_tree_walk` — param `acb`
Macros [#macros]
LV_TREE_NODE [#lv_tree_node]
```c title=" " lineNumbers=1
#define LV_TREE_NODE(n) \
((lv_tree_node_t*)(n))
```
Variables [#variables]
lv_tree_node_class [#lv_tree_node_class]
```c title=" " lineNumbers=1
const lv_tree_class_t lv_tree_node_class
```
Dependencies [#dependencies]