lv_event.h

API reference for lv_event.h

Summary

Functions

public/core/lv_event.h:287function

lv_event_desc_set_external_data

Set external data and its destructor for an event descriptor. This allows associating custom data with an event callback that will be automatically cleaned up when the event descriptor is removed or destroyed.

void lv_event_desc_set_external_data(lv_event_dsc_t *dsc, void *data, void(*free_cb)(void *data))

Name	Type	Description
`dsc`	`lv_event_dsc_t *`	pointer to an event descriptor (from lv_obj_add_event_cb)
`data`	`void *`	pointer to the external data to associate with the event descriptor May be `NULL`.
`free_cb`	`void()(void data)`	function pointer to a destructor that will be called to clean up the external data. The destructor will receive the data pointer as its parameter. May be `NULL`. When NULL no cleanup is performed.

public/core/lv_event.h:175function

lv_event_get_count

uint32_t lv_event_get_count(lv_event_list_t *list)

Name	Type
`list`	`lv_event_list_t *`

public/core/lv_event.h:177function

lv_event_get_dsc

lv_event_dsc_t * lv_event_get_dsc(lv_event_list_t *list, uint32_t index)

Name	Type
`list`	`lv_event_list_t *`
`index`	`uint32_t`

public/core/lv_event.h:179function

lv_event_dsc_get_cb

lv_event_cb_t lv_event_dsc_get_cb(lv_event_dsc_t *dsc)

Name	Type
`dsc`	`lv_event_dsc_t *`

public/core/lv_event.h:181function

lv_event_dsc_get_user_data

void * lv_event_dsc_get_user_data(lv_event_dsc_t *dsc)

Name	Type
`dsc`	`lv_event_dsc_t *`

public/core/lv_event.h:192function

lv_event_get_target

Get Widget originally targeted by the event. It's the same even if event was bubbled.

void * lv_event_get_target(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

Returns: void * — the target of the event_code

public/core/lv_event.h:200function

lv_event_get_current_target

Get current target of the event. It's the Widget for which the event handler being called. If the event is not bubbled it's the same as "normal" target.

void * lv_event_get_current_target(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

Returns: void * — pointer to the current target of the event_code

public/core/lv_event.h:207function

lv_event_get_code

Get event code of an event.

lv_event_code_t lv_event_get_code(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

Returns: lv_event_code_t — the event code. (E.g. LV_EVENT_CLICKED, LV_EVENT_FOCUSED, etc)

public/core/lv_event.h:214function

lv_event_get_param

Get parameter passed when event was sent.

void * lv_event_get_param(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

Returns: void * — pointer to the parameter

public/core/lv_event.h:221function

lv_event_get_user_data

Get user_data passed when event was registered on Widget.

void * lv_event_get_user_data(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

Returns: void * — pointer to the user_data

public/core/lv_event.h:273function

lv_event_code_get_name

Get the name of an event code.

const char * lv_event_code_get_name(lv_event_code_t code)

Name	Type	Description
`code`	`lv_event_code_t`	the event code

Returns: const char * — the name of the event code as a string

public/core/lv_event.h:158function

lv_event_send

Event callback. Events are used to notify the user of some action being taken on Widget. For details, see lv_event_t.

Send an event to the callbacks of an event list.

lv_result_t lv_event_send(lv_event_list_t *list, lv_event_t *e, bool preprocess)

Name	Type	Description
`list`	`lv_event_list_t *`	pointer to an event list. May be `NULL`. When NULL there is nothing to notify and LV_RESULT_OK is returned. Widgets without `spec_attr` legitimately have no list.
`e`	`lv_event_t *`	pointer to the event to send
`preprocess`	`bool`	true: send only to the preprocess callbacks

Returns: lv_result_t — LV_RESULT_OK: the target wasn't deleted in the event

public/core/lv_event.h:171function

lv_event_add

Add an event callback to an event list.

lv_event_dsc_t * lv_event_add(lv_event_list_t *list, lv_event_cb_t cb, lv_event_code_t filter, void *user_data)

Name	Type	Description
`list`	`lv_event_list_t *`	pointer to an event list
`cb`	`lv_event_cb_t`	the callback to invoke when a matching event is sent
`filter`	`lv_event_code_t`	event code to react to
`user_data`	`void *`	custom pointer stored with the callback and retrievable inside it via `lv_event_get_user_data()`. May be `NULL`..

Returns: lv_event_dsc_t * — pointer to the newly created event descriptor, or NULL on failure. Can be passed to lv_event_remove_dsc() later.

public/core/lv_event.h:173function

lv_event_remove_dsc

bool lv_event_remove_dsc(lv_event_list_t *list, lv_event_dsc_t *dsc)

Name	Type
`list`	`lv_event_list_t *`
`dsc`	`lv_event_dsc_t *`

public/core/lv_event.h:183function

lv_event_remove

bool lv_event_remove(lv_event_list_t *list, uint32_t index)

Name	Type
`list`	`lv_event_list_t *`
`index`	`uint32_t`

public/core/lv_event.h:185function

lv_event_remove_all

void lv_event_remove_all(lv_event_list_t *list)

Name	Type
`list`	`lv_event_list_t *`

public/core/lv_event.h:228function

lv_event_stop_bubbling

Stop event from bubbling. This is only valid when called in the middle of an event processing chain.

void lv_event_stop_bubbling(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

public/core/lv_event.h:235function

lv_event_stop_trickling

Stop event from trickling down to children. This is only valid when called in the middle of an event processing chain.

void lv_event_stop_trickling(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

public/core/lv_event.h:242function

lv_event_stop_processing

Stop processing this event. This is only valid when called in the middle of an event processing chain.

void lv_event_stop_processing(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to the event descriptor

public/core/lv_event.h:249function

lv_event_free_user_data_cb

Helper function typically used in LV_EVENT_DELETE to free the event's user_data

void lv_event_free_user_data_cb(lv_event_t *e)

Name	Type	Description
`e`	`lv_event_t *`	pointer to an event descriptor

public/core/lv_event.h:266function

lv_event_register_id

uint32_t LV_EVENT_MINE = 0;
...
e = lv_event_register_id();
...
lv_obj_send_event(obj, LV_EVENT_MINE, &some_data);

uint32_t lv_event_register_id(void)

Returns: uint32_t — the new event id, or LV_EVENT_LAST if LV_EVENT_LAST_CUSTOM is reached

Enums

public/core/lv_event.h:34enum

lv_event_code_t

Type of event being sent to Widget

Name	Value	Description
`LV_EVENT_ALL`	`0`
`LV_EVENT_PRESSED`		Input device events Widget has been pressed
`LV_EVENT_PRESSING`		Widget is being pressed (sent continuously while pressing)
`LV_EVENT_PRESS_LOST`		Widget is still being pressed but slid cursor/finger off Widget
`LV_EVENT_SHORT_CLICKED`		Widget was pressed for a short period of time, then released. Not sent if scrolled.
`LV_EVENT_SINGLE_CLICKED`		Sent for first short click within a small distance and short time
`LV_EVENT_DOUBLE_CLICKED`		Sent for second short click within small distance and short time
`LV_EVENT_TRIPLE_CLICKED`		Sent for third short click within small distance and short time
`LV_EVENT_LONG_PRESSED`		Object has been pressed for at least `long_press_time`. Not sent if scrolled.
`LV_EVENT_LONG_PRESSED_REPEAT`		Sent after `long_press_time` in every `long_press_repeat_time` ms. Not sent if scrolled.
`LV_EVENT_CLICKED`		Sent on release if not scrolled (regardless to long press)
`LV_EVENT_RELEASED`		Sent in every cases when Widget has been released
`LV_EVENT_SCROLL_BEGIN`		Scrolling begins. The event parameter is a pointer to the animation of the scroll. Can be modified
`LV_EVENT_SCROLL_THROW_BEGIN`
`LV_EVENT_SCROLL_END`		Scrolling ends
`LV_EVENT_SCROLL`		Scrolling
`LV_EVENT_GESTURE`		A gesture is detected. Get gesture with `lv_indev_get_gesture_dir(lv_indev_active());`
`LV_EVENT_GESTURE_UP`		An upwards gesture is detected. Sent right after `LV_EVENT_GESTURE`.
`LV_EVENT_GESTURE_DOWN`		A downwards gesture is detected. Sent right after `LV_EVENT_GESTURE`.
`LV_EVENT_GESTURE_LEFT`		A leftwards gesture is detected. Sent right after `LV_EVENT_GESTURE`.
`LV_EVENT_GESTURE_RIGHT`		A rightwards gesture is detected. Sent right after `LV_EVENT_GESTURE`.
`LV_EVENT_KEY`		A key is sent to Widget. Get key with `lv_indev_get_key(lv_indev_active());`
`LV_EVENT_ROTARY`		An encoder or wheel was rotated. Get rotation count with `lv_event_get_rotary_diff(e);`
`LV_EVENT_FOCUSED`		Widget received focus
`LV_EVENT_DEFOCUSED`		Widget's focus has been lost
`LV_EVENT_LEAVE`		Widget's focus has been lost but is still selected
`LV_EVENT_HIT_TEST`		Perform advanced hit-testing
`LV_EVENT_INDEV_RESET`		Indev has been reset
`LV_EVENT_HOVER_OVER`		Indev hover over object
`LV_EVENT_HOVER_LEAVE`		Indev hover leave object
`LV_EVENT_COVER_CHECK`		Drawing events Check if Widget fully covers an area. The event parameter is `lv_cover_check_info_t *`.
`LV_EVENT_REFR_EXT_DRAW_SIZE`		Get required extra draw area around Widget (e.g. for shadow). The event parameter is `int32_t *` to store the size.
`LV_EVENT_DRAW_MAIN_BEGIN`		Starting the main drawing phase
`LV_EVENT_DRAW_MAIN`		Perform the main drawing
`LV_EVENT_DRAW_MAIN_END`		Finishing the main drawing phase
`LV_EVENT_DRAW_POST_BEGIN`		Starting the post draw phase (when all children are drawn)
`LV_EVENT_DRAW_POST`		Perform the post draw phase (when all children are drawn)
`LV_EVENT_DRAW_POST_END`		Finishing the post draw phase (when all children are drawn)
`LV_EVENT_DRAW_TASK_ADDED`		Adding a draw task. The `LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS` flag needs to be set
`LV_EVENT_VALUE_CHANGED`		Special events Widget's value has changed (i.e. slider moved)
`LV_EVENT_INSERT`		Text has been inserted into Widget. The event data is `char *` being inserted.
`LV_EVENT_REFRESH`		Notify Widget to refresh something on it (for user)
`LV_EVENT_READY`		A process has finished
`LV_EVENT_CANCEL`		A process has been cancelled
`LV_EVENT_STATE_CHANGED`		The state of the widget changed
`LV_EVENT_CHECKED`		A checkable Widget became checked. Sent right after `LV_EVENT_VALUE_CHANGED`.
`LV_EVENT_UNCHECKED`		A checkable Widget became unchecked. Sent right after `LV_EVENT_VALUE_CHANGED`.
`LV_EVENT_CREATE`		Other events Object is being created
`LV_EVENT_DELETE`		Object is being deleted
`LV_EVENT_CHILD_CHANGED`		Child was removed, added, or its size, position were changed
`LV_EVENT_CHILD_CREATED`		Child was created, always bubbles up to all parents
`LV_EVENT_CHILD_DELETED`		Child was deleted, always bubbles up to all parents
`LV_EVENT_SCREEN_UNLOAD_START`		A screen unload started, fired immediately when scr_load is called
`LV_EVENT_SCREEN_LOAD_START`		A screen load started, fired when the screen change delay is expired
`LV_EVENT_SCREEN_LOADED`		A screen was loaded
`LV_EVENT_SCREEN_UNLOADED`		A screen was unloaded
`LV_EVENT_SIZE_CHANGED`		Object coordinates/size have changed
`LV_EVENT_STYLE_CHANGED`		Object's style has changed
`LV_EVENT_LAYOUT_CHANGED`		A child's position position has changed due to a layout recalculation
`LV_EVENT_GET_SELF_SIZE`		Get internal size of a widget
`LV_EVENT_INVALIDATE_AREA`		Events of optional LVGL components An area is invalidated (marked for redraw). `lv_event_get_param(e)` returns a pointer to an `lv_area_t` object with the coordinates of the area to be invalidated. The area can be freely modified if needed to adapt it a special requirement of the display. Usually needed with monochrome displays to invalidate `N x 8` rows or columns in one pass.
`LV_EVENT_RESOLUTION_CHANGED`		Sent when the resolution changes due to `lv_display_set_resolution()` or `lv_display_set_rotation()`.
`LV_EVENT_COLOR_FORMAT_CHANGED`		Sent as a result of any call to `lv_display_set_color_format()`.
`LV_EVENT_REFR_REQUEST`		Sent when something happened that requires redraw.
`LV_EVENT_REFR_START`		Sent before a refreshing cycle starts. Sent even if there is nothing to redraw.
`LV_EVENT_REFR_READY`		Sent when refreshing has been completed (after rendering and calling flush callback). Sent even if no redraw happened.
`LV_EVENT_RENDER_START`		Sent just before rendering begins.
`LV_EVENT_RENDER_READY`		Sent after rendering has been completed.
`LV_EVENT_FLUSH_START`		Sent before flush callback is called.
`LV_EVENT_FLUSH_FINISH`		Sent after flush callback call has returned.
`LV_EVENT_FLUSH_WAIT_START`		Sent before flush wait callback is called.
`LV_EVENT_FLUSH_WAIT_FINISH`		Sent after flush wait callback call has returned.
`LV_EVENT_SYNC_START`		Sent before sync callback is called.
`LV_EVENT_SYNC_FINISH`		Sent after sync callback call has returned.
`LV_EVENT_SYNC_WAIT_START`		Sent before sync wait callback is called.
`LV_EVENT_SYNC_WAIT_FINISH`		Sent after sync wait callback call has returned.
`LV_EVENT_UPDATE_LAYOUT_COMPLETED`		Sent after layout update completes
`LV_EVENT_VSYNC`
`LV_EVENT_VSYNC_REQUEST`
`LV_EVENT_TRANSLATION_LANGUAGE_CHANGED`		Sent when the translation language changed.
`LV_EVENT_LAST`
`LV_EVENT_LAST_CUSTOM`	`0x7FFF`	Number of default events
`LV_EVENT_PREPROCESS`	`0x8000`	Sentinel for the last custom event code
`LV_EVENT_MARKED_DELETING`	`0x10000`	This is a flag that can be set with an event so it's processed before the class default event processing

Used by 21 functions

lv_gltf_model_node_add_event_cb — param filter_list
lv_gltf_model_node_add_event_cb_with_world_position — param filter_list
lv_event_add — param filter
lv_event_code_get_name — param code
lv_obj_add_screen_load_event — param trigger
lv_obj_add_screen_create_event — param trigger
lv_obj_add_play_timeline_event — param trigger
lv_obj_send_event — param event_code
lv_obj_add_event_cb — param filter
lv_obj_add_subject_increment_event — param trigger
lv_obj_add_subject_toggle_event — param trigger
lv_obj_add_subject_set_int_event — param trigger
lv_obj_add_subject_set_float_event — param trigger
lv_obj_add_subject_set_string_event — param trigger
lv_display_add_event_cb — param filter
lv_display_send_event — param code
lv_draw_unit_send_event — param code
lv_freetype_outline_add_event — param filter
lv_indev_add_event_cb — param filter
lv_indev_send_event — param code
lv_event_push_and_send — param code

Typedefs

public/core/lv_event.h:29typedef

lv_event_cb_t

typedef void(* lv_event_cb_t) (lv_event_t *e)

Used by 13 functions

lv_gltf_model_node_add_event_cb — param cb
lv_gltf_model_node_add_event_cb_with_world_position — param cb
lv_event_add — param cb
lv_obj_add_event_cb — param event_cb
lv_obj_remove_event_cb — param event_cb
lv_obj_remove_event_cb_with_user_data — param event_cb
lv_display_add_event_cb — param event_cb
lv_display_remove_event_cb_with_user_data — param event_cb
lv_display_register_vsync_event — param event_cb
lv_display_unregister_vsync_event — param event_cb
lv_freetype_outline_add_event — param event_cb
lv_indev_add_event_cb — param event_cb
lv_indev_remove_event_cb_with_user_data — param event_cb