~~Title: Evas Object Events~~
{{page>index}}
----
===== Evas Object Events =====

Each of the evas objects on a given evas canvas can be manipulated
independently. They send events, to which callbacks can be attached through
''evas_object_event_callback_add()'' and removed with
''evas_object_event_callback_del()''. These events all relate to single
objects, not the whole canvas.

=== Table of Contents ===

  * [[#Adding_and_Removing_Callbacks:_evas_object_event_callback_add/del|Adding and Removing Callbacks: evas_object_event_callback_add/del]]
  * [[#Types_of_Evas_Object_Events|Types of Evas Object Events]]

=== Related Info ===

  * [[https://build.enlightenment.org/job/nightly_efl_gcc_x86_64/lastSuccessfulBuild/artifact/doc/html/group__Evas__Object__Group__Events.html|Object Events API]]

==== Adding and Removing Callbacks: evas_object_event_callback_add/del ====

Callbacks are added with ''evas_event_callback_add()''. Its prototype is

<code c>
void evas_object_event_callback_add(Evas_Object*         obj,
                                    Evas_Callback_Type   type,
                                    Evas_Object_Event_Cb func,
                                    const void*          data
                                   )
</code>


  * ''obj'' is the object to attach the callback to.
  * ''type'' is the type of event that triggers the callback (the list is in the next section).
  * ''func'' is the function that is called.
  * ''data'' is a pointer to additional data that is given as the argument to the callback. It is optional and ''NULL'' is an acceptable value.

The type of the callback function is defined as follows.

<code c>
void (* Evas_Object_Event_Cb) (void *data, Evas *e, Evas_Object *obj, void *event_info)
</code>

The callback function definition is similar to

<code c>
void some_evas_object_event_cb(void *data, Evas *e, Evas_Object *obj, void *event_info);
</code>


  * ''data'' is the same as the data which was given as the parameter to ''evas_object_smart_callback_add()''.
  * ''e'' is the canvas on which the event occurred.
  * ''obj'' is the object to which the event happened.
  * ''event_info'' is data which depends on the object type and event at play. The documentation must be read for each event.

==== Types of Evas Object Events ====

The values are defined from the ''Evas_Callback_Type'' enum. Some of them are
not used for ''evas_object_event_callback_add()'', but are used in the next
section.

   * ''EVAS_CALLBACK_MOUSE_IN'': the pointer got over an object (with no other object between the two). This takes place no matter how the pointer becomes directly above the object. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_In'' struct.
   * ''EVAS_CALLBACK_MOUSE_OUT'': triggered similarly to ''EVAS_CALLBACK_MOUSE_IN'', but when the pointer goes outside an object's area. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_Out'' struct.
   * ''EVAS_CALLBACK_MOUSE_DOWN'': a mouse button is pressed while the object is receiving events (either because the pointer is on top of the object or because the object had focus). ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_Down'' struct.
   * ''EVAS_CALLBACK_MOUSE_UP'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_Up'' struct.
   * ''EVAS_CALLBACK_MOUSE_MOVE'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_Move'' struct.
   * ''EVAS_CALLBACK_MOUSE_WHEEL'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_Wheel'' struct.
   * ''EVAS_CALLBACK_MULTI_DOWN'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Multi_Down'' struct.
   * ''EVAS_CALLBACK_MULTI_UP'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Multi_Up'' struct.
   * ''EVAS_CALLBACK_MULTI_MOVE'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Multi_Move'' struct.
   * ''EVAS_CALLBACK_KEY_DOWN'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Key_Down'' struct.
   * ''EVAS_CALLBACK_KEY_UP'': triggered similarly to ''EVAS_CALLBACK_MOUSE_DOWN''. ''event_info'' in the callback is a pointer to an ''Evas_Event_Key_Up'' struct.
   * ''EVAS_CALLBACK_FOCUS_IN'': the object gained focus. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_In'' struct.
   * ''EVAS_CALLBACK_FOCUS_OUT'': the object lost focus. ''event_info'' in the callback is a pointer to an ''Evas_Event_Mouse_In'' struct.
   * ''EVAS_CALLBACK_SHOW'': the object is shown by a call to ''evas_object_show()''. ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_HIDE'': the object is hidden by a call to ''evas_object_hide()''. ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_MOVE'': the object's origin was moved (origin is the top-left corner at the creation time of the object). ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_RESIZE'': the object is resized. ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_RESTACK'': the object is re-stacked by ''evas_object_stack_below()'', ''evas_object_stack_above()'' or other events. ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_DEL'': the object is deleted.
   * ''EVAS_CALLBACK_FREE'': for internal use only. Do not use (the object resources are about to be freed). ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_HOLD'': for internal use only. ''event_info'' in the callback is a pointer to an ''Evas_Event_Hold'' struct.
   * ''EVAS_CALLBACK_CHANGED_SIZE_HINTS'': the size hints of the object changed.
   * ''EVAS_CALLBACK_IMAGE_PRELOADED'': an image which was preloaded through ''evas_object_image_preload()'' is loaded. ''event_info'' in the callback is NULL.
   * ''EVAS_CALLBACK_IMAGE_UNLOADED'': the image data is unloaded. ''event_info'' in the callback is NULL.