Evas Events

Evas events happen on a canvas as a whole. This kind of events are too low-level for writing applications and are most often used when writing the graphical toolkit itself.

Table of Contents

Adding Callbacks to Canvases: evas_event_callback_add/del

The callbacks are added with evas_event_callback_add(). Its prototype is

void evas_event_callback_add(Evas*              e,
                             Evas_Callback_Type type,
                             Evas_Event_Cb      func,
                             const void*        data
  • e is the evas canvas on which the events happen. If needed, it can be

obtained from an Evas_Object through the evas_object_evas_get() function.

  • 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 an argument to the callback. It is optional and NULL is an acceptable value.

The type of the callback function is defined as follows.

void (* Evas_Event_Cb) (void *data, Evas *e, void *event_info)

The callback function definition is similar to

void some_evas_object_event_cb(void *data, Evas *e, void *event_info);
  • data is the same as the data which was given as the parameter to evas_event_callback_add().
  • e is the canvas on which the event occurred.
  • event_info is data which depends on the object type and the event at play. The documentation must be read for each such event.

Types of Evas Events

The values are defined from the Evas_Callback_Type enum. Some of them are not used for evas_event_callback_add() but are used in the previous section.

  • EVAS_CALLBACK_CANVAS_FOCUS_IN : Image has been preloaded.
  • EVAS_CALLBACK_CANVAS_FOCUS_OUT : Canvas got focus as a whole.
  • EVAS_CALLBACK_RENDER_FLUSH_PRE : Canvas lost focus as a whole.
  • EVAS_CALLBACK_RENDER_FLUSH_POST : Called just before rendering is updated on the canvas target.
  • EVAS_CALLBACK_CANVAS_OBJECT_FOCUS_IN : Called just after rendering is updated on the canvas target.
  • EVAS_CALLBACK_CANVAS_OBJECT_FOCUS_OUT: Canvas object got focus.