Modules | Data Structures | Typedefs | Enumerations | Functions
Canvas Events

Functions relating to canvas events that report on changes of its internal states (an object got focused, the rendering is updated, etc). More...

Modules

 Input Events Freezing Functions
 Functions that deal with the freezing of input event processing of an Evas canvas.
 
 Input Events Feeding Functions
 Functions to tell Evas that input events happened and should be processed.
 

Data Structures

struct  _Evas_Event_Mouse_Down
 Mouse button press event. More...
 
struct  _Evas_Event_Mouse_Up
 Mouse button release event. More...
 
struct  _Evas_Event_Mouse_In
 Mouse enter event. More...
 
struct  _Evas_Event_Mouse_Out
 Mouse leave event. More...
 
struct  _Evas_Event_Mouse_Move
 Mouse move event. More...
 
struct  _Evas_Event_Mouse_Wheel
 Wheel event. More...
 
struct  _Evas_Event_Multi_Down
 Multi button press event. More...
 
struct  _Evas_Event_Multi_Up
 Multi button release event. More...
 
struct  _Evas_Event_Multi_Move
 Multi button down event. More...
 
struct  _Evas_Event_Key_Down
 Key press event. More...
 
struct  _Evas_Event_Key_Up
 Key release event. More...
 
struct  _Evas_Event_Hold
 Hold change event. More...
 
struct  _Evas_Axis
 
struct  _Evas_Event_Axis_Update
 

Typedefs

typedef struct _Evas_Event_Mouse_Down Evas_Event_Mouse_Down
 Event structure for EVAS_CALLBACK_MOUSE_DOWN event callbacks.
 
typedef struct _Evas_Event_Mouse_Up Evas_Event_Mouse_Up
 Event structure for EVAS_CALLBACK_MOUSE_UP event callbacks.
 
typedef struct _Evas_Event_Mouse_In Evas_Event_Mouse_In
 Event structure for EVAS_CALLBACK_MOUSE_IN event callbacks.
 
typedef struct _Evas_Event_Mouse_Out Evas_Event_Mouse_Out
 Event structure for EVAS_CALLBACK_MOUSE_OUT event callbacks.
 
typedef struct _Evas_Event_Mouse_Move Evas_Event_Mouse_Move
 Event structure for EVAS_CALLBACK_MOUSE_MOVE event callbacks.
 
typedef struct _Evas_Event_Mouse_Wheel Evas_Event_Mouse_Wheel
 Event structure for EVAS_CALLBACK_MOUSE_WHEEL event callbacks.
 
typedef struct _Evas_Event_Multi_Down Evas_Event_Multi_Down
 Event structure for EVAS_CALLBACK_MULTI_DOWN event callbacks.
 
typedef struct _Evas_Event_Multi_Up Evas_Event_Multi_Up
 Event structure for EVAS_CALLBACK_MULTI_UP event callbacks.
 
typedef struct _Evas_Event_Multi_Move Evas_Event_Multi_Move
 Event structure for EVAS_CALLBACK_MULTI_MOVE event callbacks.
 
typedef struct _Evas_Event_Key_Down Evas_Event_Key_Down
 Event structure for EVAS_CALLBACK_KEY_DOWN event callbacks.
 
typedef struct _Evas_Event_Key_Up Evas_Event_Key_Up
 Event structure for EVAS_CALLBACK_KEY_UP event callbacks.
 
typedef struct _Evas_Event_Hold Evas_Event_Hold
 Event structure for EVAS_CALLBACK_HOLD event callbacks.
 
typedef struct _Evas_Event_Axis_Update Evas_Event_Axis_Update
 Event structure for EVAS_CALLBACK_AXIS_UPDATE event callbacks. More...
 
typedef enum _Evas_Axis_Label Evas_Axis_Label
 Types of recognized device axes. More...
 
typedef struct _Evas_Axis Evas_Axis
 

Enumerations

enum  _Evas_Axis_Label {
  EVAS_AXIS_LABEL_UNKNOWN ,
  EVAS_AXIS_LABEL_X ,
  EVAS_AXIS_LABEL_Y ,
  EVAS_AXIS_LABEL_PRESSURE ,
  EVAS_AXIS_LABEL_DISTANCE ,
  EVAS_AXIS_LABEL_AZIMUTH ,
  EVAS_AXIS_LABEL_TILT ,
  EVAS_AXIS_LABEL_TWIST ,
  EVAS_AXIS_LABEL_TOUCH_WIDTH_MAJOR ,
  EVAS_AXIS_LABEL_TOUCH_WIDTH_MINOR ,
  EVAS_AXIS_LABEL_TOOL_WIDTH_MAJOR ,
  EVAS_AXIS_LABEL_TOOL_WIDTH_MINOR ,
  EVAS_AXIS_LABEL_WINDOW_X ,
  EVAS_AXIS_LABEL_WINDOW_Y ,
  EVAS_AXIS_LABEL_NORMAL_X ,
  EVAS_AXIS_LABEL_NORMAL_Y
}
 

Functions

EVAS_API void evas_event_callback_add (Evas *e, Evas_Callback_Type type, Evas_Event_Cb func, const void *data)
 Add (register) a callback function to a given canvas event. More...
 
EVAS_API void evas_event_callback_priority_add (Evas *e, Evas_Callback_Type type, Evas_Callback_Priority priority, Evas_Event_Cb func, const void *data)
 Add (register) a callback function to a given canvas event with a non-default priority set. More...
 
EVAS_API void * evas_event_callback_del (Evas *e, Evas_Callback_Type type, Evas_Event_Cb func)
 Delete a callback function from the canvas. More...
 
EVAS_API void * evas_event_callback_del_full (Evas *e, Evas_Callback_Type type, Evas_Event_Cb func, const void *data)
 Delete (unregister) a callback function registered to a given canvas event. More...
 
EVAS_API void evas_post_event_callback_push (Evas *e, Evas_Object_Event_Post_Cb func, const void *data)
 Push a callback on the post-event callback stack. More...
 
EVAS_API void evas_post_event_callback_remove (Evas *e, Evas_Object_Event_Post_Cb func)
 Remove a callback from the post-event callback stack. More...
 
EVAS_API void evas_post_event_callback_remove_full (Evas *e, Evas_Object_Event_Post_Cb func, const void *data)
 Remove a callback from the post-event callback stack. More...
 

Detailed Description

Functions relating to canvas events that report on changes of its internal states (an object got focused, the rendering is updated, etc).

Some of the functions in this group are exemplified here.

Typedef Documentation

◆ Evas_Event_Axis_Update

Event structure for EVAS_CALLBACK_AXIS_UPDATE event callbacks.

Since
1.13

◆ Evas_Axis_Label

Types of recognized device axes.

Since
1.13

Enumeration Type Documentation

◆ _Evas_Axis_Label

Enumerator
EVAS_AXIS_LABEL_UNKNOWN 

Axis containing unknown (or not yet representable) data.

Range: Unbounded. Unit: Undefined.

Since
1.13
EVAS_AXIS_LABEL_X 

Position along physical X axis; not window relative.

Range: Unbounded. Unit: Undefined.

Since
1.13
EVAS_AXIS_LABEL_Y 

Position along physical Y axis; not window relative.

Range: Unbounded. Unit: Undefined.

Since
1.13
EVAS_AXIS_LABEL_PRESSURE 

Force applied to tool tip.

Range: [0.0, 1.0]. Unit: Unitless.

Since
1.13
EVAS_AXIS_LABEL_DISTANCE 

Relative distance along physical Z axis.

Range: [0.0, 1.0]. Unit: Unitless

Since
1.13
EVAS_AXIS_LABEL_AZIMUTH 

Angle of tool about the Z axis from positive X axis.

Range: [-PI, PI]. Unit: Radians.

Since
1.13
EVAS_AXIS_LABEL_TILT 

Angle of tool about plane of sensor from positive Z axis.

Range: [0.0, PI]. Unit: Radians.

Since
1.13
EVAS_AXIS_LABEL_TWIST 

Rotation of tool about its major axis from its "natural" position.

Range: [-PI, PI] Unit: Radians.

Since
1.13
EVAS_AXIS_LABEL_TOUCH_WIDTH_MAJOR 

Length of contact ellipse along AZIMUTH.

Range: Unbounded: Unit: Same as EVAS_AXIS_LABEL_{X,Y}.

Since
1.13
EVAS_AXIS_LABEL_TOUCH_WIDTH_MINOR 

Length of contact ellipse perpendicular to AZIMUTH.

Range: Unbounded. Unit: Same as EVAS_AXIS_LABEL_{X,Y}.

Since
1.13
EVAS_AXIS_LABEL_TOOL_WIDTH_MAJOR 

Length of tool ellipse along AZIMUTH.

Range: Unbounded. Unit: Same as EVAS_AXIS_LABEL_{X,Y}.

Since
1.13
EVAS_AXIS_LABEL_TOOL_WIDTH_MINOR 

Length of tool ellipse perpendicular to AZIMUTH.

Range: Unbounded. Unit: Same as EVAS_AXIS_LABEL_{X,Y}.

Since
1.13
EVAS_AXIS_LABEL_WINDOW_X 

X coordinate mapped to the window.

Since
1.19
EVAS_AXIS_LABEL_WINDOW_Y 

Y coordinate mapped to the window.

Since
1.19
EVAS_AXIS_LABEL_NORMAL_X 

X normalized to the [0, 1] range.

Since
1.19
EVAS_AXIS_LABEL_NORMAL_Y 

Y normalized to the [0, 1] range.

Since
1.19

Function Documentation

◆ evas_event_callback_add()

EVAS_API void evas_event_callback_add ( Evas e,
Evas_Callback_Type  type,
Evas_Event_Cb  func,
const void *  data 
)

Add (register) a callback function to a given canvas event.

Parameters
eCanvas to attach a callback to
typeThe type of event that will trigger the callback
funcThe (callback) function to be called when the event is triggered
dataThe data pointer to be passed to func

This function adds a function callback to the canvas e when the event of type type occurs on it. The function pointer is func.

In the event of a memory allocation error during the addition of the callback to the canvas, evas_alloc_error() should be used to determine the nature of the error, if any, and the program should sensibly try and recover.

A callback function must have the Evas_Event_Cb prototype definition. The first parameter (data) in this definition will have the same value passed to evas_event_callback_add() as the data parameter, at runtime. The second parameter e is the canvas pointer on which the event occurred. The third parameter event_info is a pointer to a data structure that may or may not be passed to the callback, depending on the event type that triggered the callback. This is so because some events don't carry extra context with them, but others do.

The event type type to trigger the function may be one of EVAS_CALLBACK_RENDER_FLUSH_PRE, EVAS_CALLBACK_RENDER_FLUSH_POST, EVAS_CALLBACK_CANVAS_FOCUS_IN, EVAS_CALLBACK_CANVAS_FOCUS_OUT, EVAS_CALLBACK_CANVAS_OBJECT_FOCUS_IN and EVAS_CALLBACK_CANVAS_OBJECT_FOCUS_OUT. This determines the kind of event that will trigger the callback to be called. Only the last two of the event types listed here provide useful event information data – a pointer to the recently focused Evas object. For the others the event_info pointer is going to be NULL.

Example:

_render_flush_cb, NULL);
{
fprintf(stderr, "ERROR: Callback registering failed! Aborting.\n");
goto panic;
}
_object_focus_in_cb, NULL);
{
fprintf(stderr, "ERROR: Callback registering failed! Aborting.\n");
goto panic;
} /* two canvas event callbacks */
@ EVAS_ALLOC_ERROR_NONE
No allocation error.
Definition: Evas_Common.h:270
@ EVAS_CALLBACK_RENDER_FLUSH_PRE
Called after render update regions have been calculated, but only if update regions exist.
Definition: Evas_Common.h:445
@ EVAS_CALLBACK_CANVAS_OBJECT_FOCUS_IN
Canvas object got focus.
Definition: Evas_Common.h:450
EVAS_API void evas_event_callback_add(Evas *eo_e, Evas_Callback_Type type, Evas_Event_Cb func, const void *data)
Add (register) a callback function to a given canvas event.
Definition: evas_callbacks.c:573
EVAS_API Evas_Alloc_Error evas_alloc_error(void)
Get the error status of the most recent memory allocation call.
Definition: main.c:17

Looking to the callbacks registered above,

/* called when our rectangle gets focus */
static void
_object_focus_in_cb(void *data EINA_UNUSED,
Evas *e,
void *event_info)
{
printf("An object got focused: %s\n",
evas_object_name_get(event_info));
printf("Let's recheck it: %s\n",
printf("And again: %s\n", evas_object_focus_get(event_info) ?
"OK!" : "Oops, something is bad.");
}
/* render flush callback */
static void
_render_flush_cb(void *data EINA_UNUSED,
void *event_info EINA_UNUSED)
{
printf("Canvas is about to flush its rendering pipeline!\n");
}
/* put some action in the canvas */
static Eina_Bool
_resize_cb(void *data EINA_UNUSED)
{
int w, h, cw, ch;
evas_object_geometry_get(d.img, NULL, NULL, &w, &h);
ecore_evas_geometry_get(d.ee, NULL, NULL, &cw, &ch);
if (w < cw)
evas_object_resize(d.img, cw, ch);
else
evas_object_resize(d.img, cw / 2, ch / 2);
return EINA_TRUE; /* re-issue the timer */
}
/* let's have our events back */
EAPI void ecore_evas_geometry_get(const Ecore_Evas *ee, int *x, int *y, int *w, int *h)
Gets the geometry of an Ecore_Evas.
Definition: ecore_evas.c:1362
#define EINA_TRUE
boolean value TRUE (numerical value 1)
Definition: eina_types.h:539
unsigned char Eina_Bool
Type to mimic a boolean.
Definition: eina_types.h:527
#define EINA_UNUSED
Used to indicate that a function parameter is purposely unused.
Definition: eina_types.h:339
Eo Evas
An opaque handle to an Evas canvas.
Definition: Evas_Common.h:163
EVAS_API Efl_Canvas_Object * evas_focus_get(const Evas_Canvas *obj)
Retrieve the object focused by the default seat.
Definition: evas_canvas_eo.legacy.c:51
EVAS_API const char * evas_object_name_get(const Evas_Object *eo_obj)
Retrieves the name of the given Evas object.
Definition: evas_name.c:26
EVAS_API void evas_object_geometry_get(const Evas_Object *eo_obj, Evas_Coord *x, Evas_Coord *y, Evas_Coord *w, Evas_Coord *h)
Retrieves the position and (rectangular) size of the given Evas object.
Definition: evas_object_main.c:1335
EVAS_API Eina_Bool evas_object_focus_get(const Efl_Canvas_Object *obj)
Indicates that this object is the keyboard event receiver on its canvas.
Definition: efl_canvas_object_eo.legacy.c:45
EVAS_API void evas_object_resize(Evas_Object *obj, Evas_Coord w, Evas_Coord h)
Changes the size of the given Evas object.
Definition: evas_object_main.c:1236

we see that the canvas flushes its rendering pipeline (EVAS_CALLBACK_RENDER_FLUSH_PRE) whenever the _resize_cb routine takes place: it has to redraw that image at a different size. Also, the callback on an object being focused comes just after we focus it explicitly, on code.

See the full example.

Note
Be careful not to add the same callback multiple times, if that's not what you want, because Evas won't check if a callback existed before exactly as the one being registered (and thus, call it more than once on the event, in this case). This would make sense if you passed different functions and/or callback data, only.

References EVAS_CALLBACK_PRIORITY_DEFAULT, and evas_event_callback_priority_add().

◆ evas_event_callback_priority_add()

EVAS_API void evas_event_callback_priority_add ( Evas e,
Evas_Callback_Type  type,
Evas_Callback_Priority  priority,
Evas_Event_Cb  func,
const void *  data 
)

Add (register) a callback function to a given canvas event with a non-default priority set.

Except for the priority field, it's exactly the same as evas_event_callback_add

Parameters
eCanvas to attach a callback to
typeThe type of event that will trigger the callback
priorityThe priority of the callback, lower values called first.
funcThe (callback) function to be called when the event is triggered
dataThe data pointer to be passed to func
See also
evas_event_callback_add
Since
1.1

References eina_inlist_append(), EINA_INLIST_GET, EINA_SAFETY_ON_NULL_RETURN, EINA_SAFETY_ON_TRUE_RETURN, EVAS_CALLBACK_RENDER_POST, and EVAS_CANVAS_CLASS.

Referenced by evas_event_callback_add().

◆ evas_event_callback_del()

EVAS_API void * evas_event_callback_del ( Evas e,
Evas_Callback_Type  type,
Evas_Event_Cb  func 
)

Delete a callback function from the canvas.

Parameters
eCanvas to remove a callback from
typeThe type of event that was triggering the callback
funcThe function that was to be called when the event was triggered
Returns
The data pointer that was to be passed to the callback

This function removes the most recently added callback from the canvas e which was triggered by the event type type and was calling the function func when triggered. If the removal is successful it will also return the data pointer that was passed to evas_event_callback_add() when the callback was added to the canvas. If not successful NULL will be returned.

Example:

extern Evas *e;
void *my_data;
void focus_in_callback(void *data, Evas *e, void *event_info);
my_data = evas_event_callback_del(ebject, EVAS_CALLBACK_CANVAS_FOCUS_IN, focus_in_callback);
@ EVAS_CALLBACK_CANVAS_FOCUS_IN
Canvas got focus as a whole.
Definition: Evas_Common.h:443
EVAS_API void * evas_event_callback_del(Evas *eo_e, Evas_Callback_Type type, Evas_Event_Cb func)
Delete a callback function from the canvas.
Definition: evas_callbacks.c:634

References EINA_INLIST_GET, eina_inlist_remove(), EINA_INLIST_REVERSE_FOREACH, EINA_SAFETY_ON_NULL_RETURN_VAL, EVAS_CALLBACK_RENDER_POST, and EVAS_CANVAS_CLASS.

◆ evas_event_callback_del_full()

EVAS_API void * evas_event_callback_del_full ( Evas e,
Evas_Callback_Type  type,
Evas_Event_Cb  func,
const void *  data 
)

Delete (unregister) a callback function registered to a given canvas event.

Parameters
eCanvas to remove an event callback from
typeThe type of event that was triggering the callback
funcThe function that was to be called when the event was triggered
dataThe data pointer that was to be passed to the callback
Returns
The data pointer that was to be passed to the callback

This function removes the first added callback from the canvas e matching the event type type, the registered function pointer func and the callback data pointer data. If the removal is successful it will also return the data pointer that was passed to evas_event_callback_add() (that will be the same as the parameter) when the callback(s) was(were) added to the canvas. If not successful NULL will be returned. A common use would be to remove an exact match of a callback.

Example:

_render_flush_cb, NULL);
_object_focus_in_cb, NULL);
EVAS_API void * evas_event_callback_del_full(Evas *eo_e, Evas_Callback_Type type, Evas_Event_Cb func, const void *data)
Delete (unregister) a callback function registered to a given canvas event.
Definition: evas_callbacks.c:678

See the full example.

Note
For deletion of canvas events callbacks filtering by just type and function pointer, user evas_event_callback_del().

References EINA_INLIST_FOREACH, EINA_INLIST_GET, eina_inlist_remove(), EINA_INLIST_REVERSE_FOREACH, EINA_SAFETY_ON_NULL_RETURN_VAL, EVAS_CALLBACK_RENDER_POST, and EVAS_CANVAS_CLASS.

◆ evas_post_event_callback_push()

EVAS_API void evas_post_event_callback_push ( Evas e,
Evas_Object_Event_Post_Cb  func,
const void *  data 
)

Push a callback on the post-event callback stack.

Parameters
eCanvas to push the callback on
funcThe function that to be called when the stack is unwound
dataThe data pointer to be passed to the callback

Evas has a stack of callbacks that get called after all the callbacks for an event have triggered (all the objects it triggers on and all the callbacks in each object triggered). When all these have been called, the stack is unwound from most recently to least recently pushed item and removed from the stack calling the callback set for it.

This is intended for doing reverse logic-like processing, example - when a child object that happens to get the event later is meant to be able to "steal" functions from a parent and thus on unwind of this stack have its function called first, thus being able to set flags, or return 0 from the post-callback that stops all other post-callbacks in the current stack from being called (thus basically allowing a child to take control, if the event callback prepares information ready for taking action, but the post callback actually does the action).

This function should only be called from inside an evas input event callback. The event_info data may be kept up until func is called, in order to check the state of the "on-hold" flag for instance. Do not modify the canvas or otherwise trigger or feed a events to the canvas from inside func. Use jobs to safely modify the canvas.

Warning
Only use this function if you know exactly what you are doing!

References eina_list_prepend(), EINA_SAFETY_ON_NULL_RETURN, EINA_SAFETY_ON_TRUE_RETURN, ERR, EVAS_CALLBACK_LAST, and EVAS_CANVAS_CLASS.

◆ evas_post_event_callback_remove()

EVAS_API void evas_post_event_callback_remove ( Evas e,
Evas_Object_Event_Post_Cb  func 
)

Remove a callback from the post-event callback stack.

Parameters
eCanvas to push the callback on
funcThe function that to be called when the stack is unwound

This removes a callback from the stack added with evas_post_event_callback_push(). The first instance of the function in the callback stack is removed from being executed when the stack is unwound. Further instances may still be run on unwind.

References EINA_LIST_FOREACH, EINA_SAFETY_ON_NULL_RETURN, and EVAS_CANVAS_CLASS.

◆ evas_post_event_callback_remove_full()

EVAS_API void evas_post_event_callback_remove_full ( Evas e,
Evas_Object_Event_Post_Cb  func,
const void *  data 
)

Remove a callback from the post-event callback stack.

Parameters
eCanvas to push the callback on
funcThe function that to be called when the stack is unwound
dataThe data pointer to be passed to the callback

This removes a callback from the stack added with evas_post_event_callback_push(). The first instance of the function and data in the callback stack is removed from being executed when the stack is unwound. Further instances may still be run on unwind.

References EINA_LIST_FOREACH, EINA_SAFETY_ON_NULL_RETURN, and EVAS_CANVAS_CLASS.