ClutterZoomAction

ClutterZoomAction — Action enabling zooming on actors

Synopsis

struct              ClutterZoomAction;
struct              ClutterZoomActionClass;
ClutterAction *     clutter_zoom_action_new             (void);
enum                ClutterZoomAxis;
void                clutter_zoom_action_set_zoom_axis   (ClutterZoomAction *action,
                                                         ClutterZoomAxis axis);
ClutterZoomAxis     clutter_zoom_action_get_zoom_axis   (ClutterZoomAction *action);

void                clutter_zoom_action_get_focal_point (ClutterZoomAction *action,
                                                         ClutterPoint *point);
void                clutter_zoom_action_get_transformed_focal_point
                                                        (ClutterZoomAction *action,
                                                         ClutterPoint *point);

Object Hierarchy

  GObject
   +----GInitiallyUnowned
         +----ClutterActorMeta
               +----ClutterAction
                     +----ClutterGestureAction
                           +----ClutterZoomAction

Properties

  "zoom-axis"                ClutterZoomAxis       : Read / Write

Signals

  "zoom"                                           : Run Last

Description

ClutterZoomAction is a sub-class of ClutterGestureAction that implements all the necessary logic for zooming actors using a "pinch" gesture between two touch points.

The simplest usage of ClutterZoomAction consists in adding it to a ClutterActor and setting it as reactive; for instance, the following code: 

1
2
 
clutter_actor_add_action (actor, clutter_zoom_action_new ());
clutter_actor_set_reactive (actor, TRUE);

will automatically result in the actor to be scale according to the distance between two touch points.

Details

struct ClutterZoomAction

struct ClutterZoomAction;

The ClutterZoomAction structure contains only private data and should be accessed using the provided API

Since 1.12

struct ClutterZoomActionClass

struct ClutterZoomActionClass {
  gboolean (* zoom)  (ClutterZoomAction *action,
                      ClutterActor      *actor,
                      ClutterPoint      *focal_point,
                      gdouble            factor);
};

The ClutterZoomActionClass structure contains only private data

zoom ()

 class handler of the "zoom" signal

Since 1.12

clutter_zoom_action_new ()

ClutterAction *     clutter_zoom_action_new             (void);

Creates a new ClutterZoomAction instance

Returns :

 the newly created ClutterZoomAction

Since 1.12

enum ClutterZoomAxis

typedef enum {
 /*< prefix=CLUTTER_ZOOM >*/
  CLUTTER_ZOOM_X_AXIS,
  CLUTTER_ZOOM_Y_AXIS,
  CLUTTER_ZOOM_BOTH
} ClutterZoomAxis;

The axis of the constraint that should be applied by the zooming action.

CLUTTER_ZOOM_X_AXIS

 Scale only on the X axis

CLUTTER_ZOOM_Y_AXIS

 Scale only on the Y axis

CLUTTER_ZOOM_BOTH

 Scale on both axis

Since 1.12

clutter_zoom_action_set_zoom_axis ()

void                clutter_zoom_action_set_zoom_axis   (ClutterZoomAction *action,
                                                         ClutterZoomAxis axis);

Restricts the zooming action to a specific axis

action :

 a ClutterZoomAction

axis :

 the axis to constraint the zooming to

Since 1.12

clutter_zoom_action_get_zoom_axis ()

ClutterZoomAxis     clutter_zoom_action_get_zoom_axis   (ClutterZoomAction *action);

Retrieves the axis constraint set by clutter_zoom_action_set_zoom_axis()

action :

 a ClutterZoomAction

Returns :

 the axis constraint

Since 1.12

clutter_zoom_action_get_focal_point ()

void                clutter_zoom_action_get_focal_point (ClutterZoomAction *action,
                                                         ClutterPoint *point);

Retrieves the focal point of the current zoom

action :

 a ClutterZoomAction

point :

 a ClutterPoint. [out]

Since 1.12

clutter_zoom_action_get_transformed_focal_point ()

void                clutter_zoom_action_get_transformed_focal_point
                                                        (ClutterZoomAction *action,
                                                         ClutterPoint *point);

Retrieves the focal point relative to the actor's coordinates of the current zoom

action :

 a ClutterZoomAction

point :

 a ClutterPoint. [out]

Since 1.12

Property Details

The "zoom-axis" property

  "zoom-axis"                ClutterZoomAxis       : Read / Write

Constraints the zooming action to the specified axis

Default value: CLUTTER_ZOOM_BOTH

Since 1.12

Signal Details

The "zoom" signal

gboolean            user_function                      (ClutterZoomAction *action,
                                                        ClutterActor      *actor,
                                                        ClutterPoint      *focal_point,
                                                        gdouble            factor,
                                                        gpointer           user_data)        : Run Last

The ::zoom signal is emitted for each series of touch events that change the distance and focal point between the touch points.

The default handler of the signal will call clutter_actor_set_scale() on actor using the ratio of the first distance between the touch points and the current distance. To override the default behaviour, connect to this signal and return FALSE.

action :

 the ClutterZoomAction that emitted the signal

actor :

 the ClutterActor attached to the action

focal_point :

 the focal point of the zoom

factor :

 the initial distance between the 2 touch points

user_data :

 user data set when the signal handler was connected.

Returns :

 TRUE if the zoom should continue, and FALSE if the zoom should be cancelled.

Since 1.12

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