Clutter Reference Manual: ClutterZoomAction

## 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