ClutterZoomAction: Clutter Reference Manual

## ClutterZoomAction ClutterZoomAction — Action enabling zooming on actors |

## Functions

ClutterAction * | clutter_zoom_action_new ()
void | clutter_zoom_action_set_zoom_axis ()
ClutterZoomAxis | clutter_zoom_action_get_zoom_axis ()
void | clutter_zoom_action_get_focal_point ()
void | clutter_zoom_action_get_transformed_focal_point ()

## Properties

ClutterZoomAxis | zoom-axis | Read / Write

## Signals

gboolean | zoom | Run Last

## Types and Values

struct | ClutterZoomAction
struct | ClutterZoomActionClass
enum | ClutterZoomAxis

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── ClutterActorMeta
                ╰── ClutterAction
                    ╰── ClutterGestureAction
                        ╰── ClutterZoomAction

## 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.

## Functions

### clutter_zoom_action_new ()

    ClutterAction *
    clutter_zoom_action_new (void);

Creates a new ClutterZoomAction instance

#### Returns

the newly created ClutterZoomAction

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

#### Parameters

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()`

#### Parameters

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

#### Parameters

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

#### Parameters

action | a ClutterZoomAction |
point | a ClutterPoint. | [out]

Since: 1.12

## Types and Values

### 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

#### Members

`zoom` () | class handler of the “zoom” signal |

Since: 1.12

### enum ClutterZoomAxis

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

#### Members

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

## Property Details

### The `“zoom-axis”` property

      “zoom-axis”                ClutterZoomAxis

Constraints the zooming action to the specified axis

Flags: Read / Write

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)

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`.

#### Parameters

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.

Flags: Run Last

Since: 1.12