GtkGestureZoom: GTK+ 3 Reference Manual

## GtkGestureZoom GtkGestureZoom — Zoom gesture |

## Functions

GtkGesture * | gtk_gesture_zoom_new ()
gdouble | gtk_gesture_zoom_get_scale_delta ()

## Signals

void | scale-changed | Run First

## Types and Values

| GtkGestureZoom

## Object Hierarchy

        GObject
        ╰── GtkEventController
            ╰── GtkGesture
                ╰── GtkGestureZoom

## Includes

    #include <gtk/gtk.h>

## Description

GtkGestureZoom is a GtkGesture implementation able to recognize pinch/zoom gestures, whenever the distance between both tracked sequences changes, the “scale-changed” signal is emitted to report the scale factor.

## Functions

### gtk_gesture_zoom_new ()

    GtkGesture *
    gtk_gesture_zoom_new (GtkWidget *widget);

Returns a newly created GtkGesture that recognizes zoom in/out gestures (usually known as pinch/zoom).

#### Parameters

widget | a GtkWidget |

#### Returns

a newly created GtkGestureZoom

Since: 3.14

### gtk_gesture_zoom_get_scale_delta ()

    gdouble
    gtk_gesture_zoom_get_scale_delta (GtkGestureZoom *gesture);

If `gesture` is active, this function returns the zooming difference since the gesture was recognized (hence the starting point is considered 1:1). If `gesture` is not active, 1 is returned.

#### Parameters

gesture | a GtkGestureZoom |

#### Returns

the scale delta

Since: 3.14

## Signal Details

### The `“scale-changed”` signal

    void
    user_function (GtkGestureZoom *controller,
                   gdouble         scale,
                   gpointer        user_data)

This signal is emitted whenever the distance between both tracked sequences changes.

#### Parameters

controller | the object on which the signal is emitted |
scale | Scale delta, taking the initial state as 1:1 |
user_data | user data set when the signal handler was connected. |

Flags: Run First

Since: 3.14

## See Also

GtkGestureRotate