GtkGestureZoom

GtkGestureZoom — Zoom gesture

Functions

GtkGesture * gtk_gesture_zoom_new ()
double 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 (void);

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

Returns

a newly created GtkGestureZoom

gtk_gesture_zoom_get_scale_delta ()

double
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

Types and Values

GtkGestureZoom

typedef struct _GtkGestureZoom GtkGestureZoom;

Signal Details

The “scale-changed” signal

void
user_function (GtkGestureZoom *controller,
               double          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

See Also

GtkGestureRotate

© 2005–2020 The GNOME Project
Licensed under the GNU Lesser General Public License version 2.1 or later.
https://developer.gnome.org/gtk4/4.0/GtkGestureZoom.html