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/* GTK - The GIMP Toolkit
* Copyright (C) 2012, One Laptop Per Child.
* Copyright (C) 2014, Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Author(s): Carlos Garnacho <carlosg@gnome.org>
*/
/**
* SECTION:gtkgesturezoom
* @Short_description: Zoom gesture
* @Title: GtkGestureZoom
* @See_also: #GtkGestureRotate
*
* #GtkGestureZoom is a #GtkGesture implementation able to recognize
* pinch/zoom gestures, whenever the distance between both tracked
* sequences changes, the #GtkGestureZoom::scale-changed signal is
* emitted to report the scale factor.
*/
#include "config.h"
#include <math.h>
#include "gtkgesturezoom.h"
#include "gtkgesturezoomprivate.h"
typedef struct _GtkGestureZoomPrivate GtkGestureZoomPrivate;
enum {
SCALE_CHANGED,
LAST_SIGNAL
};
struct _GtkGestureZoomPrivate
{
gdouble initial_distance;
};
static guint signals[LAST_SIGNAL] = { 0 };
G_DEFINE_TYPE_WITH_PRIVATE (GtkGestureZoom, gtk_gesture_zoom, GTK_TYPE_GESTURE)
static void
gtk_gesture_zoom_init (GtkGestureZoom *gesture)
{
}
static GObject *
gtk_gesture_zoom_constructor (GType type,
guint n_construct_properties,
GObjectConstructParam *construct_properties)
{
GObject *object;
object = G_OBJECT_CLASS (gtk_gesture_zoom_parent_class)->constructor (type,
n_construct_properties,
construct_properties);
g_object_set (object, "n-points", 2, NULL);
return object;
}
static gboolean
_gtk_gesture_zoom_get_distance (GtkGestureZoom *zoom,
gdouble *distance)
{
gdouble x1, y1, x2, y2;
GtkGesture *gesture;
GList *sequences;
gdouble dx, dy;
gesture = GTK_GESTURE (zoom);
if (!gtk_gesture_is_recognized (gesture))
return FALSE;
sequences = gtk_gesture_get_sequences (gesture);
g_assert (sequences && sequences->next);
gtk_gesture_get_point (gesture, sequences->data, &x1, &y1);
gtk_gesture_get_point (gesture, sequences->next->data, &x2, &y2);
g_list_free (sequences);
dx = x1 - x2;
dy = y1 - y2;;
*distance = sqrt ((dx * dx) + (dy * dy));
return TRUE;
}
static gboolean
_gtk_gesture_zoom_check_emit (GtkGestureZoom *gesture)
{
GtkGestureZoomPrivate *priv;
gdouble distance, zoom;
if (!_gtk_gesture_zoom_get_distance (gesture, &distance))
return FALSE;
priv = gtk_gesture_zoom_get_instance_private (gesture);
if (distance == 0 || priv->initial_distance == 0)
return FALSE;
zoom = distance / priv->initial_distance;
g_signal_emit (gesture, signals[SCALE_CHANGED], 0, zoom);
return TRUE;
}
static void
gtk_gesture_zoom_begin (GtkGesture *gesture,
GdkEventSequence *sequence)
{
GtkGestureZoom *zoom = GTK_GESTURE_ZOOM (gesture);
GtkGestureZoomPrivate *priv;
priv = gtk_gesture_zoom_get_instance_private (zoom);
_gtk_gesture_zoom_get_distance (zoom, &priv->initial_distance);
}
static void
gtk_gesture_zoom_update (GtkGesture *gesture,
GdkEventSequence *sequence)
{
_gtk_gesture_zoom_check_emit (GTK_GESTURE_ZOOM (gesture));
}
static void
gtk_gesture_zoom_class_init (GtkGestureZoomClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
GtkGestureClass *gesture_class = GTK_GESTURE_CLASS (klass);
object_class->constructor = gtk_gesture_zoom_constructor;
gesture_class->begin = gtk_gesture_zoom_begin;
gesture_class->update = gtk_gesture_zoom_update;
/**
* GtkGestureZoom::scale-changed:
* @controller: the object on which the signal is emitted
* @scale: Scale delta, taking the initial state as 1:1
*
* This signal is emitted whenever the distance between both tracked
* sequences changes.
*
* Since: 3.14
*/
signals[SCALE_CHANGED] =
g_signal_new ("scale-changed",
GTK_TYPE_GESTURE_ZOOM,
G_SIGNAL_RUN_FIRST,
G_STRUCT_OFFSET (GtkGestureZoomClass, scale_changed),
NULL, NULL, NULL,
G_TYPE_NONE, 1, G_TYPE_DOUBLE);
}
/**
* gtk_gesture_zoom_new:
* @widget: a #GtkWidget
*
* Returns a newly created #GtkGesture that recognizes zoom
* in/out gestures (usually known as pinch/zoom).
*
* Returns: a newly created #GtkGestureZoom
*
* Since: 3.14
**/
GtkGesture *
gtk_gesture_zoom_new (GtkWidget *widget)
{
g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
return g_object_new (GTK_TYPE_GESTURE_ZOOM,
"widget", widget,
NULL);
}
/**
* gtk_gesture_zoom_get_scale_delta:
* @gesture: a #GtkGestureZoom
*
* 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.
*
* Returns: the scale delta
*
* Since: 3.14
**/
gdouble
gtk_gesture_zoom_get_scale_delta (GtkGestureZoom *gesture)
{
GtkGestureZoomPrivate *priv;
gdouble distance;
g_return_val_if_fail (GTK_IS_GESTURE_ZOOM (gesture), 1.0);
if (!_gtk_gesture_zoom_get_distance (gesture, &distance))
return 1.0;
priv = gtk_gesture_zoom_get_instance_private (gesture);
return distance / priv->initial_distance;
}
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