gtk2/gtk/gtkgesturezoom.c
2021-03-11 16:37:36 +00:00

259 lines
6.8 KiB
C

/* 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>
*/
/**
* GtkGestureZoom:
*
* `GtkGestureZoom` is a `GtkGesture` for 2-finger pinch/zoom gestures.
*
* Whenever the distance between both tracked sequences changes, the
* [signal@Gtk.GestureZoom::scale-changed] signal is emitted to report
* the scale factor.
*/
#include "config.h"
#include <math.h>
#include "gtkgesturezoom.h"
#include "gtkgesturezoomprivate.h"
#include "gtkintl.h"
typedef struct _GtkGestureZoomPrivate GtkGestureZoomPrivate;
enum {
SCALE_CHANGED,
LAST_SIGNAL
};
struct _GtkGestureZoomPrivate
{
double 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,
double *distance)
{
GdkEvent *last_event;
double x1, y1, x2, y2;
GtkGesture *gesture;
GList *sequences = NULL;
double dx, dy;
GdkTouchpadGesturePhase phase;
gboolean retval = FALSE;
gesture = GTK_GESTURE (zoom);
if (!gtk_gesture_is_recognized (gesture))
goto out;
sequences = gtk_gesture_get_sequences (gesture);
if (!sequences)
goto out;
last_event = gtk_gesture_get_last_event (gesture, sequences->data);
if (gdk_event_get_event_type (last_event) == GDK_TOUCHPAD_PINCH)
{
double scale;
/* Touchpad pinch */
phase = gdk_touchpad_event_get_gesture_phase (last_event);
if (phase == GDK_TOUCHPAD_GESTURE_PHASE_CANCEL)
goto out;
scale = gdk_touchpad_event_get_pinch_scale (last_event);
*distance = scale;
}
else
{
if (!sequences->next)
goto out;
gtk_gesture_get_point (gesture, sequences->data, &x1, &y1);
gtk_gesture_get_point (gesture, sequences->next->data, &x2, &y2);
dx = x1 - x2;
dy = y1 - y2;;
*distance = sqrt ((dx * dx) + (dy * dy));
}
retval = TRUE;
out:
g_list_free (sequences);
return retval;
}
static gboolean
_gtk_gesture_zoom_check_emit (GtkGestureZoom *gesture)
{
GtkGestureZoomPrivate *priv;
double 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 gboolean
gtk_gesture_zoom_filter_event (GtkEventController *controller,
GdkEvent *event)
{
/* Let 2-finger touchpad pinch events go through */
if (gdk_event_get_event_type (event) == GDK_TOUCHPAD_PINCH)
{
guint n_fingers;
n_fingers = gdk_touchpad_event_get_n_fingers (event);
if (n_fingers == 2)
return FALSE;
else
return TRUE;
}
return GTK_EVENT_CONTROLLER_CLASS (gtk_gesture_zoom_parent_class)->filter_event (controller, event);
}
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);
GtkEventControllerClass *event_controller_class = GTK_EVENT_CONTROLLER_CLASS (klass);
GtkGestureClass *gesture_class = GTK_GESTURE_CLASS (klass);
object_class->constructor = gtk_gesture_zoom_constructor;
event_controller_class->filter_event = gtk_gesture_zoom_filter_event;
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
*
* Emitted whenever the distance between both tracked sequences changes.
*/
signals[SCALE_CHANGED] =
g_signal_new (I_("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:
*
* Returns a newly created `GtkGesture` that recognizes
* pinch/zoom gestures.
*
* Returns: a newly created `GtkGestureZoom`
*/
GtkGesture *
gtk_gesture_zoom_new (void)
{
return g_object_new (GTK_TYPE_GESTURE_ZOOM,
NULL);
}
/**
* gtk_gesture_zoom_get_scale_delta:
* @gesture: a `GtkGestureZoom`
*
* Gets the scale delta.
*
* 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
*/
double
gtk_gesture_zoom_get_scale_delta (GtkGestureZoom *gesture)
{
GtkGestureZoomPrivate *priv;
double 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;
}