Add GtkGestureRotate

This gesture implementation recognizes rotations when fed with
events from two different GdkEventSequences

1 files changed, 206 insertions, 0 deletions

diff --git a/gtk/gtkgesturerotate.c b/gtk/gtkgesturerotate.c
new file mode 100644
index 0000000000..74edda487f
--- /dev/null
+++ b/gtk/gtkgesturerotate.c
@@ -0,0 +1,206 @@
+/* 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>
+ */
+#include "config.h"
+#include <math.h>
+#include <gtk/gtkgesturerotate.h>
+#include "gtkmarshalers.h"
+
+typedef struct _GtkGestureRotatePrivate GtkGestureRotatePrivate;
+
+enum {
+  ANGLE_CHANGED,
+  LAST_SIGNAL
+};
+
+struct _GtkGestureRotatePrivate
+{
+  gdouble initial_angle;
+};
+
+static guint signals[LAST_SIGNAL] = { 0 };
+
+G_DEFINE_TYPE_WITH_PRIVATE (GtkGestureRotate, gtk_gesture_rotate, GTK_TYPE_GESTURE)
+
+static void
+gtk_gesture_rotate_init (GtkGestureRotate *gesture)
+{
+}
+
+static GObject *
+gtk_gesture_rotate_constructor (GType                  type,
+                                guint                  n_construct_properties,
+                                GObjectConstructParam *construct_properties)
+{
+  GObject *object;
+
+  object = G_OBJECT_CLASS (gtk_gesture_rotate_parent_class)->constructor (type,
+                                                                          n_construct_properties,
+                                                                          construct_properties);
+  g_object_set (object, "n-points", 2, NULL);
+
+  return object;
+}
+
+static gboolean
+_gtk_gesture_rotate_get_angle (GtkGestureRotate *rotate,
+                               gdouble          *angle)
+{
+  gdouble x1, y1, x2, y2;
+  GtkGesture *gesture;
+  gdouble dx, dy;
+  GList *sequences;
+
+  gesture = GTK_GESTURE (rotate);
+
+  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;
+
+  *angle = atan2 (dx, dy);
+
+  /* Invert angle */
+  *angle = (2 * G_PI) - *angle;
+
+  /* And constraint it to 0°-360° */
+  *angle = fmod (*angle, 2 * G_PI);
+
+  return TRUE;
+}
+
+static gboolean
+_gtk_gesture_rotate_check_emit (GtkGestureRotate *gesture)
+{
+  GtkGestureRotatePrivate *priv;
+  gdouble angle;
+
+  if (!_gtk_gesture_rotate_get_angle (gesture, &angle))
+    return FALSE;
+
+  priv = gtk_gesture_rotate_get_instance_private (gesture);
+
+  g_signal_emit (gesture, signals[ANGLE_CHANGED], 0,
+                 angle, angle - priv->initial_angle);
+  return TRUE;
+}
+
+static void
+gtk_gesture_rotate_begin (GtkGesture       *gesture,
+                          GdkEventSequence *sequence)
+{
+  GtkGestureRotate *rotate = GTK_GESTURE_ROTATE (gesture);
+  GtkGestureRotatePrivate *priv;
+
+  priv = gtk_gesture_rotate_get_instance_private (rotate);
+  _gtk_gesture_rotate_get_angle (rotate, &priv->initial_angle);
+}
+
+static void
+gtk_gesture_rotate_update (GtkGesture       *gesture,
+                           GdkEventSequence *sequence)
+{
+  _gtk_gesture_rotate_check_emit (GTK_GESTURE_ROTATE (gesture));
+}
+
+static void
+gtk_gesture_rotate_class_init (GtkGestureRotateClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkGestureClass *gesture_class = GTK_GESTURE_CLASS (klass);
+
+  object_class->constructor = gtk_gesture_rotate_constructor;
+
+  gesture_class->begin = gtk_gesture_rotate_begin;
+  gesture_class->update = gtk_gesture_rotate_update;
+
+  /**
+   * GtkGestureRotate::angle-changed:
+   * @gesture: the object on which the signal is emitted
+   * @angle: Current angle in radians
+   * @angle_delta: Difference with the starting angle in radians
+   */
+  signals[ANGLE_CHANGED] =
+    g_signal_new ("angle-changed",
+                  GTK_TYPE_GESTURE_ROTATE,
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GtkGestureRotateClass, angle_changed),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+}
+
+/**
+ * gtk_gesture_rotate_new:
+ * @widget: a #GtkWidget
+ *
+ * Returns a newly created #GtkGesture that recognizes 2-touch
+ * rotation gestures.
+ *
+ * Returns: a newly created #GtkGestureRotate
+ *
+ * Since: 3.14
+ **/
+GtkGesture *
+gtk_gesture_rotate_new (GtkWidget *widget)
+{
+  return g_object_new (GTK_TYPE_GESTURE_ROTATE,
+                       "widget", widget,
+                       NULL);
+}
+
+/**
+ * gtk_gesture_rotate_get_angle_delta:
+ * @gesture: a #GtkGestureRotate
+ * @delta: (out) (transfer none): angle delta
+ *
+ * If @gesture is active, this function returns %TRUE and fills
+ * in @delta with the angle difference in radians since the
+ * gesture was first recognized.
+ *
+ * Returns: %TRUE if @controller is recognizing a rotate gesture
+ *
+ * Since: 3.14
+ **/
+gboolean
+gtk_gesture_rotate_get_angle_delta (GtkGestureRotate *gesture,
+                                    gdouble          *delta)
+{
+  GtkGestureRotatePrivate *priv;
+  gdouble angle;
+
+  g_return_val_if_fail (GTK_IS_GESTURE_ROTATE (gesture), FALSE);
+
+  if (!_gtk_gesture_rotate_get_angle (gesture, &angle))
+    return FALSE;
+
+  priv = gtk_gesture_rotate_get_instance_private (gesture);
+
+  if (delta)
+    *delta = angle - priv->initial_angle;
+
+  return TRUE;
+}