Add GtkGestureSwipe

This gesture implementation recognices swipes on any direction.
The "swipe" signal has the X/Y velocity vector components, so
those can be used for direction guessing and velocity thresholds.

1 files changed, 201 insertions, 0 deletions

diff --git a/gtk/gtkgestureswipe.c b/gtk/gtkgestureswipe.c
new file mode 100644
index 0000000000..d912703df6
--- /dev/null
+++ b/gtk/gtkgestureswipe.c
@@ -0,0 +1,201 @@
+/* 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 <gtk/gtkgestureswipe.h>
+#include "gtkmarshalers.h"
+
+#define CAPTURE_THRESHOLD_MS 150
+
+typedef struct _GtkGestureSwipePrivate GtkGestureSwipePrivate;
+typedef struct _EventData EventData;
+
+struct _EventData
+{
+  guint32 evtime;
+  GdkPoint point;
+};
+
+struct _GtkGestureSwipePrivate
+{
+  GArray *events;
+};
+
+enum {
+  SWIPE,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0 };
+
+G_DEFINE_TYPE_WITH_PRIVATE (GtkGestureSwipe, gtk_gesture_swipe, GTK_TYPE_GESTURE)
+
+static void
+gtk_gesture_swipe_finalize (GObject *object)
+{
+  GtkGestureSwipePrivate *priv;
+
+  priv = gtk_gesture_swipe_get_instance_private (GTK_GESTURE_SWIPE (object));
+  g_array_free (priv->events, TRUE);
+
+  G_OBJECT_CLASS (gtk_gesture_swipe_parent_class)->finalize (object);
+}
+
+static void
+_gtk_gesture_swipe_clear_backlog (GtkGestureSwipe *gesture,
+                                  guint32          evtime)
+{
+  GtkGestureSwipePrivate *priv;
+  gint i, length = 0;
+
+  priv = gtk_gesture_swipe_get_instance_private (gesture);
+
+  for (i = 0; i < (gint) priv->events->len; i++)
+    {
+      EventData *data;
+
+      data = &g_array_index (priv->events, EventData, i);
+
+      if (data->evtime >= evtime - CAPTURE_THRESHOLD_MS)
+        {
+          length = i - 1;
+          break;
+        }
+    }
+
+  if (length > 0)
+    g_array_remove_range (priv->events, 0, length);
+}
+
+static void
+gtk_gesture_swipe_update (GtkGesture       *gesture,
+                          GdkEventSequence *sequence)
+{
+  GtkGestureSwipe *swipe = GTK_GESTURE_SWIPE (gesture);
+  GtkGestureSwipePrivate *priv;
+  EventData new;
+  gdouble x, y;
+
+  priv = gtk_gesture_swipe_get_instance_private (swipe);
+  gtk_gesture_get_last_update_time (gesture, sequence, &new.evtime);
+  gtk_gesture_get_point (gesture, sequence, &x, &y);
+
+  new.point.x = x;
+  new.point.y = y;
+
+  _gtk_gesture_swipe_clear_backlog (swipe, new.evtime);
+  g_array_append_val (priv->events, new);
+}
+
+static void
+_gtk_gesture_swipe_calculate_velocity (GtkGestureSwipe *gesture,
+                                       gdouble         *velocity_x,
+                                       gdouble         *velocity_y)
+{
+  GtkGestureSwipePrivate *priv;
+  EventData *start, *end;
+  gdouble diff_x, diff_y;
+  guint32 diff_time;
+
+  priv = gtk_gesture_swipe_get_instance_private (gesture);
+  *velocity_x = *velocity_y = 0;
+
+  if (priv->events->len == 0)
+    return;
+
+  start = &g_array_index (priv->events, EventData, 0);
+  end = &g_array_index (priv->events, EventData, priv->events->len - 1);
+
+  diff_time = end->evtime - start->evtime;
+  diff_x = end->point.x - start->point.x;
+  diff_y = end->point.y - start->point.y;
+
+  if (diff_time == 0)
+    return;
+
+  /* Velocity in pixels/sec */
+  *velocity_x = diff_x * 1000 / diff_time;
+  *velocity_y = diff_y * 1000 / diff_time;
+}
+
+static void
+gtk_gesture_swipe_end (GtkGesture       *gesture,
+                       GdkEventSequence *sequence)
+{
+  GtkGestureSwipe *swipe = GTK_GESTURE_SWIPE (gesture);
+  GtkGestureSwipePrivate *priv;
+  gdouble velocity_x, velocity_y;
+  guint32 evtime;
+
+  priv = gtk_gesture_swipe_get_instance_private (swipe);
+  gtk_gesture_get_last_update_time (gesture, sequence, &evtime);
+  _gtk_gesture_swipe_clear_backlog (swipe, evtime);
+  _gtk_gesture_swipe_calculate_velocity (swipe, &velocity_x, &velocity_y);
+  g_signal_emit (gesture, signals[SWIPE], 0, velocity_x, velocity_y);
+
+  if (priv->events->len > 0)
+    g_array_remove_range (priv->events, 0, priv->events->len);
+}
+
+static void
+gtk_gesture_swipe_class_init (GtkGestureSwipeClass *klass)
+{
+  GtkGestureClass *gesture_class = GTK_GESTURE_CLASS (klass);
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = gtk_gesture_swipe_finalize;
+
+  gesture_class->update = gtk_gesture_swipe_update;
+  gesture_class->end = gtk_gesture_swipe_end;
+
+  signals[SWIPE] =
+    g_signal_new ("swipe",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureSwipeClass, swipe),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+}
+
+static void
+gtk_gesture_swipe_init (GtkGestureSwipe *gesture)
+{
+  GtkGestureSwipePrivate *priv;
+
+  priv = gtk_gesture_swipe_get_instance_private (gesture);
+  priv->events = g_array_new (FALSE, FALSE, sizeof (EventData));
+}
+
+/**
+ * gtk_gesture_swipe_new:
+ * @widget: a #GtkWidget
+ *
+ * Returns a newly created #GtkGesture that recognizes swipes
+ *
+ * Returns: a newly created #GtkGestureSwipe
+ *
+ * Since: 3.14
+ **/
+GtkGesture *
+gtk_gesture_swipe_new (GtkWidget *widget)
+{
+  return g_object_new (GTK_TYPE_GESTURE_SWIPE,
+                       "widget", widget,
+                       NULL);
+}