[gtk+/gestures: 4/8] Add GtkGestureSwipe

[Carlos Garnacho <carlosg src gnome org>]

commit ccbd3a3ce9c0c38680f0d3fc638db5fea584de27
Author: Carlos Garnacho <carlos lanedo com>
Date:   Thu Jan 17 21:02:28 2013 +0100

    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.

 gtk/Makefile.am       |    2 +
 gtk/gtk.h             |    1 +
 gtk/gtkgestureswipe.c |  191 +++++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtkgestureswipe.h |   62 ++++++++++++++++
 4 files changed, 256 insertions(+), 0 deletions(-)
---
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index a846c5f..9285464 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -259,6 +259,7 @@ gtk_public_h_sources = 		\
 	gtkframe.h		\
 	gtkgesture.h		\
 	gtkgesturelongpress.h	\
+	gtkgestureswipe.h	\
 	gtkgrid.h		\
 	gtkiconfactory.h	\
 	gtkicontheme.h		\
@@ -732,6 +733,7 @@ gtk_base_c_sources = 		\
 	gtkframe.c		\
 	gtkgesture.c		\
 	gtkgesturelongpress.c	\
+	gtkgestureswipe.c	\
 	gtkgrid.c		\
 	gtkhsla.c		\
 	gtkiconcache.c		\
diff --git a/gtk/gtk.h b/gtk/gtk.h
index 0850a2b..06c6ee4 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -110,6 +110,7 @@
 #include <gtk/gtkframe.h>
 #include <gtk/gtkgesture.h>
 #include <gtk/gtkgesturelongpress.h>
+#include <gtk/gtkgestureswipe.h>
 #include <gtk/gtkgrid.h>
 #include <gtk/gtkiconfactory.h>
 #include <gtk/gtkicontheme.h>
diff --git a/gtk/gtkgestureswipe.c b/gtk/gtkgestureswipe.c
new file mode 100644
index 0000000..21f9616
--- /dev/null
+++ b/gtk/gtkgestureswipe.c
@@ -0,0 +1,191 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2012, One Laptop Per Child.
+ *
+ * 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 <carlos lanedo com>
+ */
+#include <gtk/gtkgestureswipe.h>
+#include "gtkmarshalers.h"
+
+#define CAPTURE_THRESHOLD_MS 150
+
+typedef struct _EventData EventData;
+
+struct _EventData
+{
+  guint32 evtime;
+  GdkPoint point;
+};
+
+struct _GtkGestureSwipePriv
+{
+  GArray *events;
+};
+
+enum {
+  SWIPE,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0 };
+
+G_DEFINE_TYPE (GtkGestureSwipe, gtk_gesture_swipe, GTK_TYPE_GESTURE)
+
+static void
+gtk_gesture_swipe_finalize (GObject *object)
+{
+  GtkGestureSwipePriv *priv = GTK_GESTURE_SWIPE (object)->_priv;
+
+  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)
+{
+  GtkGestureSwipePriv *priv = gesture->_priv;
+  gint i, length = 0;
+
+  for (i = 0; i < 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);
+  GtkGestureSwipePriv *priv = swipe->_priv;
+  EventData new;
+  gdouble x, y;
+
+  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)
+{
+  GtkGestureSwipePriv *priv = gesture->_priv;
+  EventData *start, *end;
+  gdouble diff_x, diff_y;
+  guint32 diff_time;
+
+  *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)
+{
+  GtkGestureSwipe *swipe = GTK_GESTURE_SWIPE (gesture);
+  GtkGestureSwipePriv *priv = swipe->_priv;
+  gdouble velocity_x, velocity_y;
+  guint32 evtime;
+
+  gtk_gesture_get_last_update_time (gesture, 0, &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,
+                  _gtk_marshal_VOID__DOUBLE_DOUBLE,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+
+  g_type_class_add_private (klass, sizeof (GtkGestureSwipePriv));
+}
+
+static void
+gtk_gesture_swipe_init (GtkGestureSwipe *gesture)
+{
+  gesture->_priv = G_TYPE_INSTANCE_GET_PRIVATE (gesture,
+                                                GTK_TYPE_GESTURE_SWIPE,
+                                                GtkGestureSwipePriv);
+  gesture->_priv->events = g_array_new (FALSE, FALSE, sizeof (EventData));
+}
+
+/**
+ * gtk_gesture_swipe_new:
+ *
+ * Returns a newly created #GtkGesture that recognizes swipes
+ *
+ * Returns: a newly created #GtkGestureSwipe
+ *
+ * Since: 3.8
+ **/
+GtkGesture *
+gtk_gesture_swipe_new (void)
+{
+  return g_object_new (GTK_TYPE_GESTURE_SWIPE, NULL);
+}
diff --git a/gtk/gtkgestureswipe.h b/gtk/gtkgestureswipe.h
new file mode 100644
index 0000000..df6bd19
--- /dev/null
+++ b/gtk/gtkgestureswipe.h
@@ -0,0 +1,62 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2012, One Laptop Per Child.
+ *
+ * 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 <carlos lanedo com>
+ */
+#ifndef __GTK_GESTURE_SWIPE_H__
+#define __GTK_GESTURE_SWIPE_H__
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gtk/gtkgesture.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_GESTURE_SWIPE         (gtk_gesture_swipe_get_type ())
+#define GTK_GESTURE_SWIPE(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_GESTURE_SWIPE, GtkGestureSwipe))
+#define GTK_GESTURE_SWIPE_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST ((k), GTK_TYPE_GESTURE_SWIPE, GtkGestureSwipeClass))
+#define GTK_IS_GESTURE_SWIPE(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_GESTURE_SWIPE))
+#define GTK_IS_GESTURE_SWIPE_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), GTK_TYPE_GESTURE_SWIPE))
+#define GTK_GESTURE_SWIPE_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_GESTURE_SWIPE, GtkGestureSwipeClass))
+
+typedef struct _GtkGestureSwipe GtkGestureSwipe;
+typedef struct _GtkGestureSwipeClass GtkGestureSwipeClass;
+typedef struct _GtkGestureSwipePriv GtkGestureSwipePriv;
+
+struct _GtkGestureSwipe
+{
+  GtkGesture parent_instance;
+  GtkGestureSwipePriv *_priv;
+};
+
+struct _GtkGestureSwipeClass
+{
+  GtkGestureClass parent_class;
+
+  void (* swipe) (GtkGestureSwipe *gesture,
+                  gdouble          velocity_x,
+                  gdouble          velocity_y);
+};
+
+GType        gtk_gesture_swipe_get_type  (void) G_GNUC_CONST;
+
+GtkGesture * gtk_gesture_swipe_new       (void);
+
+G_END_DECLS
+
+#endif /* __GTK_GESTURE_SWIPE_H__ */