Add GtkGestureDrag

This gesture interprets and reports drags as an offset to the drag
start point.

gtk/gtkgesturedrag.c

@@ -0,0 +1,210 @@
+/* GTK - The GIMP Toolkit
+ * 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/gtkgesturedrag.h>
+
+#define CAPTURE_THRESHOLD_MS 150
+
+typedef struct _GtkGestureDragPrivate GtkGestureDragPrivate;
+typedef struct _EventData EventData;
+
+struct _GtkGestureDragPrivate
+{
+  gdouble start_x;
+  gdouble start_y;
+  gdouble last_x;
+  gdouble last_y;
+};
+
+enum {
+  DRAG_BEGIN,
+  DRAG_UPDATE,
+  DRAG_END,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0 };
+
+G_DEFINE_TYPE_WITH_PRIVATE (GtkGestureDrag, gtk_gesture_drag, GTK_TYPE_GESTURE)
+
+static void
+gtk_gesture_drag_begin (GtkGesture       *gesture,
+                        GdkEventSequence *sequence)
+{
+  GtkGestureDragPrivate *priv;
+
+  priv = gtk_gesture_drag_get_instance_private (GTK_GESTURE_DRAG (gesture));
+  gtk_gesture_get_point (gesture, sequence, &priv->start_x, &priv->start_y);
+  g_signal_emit (gesture, signals[DRAG_BEGIN], 0, priv->start_x, priv->start_y);
+}
+
+static void
+gtk_gesture_drag_update (GtkGesture       *gesture,
+                         GdkEventSequence *sequence)
+{
+  GtkGestureDragPrivate *priv;
+  gdouble x, y;
+
+  priv = gtk_gesture_drag_get_instance_private (GTK_GESTURE_DRAG (gesture));
+  gtk_gesture_get_point (gesture, sequence, &priv->last_x, &priv->last_y);
+  x = priv->last_x - priv->start_x;
+  y = priv->last_y - priv->start_y;
+
+  g_signal_emit (gesture, signals[DRAG_UPDATE], 0, x, y);
+}
+
+static void
+gtk_gesture_drag_end (GtkGesture       *gesture,
+                      GdkEventSequence *sequence)
+{
+  GtkGestureDragPrivate *priv;
+  gdouble x, y;
+
+  priv = gtk_gesture_drag_get_instance_private (GTK_GESTURE_DRAG (gesture));
+  gtk_gesture_get_point (gesture, sequence, &priv->last_x, &priv->last_y);
+  x = priv->last_x - priv->start_x;
+  y = priv->last_y - priv->start_y;
+
+  g_signal_emit (gesture, signals[DRAG_END], 0, x, y);
+}
+
+static void
+gtk_gesture_drag_class_init (GtkGestureDragClass *klass)
+{
+  GtkGestureClass *gesture_class = GTK_GESTURE_CLASS (klass);
+
+  gesture_class->begin = gtk_gesture_drag_begin;
+  gesture_class->update = gtk_gesture_drag_update;
+  gesture_class->end = gtk_gesture_drag_end;
+
+  signals[DRAG_BEGIN] =
+    g_signal_new ("drag-begin",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureDragClass, drag_begin),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+  signals[DRAG_UPDATE] =
+    g_signal_new ("drag-update",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureDragClass, drag_update),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+  signals[DRAG_END] =
+    g_signal_new ("drag-end",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkGestureDragClass, drag_end),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
+}
+
+static void
+gtk_gesture_drag_init (GtkGestureDrag *gesture)
+{
+}
+
+/**
+ * gtk_gesture_drag_new:
+ * @widget: a #GtkWidget
+ *
+ * Returns a newly created #GtkGesture that recognizes drags
+ *
+ * Returns: a newly created #GtkGestureDrag
+ *
+ * Since: 3.14
+ **/
+GtkGesture *
+gtk_gesture_drag_new (GtkWidget *widget)
+{
+  return g_object_new (GTK_TYPE_GESTURE_DRAG,
+                       "widget", widget,
+                       NULL);
+}
+
+/**
+ * gtk_gesture_drag_get_start_point:
+ * @gesture: a #GtkGesture
+ * @x: X coordinate for the drag start point
+ * @y: Y coordinate for the drag start point
+ *
+ * If the @gesture is active, this function returns %TRUE
+ * and fills in @x and @y with the drag start coordinates,
+ * in window-relative coordinates.
+ *
+ * Returns: #TRUE if the gesture is active.
+ *
+ * Since: 3.14
+ **/
+gboolean
+gtk_gesture_drag_get_start_point (GtkGestureDrag *gesture,
+                                  gint           *x,
+                                  gint           *y)
+{
+  GtkGestureDragPrivate *priv;
+
+  if (!gtk_gesture_is_recognized (GTK_GESTURE (gesture)))
+    return FALSE;
+
+  priv = gtk_gesture_drag_get_instance_private (gesture);
+
+  if (x)
+    *x = priv->start_x;
+
+  if (y)
+    *y = priv->start_y;
+
+  return TRUE;
+}
+
+/**
+ * gtk_gesture_drag_get_current_point:
+ * @gesture: a #GtkGesture
+ * @x: X coordinate for the current point
+ * @y: Y coordinate for the current point
+ *
+ * If the @gesture is active, this function returns %TRUE and
+ * fills in @x and @y with the coordinates of the current point,
+ * as an offset to the starting drag point.
+ *
+ * Returns: #TRUE if the gesture is active.
+ *
+ * Since: 3.14
+ **/
+gboolean
+gtk_gesture_drag_get_current_point (GtkGestureDrag *gesture,
+                                    gint           *x,
+                                    gint           *y)
+{
+  GtkGestureDragPrivate *priv;
+
+  if (!gtk_gesture_is_recognized (GTK_GESTURE (gesture)))
+    return FALSE;
+
+  priv = gtk_gesture_drag_get_instance_private (gesture);
+
+  if (x)
+    *x = priv->last_x;
+
+  if (y)
+    *y = priv->last_y;
+
+  return TRUE;
+}