mutter/clutter/clutter-swipe-action.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Copyright (C) 2010  Intel Corporation.
 * Copyright (C) 2011  Robert Bosch Car Multimedia GmbH.
 *
 * 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:
 *   Tomeu Vizoso <tomeu.vizoso@collabora.co.uk>
 *
 * Based on ClutterDragAction, written by:
 *   Emmanuele Bassi <ebassi@linux.intel.com>
 */

/**
 * SECTION:clutter-swipe-action
 * @Title: ClutterSwipeAction
 * @Short_Description: Action for swipe gestures
 *
 * #ClutterSwipeAction is a sub-class of #ClutterAction that implements
 * the logic for recognizing swipe gestures. It listens for low level events
 * such as #ClutterButtonEvent and #ClutterMotionEvent on the stage to raise
 * the signals #ClutterSwipeAction::swipe-begin, #ClutterSwipeAction::swipe-motion and
 * #ClutterSwipeAction::swipe-end.
 *
 * To use #ClutterSwipeAction you just need to apply it to a #ClutterActor
 * using clutter_actor_add_action() and connect to the signals:
 *
 * |[
 *   ClutterAction *action = clutter_swipe_action_new ();
 *
 *   clutter_actor_add_action (actor, action);
 *
 *   g_signal_connect (action, "swipe-begin", G_CALLBACK (on_swipe_begin), NULL);
 *   g_signal_connect (action, "swipe-motion", G_CALLBACK (on_swipe_motion), NULL);
 *   g_signal_connect (action, "swipe-end", G_CALLBACK (on_swipe_end), NULL);
 * ]|
 *
 * Since: 1.8
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "clutter-swipe-action.h"

#include "clutter-debug.h"
#include "clutter-enum-types.h"
#include "clutter-marshal.h"
#include "clutter-private.h"

struct _ClutterSwipeActionPrivate
{
  ClutterSwipeDirection h_direction;
  ClutterSwipeDirection v_direction;
  gfloat last_motion_x;
  gfloat last_motion_y;
};

enum
{
  SWEPT,

  LAST_SIGNAL
};

static guint swipe_signals[LAST_SIGNAL] = { 0, };

G_DEFINE_TYPE (ClutterSwipeAction, clutter_swipe_action,
               CLUTTER_TYPE_GESTURE_ACTION);

static gboolean
gesture_begin (ClutterGestureAction  *action,
               ClutterActor          *actor)
{
  ClutterSwipeActionPrivate *priv = CLUTTER_SWIPE_ACTION (action)->priv;

  priv->h_direction = 0;
  priv->v_direction = 0;

  return TRUE;
}

static gboolean
gesture_progress (ClutterGestureAction  *action,
                  ClutterActor          *actor)
{
  ClutterSwipeActionPrivate *priv = CLUTTER_SWIPE_ACTION (action)->priv;
  gfloat press_x, press_y;
  gfloat motion_x, motion_y;
  gfloat delta_x, delta_y;
  ClutterSwipeDirection h_direction = 0, v_direction = 0;
  ClutterSettings *settings = clutter_settings_get_default ();
  gint drag_threshold;

  clutter_gesture_action_get_press_coords (action,
                                           0,
                                           &press_x,
                                           &press_y);

  clutter_gesture_action_get_motion_coords (action,
                                            0,
                                            &motion_x,
                                            &motion_y);

  delta_x = press_x - motion_x;
  delta_y = press_y - motion_y;

  g_object_get (settings,
                "dnd-drag-threshold", &drag_threshold,
                NULL);

  if (delta_x >= drag_threshold)
    h_direction = CLUTTER_SWIPE_DIRECTION_RIGHT;
  else if (delta_x < -drag_threshold)
    h_direction = CLUTTER_SWIPE_DIRECTION_LEFT;

  if (delta_y >= drag_threshold)
    v_direction = CLUTTER_SWIPE_DIRECTION_DOWN;
  else if (delta_y < -drag_threshold)
    v_direction = CLUTTER_SWIPE_DIRECTION_UP;

  /* cancel gesture on direction reversal */

  if (priv->h_direction == 0)
    priv->h_direction = h_direction;

  if (priv->v_direction == 0)
    priv->v_direction = v_direction;

  if (priv->h_direction != h_direction)
    return FALSE;

  if (priv->v_direction != v_direction)
    return FALSE;

  return TRUE;
}


static void
gesture_end (ClutterGestureAction  *action,
             ClutterActor          *actor)
{
  gfloat press_x, press_y;
  gfloat release_x, release_y;
  ClutterSwipeDirection direction = 0;
  ClutterSettings *settings = clutter_settings_get_default ();
  gint drag_threshold;

  clutter_gesture_action_get_press_coords (CLUTTER_GESTURE_ACTION (action),
                                           0,
                                           &press_x, &press_y);

  clutter_gesture_action_get_release_coords (CLUTTER_GESTURE_ACTION (action),
                                             0,
                                             &release_x, &release_y);

  g_object_get (settings,
                "dnd-drag-threshold", &drag_threshold,
                NULL);

  if (release_x - press_x > drag_threshold)
    direction |= CLUTTER_SWIPE_DIRECTION_RIGHT;
  else if (press_x - release_x > drag_threshold)
    direction |= CLUTTER_SWIPE_DIRECTION_LEFT;

  if (release_y - press_y > drag_threshold)
    direction |= CLUTTER_SWIPE_DIRECTION_DOWN;
  else if (press_y - release_y > drag_threshold)
    direction |= CLUTTER_SWIPE_DIRECTION_UP;

  g_signal_emit (action, swipe_signals[SWEPT], 0, actor, direction);
}

static void
clutter_swipe_action_class_init (ClutterSwipeActionClass *klass)
{
  ClutterGestureActionClass *gesture_class =
      CLUTTER_GESTURE_ACTION_CLASS (klass);

  g_type_class_add_private (klass, sizeof (ClutterSwipeActionPrivate));

  gesture_class->gesture_begin = gesture_begin;
  gesture_class->gesture_progress = gesture_progress;
  gesture_class->gesture_end = gesture_end;

  /**
   * ClutterSwipeAction::swept:
   * @action: the #ClutterSwipeAction that emitted the signal
   * @actor: the #ClutterActor attached to the @action
   * @direction: the main direction of the swipe gesture
   *
   * The ::swept signal is emitted when a swipe gesture is recognized on the
   * attached actor.
   *
   * Since: 1.8
   */
  swipe_signals[SWEPT] =
    g_signal_new (I_("swept"),
                  G_TYPE_FROM_CLASS (klass),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (ClutterSwipeActionClass, swept),
                  NULL, NULL,
                  _clutter_marshal_VOID__OBJECT_INT,
                  G_TYPE_NONE, 2,
                  CLUTTER_TYPE_ACTOR,
                  G_TYPE_INT);
}

static void
clutter_swipe_action_init (ClutterSwipeAction *self)
{
  self->priv = G_TYPE_INSTANCE_GET_PRIVATE (self, CLUTTER_TYPE_SWIPE_ACTION,
                                            ClutterSwipeActionPrivate);

  clutter_gesture_action_set_required_devices (CLUTTER_GESTURE_ACTION (self),
                                               1);
}

/**
 * clutter_swipe_action_new:
 *
 * Creates a new #ClutterSwipeAction instance
 *
 * Return value: the newly created #ClutterSwipeAction
 *
 * Since: 1.8
 */
ClutterAction *
clutter_swipe_action_new (void)
{
  return g_object_new (CLUTTER_TYPE_SWIPE_ACTION, NULL);
}