mutter/clutter/clutter-layout-manager.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Copyright (C) 2009  Intel Corporation.
 *
 * 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:
 *   Emmanuele Bassi <ebassi@linux.intel.com>
 */

/**
 * SECTION:clutter-layout-manager
 * @short_description: Layout managers base class
 *
 * #ClutterLayoutManager is a base abstract class for layout managers. A
 * layout manager implements the layouting policy for a composite or a
 * container actor: it controls the preferred size of the actor to which
 * it has been paired, and it controls the allocation of its children.
 *
 * Any composite or container #ClutterActor subclass can delegate the
 * layouting of its children to a #ClutterLayoutManager. Clutter provides
 * a generic container using #ClutterLayoutManager called #ClutterBox.
 *
 * Clutter provides some simple #ClutterLayoutManager sub-classes, like
 * #ClutterFixedLayout and #ClutterBinLayout.
 *
 * #ClutterLayoutManager is available since Clutter 1.2
 */

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

#include "clutter-debug.h"
#include "clutter-layout-manager.h"
#include "clutter-marshal.h"
#include "clutter-private.h"

#define LAYOUT_MANAGER_WARN_NOT_IMPLEMENTED(m,method)   G_STMT_START {  \
        GObject *_obj = G_OBJECT (m);                                   \
        g_warning ("Layout managers of type %s do not implement "       \
                   "the ClutterLayoutManager::%s method",               \
                   G_OBJECT_TYPE_NAME (_obj),                           \
                   (method));                           } G_STMT_END

enum
{
  LAYOUT_CHANGED,

  LAST_SIGNAL
};

G_DEFINE_ABSTRACT_TYPE (ClutterLayoutManager,
                        clutter_layout_manager,
                        G_TYPE_INITIALLY_UNOWNED);

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

static void
layout_manager_real_get_preferred_width (ClutterLayoutManager *manager,
                                         ClutterContainer     *container,
                                         gfloat                for_height,
                                         gfloat               *min_width_p,
                                         gfloat               *nat_width_p)
{
  LAYOUT_MANAGER_WARN_NOT_IMPLEMENTED (manager, "get_preferred_width");

  if (min_width_p)
    *min_width_p = 0.0;

  if (nat_width_p)
    *nat_width_p = 0.0;
}

static void
layout_manager_real_get_preferred_height (ClutterLayoutManager *manager,
                                          ClutterContainer     *container,
                                          gfloat                for_width,
                                          gfloat               *min_height_p,
                                          gfloat               *nat_height_p)
{
  LAYOUT_MANAGER_WARN_NOT_IMPLEMENTED (manager, "get_preferred_height");

  if (min_height_p)
    *min_height_p = 0.0;

  if (nat_height_p)
    *nat_height_p = 0.0;
}

static void
layout_manager_real_allocate (ClutterLayoutManager   *manager,
                              ClutterContainer       *container,
                              const ClutterActorBox  *allocation,
                              ClutterAllocationFlags  flags)
{
  LAYOUT_MANAGER_WARN_NOT_IMPLEMENTED (manager, "allocate");
}

static void
clutter_layout_manager_class_init (ClutterLayoutManagerClass *klass)
{
  klass->get_preferred_width = layout_manager_real_get_preferred_width;
  klass->get_preferred_height = layout_manager_real_get_preferred_height;
  klass->allocate = layout_manager_real_allocate;

  /**
   * ClutterLayoutManager::layout-changed:
   * @manager: the #ClutterLayoutManager that emitted the signal
   *
   * The ::layout-changed signal is emitted each time a layout manager
   * has been changed. Every #ClutterActor using the @manager instance
   * as a layout manager should connect a handler to the ::layout-changed
   * signal and queue a relayout on themselves:
   *
   * |[
   *   static void layout_changed (ClutterLayoutManager *manager,
   *                               ClutterActor         *self)
   *   {
   *     clutter_actor_queue_relayout (self);
   *   }
   *   ...
   *     self->manager = g_object_ref_sink (manager);
   *     g_signal_connect (self->manager, "layout-changed",
   *                       G_CALLBACK (layout_changed),
   *                       self);
   * ]|
   *
   * Sub-classes of #ClutterLayoutManager that implement a layout that
   * can be controlled or changed using parameters should emit the
   * ::layout-changed signal whenever one of the parameters changes,
   * by using clutter_layout_manager_layout_changed().
   *
   * Since: 1.2
   */
  manager_signals[LAYOUT_CHANGED] =
    g_signal_new (I_("layout-changed"),
                  G_TYPE_FROM_CLASS (klass),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (ClutterLayoutManagerClass,
                                   layout_changed),
                  NULL, NULL,
                  clutter_marshal_VOID__VOID,
                  G_TYPE_NONE, 0);
}

static void
clutter_layout_manager_init (ClutterLayoutManager *manager)
{
}

/**
 * clutter_layout_manager_get_preferred_width:
 * @manager: a #ClutterLayoutManager
 * @container: the #ClutterContainer using @manager
 * @for_height: the height for which the width should be computed, or -1
 * @min_width_p: (out) (allow-none): return location for the minimum width
 *   of the layout, or %NULL
 * @nat_width_p: (out) (allow-none): return location for the natural width
 *   of the layout, or %NULL
 *
 * Computes the minimum and natural widths of the @container according
 * to @manager.
 *
 * See also clutter_actor_get_preferred_width()
 *
 * Since: 1.2
 */
void
clutter_layout_manager_get_preferred_width (ClutterLayoutManager *manager,
                                            ClutterContainer     *container,
                                            gfloat                for_height,
                                            gfloat               *min_width_p,
                                            gfloat               *nat_width_p)
{
  ClutterLayoutManagerClass *klass;

  g_return_if_fail (CLUTTER_IS_LAYOUT_MANAGER (manager));
  g_return_if_fail (CLUTTER_IS_CONTAINER (container));

  klass = CLUTTER_LAYOUT_MANAGER_GET_CLASS (manager);
  klass->get_preferred_width (manager, container, for_height,
                              min_width_p,
                              nat_width_p);
}

/**
 * clutter_layout_manager_get_preferred_height:
 * @manager: a #ClutterLayoutManager
 * @container: the #ClutterContainer using @manager
 * @for_width: the width for which the height should be computed, or -1
 * @min_height_p: (out) (allow-none): return location for the minimum height
 *   of the layout, or %NULL
 * @nat_height_p: (out) (allow-none): return location for the natural height
 *   of the layout, or %NULL
 *
 * Computes the minimum and natural heights of the @container according
 * to @manager.
 *
 * See also clutter_actor_get_preferred_height()
 *
 * Since: 1.2
 */
void
clutter_layout_manager_get_preferred_height (ClutterLayoutManager *manager,
                                             ClutterContainer     *container,
                                             gfloat                for_width,
                                             gfloat               *min_height_p,
                                             gfloat               *nat_height_p)
{
  ClutterLayoutManagerClass *klass;

  g_return_if_fail (CLUTTER_IS_LAYOUT_MANAGER (manager));
  g_return_if_fail (CLUTTER_IS_CONTAINER (container));

  klass = CLUTTER_LAYOUT_MANAGER_GET_CLASS (manager);
  klass->get_preferred_height (manager, container, for_width,
                               min_height_p,
                               nat_height_p);
}

/**
 * clutter_layout_manager_allocate:
 * @manager: a #ClutterLayoutManager
 * @container: the #ClutterContainer using @manager
 * @allocation: the #ClutterActorBox containing the allocated area
 *   of @container
 * @flags: the allocation flags
 *
 * Allocates the children of @container given an area
 *
 * See also clutter_actor_allocate()
 *
 * Since: 1.2
 */
void
clutter_layout_manager_allocate (ClutterLayoutManager   *manager,
                                 ClutterContainer       *container,
                                 const ClutterActorBox  *allocation,
                                 ClutterAllocationFlags  flags)
{
  ClutterLayoutManagerClass *klass;

  g_return_if_fail (CLUTTER_IS_LAYOUT_MANAGER (manager));
  g_return_if_fail (CLUTTER_IS_CONTAINER (container));
  g_return_if_fail (allocation != NULL);

  klass = CLUTTER_LAYOUT_MANAGER_GET_CLASS (manager);
  klass->allocate (manager, container, allocation, flags);
}

/**
 * clutter_layout_manager_layout_changed:
 * @manager: a #ClutterLayoutManager
 *
 * Emits the #ClutterLayoutManager::layout-changed signal on @manager
 *
 * This function should only be called by implementations of the
 * #ClutterLayoutManager class
 *
 * Since: 1.2
 */
void
clutter_layout_manager_layout_changed (ClutterLayoutManager *manager)
{
  g_return_if_fail (CLUTTER_IS_LAYOUT_MANAGER (manager));

  g_signal_emit (manager, manager_signals[LAYOUT_CHANGED], 0);
}