mutter/clutter/clutter-align-constraint.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Copyright (C) 2010  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-align-constraint
 * @Title: ClutterAlignConstraint
 * @Short_Description: A constraint aligning the position of an actor
 *
 * #ClutterAlignConstraint is a #ClutterConstraint that aligns the position
 * of the #ClutterActor to which it is applied to the size of another
 * #ClutterActor using an alignment factor
 *
 * #ClutterAlignConstraint is available since Clutter 1.4
 */

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

#include "clutter-align-constraint.h"

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

#define CLUTTER_ALIGN_CONSTRAINT_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), CLUTTER_TYPE_ALIGN_CONSTRAINT, ClutterAlignConstraintClass))
#define CLUTTER_IS_ALIGN_CONSTRAINT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), CLUTTER_TYPE_ALIGN_CONSTRAINT))
#define CLUTTER_ALIGN_CONSTRAINT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), CLUTTER_TYPE_ALIGN_CONSTRAINT, ClutterAlignConstraintClass))

typedef struct _ClutterAlignConstraintClass      ClutterAlignConstraintClass;

struct _ClutterAlignConstraint
{
  ClutterConstraint parent_instance;

  ClutterActor *source;
  ClutterAlignAxis align_axis;
  gfloat factor;
};

struct _ClutterAlignConstraintClass
{
  ClutterConstraintClass parent_class;
};

enum
{
  PROP_0,

  PROP_SOURCE,
  PROP_ALIGN_AXIS,
  PROP_FACTOR
};

G_DEFINE_TYPE (ClutterAlignConstraint,
               clutter_align_constraint,
               CLUTTER_TYPE_CONSTRAINT);

static void
update_actor_position (ClutterAlignConstraint *align)
{
  gfloat source_width, source_height;
  gfloat actor_width, actor_height;
  ClutterActor *actor;

  if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (align)))
    return;

  actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (align));
  if (actor == NULL)
    return;

  clutter_actor_get_size (align->source, &source_width, &source_height);
  clutter_actor_get_size (actor, &actor_width, &actor_height);

  switch (align->align_axis)
    {
    case CLUTTER_ALIGN_X_AXIS:
      clutter_actor_set_x (actor, (source_width - actor_width) * align->factor);
      break;

    case CLUTTER_ALIGN_Y_AXIS:
      clutter_actor_set_y (actor, (source_height - actor_height) * align->factor);
      break;
    }
}

static void
source_position_changed (GObject                *gobject,
                         GParamSpec             *pspec,
                         ClutterAlignConstraint *align)
{
  if (strcmp (pspec->name, "width") == 0 ||
      strcmp (pspec->name, "height") == 0)
    {
      update_actor_position (align);
    }
}

static void
source_destroyed (ClutterActor           *actor,
                  ClutterAlignConstraint *align)
{
  align->source = NULL;
}

static void
_clutter_align_constraint_set_source (ClutterAlignConstraint *align,
                                      ClutterActor           *source)
{
  ClutterActor *old_source = align->source;

  if (old_source != NULL)
    {
      g_signal_handlers_disconnect_by_func (old_source,
                                            G_CALLBACK (source_destroyed),
                                            align);
      g_signal_handlers_disconnect_by_func (old_source,
                                            G_CALLBACK (source_position_changed),
                                            align);
    }

  align->source = source;
  g_signal_connect (align->source, "notify",
                    G_CALLBACK (source_position_changed),
                    align);
  g_signal_connect (align->source, "destroy",
                    G_CALLBACK (source_destroyed),
                    align);

  update_actor_position (align);

  g_object_notify (G_OBJECT (align), "source");
}

static void
_clutter_align_constraint_set_align_axis (ClutterAlignConstraint *align,
                                          ClutterAlignAxis        axis)
{
  if (align->align_axis == axis)
    return;

  align->align_axis = axis;

  update_actor_position (align);

  g_object_notify (G_OBJECT (align), "align-axis");
}

static void
_clutter_align_constraint_set_factor (ClutterAlignConstraint *align,
                                      gfloat                  factor)
{
  align->factor = CLAMP (factor, 0.0, 1.0);

  update_actor_position (align);

  g_object_notify (G_OBJECT (align), "factor");
}

static void
clutter_align_constraint_set_property (GObject      *gobject,
                                       guint         prop_id,
                                       const GValue *value,
                                       GParamSpec   *pspec)
{
  ClutterAlignConstraint *align = CLUTTER_ALIGN_CONSTRAINT (gobject);

  switch (prop_id)
    {
    case PROP_SOURCE:
      _clutter_align_constraint_set_source (align, g_value_get_object (value));
      break;

    case PROP_ALIGN_AXIS:
      _clutter_align_constraint_set_align_axis (align, g_value_get_enum (value));
      break;

    case PROP_FACTOR:
      _clutter_align_constraint_set_factor (align, g_value_get_float (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_align_constraint_get_property (GObject    *gobject,
                                       guint       prop_id,
                                       GValue     *value,
                                       GParamSpec *pspec)
{
  ClutterAlignConstraint *align = CLUTTER_ALIGN_CONSTRAINT (gobject);

  switch (prop_id)
    {
    case PROP_SOURCE:
      g_value_set_object (value, align->source);
      break;

    case PROP_ALIGN_AXIS:
      g_value_set_enum (value, align->align_axis);
      break;

    case PROP_FACTOR:
      g_value_set_float (value, align->factor);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_align_constraint_class_init (ClutterAlignConstraintClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GParamSpec *pspec;

  gobject_class->set_property = clutter_align_constraint_set_property;
  gobject_class->get_property = clutter_align_constraint_get_property;

  /**
   * ClutterAlignConstraint:source:
   *
   * The #ClutterActor used as the source for the alignment
   *
   * Since: 1.4
   */
  pspec = g_param_spec_object ("source",
                               "Source",
                               "The source of the alignment",
                               CLUTTER_TYPE_ACTOR,
                               CLUTTER_PARAM_READWRITE |
                               G_PARAM_CONSTRUCT);
  g_object_class_install_property (gobject_class, PROP_SOURCE, pspec);

  /**
   * ClutterAlignConstraint:align-axis:
   *
   * The axis to be used to compute the alignment
   *
   * Since: 1.4
   */
  pspec = g_param_spec_enum ("align-axis",
                             "Align Axis",
                             "The axis to align the position to",
                             CLUTTER_TYPE_ALIGN_AXIS,
                             CLUTTER_ALIGN_X_AXIS,
                             CLUTTER_PARAM_READWRITE |
                             G_PARAM_CONSTRUCT);
  g_object_class_install_property (gobject_class, PROP_ALIGN_AXIS, pspec);

  /**
   * ClutterAlignConstraint:factor:
   *
   * The alignment factor, as a normalized value between 0.0 and 1.0
   *
   * The #ClutterAlignConstraint:factor depends on the
   * #ClutterAlignConstraint:align-axis value: with %CLUTTER_ALIGN_X_AXIS,
   * 0.0 means left and 1.0 means right; with %CLUTTER_ALIGN_Y_AXIS, 0.0
   * means top and 1.0 means bottom
   *
   * Since: 1.4
   */
  pspec = g_param_spec_float ("factor",
                              "Factor",
                              "The alignment factor, between 0.0 and 1.0",
                              0.0, 1.0,
                              0.0,
                              CLUTTER_PARAM_READWRITE |
                              G_PARAM_CONSTRUCT);
  g_object_class_install_property (gobject_class, PROP_FACTOR, pspec);
}

static void
clutter_align_constraint_init (ClutterAlignConstraint *self)
{
  self->source = NULL;
  self->align_axis = CLUTTER_ALIGN_X_AXIS;
  self->factor = 0.0f;
}

/**
 * clutter_align_constraint_new:
 * @source: the #ClutterActor to use as the source of the alignment
 * @axis: the axis to be used to compute the alignment
 * @factor: the alignment factor, between 0.0 and 1.0
 *
 * Creates a new constraint, aligning a #ClutterActor's position with
 * regards of the size of the actor to @source, with the given alignment
 * @factor
 *
 * Return value: the newly created #ClutterAlignConstraint
 *
 * Since: 1.4
 */
ClutterConstraint *
clutter_align_constraint_new (ClutterActor     *source,
                              ClutterAlignAxis  axis,
                              gfloat            factor)
{
  g_return_val_if_fail (CLUTTER_IS_ACTOR (source), NULL);

  return g_object_new (CLUTTER_TYPE_ALIGN_CONSTRAINT,
                       "source", source,
                       "align-axis", axis,
                       "factor", factor,
                       NULL);
}