gtk2/gtk/gtkscalebutton.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 2005 Ronald S. Bultje
 * Copyright (C) 2006, 2007 Christian Persch
 * Copyright (C) 2006 Jan Arne Petersen
 * Copyright (C) 2005-2007 Red Hat, Inc.
 *
 * Authors:
 * - Ronald S. Bultje <rbultje@ronald.bitfreak.net>
 * - Bastien Nocera <bnocera@redhat.com>
 * - Jan Arne Petersen <jpetersen@jpetersen.org>
 * - Christian Persch <chpe@svn.gnome.org>
 *
 * 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/>.
 */

/*
 * Modified by the GTK+ Team and others 2007.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */

#include "config.h"

#include "gtkscalebutton.h"

#ifndef _WIN32
#define _GNU_SOURCE
#endif
#include <math.h>
#include <stdlib.h>
#include <string.h>

#include "gtkadjustment.h"
#include "gtkbindings.h"
#include "gtkframe.h"
#include "gtkmain.h"
#include "gtkmarshalers.h"
#include "gtkorientable.h"
#include "gtkprivate.h"
#include "gtkscale.h"
#include "gtkbox.h"
#include "gtkwindow.h"
#include "gtktypebuiltins.h"
#include "gtkintl.h"
#include "a11y/gtkscalebuttonaccessible.h"

/**
 * SECTION:gtkscalebutton
 * @Short_description: A button which pops up a scale
 * @Title: GtkScaleButton
 *
 * #GtkScaleButton provides a button which pops up a scale widget.
 * This kind of widget is commonly used for volume controls in multimedia
 * applications, and GTK+ provides a #GtkVolumeButton subclass that
 * is tailored for this use case.
 */


#define SCALE_SIZE 100
#define CLICK_TIMEOUT 250

enum
{
  VALUE_CHANGED,
  POPUP,
  POPDOWN,

  LAST_SIGNAL
};

enum
{
  PROP_0,

  PROP_ORIENTATION,
  PROP_VALUE,
  PROP_SIZE,
  PROP_ADJUSTMENT,
  PROP_ICONS
};

struct _GtkScaleButtonPrivate
{
  GtkWidget *plus_button;
  GtkWidget *minus_button;
  GtkWidget *dock;
  GtkWidget *box;
  GtkWidget *scale;
  GtkWidget *image;

  GtkIconSize size;
  GtkOrientation orientation;

  guint click_id;
  gint click_timeout;
  guint timeout : 1;
  gdouble direction;
  guint32 pop_time;

  gchar **icon_list;

  GdkDevice *grab_pointer;
  GdkDevice *grab_keyboard;

  GtkAdjustment *adjustment; /* needed because it must be settable in init() */
};

static GObject* gtk_scale_button_constructor    (GType                  type,
                                                 guint                  n_construct_properties,
                                                 GObjectConstructParam *construct_params);
static void	gtk_scale_button_dispose	(GObject             *object);
static void     gtk_scale_button_finalize       (GObject             *object);
static void	gtk_scale_button_set_property	(GObject             *object,
						 guint                prop_id,
						 const GValue        *value,
						 GParamSpec          *pspec);
static void	gtk_scale_button_get_property	(GObject             *object,
						 guint                prop_id,
						 GValue              *value,
						 GParamSpec          *pspec);
static void gtk_scale_button_set_orientation_private (GtkScaleButton *button,
                                                      GtkOrientation  orientation);
static gboolean	gtk_scale_button_scroll		(GtkWidget           *widget,
						 GdkEventScroll      *event);
static void gtk_scale_button_screen_changed	(GtkWidget           *widget,
						 GdkScreen           *previous_screen);
static gboolean	gtk_scale_button_press		(GtkWidget           *widget,
						 GdkEventButton      *event);
static gboolean gtk_scale_button_key_release	(GtkWidget           *widget,
    						 GdkEventKey         *event);
static void     gtk_scale_button_popup          (GtkWidget           *widget);
static void     gtk_scale_button_popdown        (GtkWidget           *widget);
static gboolean cb_dock_button_press		(GtkWidget           *widget,
						 GdkEventButton      *event,
						 gpointer             user_data);
static gboolean cb_dock_key_release		(GtkWidget           *widget,
						 GdkEventKey         *event,
						 gpointer             user_data);
static gboolean cb_button_press			(GtkWidget           *widget,
						 GdkEventButton      *event,
						 gpointer             user_data);
static gboolean cb_button_release		(GtkWidget           *widget,
						 GdkEventButton      *event,
						 gpointer             user_data);
static void cb_dock_grab_notify			(GtkWidget           *widget,
						 gboolean             was_grabbed,
						 gpointer             user_data);
static gboolean cb_dock_grab_broken_event	(GtkWidget           *widget,
						 gboolean             was_grabbed,
						 gpointer             user_data);
static void cb_scale_grab_notify		(GtkWidget           *widget,
						 gboolean             was_grabbed,
						 gpointer             user_data);
static void gtk_scale_button_update_icon	(GtkScaleButton      *button);
static void gtk_scale_button_scale_value_changed(GtkRange            *range);

G_DEFINE_TYPE_WITH_CODE (GtkScaleButton, gtk_scale_button, GTK_TYPE_BUTTON,
                         G_ADD_PRIVATE (GtkScaleButton)
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_ORIENTABLE,
                                                NULL))

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

/*
 * ScaleButtonScale forward declarations
 */
#define GTK_TYPE_SCALE_BUTTON_SCALE    (_gtk_scale_button_scale_get_type ())
#define GTK_SCALE_BUTTON_SCALE(obj)    (G_TYPE_CHECK_INSTANCE_CAST ((obj), GTK_TYPE_SCALE_BUTTON_SCALE, GtkScaleButtonScale))
#define GTK_IS_SCALE_BUTTON_SCALE(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_SCALE_BUTTON_SCALE))
GType _gtk_scale_button_scale_get_type (void);

typedef struct _GtkScaleButtonScale
{
  GtkScale parent_instance;
  GtkScaleButton *button;
} GtkScaleButtonScale;


static void
gtk_scale_button_class_init (GtkScaleButtonClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
  GtkBindingSet *binding_set;

  gobject_class->constructor = gtk_scale_button_constructor;
  gobject_class->finalize = gtk_scale_button_finalize;
  gobject_class->dispose = gtk_scale_button_dispose;
  gobject_class->set_property = gtk_scale_button_set_property;
  gobject_class->get_property = gtk_scale_button_get_property;

  widget_class->button_press_event = gtk_scale_button_press;
  widget_class->key_release_event = gtk_scale_button_key_release;
  widget_class->scroll_event = gtk_scale_button_scroll;
  widget_class->screen_changed = gtk_scale_button_screen_changed;

  /**
   * GtkScaleButton:orientation:
   *
   * The orientation of the #GtkScaleButton's popup window.
   *
   * Note that since GTK+ 2.16, #GtkScaleButton implements the
   * #GtkOrientable interface which has its own @orientation
   * property. However we redefine the property here in order to
   * override its default horizontal orientation.
   *
   * Since: 2.14
   **/
  g_object_class_override_property (gobject_class,
				    PROP_ORIENTATION,
				    "orientation");

  g_object_class_install_property (gobject_class,
				   PROP_VALUE,
				   g_param_spec_double ("value",
							P_("Value"),
							P_("The value of the scale"),
							-G_MAXDOUBLE,
							G_MAXDOUBLE,
							0,
							GTK_PARAM_READWRITE));

  g_object_class_install_property (gobject_class,
				   PROP_SIZE,
				   g_param_spec_enum ("size",
						      P_("Icon size"),
						      P_("The icon size"),
						      GTK_TYPE_ICON_SIZE,
						      GTK_ICON_SIZE_SMALL_TOOLBAR,
						      GTK_PARAM_READWRITE));

  g_object_class_install_property (gobject_class,
                                   PROP_ADJUSTMENT,
                                   g_param_spec_object ("adjustment",
							P_("Adjustment"),
							P_("The GtkAdjustment that contains the current value of this scale button object"),
                                                        GTK_TYPE_ADJUSTMENT,
                                                        GTK_PARAM_READWRITE));

  /**
   * GtkScaleButton:icons:
   *
   * The names of the icons to be used by the scale button.
   * The first item in the array will be used in the button
   * when the current value is the lowest value, the second
   * item for the highest value. All the subsequent icons will
   * be used for all the other values, spread evenly over the
   * range of values.
   *
   * If there's only one icon name in the @icons array, it will
   * be used for all the values. If only two icon names are in
   * the @icons array, the first one will be used for the bottom
   * 50% of the scale, and the second one for the top 50%.
   *
   * It is recommended to use at least 3 icons so that the
   * #GtkScaleButton reflects the current value of the scale
   * better for the users.
   *
   * Since: 2.12
   */
  g_object_class_install_property (gobject_class,
                                   PROP_ICONS,
                                   g_param_spec_boxed ("icons",
                                                       P_("Icons"),
                                                       P_("List of icon names"),
                                                       G_TYPE_STRV,
                                                       GTK_PARAM_READWRITE));

  /**
   * GtkScaleButton::value-changed:
   * @button: the object which received the signal
   * @value: the new value
   *
   * The ::value-changed signal is emitted when the value field has
   * changed.
   *
   * Since: 2.12
   */
  signals[VALUE_CHANGED] =
    g_signal_new (I_("value-changed"),
		  G_TYPE_FROM_CLASS (klass),
		  G_SIGNAL_RUN_LAST,
		  G_STRUCT_OFFSET (GtkScaleButtonClass, value_changed),
		  NULL, NULL,
		  _gtk_marshal_VOID__DOUBLE,
		  G_TYPE_NONE, 1, G_TYPE_DOUBLE);

  /**
   * GtkScaleButton::popup:
   * @button: the object which received the signal
   *
   * The ::popup signal is a
   * <link linkend="keybinding-signals">keybinding signal</link>
   * which gets emitted to popup the scale widget.
   *
   * The default bindings for this signal are Space, Enter and Return.
   *
   * Since: 2.12
   */
  signals[POPUP] =
    g_signal_new_class_handler (I_("popup"),
                                G_OBJECT_CLASS_TYPE (klass),
                                G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                                G_CALLBACK (gtk_scale_button_popup),
                                NULL, NULL,
                                g_cclosure_marshal_VOID__VOID,
                                G_TYPE_NONE, 0);

  /**
   * GtkScaleButton::popdown:
   * @button: the object which received the signal
   *
   * The ::popdown signal is a
   * <link linkend="keybinding-signals">keybinding signal</link>
   * which gets emitted to popdown the scale widget.
   *
   * The default binding for this signal is Escape.
   *
   * Since: 2.12
   */
  signals[POPDOWN] =
    g_signal_new_class_handler (I_("popdown"),
                                G_OBJECT_CLASS_TYPE (klass),
                                G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                                G_CALLBACK (gtk_scale_button_popdown),
                                NULL, NULL,
                                g_cclosure_marshal_VOID__VOID,
                                G_TYPE_NONE, 0);

  /* Key bindings */
  binding_set = gtk_binding_set_by_class (widget_class);

  gtk_binding_entry_add_signal (binding_set, GDK_KEY_space, 0,
				"popup", 0);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_KP_Space, 0,
				"popup", 0);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_Return, 0,
				"popup", 0);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_ISO_Enter, 0,
				"popup", 0);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_KP_Enter, 0,
				"popup", 0);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_Escape, 0,
				"popdown", 0);

  /* Bind class to template
   */
  gtk_widget_class_set_template_from_resource (widget_class,
					       "/org/gtk/libgtk/gtkscalebutton.ui");

  gtk_widget_class_bind_child_internal (widget_class, GtkScaleButtonPrivate, plus_button);
  gtk_widget_class_bind_child_internal (widget_class, GtkScaleButtonPrivate, minus_button);
  gtk_widget_class_bind_child (widget_class, GtkScaleButtonPrivate, dock);
  gtk_widget_class_bind_child (widget_class, GtkScaleButtonPrivate, box);
  gtk_widget_class_bind_child (widget_class, GtkScaleButtonPrivate, scale);
  gtk_widget_class_bind_child (widget_class, GtkScaleButtonPrivate, image);
  gtk_widget_class_bind_child (widget_class, GtkScaleButtonPrivate, adjustment);

  gtk_widget_class_bind_callback (widget_class, cb_dock_button_press);
  gtk_widget_class_bind_callback (widget_class, cb_dock_key_release);
  gtk_widget_class_bind_callback (widget_class, cb_dock_grab_notify);
  gtk_widget_class_bind_callback (widget_class, cb_dock_grab_broken_event);
  gtk_widget_class_bind_callback (widget_class, cb_button_press);
  gtk_widget_class_bind_callback (widget_class, cb_button_release);
  gtk_widget_class_bind_callback (widget_class, cb_scale_grab_notify);

  gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_SCALE_BUTTON_ACCESSIBLE);
}

static void
gtk_scale_button_init (GtkScaleButton *button)
{
  GtkScaleButtonPrivate *priv;

  button->priv = priv = gtk_scale_button_get_instance_private (button);

  priv->timeout = FALSE;
  priv->click_id = 0;
  priv->click_timeout = CLICK_TIMEOUT;
  priv->orientation = GTK_ORIENTATION_VERTICAL;

  g_type_ensure (GTK_TYPE_SCALE_BUTTON_SCALE);
  gtk_widget_init_template (GTK_WIDGET (button));

  /* Assign GtkScaleButtonScale pointer back to 'button',
   * since there's no property for that we can't do it in the template
   */
  GTK_SCALE_BUTTON_SCALE (priv->scale)->button = button;

  /* Need a local reference to the adjustment */
  g_object_ref (priv->adjustment);

  gtk_widget_add_events (GTK_WIDGET (button), GDK_SCROLL_MASK);
}

static GObject *
gtk_scale_button_constructor (GType                  type,
                              guint                  n_construct_properties,
                              GObjectConstructParam *construct_params)
{
  GObject *object;
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;

  object = G_OBJECT_CLASS (gtk_scale_button_parent_class)->constructor (type, n_construct_properties, construct_params);

  button = GTK_SCALE_BUTTON (object);

  priv = button->priv;

  /* set button text and size */
  priv->size = GTK_ICON_SIZE_SMALL_TOOLBAR;
  gtk_scale_button_update_icon (button);

  return object;
}

static void
gtk_scale_button_set_property (GObject       *object,
			       guint          prop_id,
			       const GValue  *value,
			       GParamSpec    *pspec)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON (object);

  switch (prop_id)
    {
    case PROP_ORIENTATION:
      gtk_scale_button_set_orientation_private (button, g_value_get_enum (value));
      break;
    case PROP_VALUE:
      gtk_scale_button_set_value (button, g_value_get_double (value));
      break;
    case PROP_SIZE:
      {
	GtkIconSize size;
	size = g_value_get_enum (value);
	if (button->priv->size != size)
	  {
	    button->priv->size = size;
	    gtk_scale_button_update_icon (button);
	  }
      }
      break;
    case PROP_ADJUSTMENT:
      gtk_scale_button_set_adjustment (button, g_value_get_object (value));
      break;
    case PROP_ICONS:
      gtk_scale_button_set_icons (button,
                                  (const gchar **)g_value_get_boxed (value));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
gtk_scale_button_get_property (GObject     *object,
			       guint        prop_id,
			       GValue      *value,
			       GParamSpec  *pspec)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON (object);
  GtkScaleButtonPrivate *priv = button->priv;

  switch (prop_id)
    {
    case PROP_ORIENTATION:
      g_value_set_enum (value, priv->orientation);
      break;
    case PROP_VALUE:
      g_value_set_double (value, gtk_scale_button_get_value (button));
      break;
    case PROP_SIZE:
      g_value_set_enum (value, priv->size);
      break;
    case PROP_ADJUSTMENT:
      g_value_set_object (value, gtk_scale_button_get_adjustment (button));
      break;
    case PROP_ICONS:
      g_value_set_boxed (value, priv->icon_list);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
gtk_scale_button_finalize (GObject *object)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON (object);
  GtkScaleButtonPrivate *priv = button->priv;

  if (priv->icon_list)
    {
      g_strfreev (priv->icon_list);
      priv->icon_list = NULL;
    }

  if (priv->adjustment)
    {
      g_object_unref (priv->adjustment);
      priv->adjustment = NULL;
    }

  G_OBJECT_CLASS (gtk_scale_button_parent_class)->finalize (object);
}

static void
gtk_scale_button_dispose (GObject *object)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON (object);
  GtkScaleButtonPrivate *priv = button->priv;

  if (priv->dock)
    {
      gtk_widget_destroy (priv->dock);
      priv->dock = NULL;
    }

  if (priv->click_id != 0)
    {
      g_source_remove (priv->click_id);
      priv->click_id = 0;
    }

  G_OBJECT_CLASS (gtk_scale_button_parent_class)->dispose (object);
}

/**
 * gtk_scale_button_new:
 * @size: (type int): a stock icon size
 * @min: the minimum value of the scale (usually 0)
 * @max: the maximum value of the scale (usually 100)
 * @step: the stepping of value when a scroll-wheel event,
 *        or up/down arrow event occurs (usually 2)
 * @icons: (allow-none) (array zero-terminated=1): a %NULL-terminated
 *         array of icon names, or %NULL if you want to set the list
 *         later with gtk_scale_button_set_icons()
 *
 * Creates a #GtkScaleButton, with a range between @min and @max, with
 * a stepping of @step.
 *
 * Return value: a new #GtkScaleButton
 *
 * Since: 2.12
 */
GtkWidget *
gtk_scale_button_new (GtkIconSize   size,
		      gdouble       min,
		      gdouble       max,
		      gdouble       step,
		      const gchar **icons)
{
  GtkScaleButton *button;
  GtkAdjustment *adjustment;

  adjustment = gtk_adjustment_new (min, min, max, step, 10 * step, 0);

  button = g_object_new (GTK_TYPE_SCALE_BUTTON,
                         "adjustment", adjustment,
                         "icons", icons,
                         "size", size,
                         NULL);

  return GTK_WIDGET (button);
}

/**
 * gtk_scale_button_get_value:
 * @button: a #GtkScaleButton
 *
 * Gets the current value of the scale button.
 *
 * Return value: current value of the scale button
 *
 * Since: 2.12
 */
gdouble
gtk_scale_button_get_value (GtkScaleButton * button)
{
  GtkScaleButtonPrivate *priv;

  g_return_val_if_fail (GTK_IS_SCALE_BUTTON (button), 0);

  priv = button->priv;

  return gtk_adjustment_get_value (priv->adjustment);
}

/**
 * gtk_scale_button_set_value:
 * @button: a #GtkScaleButton
 * @value: new value of the scale button
 *
 * Sets the current value of the scale; if the value is outside
 * the minimum or maximum range values, it will be clamped to fit
 * inside them. The scale button emits the #GtkScaleButton::value-changed
 * signal if the value changes.
 *
 * Since: 2.12
 */
void
gtk_scale_button_set_value (GtkScaleButton *button,
			    gdouble         value)
{
  GtkScaleButtonPrivate *priv;

  g_return_if_fail (GTK_IS_SCALE_BUTTON (button));

  priv = button->priv;

  gtk_range_set_value (GTK_RANGE (priv->scale), value);
}

/**
 * gtk_scale_button_set_icons:
 * @button: a #GtkScaleButton
 * @icons: (array zero-terminated=1): a %NULL-terminated array of icon names
 *
 * Sets the icons to be used by the scale button.
 * For details, see the #GtkScaleButton:icons property.
 *
 * Since: 2.12
 */
void
gtk_scale_button_set_icons (GtkScaleButton  *button,
			    const gchar    **icons)
{
  GtkScaleButtonPrivate *priv;
  gchar **tmp;

  g_return_if_fail (GTK_IS_SCALE_BUTTON (button));

  priv = button->priv;

  tmp = priv->icon_list;
  priv->icon_list = g_strdupv ((gchar **) icons);
  g_strfreev (tmp);
  gtk_scale_button_update_icon (button);

  g_object_notify (G_OBJECT (button), "icons");
}

/**
 * gtk_scale_button_get_adjustment:
 * @button: a #GtkScaleButton
 *
 * Gets the #GtkAdjustment associated with the #GtkScaleButton's scale.
 * See gtk_range_get_adjustment() for details.
 *
 * Returns: (transfer none): the adjustment associated with the scale
 *
 * Since: 2.12
 */
GtkAdjustment*
gtk_scale_button_get_adjustment	(GtkScaleButton *button)
{
  g_return_val_if_fail (GTK_IS_SCALE_BUTTON (button), NULL);

  return button->priv->adjustment;
}

/**
 * gtk_scale_button_set_adjustment:
 * @button: a #GtkScaleButton
 * @adjustment: a #GtkAdjustment
 *
 * Sets the #GtkAdjustment to be used as a model
 * for the #GtkScaleButton's scale.
 * See gtk_range_set_adjustment() for details.
 *
 * Since: 2.12
 */
void
gtk_scale_button_set_adjustment	(GtkScaleButton *button,
				 GtkAdjustment  *adjustment)
{
  g_return_if_fail (GTK_IS_SCALE_BUTTON (button));

  if (!adjustment)
    adjustment = gtk_adjustment_new (0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
  else
    g_return_if_fail (GTK_IS_ADJUSTMENT (adjustment));

  if (button->priv->adjustment != adjustment)
    {
      if (button->priv->adjustment)
        g_object_unref (button->priv->adjustment);
      button->priv->adjustment = g_object_ref_sink (adjustment);

      if (button->priv->scale)
        gtk_range_set_adjustment (GTK_RANGE (button->priv->scale), adjustment);

      g_object_notify (G_OBJECT (button), "adjustment");
    }
}

/**
 * gtk_scale_button_get_plus_button:
 * @button: a #GtkScaleButton
 *
 * Retrieves the plus button of the #GtkScaleButton.
 *
 * Returns: (transfer none): the plus button of the #GtkScaleButton
 *
 * Since: 2.14
 */
GtkWidget *
gtk_scale_button_get_plus_button (GtkScaleButton *button)
{
  g_return_val_if_fail (GTK_IS_SCALE_BUTTON (button), NULL);

  return button->priv->plus_button;
}

/**
 * gtk_scale_button_get_minus_button:
 * @button: a #GtkScaleButton
 *
 * Retrieves the minus button of the #GtkScaleButton.
 *
 * Returns: (transfer none): the minus button of the #GtkScaleButton
 *
 * Since: 2.14
 */
GtkWidget *
gtk_scale_button_get_minus_button (GtkScaleButton *button)
{
  g_return_val_if_fail (GTK_IS_SCALE_BUTTON (button), NULL);

  return button->priv->minus_button;
}

/**
 * gtk_scale_button_get_popup:
 * @button: a #GtkScaleButton
 *
 * Retrieves the popup of the #GtkScaleButton.
 *
 * Returns: (transfer none): the popup of the #GtkScaleButton
 *
 * Since: 2.14
 */
GtkWidget *
gtk_scale_button_get_popup (GtkScaleButton *button)
{
  g_return_val_if_fail (GTK_IS_SCALE_BUTTON (button), NULL);

  return button->priv->dock;
}

static void
gtk_scale_button_set_orientation_private (GtkScaleButton *button,
                                          GtkOrientation  orientation)
{
  GtkScaleButtonPrivate *priv = button->priv;

  if (orientation != priv->orientation)
    {
      priv->orientation = orientation;

      gtk_orientable_set_orientation (GTK_ORIENTABLE (priv->box),
                                      orientation);
      gtk_container_child_set (GTK_CONTAINER (priv->box),
                               priv->plus_button,
                               "pack-type",
                               orientation == GTK_ORIENTATION_VERTICAL ?
                               GTK_PACK_START : GTK_PACK_END,
                               NULL);
      gtk_container_child_set (GTK_CONTAINER (priv->box),
                               priv->minus_button,
                               "pack-type",
                               orientation == GTK_ORIENTATION_VERTICAL ?
                               GTK_PACK_END : GTK_PACK_START,
                               NULL);

      gtk_orientable_set_orientation (GTK_ORIENTABLE (priv->scale),
                                      orientation);

      if (orientation == GTK_ORIENTATION_VERTICAL)
        {
          gtk_widget_set_size_request (GTK_WIDGET (priv->scale),
                                       -1, SCALE_SIZE);
          gtk_range_set_inverted (GTK_RANGE (priv->scale), TRUE);
        }
      else
        {
          gtk_widget_set_size_request (GTK_WIDGET (priv->scale),
                                       SCALE_SIZE, -1);
          gtk_range_set_inverted (GTK_RANGE (priv->scale), FALSE);
        }

      /* FIXME: without this, the popup window appears as a square
       * after changing the orientation
       */
      gtk_window_resize (GTK_WINDOW (priv->dock), 1, 1);

      g_object_notify (G_OBJECT (button), "orientation");
    }
}

/*
 * button callbacks.
 */

static gboolean
gtk_scale_button_scroll (GtkWidget      *widget,
			 GdkEventScroll *event)
{
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;
  GtkAdjustment *adjustment;
  gdouble d;

  button = GTK_SCALE_BUTTON (widget);
  priv = button->priv;
  adjustment = priv->adjustment;

  if (event->type != GDK_SCROLL)
    return FALSE;

  d = gtk_scale_button_get_value (button);
  if (event->direction == GDK_SCROLL_UP)
    {
      d += gtk_adjustment_get_step_increment (adjustment);
      if (d > gtk_adjustment_get_upper (adjustment))
	d = gtk_adjustment_get_upper (adjustment);
    }
  else
    {
      d -= gtk_adjustment_get_step_increment (adjustment);
      if (d < gtk_adjustment_get_lower (adjustment))
	d = gtk_adjustment_get_lower (adjustment);
    }
  gtk_scale_button_set_value (button, d);

  return TRUE;
}

static void
gtk_scale_button_screen_changed (GtkWidget *widget,
				 GdkScreen *previous_screen)
{
  GtkScaleButton *button = (GtkScaleButton *) widget;
  GtkScaleButtonPrivate *priv;
  GdkScreen *screen;
  GValue value = G_VALUE_INIT;

  if (gtk_widget_has_screen (widget) == FALSE)
    return;

  priv = button->priv;

  screen = gtk_widget_get_screen (widget);
  g_value_init (&value, G_TYPE_INT);
  if (gdk_screen_get_setting (screen,
			      "gtk-double-click-time",
			      &value) == FALSE)
    {
      priv->click_timeout = CLICK_TIMEOUT;
      return;
    }

  priv->click_timeout = g_value_get_int (&value);
}

static gboolean
gtk_scale_popup (GtkWidget *widget,
		 GdkEvent  *event,
		 guint32    time)
{
  GtkAllocation allocation, dock_allocation, scale_allocation;
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;
  GtkAdjustment *adjustment;
  gint x, y, m, dx, dy, sx, sy, startoff;
  gint min_slider_size;
  gdouble v;
  GdkScreen *screen;
  gboolean is_moved;
  GdkDevice *device, *keyboard, *pointer;

  is_moved = FALSE;
  button = GTK_SCALE_BUTTON (widget);
  priv = button->priv;
  adjustment = priv->adjustment;

  screen = gtk_widget_get_screen (widget);
  gtk_widget_get_allocation (widget, &allocation);

  /* position roughly */
  gtk_window_set_screen (GTK_WINDOW (priv->dock), screen);

  gdk_window_get_origin (gtk_widget_get_window (widget),
                         &x, &y);
  x += allocation.x;
  y += allocation.y;

  if (priv->orientation == GTK_ORIENTATION_VERTICAL)
    gtk_window_move (GTK_WINDOW (priv->dock), x, y - (SCALE_SIZE / 2));
  else
    gtk_window_move (GTK_WINDOW (priv->dock), x - (SCALE_SIZE / 2), y);

  gtk_widget_show_all (priv->dock);

  gdk_window_get_origin (gtk_widget_get_window (priv->dock),
                         &dx, &dy);
  gtk_widget_get_allocation (priv->dock, &dock_allocation);
  dx += dock_allocation.x;
  dy += dock_allocation.y;


  gdk_window_get_origin (gtk_widget_get_window (priv->scale),
                         &sx, &sy);
  gtk_widget_get_allocation (priv->scale, &scale_allocation);
  sx += scale_allocation.x;
  sy += scale_allocation.y;

  priv->timeout = TRUE;

  /* position (needs widget to be shown already) */
  v = gtk_scale_button_get_value (button) / (gtk_adjustment_get_upper (adjustment) - gtk_adjustment_get_lower (adjustment));
  min_slider_size = gtk_range_get_min_slider_size (GTK_RANGE (priv->scale));

  if (priv->orientation == GTK_ORIENTATION_VERTICAL)
    {
      startoff = sy - dy;

      x += (allocation.width - dock_allocation.width) / 2;
      y -= startoff;
      y -= min_slider_size / 2;
      m = scale_allocation.height - min_slider_size;
      y -= m * (1.0 - v);
    }
  else
    {
      startoff = sx - dx;

      x -= startoff;
      y += (allocation.height - dock_allocation.height) / 2;
      x -= min_slider_size / 2;
      m = scale_allocation.width - min_slider_size;
      x -= m * v;
    }

  /* Make sure the dock stays inside the monitor */
  if (event->type == GDK_BUTTON_PRESS)
    {
      GtkAllocation d_allocation;
      int monitor;
      GdkEventButton *button_event = (GdkEventButton *) event;
      GdkRectangle rect;
      GtkWidget *d;

      d = GTK_WIDGET (priv->dock);
      monitor = gdk_screen_get_monitor_at_point (screen,
						 button_event->x_root,
						 button_event->y_root);
      gdk_screen_get_monitor_workarea (screen, monitor, &rect);

      if (priv->orientation == GTK_ORIENTATION_VERTICAL)
        y += button_event->y;
      else
        x += button_event->x;

      /* Move the dock, but set is_moved so we
       * don't forward the first click later on,
       * as it could make the scale go to the bottom */
      gtk_widget_get_allocation (d, &d_allocation);
      if (y < rect.y)
        {
          y = rect.y;
          is_moved = TRUE;
        }
      else if (y + d_allocation.height > rect.height + rect.y)
        {
          y = rect.y + rect.height - d_allocation.height;
          is_moved = TRUE;
        }

      if (x < rect.x)
        {
          x = rect.x;
          is_moved = TRUE;
        }
      else if (x + d_allocation.width > rect.width + rect.x)
        {
          x = rect.x + rect.width - d_allocation.width;
          is_moved = TRUE;
        }
    }

  gtk_window_move (GTK_WINDOW (priv->dock), x, y);

  if (event->type == GDK_BUTTON_PRESS)
    GTK_WIDGET_CLASS (gtk_scale_button_parent_class)->button_press_event (widget, (GdkEventButton *) event);

  device = gdk_event_get_device (event);

  if (gdk_device_get_source (device) == GDK_SOURCE_KEYBOARD)
    {
      keyboard = device;
      pointer = gdk_device_get_associated_device (device);
    }
  else
    {
      pointer = device;
      keyboard = gdk_device_get_associated_device (device);
    }

  /* grab focus */
  gtk_device_grab_add (priv->dock, pointer, TRUE);

  if (gdk_device_grab (pointer, gtk_widget_get_window (priv->dock),
                       GDK_OWNERSHIP_WINDOW, TRUE,
                       GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
                       GDK_POINTER_MOTION_MASK, NULL, time) != GDK_GRAB_SUCCESS)
    {
      gtk_device_grab_remove (priv->dock, pointer);
      gtk_widget_hide (priv->dock);
      return FALSE;
    }

  if (gdk_device_grab (keyboard, gtk_widget_get_window (priv->dock),
                       GDK_OWNERSHIP_WINDOW, TRUE,
                       GDK_KEY_PRESS_MASK | GDK_KEY_RELEASE_MASK,
                       NULL, time) != GDK_GRAB_SUCCESS)
    {
      gdk_device_ungrab (pointer, time);
      gtk_device_grab_remove (priv->dock, pointer);
      gtk_widget_hide (priv->dock);
      return FALSE;
    }

  gtk_widget_grab_focus (priv->dock);
  priv->grab_keyboard = keyboard;
  priv->grab_pointer = pointer;

  if (event->type == GDK_BUTTON_PRESS && !is_moved)
    {
      GdkEventButton *e;
      GdkEventButton *button_event = (GdkEventButton *) event;

      /* forward event to the slider */
      e = (GdkEventButton *) gdk_event_copy ((GdkEvent *) event);
      e->window = gtk_widget_get_window (priv->scale);

      /* position: the X position isn't relevant, halfway will work just fine.
       * The vertical position should be *exactly* in the middle of the slider
       * of the scale; if we don't do that correctly, it'll move from its current
       * position, which means a position change on-click, which is bad.
       */
      gtk_widget_get_allocation (priv->scale, &scale_allocation);
      if (priv->orientation == GTK_ORIENTATION_VERTICAL)
        {
          e->x = scale_allocation.width / 2;
          m = scale_allocation.height - min_slider_size;
          e->y = ((1.0 - v) * m) + min_slider_size / 2;
        }
      else
        {
          e->y = scale_allocation.height / 2;
          m = scale_allocation.width - min_slider_size;
          e->x = (v * m) + min_slider_size / 2;
        }

      gtk_widget_event (priv->scale, (GdkEvent *) e);
      e->window = button_event->window;
      gdk_event_free ((GdkEvent *) e);
    }

  gtk_widget_grab_focus (priv->scale);

  priv->pop_time = time;

  return TRUE;
}

static gboolean
gtk_scale_button_press (GtkWidget      *widget,
			GdkEventButton *event)
{
  return gtk_scale_popup (widget, (GdkEvent *) event, event->time);
}

static void
gtk_scale_button_popup (GtkWidget *widget)
{
  GdkEvent *ev;

  /* This is a callback for a keybinding signal,
   * current event should  be the key event that
   * triggered it.
   */
  ev = gtk_get_current_event ();

  if (ev->type != GDK_KEY_PRESS &&
      ev->type != GDK_KEY_RELEASE)
    {
      gdk_event_free (ev);
      ev = gdk_event_new (GDK_KEY_RELEASE);
      ev->key.time = GDK_CURRENT_TIME;
    }

  gtk_scale_popup (widget, ev, ev->key.time);
  gdk_event_free (ev);
}

static gboolean
gtk_scale_button_key_release (GtkWidget   *widget,
			      GdkEventKey *event)
{
  return gtk_bindings_activate_event (G_OBJECT (widget), event);
}

/* This is called when the grab is broken for
 * either the dock, or the scale itself */
static void
gtk_scale_button_grab_notify (GtkScaleButton *button,
                              gboolean        was_grabbed)
{
  GtkScaleButtonPrivate *priv;
  GtkWidget *toplevel, *grab_widget;
  GtkWindowGroup *group;

  priv = button->priv;

  if (!priv->grab_pointer ||
      !gtk_widget_device_is_shadowed (GTK_WIDGET (button), priv->grab_pointer))
    return;

  toplevel = gtk_widget_get_toplevel (GTK_WIDGET (button));

  if (GTK_IS_WINDOW (toplevel))
    group = gtk_window_get_group (GTK_WINDOW (toplevel));
  else
    group = gtk_window_get_group (NULL);

  grab_widget = gtk_window_group_get_current_device_grab (group, priv->grab_pointer);

  if (grab_widget &&
      gtk_widget_is_ancestor (grab_widget, priv->dock))
    return;

  gdk_device_ungrab (priv->grab_keyboard, GDK_CURRENT_TIME);
  gdk_device_ungrab (priv->grab_pointer, GDK_CURRENT_TIME);
  gtk_device_grab_remove (priv->dock, priv->grab_pointer);

  priv->grab_keyboard = NULL;
  priv->grab_pointer = NULL;

  /* hide again */
  gtk_widget_hide (priv->dock);
  priv->timeout = FALSE;
}

/*
 * +/- button callbacks.
 */

static gboolean
cb_button_timeout (gpointer user_data)
{
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;
  GtkAdjustment *adjustment;
  gdouble val;
  gboolean res = TRUE;

  button = GTK_SCALE_BUTTON (user_data);
  priv = button->priv;

  if (priv->click_id == 0)
    return FALSE;

  adjustment = priv->adjustment;

  val = gtk_scale_button_get_value (button);
  val += priv->direction;
  if (val <= gtk_adjustment_get_lower (adjustment))
    {
      res = FALSE;
      val = gtk_adjustment_get_lower (adjustment);
    }
  else if (val > gtk_adjustment_get_upper (adjustment))
    {
      res = FALSE;
      val = gtk_adjustment_get_upper (adjustment);
    }
  gtk_scale_button_set_value (button, val);

  if (!res)
    {
      g_source_remove (priv->click_id);
      priv->click_id = 0;
    }

  return res;
}

static gboolean
cb_button_press (GtkWidget      *widget,
		 GdkEventButton *event,
		 gpointer        user_data)
{
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;
  GtkAdjustment *adjustment;

  button = GTK_SCALE_BUTTON (user_data);
  priv = button->priv;
  adjustment = priv->adjustment;

  if (priv->click_id != 0)
    g_source_remove (priv->click_id);

  if (widget == priv->plus_button)
    priv->direction = fabs (gtk_adjustment_get_page_increment (adjustment));
  else
    priv->direction = - fabs (gtk_adjustment_get_page_increment (adjustment));

  priv->click_id = gdk_threads_add_timeout (priv->click_timeout,
                                            cb_button_timeout,
                                            button);
  cb_button_timeout (button);

  return TRUE;
}

static gboolean
cb_button_release (GtkWidget      *widget,
		   GdkEventButton *event,
		   gpointer        user_data)
{
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;

  button = GTK_SCALE_BUTTON (user_data);
  priv = button->priv;

  if (priv->click_id != 0)
    {
      g_source_remove (priv->click_id);
      priv->click_id = 0;
    }

  return TRUE;
}

static void
cb_dock_grab_notify (GtkWidget *widget,
		     gboolean   was_grabbed,
		     gpointer   user_data)
{
  GtkScaleButton *button = (GtkScaleButton *) user_data;

  gtk_scale_button_grab_notify (button, was_grabbed);
}

static gboolean
cb_dock_grab_broken_event (GtkWidget *widget,
                           gboolean   was_grabbed,
			   gpointer   user_data)
{
  GtkScaleButton *button = (GtkScaleButton *) user_data;

  gtk_scale_button_grab_notify (button, FALSE);

  return FALSE;
}

/* Scale callbacks  */

static void
gtk_scale_button_release_grab (GtkScaleButton *button,
                               GdkEventButton *event)
{
  GdkEventButton *e;
  GtkScaleButtonPrivate *priv;

  priv = button->priv;

  /* ungrab focus */
  gdk_device_ungrab (priv->grab_keyboard, event->time);
  gdk_device_ungrab (priv->grab_pointer, event->time);
  gtk_device_grab_remove (priv->dock, priv->grab_pointer);

  priv->grab_keyboard = NULL;
  priv->grab_pointer = NULL;

  /* hide again */
  gtk_widget_hide (priv->dock);
  priv->timeout = FALSE;

  e = (GdkEventButton *) gdk_event_copy ((GdkEvent *) event);
  e->window = gtk_widget_get_window (GTK_WIDGET (button));
  e->type = GDK_BUTTON_RELEASE;
  gtk_widget_event (GTK_WIDGET (button), (GdkEvent *) e);
  e->window = event->window;
  gdk_event_free ((GdkEvent *) e);
}

static gboolean
cb_dock_button_press (GtkWidget      *widget,
		      GdkEventButton *event,
		      gpointer        user_data)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON (user_data);

  if (event->type == GDK_BUTTON_PRESS)
    {
      gtk_scale_button_release_grab (button, event);
      return TRUE;
    }

  return FALSE;
}

static void
gtk_scale_button_popdown (GtkWidget *widget)
{
  GtkScaleButton *button;
  GtkScaleButtonPrivate *priv;

  button = GTK_SCALE_BUTTON (widget);
  priv = button->priv;

  /* ungrab focus */
  gdk_device_ungrab (priv->grab_keyboard, GDK_CURRENT_TIME);
  gdk_device_ungrab (priv->grab_pointer, GDK_CURRENT_TIME);
  gtk_device_grab_remove (priv->dock, priv->grab_pointer);

  priv->grab_keyboard = NULL;
  priv->grab_pointer = NULL;

  /* hide again */
  gtk_widget_hide (priv->dock);
  priv->timeout = FALSE;
}

static gboolean
cb_dock_key_release (GtkWidget   *widget,
		     GdkEventKey *event,
		     gpointer     user_data)
{
  if (event->keyval == GDK_KEY_Escape)
    {
      gtk_scale_button_popdown (GTK_WIDGET (user_data));
      return TRUE;
    }

  if (!gtk_bindings_activate_event (G_OBJECT (widget), event))
    {
      /* The popup hasn't managed the event, pass onto the button */
      gtk_bindings_activate_event (G_OBJECT (user_data), event);
    }

  return TRUE;
}

static void
cb_scale_grab_notify (GtkWidget *widget,
		      gboolean   was_grabbed,
		      gpointer   user_data)
{
  GtkScaleButton *button = (GtkScaleButton *) user_data;

  gtk_scale_button_grab_notify (button, was_grabbed);
}

/*
 * Scale stuff.
 */
typedef struct _GtkScaleButtonScaleClass
{
  GtkScaleClass parent_class;
} GtkScaleButtonScaleClass;

static gboolean	gtk_scale_button_scale_press   (GtkWidget      *widget,
                                                GdkEventButton *event);
static gboolean gtk_scale_button_scale_release (GtkWidget      *widget,
                                                GdkEventButton *event);

G_DEFINE_TYPE (GtkScaleButtonScale, _gtk_scale_button_scale, GTK_TYPE_SCALE)

static void
_gtk_scale_button_scale_class_init (GtkScaleButtonScaleClass *klass)
{
  GtkWidgetClass *gtkwidget_class = GTK_WIDGET_CLASS (klass);
  GtkRangeClass *gtkrange_class = GTK_RANGE_CLASS (klass);

  gtkwidget_class->button_press_event = gtk_scale_button_scale_press;
  gtkwidget_class->button_release_event = gtk_scale_button_scale_release;
  gtkrange_class->value_changed = gtk_scale_button_scale_value_changed;
}

static void
_gtk_scale_button_scale_init (GtkScaleButtonScale *scale)
{
}

static gboolean
gtk_scale_button_scale_press (GtkWidget      *widget,
			      GdkEventButton *event)
{
  GtkScaleButtonPrivate *priv;

  /* Avoid a crash when using a GtkScaleButtonScale without a GtkScaleButton,
   * this can happen while editing gtkscalebutton.ui in Glade
   */
  if (!GTK_SCALE_BUTTON_SCALE (widget)->button)
    return GTK_WIDGET_CLASS (_gtk_scale_button_scale_parent_class)->button_release_event (widget, event);

  priv = GTK_SCALE_BUTTON_SCALE (widget)->button->priv;

  /* the scale will grab input; if we have input grabbed, all goes
   * horribly wrong, so let's not do that.
   */
  gtk_device_grab_remove (priv->dock, event->device);

  return GTK_WIDGET_CLASS (_gtk_scale_button_scale_parent_class)->button_press_event (widget, event);
}

static gboolean
gtk_scale_button_scale_release (GtkWidget      *widget,
				GdkEventButton *event)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON_SCALE (widget)->button;
  gboolean res;

  /* Avoid a crash when using a GtkScaleButtonScale without a GtkScaleButton,
   * this can happen while editing gtkscalebutton.ui in Glade
   */
  if (!button)
    return GTK_WIDGET_CLASS (_gtk_scale_button_scale_parent_class)->button_release_event (widget, event);

  if (button->priv->timeout)
    {
      /* if we did a quick click, leave the window open; else, hide it */
      if (event->time > button->priv->pop_time + button->priv->click_timeout)
        {

	  gtk_scale_button_release_grab (button, event);
	  GTK_WIDGET_CLASS (_gtk_scale_button_scale_parent_class)->button_release_event (widget, event);

	  return TRUE;
	}

      button->priv->timeout = FALSE;
    }

  res = GTK_WIDGET_CLASS (_gtk_scale_button_scale_parent_class)->button_release_event (widget, event);

  /* the scale will release input; right after that, we *have to* grab
   * it back so we can catch out-of-scale clicks and hide the popup,
   * so I basically want a g_signal_connect_after_always(), but I can't
   * find that, so we do this complex 'first-call-parent-then-do-actual-
   * action' thingy...
   */
  gtk_device_grab_add (button->priv->dock, event->device, TRUE);

  return res;
}

static void
gtk_scale_button_update_icon (GtkScaleButton *button)
{
  GtkScaleButtonPrivate *priv;
  GtkAdjustment *adjustment;
  gdouble value;
  const gchar *name;
  guint num_icons;

  priv = button->priv;

  if (!priv->icon_list || priv->icon_list[0] == '\0')
    {
      gtk_image_set_from_icon_name (GTK_IMAGE (priv->image),
                                    "image-missing",
                                    priv->size);
      return;
    }

  num_icons = g_strv_length (priv->icon_list);

  /* The 1-icon special case */
  if (num_icons == 1)
    {
      gtk_image_set_from_icon_name (GTK_IMAGE (priv->image),
                                    priv->icon_list[0],
                                    priv->size);
      return;
    }

  adjustment = priv->adjustment;
  value = gtk_scale_button_get_value (button);

  /* The 2-icons special case */
  if (num_icons == 2)
    {
      gdouble limit;

      limit = (gtk_adjustment_get_upper (adjustment) - gtk_adjustment_get_lower (adjustment)) / 2 + gtk_adjustment_get_lower (adjustment);
      if (value < limit)
        name = priv->icon_list[0];
      else
        name = priv->icon_list[1];

      gtk_image_set_from_icon_name (GTK_IMAGE (priv->image),
                                    name,
                                    priv->size);
      return;
    }

  /* With 3 or more icons */
  if (value == gtk_adjustment_get_lower (adjustment))
    {
      name = priv->icon_list[0];
    }
  else if (value == gtk_adjustment_get_upper (adjustment))
    {
      name = priv->icon_list[1];
    }
  else
    {
      gdouble step;
      guint i;

      step = (gtk_adjustment_get_upper (adjustment) - gtk_adjustment_get_lower (adjustment)) / (num_icons - 2);
      i = (guint) ((value - gtk_adjustment_get_lower (adjustment)) / step) + 2;
      g_assert (i < num_icons);
      name = priv->icon_list[i];
    }

  gtk_image_set_from_icon_name (GTK_IMAGE (priv->image),
                                name,
                                priv->size);
}

static void
gtk_scale_button_scale_value_changed (GtkRange *range)
{
  GtkScaleButton *button = GTK_SCALE_BUTTON_SCALE (range)->button;
  gdouble value;

  /* Avoid a crash when using a GtkScaleButtonScale without a GtkScaleButton,
   * this can happen while editing gtkscalebutton.ui in Glade
   */
  if (!button)
    return;

  value = gtk_range_get_value (range);

  gtk_scale_button_update_icon (button);

  g_signal_emit (button, signals[VALUE_CHANGED], 0, value);
  g_object_notify (G_OBJECT (button), "value");
}