atk/atkvalue.c

   1 /* ATK -  Accessibility Toolkit
   2  * Copyright 2001, 2002, 2003 Sun Microsystems Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #include <string.h>
  21 #include "atkvalue.h"
  22
  23 /**
  24  * SECTION:atkvalue
  25  * @Short_description: The ATK interface implemented by valuators and
  26  *  components which display or select a value from a bounded range of
  27  *  values.
  28  * @Title:AtkValue
  29  *
  30  * #AtkValue should be implemented for components which either display
  31  * a value from a bounded range, or which allow the user to specify a
  32  * value from a bounded range, or both.  For instance, most sliders
  33  * and range controls, as well as dials, should have #AtkObject
  34  * representations which implement #AtkValue on the component's
  35  * behalf.  #AtKValues may be read-only, in which case attempts to
  36  * alter the value return FALSE to indicate failure.
  37  */
  38
  39 GType
  40 atk_value_get_type (void)
  41 {
  42   static GType type = 0;
  43
  44   if (!type) {
  45     GTypeInfo tinfo =
  46     {
  47       sizeof (AtkValueIface),
  48       (GBaseInitFunc) NULL,
  49       (GBaseFinalizeFunc) NULL,
  50
  51     };
  52
  53     type = g_type_register_static (G_TYPE_INTERFACE, "AtkValue", &tinfo, 0);
  54   }
  55
  56   return type;
  57 }
  58
  59 /**
  60  * atk_value_get_current_value:
  61  * @obj: a GObject instance that implements AtkValueIface
  62  * @value: a #GValue representing the current accessible value
  63  *
  64  * Gets the value of this object.
  65  **/
  66 void
  67 atk_value_get_current_value (AtkValue *obj,
  68                              GValue   *value)
  69 {
  70   AtkValueIface *iface;
  71
  72   g_return_if_fail (value != NULL);
  73   g_return_if_fail (ATK_IS_VALUE (obj));
  74
  75   iface = ATK_VALUE_GET_IFACE (obj);
  76
  77   if (iface->get_current_value)
  78     {
  79       if (G_IS_VALUE (value))
  80         g_value_unset (value);
  81       else
  82         memset (value, 0, sizeof (*value));
  83
  84       (iface->get_current_value) (obj, value);
  85     }
  86 }
  87
  88 /**
  89  * atk_value_get_maximum_value:
  90  * @obj: a GObject instance that implements AtkValueIface
  91  * @value: a #GValue representing the maximum accessible value
  92  *
  93  * Gets the maximum value of this object.
  94  **/
  95 void
  96 atk_value_get_maximum_value  (AtkValue *obj,
  97                               GValue   *value)
  98 {
  99   AtkValueIface *iface;
 100
 101   g_return_if_fail (value != NULL);
 102   g_return_if_fail (ATK_IS_VALUE (obj));
 103
 104   iface = ATK_VALUE_GET_IFACE (obj);
 105
 106   if (iface->get_maximum_value)
 107     {
 108       if (G_IS_VALUE (value))
 109         g_value_unset (value);
 110       else
 111         memset (value, 0, sizeof (*value));
 112
 113       (iface->get_maximum_value) (obj, value);
 114     }
 115 }
 116
 117 /**
 118  * atk_value_get_minimum_value:
 119  * @obj: a GObject instance that implements AtkValueIface
 120  * @value: a #GValue representing the minimum accessible value
 121  *
 122  * Gets the minimum value of this object.
 123  **/
 124 void
 125 atk_value_get_minimum_value (AtkValue *obj,
 126                              GValue   *value)
 127 {
 128   AtkValueIface *iface;
 129
 130   g_return_if_fail (value != NULL);
 131   g_return_if_fail (ATK_IS_VALUE (obj));
 132
 133   iface = ATK_VALUE_GET_IFACE (obj);
 134
 135   if (iface->get_minimum_value)
 136     {
 137       if (G_IS_VALUE (value))
 138         g_value_unset (value);
 139       else
 140         memset (value, 0, sizeof (*value));
 141
 142       (iface->get_minimum_value) (obj, value);
 143     }
 144 }
 145
 146 /**
 147  * atk_value_get_minimum_increment:
 148  * @obj: a GObject instance that implements AtkValueIface
 149  * @value: a #GValue representing the minimum increment by which the accessible value may be changed
 150  *
 151  * Gets the minimum increment by which the value of this object may be changed.  If zero,
 152  * the minimum increment is undefined, which may mean that it is limited only by the
 153  * floating point precision of the platform.
 154  *
 155  * Since: 1.12
 156  **/
 157 void
 158 atk_value_get_minimum_increment (AtkValue *obj,
 159                              GValue   *value)
 160 {
 161   AtkValueIface *iface;
 162
 163   g_return_if_fail (value != NULL);
 164   g_return_if_fail (ATK_IS_VALUE (obj));
 165
 166   iface = ATK_VALUE_GET_IFACE (obj);
 167
 168   if (iface->get_minimum_increment)
 169     {
 170       if (G_IS_VALUE (value))
 171         g_value_unset (value);
 172       else
 173         memset (value, 0, sizeof (*value));
 174
 175       (iface->get_minimum_increment) (obj, value);
 176     }
 177 }
 178
 179 /**
 180  * atk_value_set_current_value:
 181  * @obj: a GObject instance that implements AtkValueIface
 182  * @value: a #GValue which is the desired new accessible value.
 183  *
 184  * Sets the value of this object.
 185  *
 186  * Returns: %TRUE if new value is successfully set, %FALSE otherwise.
 187  **/
 188 gboolean
 189 atk_value_set_current_value (AtkValue       *obj,
 190                              const GValue   *value)
 191 {
 192   AtkValueIface *iface;
 193
 194   g_return_val_if_fail (ATK_IS_VALUE (obj), FALSE);
 195   g_return_val_if_fail (G_IS_VALUE (value), FALSE);
 196
 197   iface = ATK_VALUE_GET_IFACE (obj);
 198
 199   if (iface->set_current_value)
 200     return (iface->set_current_value) (obj, value);
 201   else
 202     return FALSE;
 203 }