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/* ATK - Accessibility Toolkit
* Copyright 2001, 2002, 2003 Sun Microsystems Inc.
*
* 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <glib/gi18n-lib.h>
#include <string.h>
#include "atk-enum-types.h"
#include "atkmarshal.h"
#include "atkprivate.h"
#include "atkvalue.h"
/**
* AtkValue:
* The ATK interface implemented by valuators and components which display or select a value from a bounded range of values.
* #AtkValue should be implemented for components which either display
* a value from a bounded range, or which allow the user to specify a
* value from a bounded range, or both. For instance, most sliders and
* range controls, as well as dials, should have #AtkObject
* representations which implement #AtkValue on the component's
* behalf. #AtKValues may be read-only, in which case attempts to
* alter the value return would fail.
* <refsect1 id="current-value-text">
* <title>On the subject of current value text</title>
* <para>
* In addition to providing the current value, implementors can
* optionally provide an end-user-consumable textual description
* associated with this value. This description should be included
* when the numeric value fails to convey the full, on-screen
* representation seen by users.
* </para>
* <example>
* <title>Password strength</title>
* A password strength meter whose value changes as the user types
* their new password. Red is used for values less than 4.0, yellow
* for values between 4.0 and 7.0, and green for values greater than
* 7.0. In this instance, value text should be provided by the
* implementor. Appropriate value text would be "weak", "acceptable,"
* and "strong" respectively.
* </example>
* A level bar whose value changes to reflect the battery charge. The
* color remains the same regardless of the charge and there is no
* on-screen text reflecting the fullness of the battery. In this
* case, because the position within the bar is the only indication
* the user has of the current charge, value text should not be
* provided by the implementor.
* <refsect2 id="implementor-notes">
* <title>Implementor Notes</title>
* Implementors should bear in mind that assistive technologies will
* likely prefer the value text provided over the numeric value when
* presenting a widget's value. As a result, strings not intended for
* end users should not be exposed in the value text, and strings
* which are exposed should be localized. In the case of widgets which
* display value text on screen, for instance through a separate label
* in close proximity to the value-displaying widget, it is still
* expected that implementors will expose the value text using the
* above API.
* #AtkValue should NOT be implemented for widgets whose displayed
* value is not reflective of a meaningful amount. For instance, a
* progress pulse indicator whose value alternates between 0.0 and 1.0
* to indicate that some process is still taking place should not
* implement #AtkValue because the current value does not reflect
* progress towards completion.
* </refsect2>
* </refsect1>
* <refsect1 id="ranges">
* <title>On the subject of ranges</title>
* In addition to providing the minimum and maximum values,
* implementors can optionally provide details about subranges
* associated with the widget. These details should be provided by the
* implementor when both of the following are communicated visually to
* the end user:
* <itemizedlist>
* <listitem>The existence of distinct ranges such as "weak",
* "acceptable", and "strong" indicated by color, bar tick marks,
* and/or on-screen text.</listitem>
* <listitem>Where the current value stands within a given subrange,
* for instance illustrating progression from very "weak" towards
* nearly "acceptable" through changes in shade and/or position on
* the bar within the "weak" subrange.</listitem>
* </itemizedlist>
* If both of the above do not apply to the widget, it should be
* sufficient to expose the numeric value, along with the value text
* if appropriate, to make the widget accessible.
* <refsect2 id="ranges-implementor-notes">
* If providing subrange details is deemed necessary, all possible
* values of the widget are expected to fall within one of the
* subranges defined by the implementor.
* <refsect1 id="localization">
* <title>On the subject of localization of end-user-consumable text
* values</title>
* Because value text and subrange descriptors are human-consumable,
* implementors are expected to provide localized strings which can be
* directly presented to end users via their assistive technology. In
* order to simplify this for implementors, implementors can use
* atk_value_type_get_localized_name() with the following
* already-localized constants for commonly-needed values can be used:
* <listitem>ATK_VALUE_VERY_WEAK</listitem>
* <listitem>ATK_VALUE_WEAK</listitem>
* <listitem>ATK_VALUE_ACCEPTABLE</listitem>
* <listitem>ATK_VALUE_STRONG</listitem>
* <listitem>ATK_VALUE_VERY_STRONG</listitem>
* <listitem>ATK_VALUE_VERY_LOW</listitem>
* <listitem>ATK_VALUE_LOW</listitem>
* <listitem>ATK_VALUE_MEDIUM</listitem>
* <listitem>ATK_VALUE_HIGH</listitem>
* <listitem>ATK_VALUE_VERY_HIGH</listitem>
* <listitem>ATK_VALUE_VERY_BAD</listitem>
* <listitem>ATK_VALUE_BAD</listitem>
* <listitem>ATK_VALUE_GOOD</listitem>
* <listitem>ATK_VALUE_VERY_GOOD</listitem>
* <listitem>ATK_VALUE_BEST</listitem>
* <listitem>ATK_VALUE_SUBSUBOPTIMAL</listitem>
* <listitem>ATK_VALUE_SUBOPTIMAL</listitem>
* <listitem>ATK_VALUE_OPTIMAL</listitem>
* Proposals for additional constants, along with their use cases,
* should be submitted to the GNOME Accessibility Team.
* <refsect1 id="changes">
* <title>On the subject of changes</title>
* Note that if there is a textual description associated with the new
* numeric value, that description should be included regardless of
* whether or not it has also changed.
static GPtrArray *value_type_names = NULL;
enum
{
VALUE_CHANGED,
LAST_SIGNAL
};
/* These are listed here for extraction by intltool */
#if 0
/* Translators: This string describes a range within value-related
* widgets such as a password-strength meter. Note that what such a
* widget presents is controlled by application developers. Thus
* assistive technologies such as screen readers are expected to
* present this string alone or as a token in a list.
N_("very weak")
N_("weak")
N_("acceptable")
N_("strong")
N_("very strong")
* widgets such as a volume slider. Note that what such a widget
* presents (e.g. temperature, volume, price) is controlled by
* application developers. Thus assistive technologies such as screen
* readers are expected to present this string alone or as a token in
* a list.
N_("very low")
N_("medium")
N_("high")
N_("very high")
* widgets such as a hard drive usage. Note that what such a widget
* presents (e.g. hard drive usage, network traffic) is controlled by
N_("very bad")
N_("bad")
N_("good")
N_("very good")
N_("best")
#endif
static void atk_value_base_init (AtkValueIface *class);
static guint atk_value_signals[LAST_SIGNAL] = { 0 };
GType
atk_value_get_type (void)
static GType type = 0;
if (!type)
GTypeInfo tinfo = {
sizeof (AtkValueIface),
(GBaseInitFunc) atk_value_base_init,
(GBaseFinalizeFunc) NULL,
type = g_type_register_static (G_TYPE_INTERFACE, "AtkValue", &tinfo, 0);
}
return type;
static void
atk_value_base_init (AtkValueIface *class)
static gboolean initialized = FALSE;
if (!initialized)
* AtkValue::value-changed:
* @atkvalue: the object on which the signal was emitted.
* @value: the new value in a numerical form.
* @text: human readable text alternative (also called
* description) of this object. NULL if not available.
* The 'value-changed' signal is emitted when the current value
* that represent the object changes. @value is the numerical
* representation of this new value. @text is the human
* readable text alternative of @value, and can be NULL if it is
* not available. Note that if there is a textual description
* associated with the new numeric value, that description
* should be included regardless of whether or not it has also
* changed.
* Example: a password meter whose value changes as the user
* types their new password. Appropiate value text would be
* "weak", "acceptable" and "strong".
* Since: 2.12
atk_value_signals[VALUE_CHANGED] =
g_signal_new ("value_changed",
ATK_TYPE_VALUE,
G_SIGNAL_RUN_LAST,
0,
(GSignalAccumulator) NULL, NULL,
atk_marshal_VOID__DOUBLE_STRING,
G_TYPE_NONE,
2, G_TYPE_DOUBLE, G_TYPE_STRING);
initialized = TRUE;
* atk_value_get_current_value:
* @obj: a GObject instance that implements AtkValueIface
* @value: (out): a #GValue representing the current accessible value
* Gets the value of this object.
* Deprecated: Since 2.12. Use atk_value_get_value_and_text()
* instead.
**/
void
atk_value_get_current_value (AtkValue *obj,
GValue *value)
AtkValueIface *iface;
g_return_if_fail (value != NULL);
g_return_if_fail (ATK_IS_VALUE (obj));
iface = ATK_VALUE_GET_IFACE (obj);
if (iface->get_current_value)
if (G_IS_VALUE (value))
g_value_unset (value);
else
memset (value, 0, sizeof (*value));
(iface->get_current_value) (obj, value);
* atk_value_get_maximum_value:
* @value: (out): a #GValue representing the maximum accessible value
* Gets the maximum value of this object.
* Deprecated: Since 2.12. Use atk_value_get_range() instead.
atk_value_get_maximum_value (AtkValue *obj,
if (iface->get_maximum_value)
(iface->get_maximum_value) (obj, value);
* atk_value_get_minimum_value:
* @value: (out): a #GValue representing the minimum accessible value
* Gets the minimum value of this object.
atk_value_get_minimum_value (AtkValue *obj,
if (iface->get_minimum_value)
(iface->get_minimum_value) (obj, value);
* atk_value_get_minimum_increment:
* @value: (out): a #GValue representing the minimum increment by which the accessible value may be changed
* Gets the minimum increment by which the value of this object may be changed. If zero,
* the minimum increment is undefined, which may mean that it is limited only by the
* floating point precision of the platform.
* Since: 1.12
* Deprecated: Since 2.12. Use atk_value_get_increment() instead.
atk_value_get_minimum_increment (AtkValue *obj,
if (iface->get_minimum_increment)
(iface->get_minimum_increment) (obj, value);
* atk_value_set_current_value:
* @value: a #GValue which is the desired new accessible value.
* Sets the value of this object.
* Returns: %TRUE if new value is successfully set, %FALSE otherwise.
* Deprecated: Since 2.12. Use atk_value_set_value() instead.
gboolean
atk_value_set_current_value (AtkValue *obj,
const GValue *value)
g_return_val_if_fail (ATK_IS_VALUE (obj), FALSE);
g_return_val_if_fail (G_IS_VALUE (value), FALSE);
if (iface->set_current_value)
return (iface->set_current_value) (obj, value);
return FALSE;
* atk_value_get_value_and_text:
* @value: (out): address of #gdouble to put the current value of @obj
* @text: (out) (allow-none): address of #gchar to put the human
* readable text alternative for @value
* Gets the current value and the human readable text alternative of
* @obj. @text is a newly created string, that must be freed by the
* caller. Can be NULL if no descriptor is available.
atk_value_get_value_and_text (AtkValue *obj,
gdouble *value,
gchar **text)
if (iface->get_value_and_text)
(iface->get_value_and_text) (obj, value, text);
*value = 0.0;
if (text)
*text = NULL;
* atk_value_get_range:
* Gets the range of this object.
* Returns: (nullable) (transfer full): a newly allocated #AtkRange
* that represents the minimum, maximum and descriptor (if available)
* of @obj. NULL if that range is not defined.
AtkRange *
atk_value_get_range (AtkValue *obj)
g_return_val_if_fail (ATK_IS_VALUE (obj), NULL);
if (iface->get_range)
return (iface->get_range) (obj);
return NULL;
* atk_value_get_increment:
* Gets the minimum increment by which the value of this object may be
* changed. If zero, the minimum increment is undefined, which may
* mean that it is limited only by the floating point precision of the
* platform.
* Return value: the minimum increment by which the value of this
* object may be changed. zero if undefined.
gdouble
atk_value_get_increment (AtkValue *obj)
g_return_val_if_fail (ATK_IS_VALUE (obj), 0);
if (iface->get_increment)
return (iface->get_increment) (obj);
return 0;
* atk_value_get_sub_ranges:
* Gets the list of subranges defined for this object. See #AtkValue
* introduction for examples of subranges and when to expose them.
* Returns: (element-type AtkRange) (transfer full): an #GSList of
* #AtkRange which each of the subranges defined for this object. Free
* the returns list with g_slist_free().
GSList *
atk_value_get_sub_ranges (AtkValue *obj)
if (iface->get_sub_ranges)
return (iface->get_sub_ranges) (obj);
* atk_value_set_value:
* @new_value: a double which is the desired new accessible value.
* This method is intended to provide a way to change the value of the
* object. In any case, it is possible that the value can't be
* modified (ie: a read-only component). If the value changes due this
* call, it is possible that the text could change, and will trigger
* an #AtkValue::value-changed signal emission.
* Note for implementors: the deprecated atk_value_set_current_value()
* method returned TRUE or FALSE depending if the value was assigned
* or not. In the practice several implementors were not able to
* decide it, and returned TRUE in any case. For that reason it is not
* required anymore to return if the value was properly assigned or
* not.
atk_value_set_value (AtkValue *obj,
const gdouble new_value)
if (iface->set_value)
(iface->set_value) (obj, new_value);
initialize_value_type_names ()
GTypeClass *enum_class;
GEnumValue *enum_value;
int i;
gchar *value_type_name = NULL;
if (value_type_names)
return;
value_type_names = g_ptr_array_new ();
enum_class = g_type_class_ref (ATK_TYPE_VALUE_TYPE);
if (!G_IS_ENUM_CLASS (enum_class))
for (i = 0; i < ATK_VALUE_LAST_DEFINED; i++)
enum_value = g_enum_get_value (G_ENUM_CLASS (enum_class), i);
value_type_name = g_strdup (enum_value->value_nick);
_compact_name (value_type_name);
g_ptr_array_add (value_type_names, value_type_name);
g_type_class_unref (enum_class);
* atk_value_type_get_name:
* @value_type: The #AtkValueType whose name is required
* Gets the description string describing the #AtkValueType @value_type.
* Returns: the string describing the #AtkValueType
const gchar *
atk_value_type_get_name (AtkValueType value_type)
g_return_val_if_fail (value_type >= 0, NULL);
if (!value_type_names)
initialize_value_type_names ();
if (value_type < value_type_names->len)
return g_ptr_array_index (value_type_names, value_type);
* atk_value_type_get_localized_name:
* @value_type: The #AtkValueType whose localized name is required
* Gets the localized description string describing the #AtkValueType @value_type.
* Returns: the localized string describing the #AtkValueType
atk_value_type_get_localized_name (AtkValueType value_type)
_gettext_initialization ();
return dgettext (GETTEXT_PACKAGE, atk_value_type_get_name (value_type));