Description
The GSettings class provides a convenient API for storing and retrieving
application settings.
Reads and writes can be considered to be non-blocking. Reading
settings with GSettings is typically extremely fast: on
approximately the same order of magnitude (but slower than) a
GHashTable lookup. Writing settings is also extremely fast in terms
of time to return to your application, but can be extremely expensive
for other threads and other processes. Many settings backends
(including dconf) have lazy initialisation which means in the common
case of the user using their computer without modifying any settings
a lot of work can be avoided. For dconf, the D-Bus service doesn't
even need to be started in this case. For this reason, you should
only ever modify GSettings keys in response to explicit user action.
Particular care should be paid to ensure that modifications are not
made during startup -- for example, when setting the initial value
of preferences widgets. The built-in g_settings_bind() functionality
is careful not to write settings in response to notify signals as a
result of modifications that it makes to widgets.
When creating a GSettings instance, you have to specify a schema
that describes the keys in your settings and their types and default
values, as well as some other information.
Normally, a schema has a fixed path that determines where the settings
are stored in the conceptual global tree of settings. However, schemas
can also be 'relocatable', i.e. not equipped with
a fixed path. This is
useful e.g. when the schema describes an 'account', and you want to be
able to store a arbitrary number of accounts.
Paths must start with and end with a forward slash character ('/')
and must not contain two sequential slash characters. Paths should
be chosen based on a domain name associated with the program or
library to which the settings belong. Examples of paths are
"/org/gtk/settings/file-chooser/" and "/ca/desrt/dconf-editor/".
Paths should not start with "/apps/", "/desktop/" or "/system/" as
they often did in GConf.
Unlike other configuration systems (like GConf), GSettings does not
restrict keys to basic types like strings and numbers. GSettings stores
values as GVariant, and allows any GVariantType for keys. Key names
are restricted to lowercase characters, numbers and '-'. Furthermore,
the names must begin with a lowercase character, must not end
with a '-', and must not contain consecutive dashes.
Similar to GConf, the default values in GSettings schemas can be
localized, but the localized values are stored in gettext catalogs
and looked up with the domain that is specified in the
gettext-domain attribute of the <schemalist> or <schema>
elements and the category that is specified in the l10n attribute of
the <default> element. The string which is translated includes all text in
the <default> element, including any surrounding quotation marks.
The l10n attribute must be set to messages or time, and sets the
locale category for
translation.
The messages category should be used by default; use time for
translatable date or time formats. A translation comment can be added as an
XML comment immediately above the <default> element — it is recommended to
add these comments to aid translators understand the meaning and
implications of the default value. An optional translation context
attribute can be set on the <default> element to disambiguate multiple
defaults which use the same string.
For example:
Translations of default values must remain syntactically valid serialized
GVariants (e.g. retaining any surrounding quotation marks) or runtime
errors will occur.
GSettings uses schemas in a compact binary form that is created
by the glib-compile-schemas
utility. The input is a schema description in an XML format.
A DTD for the gschema XML format can be found here:
gschema.dtd
The glib-compile-schemas tool expects schema
files to have the extension .gschema.xml.
At runtime, schemas are identified by their id (as specified in the
id attribute of the <schema> element). The convention for schema
ids is to use a dotted name, similar in style to a D-Bus bus name,
e.g. "org.gnome.SessionManager". In particular, if the settings are
for a specific service that owns a D-Bus bus name, the D-Bus bus name
and schema id should match. For schemas which deal with settings not
associated with one named application, the id should not use
StudlyCaps, e.g. "org.gnome.font-rendering".
In addition to GVariant types, keys can have types that have
enumerated types. These can be described by a <choice>,
<enum> or <flags> element, as seen in the
example. The underlying type of such a key
is string, but you can use g_settings_get_enum(), g_settings_set_enum(),
g_settings_get_flags(), g_settings_set_flags() access the numeric values
corresponding to the string value of enum and flags keys.
An example for default value:
An example for ranges, choices and enumerated types:
Vendor overrides
Default values are defined in the schemas that get installed by
an application. Sometimes, it is necessary for a vendor or distributor
to adjust these defaults. Since patching the XML source for the schema
is inconvenient and error-prone,
glib-compile-schemas reads so-called vendor
override' files. These are keyfiles in the same directory as the XML
schema sources which can override default values. The schema id serves
as the group name in the key file, and the values are expected in
serialized GVariant form, as in the following example:
glib-compile-schemas expects schema files to have the extension
.gschema.override.
Binding
A very convenient feature of GSettings lets you bind GObject properties
directly to settings, using g_settings_bind(). Once a GObject property
has been bound to a setting, changes on either side are automatically
propagated to the other side. GSettings handles details like mapping
between GObject and GVariant types, and preventing infinite cycles.
This makes it very easy to hook up a preferences dialog to the
underlying settings. To make this even more convenient, GSettings
looks for a boolean property with the name "sensitivity" and
automatically binds it to the writability of the bound setting.
If this 'magic' gets in the way, it can be suppressed with the
G_SETTINGS_BIND_NO_SENSITIVITY flag.
Relocatable schemas
A relocatable schema is one with no path attribute specified on its
<schema> element. By using g_settings_new_with_path(), a GSettings object
can be instantiated for a relocatable schema, assigning a path to the
instance. Paths passed to g_settings_new_with_path() will typically be
constructed dynamically from a constant prefix plus some form of instance
identifier; but they must still be valid GSettings paths. Paths could also
be constant and used with a globally installed schema originating from a
dependency library.
For example, a relocatable schema could be used to store geometry information
for different windows in an application. If the schema ID was
org.foo.MyApp.Window, it could be instantiated for paths
/org/foo/MyApp/main/, /org/foo/MyApp/document-1/,
/org/foo/MyApp/document-2/, etc. If any of the paths are well-known
they can be specified as <child> elements in the parent schema, e.g.:
Build system integration
GSettings comes with autotools integration to simplify compiling and
installing schemas. To add GSettings support to an application, add the
following to your configure.ac:
In the appropriate Makefile.am, use the following snippet to compile and
install the named schema:
No changes are needed to the build system to mark a schema XML file for
translation. Assuming it sets the gettext-domain attribute, a schema may
be marked for translation by adding it to POTFILES.in, assuming gettext
0.19 is in use (the preferred method for translation):
Alternatively, if intltool 0.50.1 is in use:
GSettings will use gettext to look up translations for the <summary> and
<description> elements, and also any <default> elements which have a l10n
attribute set. Translations must not be included in the .gschema.xml file
by the build system, for example by using intltool XML rules with a
.gschema.xml.in template.
If an enumerated type defined in a C header file is to be used in a GSettings
schema, it can either be defined manually using an <enum> element in the
schema XML, or it can be extracted automatically from the C header. This
approach is preferred, as it ensures the two representations are always
synchronised. To do so, add the following to the relevant Makefile.am:
gsettings_ENUM_NAMESPACE specifies the schema namespace for the enum files,
which are specified in gsettings_ENUM_FILES. This will generate a
org.foo.MyApp.enums.xml file containing the extracted enums, which will be
automatically included in the schema compilation, install and uninstall
rules. It should not be committed to version control or included in
EXTRA_DIST.
Functions
g_settings_new ()
GSettings *
g_settings_new (const gchar *schema_id);
Creates a new GSettings object with the schema specified by
schema_id
.
Signals on the newly created GSettings object will be dispatched
via the thread-default GMainContext in effect at the time of the
call to g_settings_new(). The new GSettings will hold a reference
on the context. See g_main_context_push_thread_default().
Since: 2.26
g_settings_new_with_path ()
GSettings *
g_settings_new_with_path (const gchar *schema_id,
const gchar *path);
Creates a new GSettings object with the relocatable schema specified
by schema_id
and a given path.
You only need to do this if you want to directly create a settings
object with a schema that doesn't have a specified path of its own.
That's quite rare.
It is a programmer error to call this function for a schema that
has an explicitly specified path.
It is a programmer error if path
is not a valid path. A valid path
begins and ends with '/' and does not contain two consecutive '/'
characters.
Since: 2.26
g_settings_new_with_backend ()
GSettings *
g_settings_new_with_backend (const gchar *schema_id,
GSettingsBackend *backend);
Creates a new GSettings object with the schema specified by
schema_id
and a given GSettingsBackend.
Creating a GSettings object with a different backend allows accessing
settings from a database other than the usual one. For example, it may make
sense to pass a backend corresponding to the "defaults" settings database on
the system to get a settings object that modifies the system default
settings instead of the settings for this user.
Since: 2.26
g_settings_new_full ()
GSettings *
g_settings_new_full (GSettingsSchema *schema,
GSettingsBackend *backend,
const gchar *path);
Creates a new GSettings object with a given schema, backend and
path.
It should be extremely rare that you ever want to use this function.
It is made available for advanced use-cases (such as plugin systems
that want to provide access to schemas loaded from custom locations,
etc).
At the most basic level, a GSettings object is a pure composition of
4 things: a GSettingsSchema, a GSettingsBackend, a path within that
backend, and a GMainContext to which signals are dispatched.
This constructor therefore gives you full control over constructing
GSettings instances. The first 3 parameters are given directly as
schema
, backend
and path
, and the main context is taken from the
thread-default (as per g_settings_new()).
If backend
is NULL then the default backend is used.
If path
is NULL then the path from the schema is used. It is an
error if path
is NULL and the schema has no path of its own or if
path
is non-NULL and not equal to the path that the schema does
have.
Since: 2.32
g_settings_sync ()
void
g_settings_sync (void);
Ensures that all pending operations are complete for the default backend.
Writes made to a GSettings are handled asynchronously. For this
reason, it is very unlikely that the changes have it to disk by the
time g_settings_set() returns.
This call will block until all of the writes have made it to the
backend. Since the mainloop is not running, no change notifications
will be dispatched during this call (but some may be queued by the
time the call is done).
g_settings_get_value ()
GVariant *
g_settings_get_value (GSettings *settings,
const gchar *key);
Gets the value that is stored in settings
for key
.
It is a programmer error to give a key
that isn't contained in the
schema for settings
.
Since: 2.26
g_settings_set_value ()
gboolean
g_settings_set_value (GSettings *settings,
const gchar *key,
GVariant *value);
Sets key
in settings
to value
.
It is a programmer error to give a key
that isn't contained in the
schema for settings
or for value
to have the incorrect type, per
the schema.
If value
is floating then this function consumes the reference.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_is_writable ()
gboolean
g_settings_is_writable (GSettings *settings,
const gchar *name);
Finds out if a key can be written or not
Returns
TRUE if the key name
is writable
Since: 2.26
g_settings_delay ()
void
g_settings_delay (GSettings *settings);
Changes the GSettings object into 'delay-apply' mode. In this
mode, changes to settings
are not immediately propagated to the
backend, but kept locally until g_settings_apply() is called.
Since: 2.26
g_settings_apply ()
void
g_settings_apply (GSettings *settings);
Applies any changes that have been made to the settings. This
function does nothing unless settings
is in 'delay-apply' mode;
see g_settings_delay(). In the normal case settings are always
applied immediately.
g_settings_revert ()
void
g_settings_revert (GSettings *settings);
Reverts all non-applied changes to the settings. This function
does nothing unless settings
is in 'delay-apply' mode; see
g_settings_delay(). In the normal case settings are always applied
immediately.
Change notifications will be emitted for affected keys.
g_settings_get_has_unapplied ()
gboolean
g_settings_get_has_unapplied (GSettings *settings);
Returns whether the GSettings object has any unapplied
changes. This can only be the case if it is in 'delayed-apply' mode.
Returns
TRUE if settings
has unapplied changes
Since: 2.26
g_settings_get_child ()
GSettings *
g_settings_get_child (GSettings *settings,
const gchar *name);
Creates a child settings object which has a base path of
base-path/@name, where base-path is the base path of
settings
.
The schema for the child settings object must have been declared
in the schema of settings
using a <child> element.
Returns
a 'child' settings object.
[transfer full]
Since: 2.26
g_settings_reset ()
void
g_settings_reset (GSettings *settings,
const gchar *key);
Resets key
to its default value.
This call resets the key, as much as possible, to its default value.
That might be the value specified in the schema or the one set by the
administrator.
g_settings_get_user_value ()
GVariant *
g_settings_get_user_value (GSettings *settings,
const gchar *key);
Checks the "user value" of a key, if there is one.
The user value of a key is the last value that was set by the user.
After calling g_settings_reset() this function should always return
NULL (assuming something is not wrong with the system
configuration).
It is possible that g_settings_get_value() will return a different
value than this function. This can happen in the case that the user
set a value for a key that was subsequently locked down by the system
administrator -- this function will return the user's old value.
This function may be useful for adding a "reset" option to a UI or
for providing indication that a particular value has been changed.
It is a programmer error to give a key
that isn't contained in the
schema for settings
.
Returns
the user's value, if set.
[nullable][transfer full]
Since: 2.40
g_settings_get_default_value ()
GVariant *
g_settings_get_default_value (GSettings *settings,
const gchar *key);
Gets the "default value" of a key.
This is the value that would be read if g_settings_reset() were to be
called on the key.
Note that this may be a different value than returned by
g_settings_schema_key_get_default_value() if the system administrator
has provided a default value.
Comparing the return values of g_settings_get_default_value() and
g_settings_get_value() is not sufficient for determining if a value
has been set because the user may have explicitly set the value to
something that happens to be equal to the default. The difference
here is that if the default changes in the future, the user's key
will still be set.
This function may be useful for adding an indication to a UI of what
the default value was before the user set it.
It is a programmer error to give a key
that isn't contained in the
schema for settings
.
Returns
the default value.
[nullable][transfer full]
Since: 2.40
g_settings_list_schemas ()
const gchar * const *
g_settings_list_schemas (void);
Deprecated.
Returns
a list of GSettings
schemas that are available, in no defined order. The list must not be
modified or freed.
[element-type utf8][transfer none]
Since: 2.26
g_settings_list_relocatable_schemas ()
const gchar * const *
g_settings_list_relocatable_schemas (void);
Deprecated.
Returns
a list of relocatable
GSettings schemas that are available, in no defined order. The list must
not be modified or freed.
[element-type utf8][transfer none]
Since: 2.28
g_settings_list_keys ()
gchar **
g_settings_list_keys (GSettings *settings);
g_settings_list_keys has been deprecated since version 2.46 and should not be used in newly-written code.
Use g_settings_schema_list_keys() instead.
Introspects the list of keys on settings
.
You should probably not be calling this function from "normal" code
(since you should already know what keys are in your schema). This
function is intended for introspection reasons.
You should free the return value with g_strfreev() when you are done
with it.
Returns
a list of the keys on
settings
, in no defined order.
[transfer full][element-type utf8]
g_settings_list_children ()
gchar **
g_settings_list_children (GSettings *settings);
Gets the list of children on settings
.
The list is exactly the list of strings for which it is not an error
to call g_settings_get_child().
There is little reason to call this function from "normal" code, since
you should already know what children are in your schema. This function
may still be useful there for introspection reasons, however.
You should free the return value with g_strfreev() when you are done
with it.
Returns
a list of the children on
settings
, in no defined order.
[transfer full][element-type utf8]
g_settings_get_range ()
GVariant *
g_settings_get_range (GSettings *settings,
const gchar *key);
Queries the range of a key.
Since: 2.28
g_settings_range_check ()
gboolean
g_settings_range_check (GSettings *settings,
const gchar *key,
GVariant *value);
Checks if the given value
is of the correct type and within the
permitted range for key
.
Returns
TRUE if value
is valid for key
Since: 2.28
g_settings_get ()
void
g_settings_get (GSettings *settings,
const gchar *key,
const gchar *format,
...);
Gets the value that is stored at key
in settings
.
A convenience function that combines g_settings_get_value() with
g_variant_get().
It is a programmer error to give a key
that isn't contained in the
schema for settings
or for the GVariantType of format
to mismatch
the type given in the schema.
Since: 2.26
g_settings_set ()
gboolean
g_settings_set (GSettings *settings,
const gchar *key,
const gchar *format,
...);
Sets key
in settings
to value
.
A convenience function that combines g_settings_set_value() with
g_variant_new().
It is a programmer error to give a key
that isn't contained in the
schema for settings
or for the GVariantType of format
to mismatch
the type given in the schema.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_boolean ()
gboolean
g_settings_get_boolean (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for booleans.
It is a programmer error to give a key
that isn't specified as
having a boolean type in the schema for settings
.
Since: 2.26
g_settings_set_boolean ()
gboolean
g_settings_set_boolean (GSettings *settings,
const gchar *key,
gboolean value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for booleans.
It is a programmer error to give a key
that isn't specified as
having a boolean type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_int ()
gint
g_settings_get_int (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for 32-bit integers.
It is a programmer error to give a key
that isn't specified as
having a int32 type in the schema for settings
.
Since: 2.26
g_settings_set_int ()
gboolean
g_settings_set_int (GSettings *settings,
const gchar *key,
gint value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for 32-bit integers.
It is a programmer error to give a key
that isn't specified as
having a int32 type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_int64 ()
gint64
g_settings_get_int64 (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for 64-bit integers.
It is a programmer error to give a key
that isn't specified as
having a int64 type in the schema for settings
.
Since: 2.50
g_settings_set_int64 ()
gboolean
g_settings_set_int64 (GSettings *settings,
const gchar *key,
gint64 value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for 64-bit integers.
It is a programmer error to give a key
that isn't specified as
having a int64 type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.50
g_settings_get_uint ()
guint
g_settings_get_uint (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for 32-bit unsigned
integers.
It is a programmer error to give a key
that isn't specified as
having a uint32 type in the schema for settings
.
Returns
an unsigned integer
Since: 2.30
g_settings_set_uint ()
gboolean
g_settings_set_uint (GSettings *settings,
const gchar *key,
guint value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for 32-bit unsigned
integers.
It is a programmer error to give a key
that isn't specified as
having a uint32 type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.30
g_settings_get_uint64 ()
guint64
g_settings_get_uint64 (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for 64-bit unsigned
integers.
It is a programmer error to give a key
that isn't specified as
having a uint64 type in the schema for settings
.
Returns
a 64-bit unsigned integer
Since: 2.50
g_settings_set_uint64 ()
gboolean
g_settings_set_uint64 (GSettings *settings,
const gchar *key,
guint64 value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for 64-bit unsigned
integers.
It is a programmer error to give a key
that isn't specified as
having a uint64 type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.50
g_settings_get_double ()
gdouble
g_settings_get_double (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for doubles.
It is a programmer error to give a key
that isn't specified as
having a 'double' type in the schema for settings
.
Since: 2.26
g_settings_set_double ()
gboolean
g_settings_set_double (GSettings *settings,
const gchar *key,
gdouble value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for doubles.
It is a programmer error to give a key
that isn't specified as
having a 'double' type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_string ()
gchar *
g_settings_get_string (GSettings *settings,
const gchar *key);
Gets the value that is stored at key
in settings
.
A convenience variant of g_settings_get() for strings.
It is a programmer error to give a key
that isn't specified as
having a string type in the schema for settings
.
Returns
a newly-allocated string
Since: 2.26
g_settings_set_string ()
gboolean
g_settings_set_string (GSettings *settings,
const gchar *key,
const gchar *value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for strings.
It is a programmer error to give a key
that isn't specified as
having a string type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_strv ()
gchar **
g_settings_get_strv (GSettings *settings,
const gchar *key);
A convenience variant of g_settings_get() for string arrays.
It is a programmer error to give a key
that isn't specified as
having an array of strings type in the schema for settings
.
Returns
a
newly-allocated, NULL-terminated array of strings, the value that
is stored at key
in settings
.
[array zero-terminated=1][transfer full]
Since: 2.26
g_settings_set_strv ()
gboolean
g_settings_set_strv (GSettings *settings,
const gchar *key,
const gchar *const *value);
Sets key
in settings
to value
.
A convenience variant of g_settings_set() for string arrays. If
value
is NULL, then key
is set to be the empty array.
It is a programmer error to give a key
that isn't specified as
having an array of strings type in the schema for settings
.
Returns
TRUE if setting the key succeeded,
FALSE if the key was not writable
Since: 2.26
g_settings_get_enum ()
gint
g_settings_get_enum (GSettings *settings,
const gchar *key);
Gets the value that is stored in settings
for key
and converts it
to the enum value that it represents.
In order to use this function the type of the value must be a string
and it must be marked in the schema file as an enumerated type.
It is a programmer error to give a key
that isn't contained in the
schema for settings
or is not marked as an enumerated type.
If the value stored in the configuration database is not a valid
value for the enumerated type then this function will return the
default value.
Since: 2.26
g_settings_set_enum ()
gboolean
g_settings_set_enum (GSettings *settings,
const gchar *key,
gint value);
Looks up the enumerated type nick for value
and writes it to key
,
within settings
.
It is a programmer error to give a key
that isn't contained in the
schema for settings
or is not marked as an enumerated type, or for
value
not to be a valid value for the named type.
After performing the write, accessing key
directly with
g_settings_get_string() will return the 'nick' associated with
value
.
Returns
TRUE, if the set succeeds
g_settings_get_flags ()
guint
g_settings_get_flags (GSettings *settings,
const gchar *key);
Gets the value that is stored in settings
for key
and converts it
to the flags value that it represents.
In order to use this function the type of the value must be an array
of strings and it must be marked in the schema file as a flags type.
It is a programmer error to give a key
that isn't contained in the
schema for settings
or is not marked as a flags type.
If the value stored in the configuration database is not a valid
value for the flags type then this function will return the default
value.
Since: 2.26
g_settings_set_flags ()
gboolean
g_settings_set_flags (GSettings *settings,
const gchar *key,
guint value);
Looks up the flags type nicks for the bits specified by value
, puts
them in an array of strings and writes the array to key
, within
settings
.
It is a programmer error to give a key
that isn't contained in the
schema for settings
or is not marked as a flags type, or for value
to contain any bits that are not value for the named type.
After performing the write, accessing key
directly with
g_settings_get_strv() will return an array of 'nicks'; one for each
bit in value
.
Returns
TRUE, if the set succeeds
GSettingsGetMapping ()
gboolean
(*GSettingsGetMapping) (GVariant *value,
gpointer *result,
gpointer user_data);
The type of the function that is used to convert from a value stored
in a GSettings to a value that is useful to the application.
If the value is successfully mapped, the result should be stored at
result
and TRUE returned. If mapping fails (for example, if value
is not in the right format) then FALSE should be returned.
If value
is NULL then it means that the mapping function is being
given a "last chance" to successfully return a valid value. TRUE
must be returned in this case.
Returns
TRUE if the conversion succeeded, FALSE in case of an error
g_settings_get_mapped ()
gpointer
g_settings_get_mapped (GSettings *settings,
const gchar *key,
GSettingsGetMapping mapping,
gpointer user_data);
Gets the value that is stored at key
in settings
, subject to
application-level validation/mapping.
You should use this function when the application needs to perform
some processing on the value of the key (for example, parsing). The
mapping
function performs that processing. If the function
indicates that the processing was unsuccessful (due to a parse error,
for example) then the mapping is tried again with another value.
This allows a robust 'fall back to defaults' behaviour to be
implemented somewhat automatically.
The first value that is tried is the user's setting for the key. If
the mapping function fails to map this value, other values may be
tried in an unspecified order (system or site defaults, translated
schema default values, untranslated schema default values, etc).
If the mapping function fails for all possible values, one additional
attempt is made: the mapping function is called with a NULL value.
If the mapping function still indicates failure at this point then
the application will be aborted.
The result parameter for the mapping
function is pointed to a
gpointer which is initially set to NULL. The same pointer is given
to each invocation of mapping
. The final value of that gpointer is
what is returned by this function. NULL is valid; it is returned
just as any other value would be.
Returns
the result, which may be NULL.
[transfer full]
g_settings_bind ()
void
g_settings_bind (GSettings *settings,
const gchar *key,
gpointer object,
const gchar *property,
GSettingsBindFlags flags);
Create a binding between the key
in the settings
object
and the property property
of object
.
The binding uses the default GIO mapping functions to map
between the settings and property values. These functions
handle booleans, numeric types and string types in a
straightforward way. Use g_settings_bind_with_mapping() if
you need a custom mapping, or map between types that are not
supported by the default mapping functions.
Unless the flags
include G_SETTINGS_BIND_NO_SENSITIVITY, this
function also establishes a binding between the writability of
key
and the "sensitive" property of object
(if object
has
a boolean property by that name). See g_settings_bind_writable()
for more details about writable bindings.
Note that the lifecycle of the binding is tied to object
,
and that you can have only one binding per object property.
If you bind the same property twice on the same object, the second
binding overrides the first one.
Since: 2.26
g_settings_bind_with_mapping ()
void
g_settings_bind_with_mapping (GSettings *settings,
const gchar *key,
gpointer object,
const gchar *property,
GSettingsBindFlags flags,
GSettingsBindGetMapping get_mapping,
GSettingsBindSetMapping set_mapping,
gpointer user_data,
GDestroyNotify destroy);
Create a binding between the key
in the settings
object
and the property property
of object
.
The binding uses the provided mapping functions to map between
settings and property values.
Note that the lifecycle of the binding is tied to object
,
and that you can have only one binding per object property.
If you bind the same property twice on the same object, the second
binding overrides the first one.
[skip]
Since: 2.26
g_settings_bind_writable ()
void
g_settings_bind_writable (GSettings *settings,
const gchar *key,
gpointer object,
const gchar *property,
gboolean inverted);
Create a binding between the writability of key
in the
settings
object and the property property
of object
.
The property must be boolean; "sensitive" or "visible"
properties of widgets are the most likely candidates.
Writable bindings are always uni-directional; changes of the
writability of the setting will be propagated to the object
property, not the other way.
When the inverted
argument is TRUE, the binding inverts the
value as it passes from the setting to the object, i.e. property
will be set to TRUE if the key is not writable.
Note that the lifecycle of the binding is tied to object
,
and that you can have only one binding per object property.
If you bind the same property twice on the same object, the second
binding overrides the first one.
Since: 2.26
g_settings_unbind ()
void
g_settings_unbind (gpointer object,
const gchar *property);
Removes an existing binding for property
on object
.
Note that bindings are automatically removed when the
object is finalized, so it is rarely necessary to call this
function.
Since: 2.26
GSettingsBindSetMapping ()
GVariant *
(*GSettingsBindSetMapping) (const GValue *value,
const GVariantType *expected_type,
gpointer user_data);
The type for the function that is used to convert an object property
value to a GVariant for storing it in GSettings.
Returns
a new GVariant holding the data from value
,
or NULL in case of an error
GSettingsBindGetMapping ()
gboolean
(*GSettingsBindGetMapping) (GValue *value,
GVariant *variant,
gpointer user_data);
The type for the function that is used to convert from GSettings to
an object property. The value
is already initialized to hold values
of the appropriate type.
Returns
TRUE if the conversion succeeded, FALSE in case of an error
g_settings_create_action ()
GAction *
g_settings_create_action (GSettings *settings,
const gchar *key);
Creates a GAction corresponding to a given GSettings key.
The action has the same name as the key.
The value of the key becomes the state of the action and the action
is enabled when the key is writable. Changing the state of the
action results in the key being written to. Changes to the value or
writability of the key cause appropriate change notifications to be
emitted for the action.
For boolean-valued keys, action activations take no parameter and
result in the toggling of the value. For all other types,
activations take the new value for the key (which must have the
correct type).
Returns
a new GAction.
[transfer full]
Since: 2.32