Class SettingsBackend

java.lang.Object

org.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gio.SettingsBackend

All Implemented Interfaces:

Proxy

Direct Known Subclasses:

SettingsBackend.SettingsBackend$Impl

@Generated("org.javagi.JavaGI")
public abstract class SettingsBackend
extends GObject

The GSettingsBackend interface defines a generic interface for non-strictly-typed data that is stored in a hierarchy. To implement an alternative storage backend for Settings, you need to implement the GSettingsBackend interface and then make it implement the extension point G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.

The interface defines methods for reading and writing values, a method for determining if writing of certain values will fail (lockdown) and a change notification mechanism.

The semantics of the interface are very precisely defined and implementations must carefully adhere to the expectations of callers that are documented on each of the interface methods.

Some of the GSettingsBackend functions accept or return a GLib.Tree. These trees always have strings as keys and GLib.Variant as values.

The GSettingsBackend API is exported to allow third-party implementations, but does not carry the same stability guarantees as the public GIO API. For this reason, you have to define the C preprocessor symbol G_SETTINGS_ENABLE_BACKEND before including gio/gsettingsbackend.h.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SettingsBackend.Builder<B extends SettingsBackend.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.
static class	SettingsBackend.SettingsBackend$Impl	The SettingsBackend$Impl type represents a native instance of the abstract SettingsBackend class.
static class	SettingsBackend.SettingsBackendClass	Class structure for GSettingsBackend.

Nested classes/interfaces inherited from class GObject

GObject.NotifyCallback, GObject.ObjectClass

Constructor Summary

Constructors

Constructor	Description
SettingsBackend()	Create a new SettingsBackend.
SettingsBackend(MemorySegment address)	Create a SettingsBackend instance for the provided memory address.

Method Summary

Modifier and Type	Method	Description
protected SettingsBackend	asParent()	Return this instance as if it were its parent type.
void	changed(String key, @Nullable MemorySegment originTag)	Signals that a single key has possibly changed.
void	changedTree(Tree tree, @Nullable MemorySegment originTag)	This call is a convenience wrapper.
static void	flattenTree(Tree tree, Out<String> path, @Nullable Out<String[]> keys, @Nullable Out<Variant[]> values)	Calculate the longest common prefix of all keys in a tree and write out an array of the key names relative to that prefix and, optionally, the value to store at each of those keys.
static SettingsBackend	getDefault()	Returns the default GSettingsBackend.
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
protected Permission	getPermission(String path)	virtual method to get permission of a key
static @Nullable Type	getType()	Get the GType of the SettingsBackend class.
protected boolean	getWritable(String key)	virtual method to get if a key is writable
void	keysChanged(String path, @Nullable String @Nullable [] items, @Nullable MemorySegment originTag)	Signals that a list of keys have possibly changed.
void	pathChanged(String path, @Nullable MemorySegment originTag)	Signals that all keys below a given path may have possibly changed.
void	pathWritableChanged(String path)	Signals that the writability of all keys below a given path may have changed.
protected Variant	read(String key, VariantType expectedType, boolean defaultValue)	virtual method to read a key's value
protected Variant	readUserValue(String key, VariantType expectedType)	virtual method to read user's key value
protected void	reset(String key, @Nullable MemorySegment originTag)	virtual method to reset state
protected void	subscribe(String name)	virtual method to subscribe to key changes
protected void	sync()	virtual method to sync state
protected void	unsubscribe(String name)	virtual method to unsubscribe to key changes
void	writableChanged(String key)	Signals that the writability of a single key has possibly changed.
protected boolean	write(String key, Variant value, @Nullable MemorySegment originTag)	virtual method to change key's value
protected boolean	writeTree(Tree tree, @Nullable MemorySegment originTag)	virtual method to change a tree of keys

Methods inherited from class GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, builder, compatControl, connect, connect, connect, constructed, disconnect, dispatchPropertiesChanged, dispose, dupData, dupQdata, emit, emitNotify, finalize_, forceFloating, freezeNotify, get, getData, getProperty, getProperty, getProperty, getQdata, getv, interfaceFindProperty, interfaceInstallProperty, interfaceListProperties, isFloating, newInstance, newInstance, newv, notify, notify, notifyByPspec, onNotify, ref, refSink, removeToggleRef, removeWeakPointer, replaceData, replaceQdata, runDispose, set, setData, setDataFull, setProperty, setProperty, setProperty, setQdata, setQdataFull, setv, stealData, stealQdata, takeRef, thawNotify, unref, watchClosure, weakRef, weakUnref, withProperties

Methods inherited from class TypeInstance

callParent, callParent, cast, getPrivate, readGClass, writeGClass

Methods inherited from class ProxyInstance

equals, handle, hashCode

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SettingsBackend

public SettingsBackend(MemorySegment address)

Create a SettingsBackend instance for the provided memory address.

Parameters:

address - the memory address of the native object

SettingsBackend

public SettingsBackend()

Create a new SettingsBackend.

Method Details

getType

public static @Nullable Type getType()

Get the GType of the SettingsBackend class.

Returns:

the GType

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

asParent

protected SettingsBackend asParent()

Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.

Overrides:

asParent in class GObject

Returns:

the instance as if it were its parent type

flattenTree

public static void flattenTree(Tree tree,
 Out<String> path,
 @Nullable Out<String[]> keys,
 @Nullable Out<Variant[]> values)

Calculate the longest common prefix of all keys in a tree and write out an array of the key names relative to that prefix and, optionally, the value to store at each of those keys.

You must free the value returned in path, keys and values using g_free(). You should not attempt to free or unref the contents of keys or values.

Parameters:

tree - a GTree containing the changes

path - the location to save the path

keys - the location to save the relative keys

values - the location to save the values, or null

Since:

2.26

getDefault

public static SettingsBackend getDefault()

Returns the default GSettingsBackend. It is possible to override the default by setting the GSETTINGS_BACKEND environment variable to the name of a settings backend.

The user gets a reference to the backend.

Returns:

the default GSettingsBackend, which will be a dummy (memory) settings backend if no other settings backend is available.

Since:

2.28

changed

public void changed(String key,
 @Nullable MemorySegment originTag)

Signals that a single key has possibly changed. Backend implementations should call this if a key has possibly changed its value.

key must be a valid key (ie starting with a slash, not containing '//', and not ending with a slash).

The implementation must call this function during any call to g_settings_backend_write(), before the call returns (except in the case that no keys are actually changed and it cares to detect this fact). It may not rely on the existence of a mainloop for dispatching the signal later.

The implementation may call this function at any other time it likes in response to other events (such as changes occurring outside of the program). These calls may originate from a mainloop or may originate in response to any other action (including from calls to g_settings_backend_write()).

In the case that this call is in response to a call to g_settings_backend_write() then originTag must be set to the same value that was passed to that call.

Parameters:

key - the name of the key

originTag - the origin tag

Since:

2.26

changedTree

public void changedTree(Tree tree,
 @Nullable MemorySegment originTag)

This call is a convenience wrapper. It gets the list of changes from tree, computes the longest common prefix and calls g_settings_backend_changed().

Parameters:

tree - a GTree containing the changes

originTag - the origin tag

Since:

2.26

keysChanged

public void keysChanged(String path,
 @Nullable String @Nullable [] items,
 @Nullable MemorySegment originTag)

Signals that a list of keys have possibly changed. Backend implementations should call this if keys have possibly changed their values.

path must be a valid path (ie starting and ending with a slash and not containing '//'). Each string in items must form a valid key name when path is prefixed to it (ie: each item must not start or end with '/' and must not contain '//').

The meaning of this signal is that any of the key names resulting from the concatenation of path with each item in items may have changed.

The same rules for when notifications must occur apply as per g_settings_backend_changed(). These two calls can be used interchangeably if exactly one item has changed (although in that case g_settings_backend_changed() is definitely preferred).

For efficiency reasons, the implementation should strive for path to be as long as possible (ie: the longest common prefix of all of the keys that were changed) but this is not strictly required.

Parameters:

path - the path containing the changes

items - the null-terminated list of changed keys

originTag - the origin tag

Since:

2.26

pathChanged

public void pathChanged(String path,
 @Nullable MemorySegment originTag)

Signals that all keys below a given path may have possibly changed. Backend implementations should call this if an entire path of keys have possibly changed their values.

path must be a valid path (ie starting and ending with a slash and not containing '//').

The meaning of this signal is that any of the key which has a name starting with path may have changed.

The same rules for when notifications must occur apply as per g_settings_backend_changed(). This call might be an appropriate reasponse to a 'reset' call but implementations are also free to explicitly list the keys that were affected by that call if they can easily do so.

For efficiency reasons, the implementation should strive for path to be as long as possible (ie: the longest common prefix of all of the keys that were changed) but this is not strictly required. As an example, if this function is called with the path of "/" then every single key in the application will be notified of a possible change.

Parameters:

path - the path containing the changes

originTag - the origin tag

Since:

2.26

pathWritableChanged

public void pathWritableChanged(String path)

Signals that the writability of all keys below a given path may have changed.

Since GSettings performs no locking operations for itself, this call will always be made in response to external events.

Parameters:

path - the name of the path

Since:

2.26

writableChanged

public void writableChanged(String key)

Signals that the writability of a single key has possibly changed.

Since GSettings performs no locking operations for itself, this call will always be made in response to external events.

Parameters:

key - the name of the key

Since:

2.26

getPermission

protected Permission getPermission(String path)

virtual method to get permission of a key

getWritable

protected boolean getWritable(String key)

virtual method to get if a key is writable

read

protected Variant read(String key,
 VariantType expectedType,
 boolean defaultValue)

virtual method to read a key's value

readUserValue

protected Variant readUserValue(String key,
 VariantType expectedType)

virtual method to read user's key value

reset

protected void reset(String key,
 @Nullable MemorySegment originTag)

virtual method to reset state

subscribe

protected void subscribe(String name)

virtual method to subscribe to key changes

sync

protected void sync()

virtual method to sync state

unsubscribe

protected void unsubscribe(String name)

virtual method to unsubscribe to key changes

write

protected boolean write(String key,
 Variant value,
 @Nullable MemorySegment originTag)

virtual method to change key's value

writeTree

protected boolean writeTree(Tree tree,
 @Nullable MemorySegment originTag)

virtual method to change a tree of keys