Class Binding

java.lang.Object

org.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gobject.Binding

All Implemented Interfaces:

Proxy

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

GObject instance (or source) and another property on another GObject instance (or target).

Whenever the source property changes, the same value is applied to the target property; for instance, the following binding:

  g_object_bind_property (object1, "property-a",
                          object2, "property-b",
                          G_BINDING_DEFAULT);

will cause the property named "property-b" of object2 to be updated every time GObject.set or the specific accessor changes the value of the property "property-a" of object1.

It is possible to create a bidirectional binding between two properties of two GObject instances, so that if either property changes, the other is updated as well, for instance:

  g_object_bind_property (object1, "property-a",
                          object2, "property-b",
                          G_BINDING_BIDIRECTIONAL);

will keep the two properties in sync.

It is also possible to set a custom transformation function (in both directions, in case of a bidirectional binding) to apply a custom transformation from the source value to the target value before applying it; for instance, the following binding:

  g_object_bind_property_full (adjustment1, "value",
                               adjustment2, "value",
                               G_BINDING_BIDIRECTIONAL,
                               celsius_to_fahrenheit,
                               fahrenheit_to_celsius,
                               NULL, NULL);

will keep the "value" property of the two adjustments in sync; the celsiusToFahrenheit function will be called whenever the "value" property of adjustment1 changes and will transform the current value of the property before applying it to the "value" property of adjustment2.

Vice versa, the fahrenheitToCelsius function will be called whenever the "value" property of adjustment2 changes, and will transform the current value of the property before applying it to the "value" property of adjustment1.

Note that GBinding does not resolve cycles by itself; a cycle like

  object1:propertyA -> object2:propertyB
  object2:propertyB -> object3:propertyC
  object3:propertyC -> object1:propertyA

might lead to an infinite loop. The loop, in this particular case, can be avoided if the objects emit the GObject::notify signal only if the value has effectively been changed. A binding is implemented using the GObject::notify signal, so it is susceptible to all the various ways of blocking a signal emission, like GObjects.signalStopEmission(GObject, int, Quark) or GObjects.signalHandlerBlock(GObject, int).

A binding will be severed, and the resources it allocates freed, whenever either one of the GObject instances it refers to are finalized, or when the GBinding instance loses its last reference.

Bindings for languages with garbage collection can use unbind() to explicitly release a binding between the source and target properties, instead of relying on the last reference on the binding, source, and target instances to drop.

Since:

2.26

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Binding.Builder<B extends Binding.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.

Nested classes/interfaces inherited from class GObject

GObject.NotifyCallback, GObject.ObjectClass

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
protected Binding	asParent()	Return this instance as if it were its parent type.
static Binding.Builder<? extends Binding.Builder>	builder()	A Binding.Builder object constructs a Binding with the specified properties.
@Nullable GObject	dupSource()	Retrieves the GObject instance used as the source of the binding.
@Nullable GObject	dupTarget()	Retrieves the GObject instance used as the target of the binding.
Set<BindingFlags>	getFlags()	Retrieves the flags passed when constructing the GBinding.
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
@Nullable GObject	getSource()	Deprecated. Use g_binding_dup_source() for a safer version of this function.
String	getSourceProperty()	Retrieves the name of the property of GBinding:source used as the source of the binding.
@Nullable GObject	getTarget()	Deprecated. Use g_binding_dup_target() for a safer version of this function.
String	getTargetProperty()	Retrieves the name of the property of GBinding:target used as the target of the binding.
static @Nullable Type	getType()	Get the GType of the Binding class.
void	unbind()	Explicitly releases the binding between the source and the target property expressed by binding.

Methods inherited from class GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, 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

Binding

public Binding(MemorySegment address)

Create a Binding instance for the provided memory address.

Parameters:

address - the memory address of the native object

Binding

public Binding()

Create a new Binding.

Method Details

getType

public static @Nullable Type getType()

Get the GType of the Binding class.

Returns:

the GType

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

asParent

protected Binding 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

dupSource

public @Nullable GObject dupSource()

Retrieves the GObject instance used as the source of the binding.

A GBinding can outlive the source GObject as the binding does not hold a strong reference to the source. If the source is destroyed before the binding then this function will return null.

Returns:

the source GObject, or null if the source does not exist any more.

Since:

2.68

dupTarget

public @Nullable GObject dupTarget()

Retrieves the GObject instance used as the target of the binding.

A GBinding can outlive the target GObject as the binding does not hold a strong reference to the target. If the target is destroyed before the binding then this function will return null.

Returns:

the target GObject, or null if the target does not exist any more.

Since:

2.68

getFlags

public Set<BindingFlags> getFlags()

Retrieves the flags passed when constructing the GBinding.

Returns:

the GBindingFlags used by the GBinding

Since:

2.26

getSource

@Deprecated
public @Nullable GObject getSource()

Deprecated.

Use g_binding_dup_source() for a safer version of this function.

Retrieves the GObject instance used as the source of the binding.

A GBinding can outlive the source GObject as the binding does not hold a strong reference to the source. If the source is destroyed before the binding then this function will return null.

Use g_binding_dup_source() if the source or binding are used from different threads as otherwise the pointer returned from this function might become invalid if the source is finalized from another thread in the meantime.

Returns:

the source GObject, or null if the source does not exist any more.

Since:

2.26

getSourceProperty

public String getSourceProperty()

Retrieves the name of the property of GBinding:source used as the source of the binding.

Returns:

the name of the source property

Since:

2.26

getTarget

@Deprecated
public @Nullable GObject getTarget()

Deprecated.

Use g_binding_dup_target() for a safer version of this function.

Retrieves the GObject instance used as the target of the binding.

A GBinding can outlive the target GObject as the binding does not hold a strong reference to the target. If the target is destroyed before the binding then this function will return null.

Use g_binding_dup_target() if the target or binding are used from different threads as otherwise the pointer returned from this function might become invalid if the target is finalized from another thread in the meantime.

Returns:

the target GObject, or null if the target does not exist any more.

Since:

2.26

getTargetProperty

public String getTargetProperty()

Retrieves the name of the property of GBinding:target used as the target of the binding.

Returns:

the name of the target property

Since:

2.26

unbind

public void unbind()

Explicitly releases the binding between the source and the target property expressed by binding.

This function will release the reference that is being held on the this Binding instance if the binding is still bound; if you want to hold on to the GBinding instance after calling g_binding_unbind(), you will need to hold a reference to it.

Note however that this function does not take ownership of binding, it only unrefs the reference that was initially created by g_object_bind_property() and is owned by the binding.

Since:

2.38

builder

public static Binding.Builder<? extends Binding.Builder> builder()

A Binding.Builder object constructs a Binding with the specified properties. Use the various set...() methods to set properties, and finish construction with Binding.Builder.build().

Returns:

the builder object