Binding

gobject.object.ObjectG instance (or source) and another property on another gobject.object.ObjectG 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 method@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.object.ObjectG 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 @celsius_to_fahrenheit 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 @fahrenheit_to_celsius 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 func@GObject.signal_stop_emission or func@GObject.signal_handler_block.

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

Bindings for languages with garbage collection can use gobject.binding.Binding.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.

class Binding : ObjectG {

gobject.object.ObjectG dupSource();

gobject.object.ObjectG dupTarget();

gobject.types.BindingFlags getFlags();

gobject.object.ObjectG getSource();

string getSourceProperty();

gobject.object.ObjectG getTarget();

string getTargetProperty();

void unbind();

}

Members

Functions

dupSource gobject.object.ObjectG dupSource(): Retrieves the #GObject instance used as the source of the binding.
dupTarget gobject.object.ObjectG dupTarget(): Retrieves the #GObject instance used as the target of the binding.
getFlags gobject.types.BindingFlags getFlags(): Retrieves the flags passed when constructing the #GBinding.
getSource gobject.object.ObjectG getSource(): Retrieves the #GObject instance used as the source of the binding.
getSourceProperty string getSourceProperty(): Retrieves the name of the property of #GBinding:source used as the source of the binding.
getTarget gobject.object.ObjectG getTarget(): Retrieves the #GObject instance used as the target of the binding.
getTargetProperty string getTargetProperty(): Retrieves the name of the property of #GBinding:target used as the target of the binding.
unbind void unbind(): Explicitly releases the binding between the source and the target property expressed by binding.

Inherited Members

From ObjectG

setGObject void setGObject(void* cObj, Flag!"Take" take): Set the GObject of a D ObjectG wrapper.
cPtr void* cPtr(Flag!"Dup" dup): Get a pointer to the underlying C object.
ref_ void* ref_(void* gObj): Calls g_object_ref() on a GObject.
unref unref(void* gObj): Calls g_object_unref() on a GObject.
getType GType getType(): Get the GType of an object.
gType GType gType [@property getter]: GObject GType property.
self ObjectG self(): Convenience method to return this cast to a type. For use in D with statements.
getDObject T getDObject(void* cptr, Flag!"Take" take): Template to get the D object from a C GObject and cast it to the given D object type.
connectSignalClosure ulong connectSignalClosure(string signalDetail, DClosure closure, Flag!"After" after): Connect a D closure to an object signal.
setProperty void setProperty(string propertyName, T val): Template for setting a GObject property.
getProperty T getProperty(string propertyName): Template for getting a GObject property.
compatControl size_t compatControl(size_t what, void* data)
bindProperty gobject.binding.Binding bindProperty(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags): Creates a binding between source_property on source and target_property on target.
bindPropertyFull gobject.binding.Binding bindPropertyFull(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags, gobject.closure.Closure transformTo, gobject.closure.Closure transformFrom): Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.
forceFloating void forceFloating(): This function is intended for #GObject implementations to re-enforce a floating[floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling gobject.object.ObjectG.refSink.
freezeNotify void freezeNotify(): Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one #GObject::notify signal is emitted for each property modified while the object is frozen.
getData void* getData(string key): Gets a named field from the objects table of associations (see gobject.object.ObjectG.setData).
getProperty void getProperty(string propertyName, gobject.value.Value value): Gets a property of an object.
getQdata void* getQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata.
getv void getv(string[] names, gobject.value.Value[] values): Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
isFloating bool isFloating(): Checks whether object has a floating[floating-ref] reference.
notify void notify(string propertyName): Emits a "notify" signal for the property property_name on object.
notifyByPspec void notifyByPspec(gobject.param_spec.ParamSpec pspec): Emits a "notify" signal for the property specified by pspec on object.
refSink gobject.object.ObjectG refSink(): Increase the reference count of object, and possibly remove the floating[floating-ref] reference, if object has a floating reference.
runDispose void runDispose(): Releases all references to other objects. This can be used to break reference cycles.
setData void setData(string key, void* data): Each object carries around a table of associations from strings to pointers. This function lets you set an association.
setProperty void setProperty(string propertyName, gobject.value.Value value): Sets a property on an object.
stealData void* stealData(string key): Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
stealQdata void* stealQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:
thawNotify void thawNotify(): Reverts the effect of a previous call to gobject.object.ObjectG.freezeNotify. The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.
watchClosure void watchClosure(gobject.closure.Closure closure): This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling gobject.closure.Closure.invalidate on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, gobject.object.ObjectG.ref_ and gobject.object.ObjectG.unref are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.
connectNotify ulong connectNotify(string detail, T callback, Flag!"After" after): Connect to Notify signal.

gobject binding classes

Binding