class Gio::PropertyAction

Overview

A GPropertyAction is a way to get a Gio::Action with a state value reflecting and controlling the value of a GObject::Object property.

The state of the action will correspond to the value of the property. Changing it will change the property (assuming the requested value matches the requirements as specified in the GObject::ParamSpec).

Only the most common types are presently supported. Booleans are mapped to booleans, strings to strings, signed/unsigned integers to int32/uint32 and floats and doubles to doubles.

If the property is an enum then the state will be string-typed and conversion will automatically be performed between the enum value and ‘nick’ string as per the GObject::EnumValue table.

Flags types are not currently supported.

Properties of object types, boxed types and pointer types are not supported and probably never will be.

Properties of GLib::Variant types are not currently supported.

If the property is boolean-valued then the action will have a NULL parameter type, and activating the action (with no parameter) will toggle the value of the property.

In all other cases, the parameter type will correspond to the type of the property.

The general idea here is to reduce the number of locations where a particular piece of state is kept (and therefore has to be synchronised between). GPropertyAction does not have a separate state that is kept in sync with the property value — its state is the property value.

For example, it might be useful to create a Gio::Action corresponding to the visible-child-name property of a Gtk::Stack so that the current page can be switched from a menu. The active radio indication in the menu is then directly determined from the active page of the Gtk::Stack.

An anti-example would be binding the active-id property on a Gtk::ComboBox. This is because the state of the combo box itself is probably uninteresting and is actually being used to control something else.

Another anti-example would be to bind to the visible-child-name property of a Gtk::Stack if this value is actually stored in Gio::Settings. In that case, the real source of the value is* Gio::Settings. If you want a Gio::Action to control a setting stored in Gio::Settings, see Gio::Settings#create_action instead, and possibly combine its use with Gio::Settings#bind.

Included Modules

Defined in:

lib/gi-crystal/src/auto/gio-2.0/property_action.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Gio::Action

activate(parameter : _ | Nil) : Nil activate, change_state(value : _) : Nil change_state, enabled : Bool enabled, enabled? : Bool enabled?, name : String name, name? : String | Nil name?, parameter_type : GLib::VariantType | Nil parameter_type, parse_detailed_name(detailed_name : String) : Bool parse_detailed_name, state : GLib::Variant | Nil state, state_hint : GLib::Variant | Nil state_hint, state_type : GLib::VariantType | Nil state_type, to_unsafe to_unsafe

Constructor methods inherited from module Gio::Action

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gio::Action

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type, name_is_valid(action_name : String) : Bool name_is_valid, print_detailed_name(action_name : String, target_value : _ | Nil) : String print_detailed_name

Instance methods inherited from class GObject::Object

==(other : self) ==, bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding bind_property, bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding bind_property_full, data(key : String) : Pointer(Void) | Nil data, finalize finalize, freeze_notify : Nil freeze_notify, getv(names : Enumerable(String), values : Enumerable(_)) : Nil getv, hash(hasher) hash, notify(property_name : String) : Nil notify, notify_by_pspec(pspec : GObject::ParamSpec) : Nil notify_by_pspec, notify_signal notify_signal, property(property_name : String, value : _) : Nil property, qdata(quark : UInt32) : Pointer(Void) | Nil qdata, ref_count : UInt32 ref_count, run_dispose : Nil run_dispose, set_data(key : String, data : Pointer(Void) | Nil) : Nil set_data, set_property(property_name : String, value : _) : Nil set_property, steal_data(key : String) : Pointer(Void) | Nil steal_data, steal_qdata(quark : UInt32) : Pointer(Void) | Nil steal_qdata, thaw_notify : Nil thaw_notify, to_unsafe : Pointer(Void) to_unsafe, watch_closure(closure : GObject::Closure) : Nil watch_closure

Constructor methods inherited from class GObject::Object

cast(obj : GObject::Object) : self cast, new(pointer : Pointer(Void), transfer : GICrystal::Transfer)
new new, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv

Class methods inherited from class GObject::Object

cast?(obj : GObject::Object) : self | Nil cast?, compat_control(what : UInt64, data : Pointer(Void) | Nil) : UInt64 compat_control, g_type : UInt64 g_type, interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec interface_find_property, interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec) interface_list_properties

Macros inherited from class GObject::Object

previous_vfunc(*args) previous_vfunc, previous_vfunc!(*args) previous_vfunc!, signal(signature) signal

Constructor Detail

def self.new(name : String, object : GObject::Object, property_name : String) : self #

Creates a #GAction corresponding to the value of property property_name on object.

The property must be existent and readable and writable (and not construct-only).

This function takes a reference on object and doesn't release it until the action is destroyed.


def self.new #

Initialize a new PropertyAction.


def self.new(*, enabled : Bool | Nil = nil, invert_boolean : Bool | Nil = nil, name : String | Nil = nil, object : GObject::Object | Nil = nil, parameter_type : GLib::VariantType | Nil = nil, property_name : String | Nil = nil, state : GLib::Variant | Nil = nil, state_type : GLib::VariantType | Nil = nil) #

Class Method Detail

def self.g_type : UInt64 #

Returns the type id (GType) registered in GLib type system.


Instance Method Detail

def ==(other : self) #
Description copied from class Reference

Returns true if this reference is the same as other. Invokes same?.


def enabled? : Bool #

def hash(hasher) #
Description copied from class Reference

See Object#hash(hasher)


def invert_boolean=(value : Bool) : Bool #

def invert_boolean? : Bool #

def name : String #

def name=(value : String) : String #

def name=(value : Nil) : Nil #

Set #name property to nil.


def name? : String | Nil #

Same as #name, but can return nil.


def object=(value : GObject::Object | Nil) : GObject::Object | Nil #

def parameter_type : GLib::VariantType | Nil #

def property_name=(value : String) : String #

def property_name=(value : Nil) : Nil #

Set #property_name property to nil.


def state : GLib::Variant | Nil #

def state_type : GLib::VariantType | Nil #