PropertyAction#
Added in version 2.38.
Superclasses: Object
Implemented Interfaces: Action
A GPropertyAction
is a way to get a Action
with a state value
reflecting and controlling the value of a 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 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 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 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 Action
corresponding
to the visible-child-name
property of a `GtkStack
<https://docs.gtk.org/gtk4/class.Stack.html>`__
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 GtkStack
.
An anti-example would be binding the active-id
property on a
`GtkComboBox
<https://docs.gtk.org/gtk4/class.ComboBox.html>`__. 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 `GtkStack
<https://docs.gtk.org/gtk4/class.Stack.html>`__ if
this value is actually stored in Settings
. In that case, the
real source of the value is* Settings
. If you want
a Action
to control a setting stored in Settings
,
see create_action
instead, and possibly combine its
use with bind
.
Constructors#
- class PropertyAction
- classmethod new(name: str, object: Object, property_name: str) PropertyAction #
Creates a
Action
corresponding to the value of propertyproperty_name
onobject
.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.Added in version 2.38.
- Parameters:
name – the name of the action to create
object – the object that has the property to wrap
property_name – the name of the property
Properties#
- class PropertyAction
-
- props.parameter_type: VariantType#
The type of the None singleton.
Added in version 2.38.
- props.state_type: VariantType#
The type of the None singleton.
Added in version 2.38.