Description
A GPropertyAction is a way to get a GAction with a state value
reflecting and controlling the value of a GObject 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 GParamSpec).
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 GEnumValue 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 GVariant 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 GAction corresponding to
the "visible-child-name" property of a GtkStack 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. This is because the state of the combobox 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 if this value is actually stored in
GSettings. In that case, the real source of the value is
GSettings. If you want a GAction to control a setting stored in
GSettings, see g_settings_create_action() instead, and possibly
combine its use with g_settings_bind().
Property Details
The “enabled” property
“enabled” gboolean
If action
is currently enabled.
If the action is disabled then calls to g_action_activate() and
g_action_change_state() have no effect.
Owner: GPropertyAction
Flags: Read
Default value: TRUE
Since: 2.38
The “invert-boolean” property
“invert-boolean” gboolean
If TRUE, the state of the action will be the negation of the
property value, provided the property is boolean.
Owner: GPropertyAction
Flags: Read / Write / Construct Only
Default value: FALSE
Since: 2.46
The “name” property
“name” gchar *
The name of the action. This is mostly meaningful for identifying
the action once it has been added to a GActionMap.
Owner: GPropertyAction
Flags: Read / Write / Construct Only
Default value: NULL
Since: 2.38
The “object” property
“object” GObject *
The object to wrap a property on.
The object must be a non-NULL GObject with properties.
Owner: GPropertyAction
Flags: Write / Construct Only
Since: 2.38
The “parameter-type” property
“parameter-type” GVariantType *
The type of the parameter that must be given when activating the
action.
Owner: GPropertyAction
Flags: Read
Since: 2.38
The “property-name” property
“property-name” gchar *
The name of the property to wrap on the object.
The property must exist on the passed-in object and it must be
readable and writable (and not construct-only).
Owner: GPropertyAction
Flags: Write / Construct Only
Default value: NULL
Since: 2.38
The “state” property
“state” GVariant *
The state of the action, or NULL if the action is stateless.
Owner: GPropertyAction
Flags: Read
Allowed values: GVariant<*>
Default value: NULL
Since: 2.38
The “state-type” property
“state-type” GVariantType *
The GVariantType of the state that the action has, or NULL if the
action is stateless.
Owner: GPropertyAction
Flags: Read
Since: 2.38