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Properties
| gboolean | enabled | Read |
| gchar * | name | Read / Write / Construct Only |
| GObject * | object | Write / Construct Only |
| GVariantType * | parameter-type | Read |
| gchar * | property-name | Write / Construct Only |
| GVariant * | state | Read |
| GVariantType * | state-type | Read |
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().
Functions
g_property_action_new ()
GPropertyAction * g_property_action_new (const gchar *name,gpointer object,const gchar *property_name);
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.
Parameters
name |
the name of the action to create |
|
object |
the object that has the property to wrap. |
[type GObject.Object] |
property_name |
the name of the property |
Since 2.38
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.
Flags: Read
Default value: TRUE
Since 2.38
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.
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.
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.
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).
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.
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.
Flags: Read
Since 2.38