Package org.gnome.gio

Interface SimpleAction.ChangeStateCallback

All Superinterfaces:

FunctionPointer

Enclosing class:

SimpleAction

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public static interface SimpleAction.ChangeStateCallback
extends FunctionPointer

Functional interface declaration of the ChangeStateCallback callback.

See Also:

• run(org.gnome.glib.Variant)

Method Summary

Modifier and Type	Method	Description
void	run(@Nullable Variant value)	Indicates that the action just received a request to change its state.
default MemorySegment	toCallback(Arena arena)	Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment) method.
default void	upcall(MemorySegment sourceSimpleAction, MemorySegment value)	The upcall method is called from native code.

Method Details

run

void run(@Nullable Variant value)

Indicates that the action just received a request to change its state.

value will always be of the correct state type, i.e. the type of the initial state passed to g_simple_action_new_stateful(). If an incorrect type is given when requesting to change the state, this signal is not emitted.

If no handler is connected to this signal then the default behaviour is to call g_simple_action_set_state() to set the state to the requested value. If you connect a signal handler then no default action is taken. If the state should change then you must call g_simple_action_set_state() from the handler.

An example of a 'change-state' handler:

static void
 change_volume_state (GSimpleAction *action,
                      GVariant      *value,
                      gpointer       user_data)
 {
   gint requested;

   requested = g_variant_get_int32 (value);

   // Volume only goes from 0 to 10
   if (0 <= requested && requested <= 10)
     g_simple_action_set_state (action, value);
 }
 

The handler need not set the state to the requested value. It could set it to any value at all, or take some other action.

Since:

2.30

upcall

default void upcall(MemorySegment sourceSimpleAction,
 MemorySegment value)

The upcall method is called from native code. The parameters are marshaled and run(org.gnome.glib.Variant) is executed.

toCallback

default MemorySegment toCallback(Arena arena)

Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment) method.

Specified by:

toCallback in interface FunctionPointer

Parameters:

arena - the arena in which the function pointer is allocated

Returns:

the native function pointer