javafx.scene.command.CommandHandler Maven / Gradle / Ivy
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. JFXcore designates this
* particular file as subject to the "Classpath" exception as provided
* in the LICENSE file that accompanied this code.
*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package javafx.scene.command;
import javafx.scene.Node;
import javafx.util.Incubating;
/**
* {@code CommandHandler} provides an extension mechanism that defines a piece of behavior or configuration
* logic that is executed when a {@link Command} is attached to, or detached from, a {@link Node}.
*
* In this example, a {@code CommandHandler} is used to automatically set a {@code Button}'s text to
* the name of its attached command:
*
*
{@code
* // Define a behavior to apply the command title to Button controls.
* public class MyCommandHandler implements CommandHandler {
* @Override
* public void onAttached(Node node, Command command) {
* if (node instanceof Button b && command instanceof TaskCommand c) {
* b.textProperty().bind(c.titleProperty());
* }
* }
*
* @Override
* public void onDetached(Node node, Command command) {
* if (node instanceof Button b) {
* b.textProperty().unbind();
* }
* }
* }
*
* // Wire it up.
* var command = new TaskCommand("Custom Command");
* var handler = new MyCommandHandler();
* var button = new Button();
* button.setOnAction(new ActionEventBinding(command));
* button.setCommandHandler(handler);
* }
*
* Note that the {@link Command} class defines overridable {@link Command#onAttached onAttached} and
* {@link Command#onDetached onDetached} methods, which can also be used to implement behavior logic.
* The difference between those methods and {@code CommandHandler} is in scope:
* logic in a {@code Command} subclass generally applies to all nodes that use the command,
* while {@code CommandHandler} only applies to specific nodes on which the handler is set.
*
* @since JFXcore 18
*/
@Incubating
public interface CommandHandler {
/**
* Occurs when the command is attached to a {@link Node} by binding it to one of the {@code Node}'s events.
*
* When the command is bound to multiple events of a single {@code Node}, this method is only invoked once.
* Note that this method will be invoked once for each {@code Node} to which this command is attached.
*
* @param node the node to which the {@code command} is attached
* @param command the command
*/
void onAttached(Node node, Command command);
/**
* Occurs when the command is detached from a {@link Node}.
*
* This happens when the command is removed from its associated {@link EventBinding}, or if the
* {@code EventBinding} is removed from the {@code Node}.
* When the command is bound to multiple events of a single {@code Node}, the command is only detached
* after the last binding is removed. Note that this method will be invoked once for each {@code Node}
* from which this command is detached.
*
* @param node the node to which the {@code command} was attached
* @param command the command
*/
void onDetached(Node node, Command command);
}