how to achieve javafx mouse event “push and hold”?

问题:

I am developing a JavaFX project and I need something similar to a TouchEvent that characterizes a "push and hold" event. But It should be mapped as a MouseEvent because I'm having troubles with touch events on Linux. For instance, in Ubuntu, it won't respond to touch events.

Please, let me know if you have any ideas about how to fire a MouseEvent whenever a "push and hold" occurs on Linux?

回答1:

Just use a PauseTransition as a timer for the "hold". Start it if the mouse is pressed, stop it if it's released or dragged.

import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
import javafx.util.Duration;

public class MousePressAndHoldTest extends Application {

    @Override
    public void start(Stage primaryStage) {
        Pane root = new Pane();

        addPressAndHoldHandler(root, Duration.seconds(1), 
                event -> System.out.println("Press and hold"));


        primaryStage.setScene(new Scene(root, 400, 400));
        primaryStage.show();
    }

    private void addPressAndHoldHandler(Node node, Duration holdTime, 
            EventHandler<MouseEvent> handler) {

        class Wrapper<T> { T content ; }
        Wrapper<MouseEvent> eventWrapper = new Wrapper<>();

        PauseTransition holdTimer = new PauseTransition(holdTime);
        holdTimer.setOnFinished(event -> handler.handle(eventWrapper.content));


        node.addEventHandler(MouseEvent.MOUSE_PRESSED, event -> {
            eventWrapper.content = event ;
            holdTimer.playFromStart();
        });
        node.addEventHandler(MouseEvent.MOUSE_RELEASED, event -> holdTimer.stop());
        node.addEventHandler(MouseEvent.DRAG_DETECTED, event -> holdTimer.stop());
    }


    public static void main(String[] args) {
        launch(args);
    }
}