跟踪 javafx 中绑定的节点的变化

Question

我想要这篇文章中要求的同样的东西 track changes of nodes bound in JavaFX

我有这样的事情： （已编辑） SSCCE：

public class FloatCircle {

Node node;


Circle rectangle;
Bounds localToScreen;
static ArrayList<ObjectBinding> list = new ArrayList<>();
private ObjectBinding<Bounds> boundsInScene ;
Pane root ;

public FloatCircle(Node node,Pane root) {
    this.node = node;
   this.root =root;
    this.rectangle = new Circle();
    this.rectangle.setManaged(false);

    initSetting();

}



public Circle getFloatCircle() {
    return rectangle;
}

public void initSetting() {

   boundsInScene = Bindings.createObjectBinding(
            () -> node.localToScene(node.getBoundsInLocal()),
            node.localToSceneTransformProperty(),
            node.boundsInLocalProperty());
    boundsInScene.addListener(new ChangeListener<Bounds>() {

        @Override
        public void changed(ObservableValue<? extends Bounds> observable, Bounds oldValue, Bounds newValue) {
             setLocation(newValue);
            System.err.println("CHANGED!!!!!!");
        }

    });
    localToScreen = node.localToScene(node.getBoundsInLocal());
    setLocation(localToScreen);
    addCircle();
}

public void setLocation(Bounds localToScreen) {
    int r = 10;
            rectangle.setCenterX(localToScreen.getMinX() - r);
            rectangle.setCenterY(localToScreen.getMinY() - 5);
            rectangle.setRadius(r);

    //    return rect;

}

public void addCircle(){
            root.getChildren().add(rectangle);

}

}




public class SelfContained extends Application {

ArrayList<Node> nodes = new ArrayList<>();

@Override
public void start(Stage primaryStage) {
    Button btn = new Button();

    StackPane root = new StackPane();
    root.getChildren().add(btn);
    nodes.add(btn);

    Scene scene = new Scene(root, 300, 250);

    primaryStage.setTitle("Hello World!");
    primaryStage.setScene(scene);
    primaryStage.show();

    for (int i = 0; i < nodes.size(); i++) {
        Node n = nodes.get(i);
        FloatCircle floatCircle = new FloatCircle(n, root);

    }
}

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    launch(args);
}

}

但问题是更改的方法没有正确调用......它只被调用了一次......如果我在更改的方法而不是旧的方法中添加这个代码它被正确调用......但它是非常非常慢

           FloatCircle fc = new FloatCircle(node);
           fc.rectangle = rectangle ;
           fc.setLocation(newValue, directionID, alignment);

谁能帮帮我？ 谢谢...

Answer 1

由于本例中的Button 和Circle 位于同一个父窗格中，显然您可以通过将圆的位置绑定到按钮的boundsInParentProperty() 来更简单（有效）地完成此操作。我假设您这样做是因为您有一个真实的应用程序，其中两个节点位于不同的父节点中。

看起来localToSceneTransformProperty() 正在过早地收集垃圾（另请参阅this）。您可以使用侦听器而不是绑定来解决此问题：

public static class FloatCircle {

    Node node;

    Circle rectangle;
    Pane root;

    public FloatCircle(Node node, Pane root) {
        this.node = node;
        this.root = root;
        this.rectangle = new Circle();
        this.rectangle.setManaged(false);

        initSetting();

    }

    public Circle getFloatCircle() {
        return rectangle;
    }

    public void initSetting() {

        ChangeListener<Object> updater = (obs, oldValue, newValue) -> 
            setLocation(node.localToScene(node.getBoundsInLocal()));
        node.boundsInLocalProperty().addListener(updater);
        node.localToSceneTransformProperty().addListener(updater);

        setLocation(node.localToScene(node.getBoundsInLocal()));
        addCircle();
    }

    public void setLocation(Bounds localToScreen) {
        int r = 10;
        rectangle.setCenterX(localToScreen.getMinX() - r);
        rectangle.setCenterY(localToScreen.getMinY() - 5);
        rectangle.setRadius(r);
    }

    public void addCircle() {
        root.getChildren().add(rectangle);

    }

}