移动形状的JavaFx按钮事件处理程序

Question

我上周刚刚启动JavaFx，在尝试在窗格中设置圆圈以响应按钮事件处理程序时遇到问题。我设置了名称为左、右、上、下的按钮，当按下这些按钮时，应该会在窗格内移动圆圈。我的问题是，我根本无法让圆圈响应我的事件处理程序。我看到了另一个教程，其中包含了按键来移动圆圈，我正在尝试类似的方法，但使用了按钮。如果能帮我找到正确的方向，我将不胜感激。

package movingball;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
public class MovingBall extends Application{
  private CirclePane circlePane = new CirclePane();

@Override
public void start(Stage primaryStage) {
    StackPane pane = new StackPane();
    Circle circle = new Circle(50);
    circle.setStroke(Color.BLACK);
    circle.setFill(Color.WHITE);
    pane.getChildren().add(circle);
    HBox hBox = new HBox();
    hBox.setSpacing(10);
    hBox.setAlignment(Pos.CENTER);
    Button btLeft = new Button("Left");
    Button btRight = new Button("Right");
    Button btUp = new Button("Up");
    Button btDown = new Button("Down");
    hBox.getChildren().addAll(btLeft, btRight, btUp, btDown);
    btLeft.setOnAction(new LeftHandler());
    btRight.setOnAction(new RightHandler());
    btUp.setOnAction(new UpHandler());
    btDown.setOnAction(new DownHandler());

    BorderPane borderPane = new BorderPane();
    borderPane.setCenter(pane);
    borderPane.setBottom(hBox);
    BorderPane.setAlignment(hBox, Pos.CENTER);
    // Create a scene and place it in the stage
    Scene scene = new Scene(borderPane, 500, 350);
    primaryStage.setTitle("Move the Ball"); // Set the stage title
    primaryStage.setScene(scene); // Place the scene in the stage
    primaryStage.show(); // Display the stage
  }

class LeftHandler implements EventHandler<ActionEvent> {
    @Override
    public void handle(ActionEvent event) {
        circlePane.left();
    }
}
class RightHandler implements EventHandler<ActionEvent> {
    @Override
    public void handle(ActionEvent event) {
        circlePane.right();
    }
}
class UpHandler implements EventHandler<ActionEvent> {
    @Override
    public void handle(ActionEvent event) {
        circlePane.up();
    }
}
class DownHandler implements EventHandler<ActionEvent> {
    @Override
    public void handle(ActionEvent event) {
        circlePane.down();
    }
}
class CirclePane extends StackPane {
    private Circle circle = new Circle(50);
    public CirclePane() {
        getChildren().add(circle);
        circle.setStroke(Color.BLACK);
        circle.setFill(Color.WHITE);
    }
    public void left() {
        circle.setCenterX(circle.getCenterX() - 10);
    }
    public void right() {
        circle.setCenterX(circle.getCenterX() + 10);
    }
    public void up() {
        circle.setCenterY(circle.getCenterY() - 10);
    }
    public void down() {
        circle.setCenterY(circle.getCenterY() + 10);
    }
}

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

Answer 1

第一个问题是您正在移动CirclePane，但它不是场景的一部分。删除在start(...)方法中创建的pane和circle，将circlePane放在BorderPane的中心。

第二个问题是StackPane将使圆居中，调整其坐标系以使其在圆移动时保持居中。因此，使CirclePane成为Pane的一个子类，而不是StackPane。或者，您可以调用circle.setManaged(false);来阻止StackPane定位circle。