用于移动形状的 JavaFx 按钮事件处理程序

Question

我上周刚开始使用 JavaFx，但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。我有按钮设置，名称为左、右、上、下，按下时应将圆圈移动到窗格内。我的问题是我根本无法让圈子响应我的事件处理程序。我看到了另一个教程，其中包含按键来移动圆圈，我正在尝试类似的东西，但用按钮代替。任何帮助我朝着正确的方向前进都会非常感谢。

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，但它不是您场景的一部分。去掉你在start(...)方法中创建的pane和circle，把circlePane放在BorderPane的中间。

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。所以让CirclePane 成为Pane 的子类，而不是StackPane。或者，您可以调用circle.setManaged(false); 以防止StackPane 定位circle。