Question

我制作一个圆圈并使用4个按钮（左，上，上和下）移动它的代码可以工作，但不是从新位置移动它，而是从它的起始位置（y = 0和x = 0）移动）。

package movetheball;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
import javafx.geometry.Pos;

public class MoveTheBall extends Application {

@Override
public void start(Stage primaryStage) throws Exception {

    Circle circle = new Circle();

    circle.setRadius(50);
    circle.setStroke(Color.BLACK);
    circle.setFill(Color.WHITE);

    Button btn1 = new Button();
    btn1.setText("Left");
    btn1.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            double newY = 0; 
            double newX = 0;
            System.out.println("Went to the left.");
            newX = circle.getCenterX() - 10;

            circle.setTranslateX(newX);
            circle.setTranslateY(newY);
        }
    });

    Button btn2 = new Button();
    btn2.setText("Right");
    btn2.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            double newY = 0; 
            double newX = 0;
            System.out.println("Went to the right.");
            newX = circle.getCenterX() + 10;

            circle.setTranslateX(newX);
            circle.setTranslateY(newY);
        }
    });

    Button btn3 = new Button();
    btn3.setText("Up");
    btn3.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            double newY = 0; 
            double newX = 0;
            System.out.println("Went up.");
            newY = circle.getCenterY() - 10;

            circle.setTranslateX(newX);
            circle.setTranslateY(newY);
        }
    });
    Button btn4 = new Button();
    btn4.setText("Down");
    btn4.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            double newY = 0; 
            double newX = 0;
            System.out.println("Went down.");
            System.out.println("Went up.");
            newY = circle.getCenterY() + 10;

            circle.setTranslateX(newX);
            circle.setTranslateY(newY);
        }
    });


    BorderPane rootPane = new BorderPane();
    rootPane.setCenter(circle);
    HBox hb = new HBox(btn1, btn2, btn3, btn4);
    hb.setAlignment(Pos.CENTER);
    rootPane.setBottom(hb);




    Scene scene = new Scene(rootPane, 400, 400);
    primaryStage.setTitle("Move the circle!");
    primaryStage.setScene(scene);
    primaryStage.show();
}
}

如何将其更改为用户想要的位置并从旧位置转到新位置？

谢谢！

Answer 1

translateX和centerX是两个独立的属性，它们都会影响绘制圆的位置。如果您调整其中一个属性，则必须使用相同属性的先前值而不是其他属性。

（类似于y属性。）

您应该将事件处理程序的代码更改为以下内容：

// using only the translate properties
double newY = circle.getTranslateY();
System.out.println("Went to the left.");
double newX = circle.getTranslateX() - 10;

circle.setTranslateX(newX);
circle.setTranslateY(newY);

或

// using only the center properties
double newY = circle.getCenterY();
System.out.println("Went to the left.");
double newX = circle.getCenterX() - 10;

circle.setCenterX(newX);
circle.setCenterY(newY);

注意：代码中不需要与y坐标相关的任何内容，因为这些属性未被修改...

圆圈不会从新位置移动，而是从起始位置移动

1 个答案: