Question

我创建了这个类，它创建了一个带有背景图片的JFrame。我想在那张照片上画一个圆圈。但我只能显示图片或图片，图片上不会显示圆圈。我从我的主要叫这个班级。

对不起，如果这是一个新手问题：）

package worldofzuul;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.*;

/**
 *
 * @author JesperJørgensen
 */
public class GraphicsFrame extends JFrame {

    private JPanel man = new JPanel();

    void setupframe() {
        // Here we create the Frame 
        JFrame frame = new JFrame(); // create the frame
        frame.setLayout(new BorderLayout());
        frame.setResizable(false);

        frame.setTitle("Zuul the ultimate fridaybar game"); // sets title in top bar of frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // what will happens when the frame close (exit)

        //Here we set the background image (the map which we walk in)
        ImageIcon icon = new ImageIcon("src/Image/Kort.png");
        frame.add(new JLabel(icon));

        frame.setContentPane(new DrawPane());

        frame.pack(); // sets the size of the frame to fit all objects    inside.
        frame.setVisible(true); // show the frame 

    }

    class DrawPane extends JPanel {

        @Override
        protected void paintComponent(Graphics g) {
            g.setColor(Color.red);
            g.fillRect(20, 20, 100, 200);

        }
    }

}

Answer 1

setContentPane删除了ImageIcon只有DrawPane

的可见元素

Answer 2

见评论：

//always post an MCVE
//see http://stackoverflow.com/help/mcve
//include imports 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 *
 * @author JesperJørgensen
 */
public class GraphicsFrame extends JFrame {/*JFrame  subclassing is never used*/

    //This JPanel is never used
    private JPanel man = new JPanel();
    Image image;

    void setupframe() {
        // Here we create the Frame
        JFrame frame = new JFrame(); // create the frame
        frame.setSize(500,500);
        frame.setLayout(new BorderLayout());
        frame.setResizable(false);

        frame.setTitle("Zuul the ultimate fridaybar game"); // sets title in top bar of frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // what will happens when the frame close (exit)

        //initialize image
        image = new ImageIcon("src/Image/Kort.png").getImage();
        //frame.add(new JLabel(image));

        frame.setContentPane(new DrawPane());

        //if you don't use preferred sizes pack() will set frame to size 0.
        //frame.pack(); // sets the size of the frame to fit all objects    inside.
        frame.setVisible(true); // show the frame

    }

    class DrawPane extends JPanel {

        @Override
        protected void paintComponent(Graphics g) {

            //add draw image to paint
            g.drawImage(image,0, 0, null);

            //this draws a rectangle. change to circle if desired
            g.setColor(Color.red);
            g.fillRect(20, 20, 100, 200);

        }
    }

    //include main to make it an MCVE
    public static void main(String args[]) {

        new GraphicsFrame().setupframe();
    }
}

要使用此类正在扩展JFrame的事实，您可能希望像这样实现它：

public class GraphicsFrame extends JFrame {

    Image image;

    //introduce constructor
    public GraphicsFrame() {

        setupframe();
    }

    void setupframe() {

        // no need to create a frame. This class is a JFrame
        //JFrame frame = new JFrame(); // create the frame
        setSize(500,500);
        setLayout(new BorderLayout());
        setResizable(false);

        setTitle("Zuul the ultimate fridaybar game"); // sets title in top bar of frame
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // what will happens when the frame close (exit)

        //initialize image
        image = new ImageIcon("src/Image/Kort.png").getImage();

        setContentPane(new DrawPane());

        setVisible(true); // show the frame
    }

    class DrawPane extends JPanel {

        @Override
        protected void paintComponent(Graphics g) {

            //add draw image to paint
            g.drawImage(image,0, 0, null);

            //this draws a circle
            g.setColor(Color.red);
            g.drawOval(100, 100, 40, 40);
        }
    }

    public static void main(String args[]) {

        new GraphicsFrame();
    }
}

根据需要，请不要犹豫要求澄清。

如何在JFrame上绘制

2 个答案: