有些图像无法立即绘制

Question

我是Java GUI编程的新手。以下代码是我简化的问题。

单击Panel时会绘制两个图像。一个是使用drawVrImage()方法绘制的Red Box，另一个是使用drawRealImage()方法绘制的Red Star。所有图像中的两个沿着增加的行绘制。

这是结果图片：

点击5次后显示。但问题是drawRealImage()只会将其图像描绘4次，即使它被调用了5次。第一个红盒在哪里？为什么BufferedImage无法显示第一个红盒子。

GUI类仅用于加载图片。加载所有图像并在启动时放置HashMap。所以，我认为图像加载（Qwirkle.getImage()）不是问题。我认为缓冲图像没有Image Observer是个问题。但如果真的有问题。我怎么画第二个红盒子。

供您参考。这是代码说明。班级BIsource有一个BuffedImage。当我点击UserPanel时。 BufferedImage中的BIsource获取其图形并绘制图像。完成绘制图像后，UserPanel从BIsource获取该图像。并称为reapint()方法。 paintCompent()中的UserPanel方法仅适用于从BIsource实例中提取缓冲图像。

我该如何解决这个问题？

UserPanel类

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.util.HashMap;

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

public class UserPanel extends JPanel implements MouseListener {

    private BIsource draw;
    private BufferedImage bi;

    public UserPanel() {

        this.draw = new BIsource();
        this.bi = draw.getBI();
        this.addMouseListener(this);
    }

    @Override
    protected void paintComponent(Graphics g) {
        // TODO Auto-generated method stub
        g.drawImage(bi, 0, 0, this);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        this.draw.drawVrImage();
        this.draw.drawRealImage();
        this.draw.incIndex();
        bi = this.draw.getBI();
        this.repaint();
    }

    class BIsource {

        private BufferedImage biCanvas;

        private HashMap<String, BufferedImage> imageMap;

        private int index = 0;

        public BIsource() {

            // biCanvas Declaration
            biCanvas = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB_PRE);
            Graphics g = biCanvas.createGraphics();
            g.setColor(Color.blue);
            g.fillRect(0, 0, 500, 500);
            g.dispose();

            imageMap = new HashMap<>();
            this.createVrImage();
        }

        private void createVrImage() {
            BufferedImage vrImage = new BufferedImage(50, 50, BufferedImage.TYPE_INT_ARGB_PRE);
            Graphics g = vrImage.createGraphics();
            g.setColor(Color.red);
            g.fillRect(0, 0, 50, 48);
            g.dispose();

            this.imageMap.put("TEST IMAGE", vrImage);
        }

        public BufferedImage getBI() {
            return this.biCanvas;
        }

        public void drawVrImage() {
            Graphics g = biCanvas.createGraphics();
            g.drawImage(this.imageMap.get("TEST IMAGE"), 0, index * 50, null);
            g.dispose();
        }

        public void drawRealImage() {
            Graphics g = biCanvas.getGraphics();
            g.drawImage(Qwirkle.getImage("RED STAR"), 200, index * 50, null);
            g.dispose();
        }

        public void incIndex() {
            index += 1;
        }
    }

    public static void main(String[] args) {

        Qwirkle.loadQwirkleImage();

        JFrame mainFrame = new JFrame("Test Frame");
        mainFrame.setLayout(null);
        mainFrame.setSize(500, 500);
        mainFrame.setVisible(true);
        mainFrame.setBackground(Color.black);
        mainFrame.setLocation(800, 400);
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        UserPanel userPanel = new UserPanel();
        mainFrame.add(userPanel);
        userPanel.setSize(500, 500);
        userPanel.setVisible(true);

    }


    @Override
    public void mouseEntered(MouseEvent e) {}

    @Override
    public void mouseExited(MouseEvent e) {}

    @Override
    public void mousePressed(MouseEvent e) {}

    @Override
    public void mouseReleased(MouseEvent e) {}
}

Qwirkle Class

import java.awt.Image;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Random;

public class Qwirkle implements Serializable {

    private static HashMap<String, Image> qwirkleImages;

    // static initialize
    static {

    }

    public enum Color {
        CYAN, GREEN, ORANGE, PURPLE, RED, YELLOW
    }

    public enum Shape {
        CIRCLE, CLOVER, DIAMOND, RECTANGLE, STAR, URCHIN
    }

    private final Color color;
    private final Shape shape;
    private final int index;

    public Qwirkle(Color color, Shape shape, int index) {

        this.color = color;
        this.shape = shape;
        this.index = index;
    }

    public static void loadQwirkleImage() {

        if (Qwirkle.qwirkleImages == null) {
            Qwirkle.qwirkleImages = new HashMap<>();
                String key;
                try {
                    for (Qwirkle.Color color : Qwirkle.Color.values()) {
                        for (Qwirkle.Shape shape : Qwirkle.Shape.values()) {
                            key = new String(color.toString() + " " + shape.toString());
                            Qwirkle.qwirkleImages.put(key, GUI.loadImage(key + ".jpg"));
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
        } else {
            System.err.println("Already Loading all Qwirkle Image");
        }
    }

    public static Image getImage(String key) {
        return qwirkleImages.get(key);
    }

    synchronized public String getKey() {
        return new String(color.toString() + " " + shape.toString());
    }

    @Override
    public String toString() {
        return new String(color.toString() + " " + shape.toString() + " " + index);
    }

    public Color getColor() {
        return color;
    }

    public Shape getShape() {
        return shape;
    }


}

Answer 1

最后我得到了答案。我改变了HashMap对象。我使用HashMap来放置Image Class。但现在我将BufferedImage存储在HashMap中。它运作良好。当我第一次点击时，它会立即绘制一颗红星。然后我读到了Image和BufferedImage之间的区别。但是我不知道为什么Image不能很好地工作并且BufferedImage工作得很好。（请问你能得到吗？）

  

private HashMap<String, Image> qwirkleImages;

更改为

  

private HashMap<String, BufferedImage> qwirkleImages;

这是固定代码。这是result image

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.util.HashMap;

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

public class UserPanel extends JPanel implements MouseListener {

    private BIsource draw;
    private BufferedImage bi;

    public UserPanel() {

        this.draw = new BIsource();
        this.bi = draw.getBI();
        this.addMouseListener(this);
    }

    @Override
    protected void paintComponent(Graphics g) {
        // TODO Auto-generated method stub
        g.drawImage(bi, 0, 0, this);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        this.draw.drawVrImage();
        this.draw.drawRealImage();
        this.draw.incIndex();
        bi = this.draw.getBI();
        this.repaint();
    }

    class BIsource {

        private BufferedImage biCanvas;
//      private HashMap<String, Image> qwirkleImages;
        private HashMap<String, BufferedImage> qwirkleImages;
        private HashMap<String, BufferedImage> imageMap;

        private int index = 0;

        public BIsource() {
            this.qwirkleImages = new HashMap<>();
            this.loadAllImage();

            // biCanvas Declaration
            biCanvas = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB_PRE);
            Graphics g = biCanvas.createGraphics();
            g.setColor(Color.blue);
            g.fillRect(0, 0, 500, 500);
            g.dispose();

            imageMap = new HashMap<>();
            this.createVrImage();
        }

        public void loadAllImage() {
            String key;
            try {
                for (Qwirkle.Color color : Qwirkle.Color.values()) {
                    for (Qwirkle.Shape shape : Qwirkle.Shape.values()) {
                        key = new String(color.toString() + " " + shape.toString());
                        qwirkleImages.put(key, GUI.loadImage2(key + ".jpg"));
                        System.out.println(key);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        private void createVrImage() {
            BufferedImage vrImage = new BufferedImage(50, 50, BufferedImage.TYPE_INT_ARGB_PRE);
            Graphics g = vrImage.createGraphics();
            g.setColor(Color.red);
            g.fillRect(0, 0, 50, 48);
            g.dispose();

            this.imageMap.put("TEST IMAGE", vrImage);
        }

        public BufferedImage getBI() {
            return this.biCanvas;
        }

        public void drawVrImage() {
            Graphics g = biCanvas.createGraphics();
            g.drawImage(this.imageMap.get("TEST IMAGE"), 0, index * 50, null);
            g.dispose();
        }

        public void drawRealImage() {
            Graphics g = biCanvas.getGraphics();
            Image image = this.qwirkleImages.get("RED STAR");
            if (image == null) {
                System.out.println("image is null");
            }
            g.drawImage(image, 200, index * 50, null);
            System.out.println("DRAW Real");
            g.dispose();
        }

        public void incIndex() {
            index += 1;
        }
    }

    public static void main(String[] args) {

        System.out.println("load all images");
        JFrame mainFrame = new JFrame("Test Frame");
        mainFrame.setLayout(null);
        mainFrame.setSize(500, 500);
        mainFrame.setVisible(true);
        mainFrame.setBackground(Color.black);
        mainFrame.setLocation(800, 400);
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        UserPanel userPanel = new UserPanel();
        mainFrame.add(userPanel);
        userPanel.setSize(500, 500);
        userPanel.setVisible(true);

    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mousePressed(MouseEvent e) {
    }

    @Override
    public void mouseReleased(MouseEvent e) {
    }
}