如何逐部分绘制图像？

Question

class DrawIma extends JPanel{
    protected void paintComponent(Graphics g) {

        super.paintComponent(g);
        for (int i=0;i<20;i++){
            for (int j=0;j<20;j++) {    
                g.drawImage(BuArr[i*20+j], 20*i, 20*j, 20, 20, null);
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

在这一部分中，BuArr 是从 BufferedImage 中分割出来的 400 个块，现在我希望将它们一一绘制，但是该方法不能单独绘制块，我该怎么做？

Answer 1

Swing 是单线程的，不是线程安全的。

这意味着您不应在 IU 线程（事件调度线程）内执行任何长时间运行或阻塞 (Thread.sleep) 操作。这也意味着您不能在 EDT 上下文之外更新、修改或创建 UI 元素。

相反，使用 Swing Timer 以指定的时间间隔生成重复的回调，并将图像的部分渲染为类似 BufferedImage 的东西，您可以通过其 paintComponent 方法将其绘制到组件上。 ..

请参阅Concurrency in Swing 和How to use Swing Timers 了解更多详情

因为这是一个很好的消磨时间

这会生成Rectangles 中的List 代表我要绘制的各个块，然后我随机化List 并运行Timer，从List 中选择最上面的Rectangle 和使用BufferedImage#getSubImage 将其从主绘制到缓冲区，然后绘制到屏幕上...

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestImage {

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

    public TestImage() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage master;
        private BufferedImage copy;

        private List<Rectangle> blocks;

        public TestPane() {
            setBackground(Color.BLACK);
            try {
                master = ImageIO.read(new File("..."));
                copy = new BufferedImage(master.getWidth(), master.getHeight(), BufferedImage.TYPE_INT_ARGB);
                Graphics2D g2d = copy.createGraphics();
                AlphaComposite composite = AlphaComposite.getInstance(AlphaComposite.CLEAR, 0.0f);
                g2d.setComposite(composite);
                g2d.setColor(new Color(0, 0, 0, 0));
                g2d.fillRect(0, 0, master.getWidth(), master.getHeight());
                g2d.dispose();

                int blockSize = 40;

                int width = master.getWidth();
                int height = master.getHeight();

                float aspect = Math.min(width, height) / (float) Math.max(width, height);

                int blockHeight = blockSize;
                blocks = new ArrayList<>(blockSize * 2);
                for (int y = 0; y < master.getHeight(); y += blockHeight) {
                    if (y + blockHeight > master.getHeight()) {
                        blockHeight = master.getHeight() - y;
                    }
                    int blockWidth = blockSize;
                    for (int x = 0; x < master.getWidth(); x += blockWidth) {
                        if (x + blockWidth > master.getWidth()) {
                            blockWidth = master.getWidth() - x;
                        }
                        Rectangle block = new Rectangle(x, y, blockWidth, blockHeight);
                        blocks.add(block);
                    }
                }
                Collections.shuffle(blocks);
                Timer timer = new Timer(40, new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        if (blocks.isEmpty()) {
                            ((Timer) e.getSource()).stop();
                        } else {
                            Graphics2D g2d = copy.createGraphics();
                            Rectangle block = blocks.remove(0);
                            g2d.drawImage(master.getSubimage(block.x, block.y, block.width, block.height), block.x, block.y, TestPane.this);
                            g2d.dispose();
                            repaint();
                        }
                    }
                });

                timer.start();

            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return master == null ? new Dimension(200, 200) : new Dimension(master.getWidth(), master.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            if (copy != null) {
                int x = (getWidth() - copy.getWidth()) / 2;
                int y = (getHeight() - copy.getHeight()) / 2;
                g2d.drawImage(copy, x, y, this);
            }
            g2d.dispose();
        }

    }

}