主要問題是您在Event Dispatching Thread的上下文中執行長時間運行的任務，該任務負責處理重新繪製請求等。
@Override
public void actionPerformed(ActionEvent e) {
//...
// Nothing will be updated until after the
// actionPerformed method exists
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
System.out.println(i + " " + j);
Color c = new Color(image.getRGB(j, i));
panel.setBackground(c);
panel.invalidate();
panel.validate();
panel.repaint();
}
}
你有另外一個問題是，你必須只能從的EDT
根據您的實際需要範圍內修改UI的狀態，你可以使用一個SwingWorker，這將允許您在從EDT上下文更新UI的同時處理背景中的像素，但是，由於SwingWorker合併了更新，因此可能會錯過顏色更改。
更好的解決方案可能是使用java.swing.Timer，它允許您觸發在EDT上下文中觸發的指定時間段的更新。
見Concurrency in Swing瞭解更多詳情...
已更新，例如
爲了繪製象素，你需要一些東西來吸引他們的。現在，您可以簡單地將要繪製的每個像素添加到陣列中，並在每次需要重新繪製組件時循環該陣列，但這種方法很貴...
取而代之的是，某些類型的緩衝區，在其上繪製像素，然後將該緩衝區繪製到組件，這應該更快。
基本上，允許您提供預期的圖像的高度和寬度，然後根據您的需要提供每個像素..
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
@Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (img != null) {
int x = (getWidth() - img.getWidth())/2;
int y = (getHeight() - img.getHeight())/2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
在Performing Custom Painting瞭解更多詳情請看...
然後你需要一些方法來處理原始圖像和更新圖像面板...現在，根據更新的要求，我會使用SwingWorker，原因是SwingWorker可以緩存傳回給EDT，這允許後臺線程繼續處理並緩存輸出直到EDT（和系統）是準備好處理它...
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
@Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
@Override
protected Void doInBackground() throws Exception {
int pixelCount = (int) (points.size() * 0.005);
while (!points.isEmpty()) {
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
return null;
}
}
基本上，這SwingWorker建立的「像素點」 a List，它使用該列表中隨機從列表中刪除點，生成虛擬Pixel和publish回到EDT進行處理。工作人員一次處理大約0.5％的像素，這意味着工作總是試圖將一束「像素」發回到EDT，而不是一次一個。
最後，它將yield允許其他線程運行（與希望的EDT更新它自己）
的650x975的圖像需要大約1M和10S充分渲染器
並全面代碼...
import core.util.StopWatch;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.Timer;
public class PixelShower implements ActionListener {
private static final long serialVersionUID = 2916361361443483318L;
private JFileChooser fc = null;
private JMenuItem item1, item2;
private BufferedImage image = null;
private ImagePane panel = null;
private int width = 0;
private int height = 0;
private BorderLayout card;
private Container contentPane;
public PixelShower() {
JFrame frame = new JFrame("Image Extraction Tool");
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = frame.getContentPane();
panel = new ImagePane();
card = new BorderLayout();
panel.setLayout(card);
panel.setBackground(Color.white);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
menuBar.add(menu);
item1 = new JMenuItem("Browse an image");
item2 = new JMenuItem("Exit");
item1.addActionListener(this);
item2.addActionListener(this);
menu.add(item1);
menu.add(item2);
frame.setJMenuBar(menuBar);
contentPane.add(panel);
frame.setVisible(true);
}
public static void main(String[] args) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
@Override
public void run() {
PixelShower img = new PixelShower();
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == item1) {
if (fc == null) {
fc = new JFileChooser();
}
int retVal = fc.showOpenDialog(null);
if (retVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
image = ImageIO.read(file);
panel.reset(image.getWidth(), image.getHeight());
PixelExposerWorker worker = new PixelExposerWorker(image, panel);
worker.execute();
} catch (IOException e1) {
e1.printStackTrace();
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
if (e.getSource() == item2) {
System.exit(0);
}
}
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
@Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (img != null) {
int x = (getWidth() - img.getWidth())/2;
int y = (getHeight() - img.getHeight())/2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
public class Pixel {
private int x;
private int y;
private int color;
public Pixel(int x, int y, int color) {
this.x = x;
this.y = y;
this.color = color;
}
public int getColor() {
return color;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
@Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
@Override
protected Void doInBackground() throws Exception {
StopWatch sw = StopWatch.newInstance().start();
int pixelCount = (int) (points.size() * 0.005);
System.out.println("pixelCount = " + pixelCount + "; " + points.size());
while (!points.isEmpty()) {
StopWatch sw1 = StopWatch.newInstance().start();
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
System.out.println("Took " + sw.stop());
return null;
}
}
}
'setBackground（...）'方法將整個JPanel的背景顏色設置爲傳入的顏色，它不會設置任何「逐個像素」的東西。此外，根據Swing的線程規則，將顯示的唯一顏色將是傳遞給'setBackground（...）'的最後一個顏色。 –