How to convert Icon from JLabel to BufferedImage?

Question

Simple, very direct, but it looks like Google Uncle and I are confused.

I have one JLabel that already has its own Icon .

How to convert Icon derived from JLabel to BufferedImage ?

Is there a way: I tried to do some casting like this.

  final BufferedImage bf1 = (BufferedImage)((Image)jll_img.getIcon()); 

.. but it failed.

Answer 1

To leverage on @Andrew Thompson's answer , note that the object that implements Icon knows how to draw something, but it may not have been asked to do so. In contrast, BufferedImage has an “available image data buffer” that your program should display by calling the paintIcon() method. Here is an example.

Answer 2

 import java.awt.*; import java.awt.image.*; import javax.swing.*; import java.net.URL; class GetImage { public static void main(String[] args) throws Exception { final String text = "Mt Stromlo at sunset"; final URL url = new URL( "http://i.stack.imgur.com/lxthA.jpg"); SwingUtilities.invokeLater(new Runnable() { public void run() { ImageIcon imageIcon = new ImageIcon(url); JLabel imageLabel = new JLabel( text, imageIcon, SwingConstants.CENTER); JOptionPane.showMessageDialog(null, imageLabel); Icon icon = imageLabel.getIcon(); BufferedImage bi = new BufferedImage( icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_RGB); Graphics g = bi.createGraphics(); // paint the Icon to the BufferedImage. icon.paintIcon(null, g, 0,0); g.setColor(Color.WHITE); g.drawString(text,10,20); g.dispose(); JOptionPane.showMessageDialog( null, new JLabel(new ImageIcon(bi))); } }); } } 

Here are some old codes on the Sun forums for images that are created in memory.

 import java.awt.*; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import java.io.ByteArrayOutputStream; import java.util.Random; import javax.swing.*; class ImageCacheTest { private JLabel imageLabel; private Dimension halfScreenSize; private Random random; private JProgressBar memory; private Font bigFont = new Font("Arial", Font.BOLD, 30); private int count = 0; private int startMem = 0; private int maxMem = 0; private int peakMem = 0; private int useMem = 0; ImageCacheTest() { startMem = ((int) Runtime.getRuntime().freeMemory()); maxMem = ((int) Runtime.getRuntime().freeMemory()); peakMem = ((int) Runtime.getRuntime().freeMemory()); JPanel p = new JPanel(new BorderLayout(4, 4)); Dimension d = Toolkit.getDefaultToolkit().getScreenSize(); halfScreenSize = new Dimension(d.width / 2, d.height / 2); //halfScreenSize = new Dimension(d.width - 11, d.height - 51); random = new Random(); imageLabel = new JLabel(new ImageIcon(convertToFromBytes(getImage()))); memory = new JProgressBar(0, (int) Runtime.getRuntime().maxMemory()); p.add(imageLabel, BorderLayout.CENTER); p.add(memory, BorderLayout.SOUTH); JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setContentPane(p); f.setLocation(150, 150); f.pack(); f.setVisible(true); Runnable r = new Runnable() { @Override public void run() { while (true) { try { imageLabel.setIcon(new ImageIcon(convertToFromBytes(getImage()))); memory.setValue((int) Runtime.getRuntime().freeMemory()); useMem = ((int) Runtime.getRuntime().freeMemory()); Thread.sleep(30); } catch (InterruptedException ex) { //something exceptio }finally{ // alive that if required } } } }; Thread t = new Thread(r); t.start(); } private BufferedImage getImage() { GradientPaint gp = new GradientPaint(0f, 0f, new Color(127 + random.nextInt(128), 127 + random.nextInt(128), 127 + random.nextInt(128)), (float) halfScreenSize.width, (float) halfScreenSize.width, new Color(random.nextInt(128), random.nextInt(128), random.nextInt(128))); BufferedImage bi = new BufferedImage(halfScreenSize.width, halfScreenSize.height, BufferedImage.TYPE_INT_RGB); Graphics2D g2d = bi.createGraphics(); g2d.setPaint(gp); g2d.fillRect(0, 0, halfScreenSize.width, halfScreenSize.height); g2d.setFont(bigFont); g2d.setColor(Color.BLACK); if (maxMem < ((int) Runtime.getRuntime().freeMemory())) { maxMem = ((int) Runtime.getRuntime().freeMemory()); } if (peakMem > ((int) Runtime.getRuntime().freeMemory())) { peakMem = ((int) Runtime.getRuntime().freeMemory()); } useMem = ((int) Runtime.getRuntime().freeMemory()) - useMem; g2d.drawString("" + ++count, 20, 100); g2d.drawString("JVM memory status ---> ", 20, 195); g2d.drawString("tot. memory ---> " + ((int) Runtime.getRuntime().totalMemory()), 20, 240); g2d.drawString("max. memory ---> " + ((int) Runtime.getRuntime().maxMemory()), 20, 270); g2d.drawString("free on startUp ---> " + startMem, 20, 300); g2d.drawString("max free memory ---> " + maxMem, 20, 350); g2d.drawString("min free memory ---> " + peakMem, 20, 380); g2d.drawString("act free memory ---> " + ((int) Runtime.getRuntime().freeMemory()), 20, 410); g2d.drawString("usage of memory ---> " + useMem, 20, 450); g2d.dispose(); return bi; } /** Not entirely sure this method is necessary for indicating 'no cache', but since the claim was specific to byte arrays, we'll do it. */ private Image convertToFromBytes(BufferedImage image) { try { ByteArrayOutputStream baos = new ByteArrayOutputStream(); ImageIO.write(image, "png", baos); return Toolkit.getDefaultToolkit().createImage(baos.toByteArray()); } catch (Exception e) { return null; } } public static void main(String[] args) { Runnable r = new Runnable() { @Override public void run() { ImageCacheTest ict = new ImageCacheTest(); } }; SwingUtilities.invokeLater(r); } } 

Screenshot

Screenshot of this code with a width falling to & frac14; screen width.

Answer 3

You cannot throw ImageIcon into Image because it is not a subclass. ImageIcon has a getImage() method, which returns Image. See here

Answer 4

This is the easiest way:

 labelPicture = new JLabel("Picture"); labelPicture.setIcon(new ImageIcon("picture.png")); . . ImageIcon icon = (ImageIcon)labelPicture.getIcon() BufferedImage img = (BufferedImage)((Image) icon.getImage());