BufferedImage draw white when I say red

Question

It must be a very stupid decision, but I'm blind.

I have this code:

BufferedImage bi = new BufferedImage(800, 600, BufferedImage.TYPE_INT_RGB); bi.getGraphics().setColor(Color.red); bi.getGraphics().fillRect(300, 350, 100, 50); ImageIO.write(bi, "jpeg", new File("image.jpg")); 

And I get this black rectangle 800x600 and the white rectangle in it. Why is this?

Thanks:)

Answer 1

Each time you call getGraphics () on a BufferedImage, you get a new Graphics object, so setting the color to one does not set it to the next. So cache the graphic.

 BufferedImage bi = new BufferedImage(800, 600, BufferedImage.TYPE_INT_RGB); Graphics g = bi.getGraphics(); g.setColor(Color.red); g.fillRect(300, 350, 100, 50); ImageIO.write(bi, "jpeg", new File("/home/dave/image.jpg")); 

Answer 2

For reference, here is an example that may be useful for processing a graphics context.

 import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics2D; import java.awt.GridLayout; import java.awt.image.BufferedImage; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; /** @http://stackoverflow.com/questions/5843426 */ public class RedOrWhite extends JPanel { private static final int W = 800; private static final int H = 600; public RedOrWhite() { this.setLayout(new GridLayout()); this.setPreferredSize(new Dimension(W, H)); int w = W / 2; int h = H / 2; int r = w / 5; BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); Graphics2D g = bi.createGraphics(); g.setColor(Color.gray); g.fillRect(0, 0, w, h); g.setColor(Color.blue); g.fillRect(w / 2 - r, h / 2 - r / 2, 2 * r, r); g.dispose(); this.add(new JLabel(new ImageIcon(bi), JLabel.CENTER)); } private void display() { JFrame f = new JFrame("RedOrWhite"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(this); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new RedOrWhite().display(); } }); } }