Using Graphics2D to overlay text on a BufferedImage and return a BufferedImage

Question

I have checked similarly named questions, but they don't answer this use case.

Basically, I was to overlay some text (text) at a given coordinate (x,y) I have the below function in a package;

protected BufferedImage Process2(BufferedImage image){     Graphics2D gO = image.createGraphics();     gO.setColor(Color.red);     gO.setFont(new Font( "SansSerif", Font.BOLD, 12 ));     gO.drawString(this.text, this.x, this.y);     System.err.println(this.text+this.x+this.y);     return image; } 

I feel like im missing something patently obvious; every reference to Graphics2D I can find is dealing with either games or writing directly to a file but I just want a BufferedImage returned. with the overlay 'rendered'

In the current code, the image appears out the end unchanged.

Thanks!

Answer 1

The method drawString() uses x and y for the leftmost character's baseline. Numbers typically have no descenders; if the same is true of text, a string drawn at position (0,0) will be rendered entirely outside the image. See this example.

Addendum: You may be having trouble with an incompatible color model in your image. One simple expedient is to render the image and then modify it in situ.

import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.net.URL; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel;  /**  * @see https://stackoverflow.com/questions/2658663  */ public class TextOverlay extends JPanel {      private BufferedImage image;      public TextOverlay() {         try {             image = ImageIO.read(new URL(                 "http://cdn.sstatic.net/stackexchange/img/logos/so/so-logo.png"));         } catch (IOException e) {             e.printStackTrace();         }         image = process(image);     }      @Override     public Dimension getPreferredSize() {         return new Dimension(image.getWidth(), image.getHeight());     }      private BufferedImage process(BufferedImage old) {         int w = old.getWidth() / 3;         int h = old.getHeight() / 3;         BufferedImage img = new BufferedImage(             w, h, BufferedImage.TYPE_INT_ARGB);         Graphics2D g2d = img.createGraphics();         g2d.drawImage(old, 0, 0, w, h, this);         g2d.setPaint(Color.red);         g2d.setFont(new Font("Serif", Font.BOLD, 20));         String s = "Hello, world!";         FontMetrics fm = g2d.getFontMetrics();         int x = img.getWidth() - fm.stringWidth(s) - 5;         int y = fm.getHeight();         g2d.drawString(s, x, y);         g2d.dispose();         return img;     }      @Override     protected void paintComponent(Graphics g) {         super.paintComponent(g);         g.drawImage(image, 0, 0, null);     }      private static void create() {         JFrame f = new JFrame();         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         f.add(new TextOverlay());         f.pack();         f.setVisible(true);     }      public static void main(String[] args) {         EventQueue.invokeLater(new Runnable() {              @Override             public void run() {                 create();             }         });     } }