Drawing a font on an offscreen image

Question

I'm trying to draw a font on my own offscreen image but I had to implement a few tweaks to get it to work and I would like to know how to do it properly. Here's my code:
  private int[] getPrintMetrics(Font fnt, String txt) {
    BufferedImage bi = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);
    Graphics2D bg = (Graphics2D)bi.getGraphics();
    FontRenderContext frc = bg.getFontRenderContext();
    TextLayout tl = new TextLayout(txt, fnt, frc);
    int ret[] = new int[2];
    ret[0] = (int)tl.getBounds().getWidth();
    ret[1] = (int)(tl.getBounds().getHeight() * 1.5);
//    ret[0] = (int)tl.getPixelBounds(frc, 0, 0).getWidth();
//    ret[1] = (int)(tl.getPixelBounds(frc, 0, 0).getHeight() * 1.5);
    //BUG! WHY IS HEIGHT TOO SMALL? I HAVE TO ADD 50%
    return ret;
  public void print(Font fnt, int x, int y, String txt, int clr) {
    int size[] = getPrintMetrics(fnt, txt);
    BufferedImage bi = new BufferedImage(size[0], size[1], BufferedImage.TYPE_INT_RGB);
    Graphics2D bg = (Graphics2D)bi.getGraphics();
    FontRenderContext frc = bg.getFontRenderContext();
    TextLayout tl = new TextLayout(txt, fnt, frc);
    //this method draws the outline only
    Shape shape = tl.getOutline(AffineTransform.getTranslateInstance(0, tl.getBounds().getHeight()));
    bg.setColor(new Color(clr));
    bg.draw(shape);
    bg.setColor(new Color(clr));
    bg.setFont(fnt);
    bg.drawString(txt, 0, -1 * tl.getBaselineOffsets()[tl.getBaseline()+2]);   //BUG! HOW DO I KNOW WHICH BASELINE TO USE?
    putPixels(bi.getRGB(0,0,size[0],size[1],null,0,size[0]), x, y, size[0], size[1], 0);
  }putPixels() is my own member that will draw to my own image buffer.
1) Why must I multiply the height by 1.5 in the getPrintMetrics() ?
2) How do I know which baseline to use (I just hacked it).
Thanks.

Answer 1

Why is the height so small?
new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);The graphics context for this BufferedImage is very small.
For more size increase the width and height dimensions.
Try this.
import java.awt.*;
import java.awt.font.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class GraphicsExercise {
    private JLabel getContent() {
        BufferedImage image = createImage();
        Graphics2D g2 = image.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
                            RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        Font font = new Font("dialog", Font.PLAIN, 36);
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        String s = "Hello World";
        LineMetrics metrics = font.getLineMetrics(s, frc);
        float height = metrics.getAscent() + metrics.getDescent();
        float width = (float)font.getStringBounds(s, frc).getWidth();
        float x = (image.getWidth() - width)/2f;
        float y = (image.getHeight() + height)/2 - metrics.getDescent();
        g2.drawString(s, x, y);
        g2.dispose();
        return new JLabel(new ImageIcon(image), JLabel.CENTER);
    private BufferedImage createImage() {
        int w = 240;
        int h = 165;
        int type = BufferedImage.TYPE_INT_RGB;
        BufferedImage image = new BufferedImage(w, h, type);
        Graphics2D g2 = image.createGraphics();
        g2.setBackground(UIManager.getColor("Panel.background"));
        g2.clearRect(0,0,w,h);
        g2.dispose();
        return image;
    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new GraphicsExercise().getContent());
        f.pack();
        f.setLocation(200,200);
        f.setVisible(true);
}