How to rotate text together with a Rectangle2D?

Question

Hi forum
I hope you can help me out here. See the follow code example. I have a Rectangle2D, in which some text is rendered. What I'm trying to do here is the following: rotate the Rectangle2D - no problem here - but the text should follow - ie. still be rendered the same way inside the Rectangle2D after the rotation transform is applied. The theta value is just an example - it should work the same for any theta value.
Ie - after the rotation, the text is drawn with the first letter just right of the left angle of the rotated Rectangle2D, just as with the original drawn text.
I'm aware, that the key to doing this is to figure out what point to rotate the text around. I would believe, that the correct answer would be the same point as the Rectangle2D, but that doesn't seem to work, as you can see, if you run the code. Can someone help me to get this to work correctly?
Any help would be appreciated! Thanks in advance!
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
public class ScaleToFill extends JPanel {
    Rectangle2D.Float rect = new Rectangle2D.Float(200,200,220,35);
    float theta = 1.1748778437843f;
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        Font font = g2.getFont().deriveFont(18f);
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        String s = "This text should be rotated";
        float width = (float)font.getStringBounds(s, frc).getWidth();
        LineMetrics lm = font.getLineMetrics(s, frc);
        float height = lm.getAscent() + lm.getDescent();
        // Draw text as-is.
        // Scale text into rect.
        float xScale = rect.width / width;
        float yScale = rect.height / height;
        // Locate string origin.
        double x = rect.x;
        double y = rect.y + rect.height - yScale*lm.getDescent();
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);
        float scale;
        if (xScale > yScale)
          scale = yScale;
        else
          scale = xScale;
        at.scale(scale, scale);
        AffineTransform rotator = new AffineTransform();
        rotator.rotate(theta, rect.getX()+(rect.getWidth() / 2), rect.getY()+(rect.getHeight() / 2) );
        GeneralPath rect2 = new GeneralPath(rotator.createTransformedShape(rect));
        g2.draw(rect);
        g2.draw(rect2);
        g2.setFont(font.deriveFont(at));
        g2.setPaint(Color.red);
        g2.drawString(s, 0, 0);
        at.rotate(theta, rect.getX()+(rect.getWidth() / 2), rect.getY()+(rect.getHeight() / 2) );
        g2.draw(rect2);
        Font rotateFont = font.deriveFont(rotator);
        g2.setFont(rotateFont);
        g2.setPaint(Color.red);
        g2.drawString(s, 0, 0);
        // Check scaled string bounds.
    public static void main(String[] args) {
        ScaleToFill test = new ScaleToFill();
        test.setPreferredSize(new Dimension(800,600));
        JFrame f = new JFrame();
        f.getContentPane().add(test);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
        System.out.println(new Color(0,255,0,0));
}

Answer 1

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
public class STF extends JPanel {
    Rectangle2D.Float rect = new Rectangle2D.Float(200,200,220,35);
//    float theta = 1.1748778437843f;
    double theta = Math.PI/6;
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
                            RenderingHints.VALUE_FRACTIONALMETRICS_ON);
        g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,
                            RenderingHints.VALUE_STROKE_PURE);
        g2.setPaint(Color.blue);
        Font font = g2.getFont().deriveFont(18f);
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        String s = "This text should be rotated";
        float width = (float)font.getStringBounds(s, frc).getWidth();
        LineMetrics lm = font.getLineMetrics(s, frc);
        float height = lm.getAscent() + lm.getDescent();
        // Scale text into rect.
        float xScale = rect.width / width;
        float yScale = rect.height / height;
        float scale = (xScale > yScale) ? yScale : xScale;
        // Locate string origin.
        double x = rect.x;
        double y = rect.y + (rect.height + scale*height)/2 - scale*lm.getDescent();
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);
        at.scale(scale, scale);
        AffineTransform rotator = new AffineTransform();
        rotator.rotate(theta, rect.getCenterX(), rect.getCenterY());
        GeneralPath rect2 = new GeneralPath(rotator.createTransformedShape(rect));
        // Draw with no rotation.
        g2.draw(rect);
        g2.setPaint(Color.red);
        g2.setFont(font.deriveFont(at));
        g2.drawString(s, 0, 0);
        // Rotate once.
        g2.setPaint(Color.blue);
        g2.draw(rect2);
        rotator.concatenate(at);
        g2.setFont(font.deriveFont(rotator));
        g2.setPaint(Color.red);
        g2.drawString(s, 0, 0);
        // Rotate again.
        rotator.setToIdentity();
        rotator.rotate(2*theta, rect.getCenterX(), rect.getCenterY());
        rect2 = new GeneralPath(rotator.createTransformedShape(rect));
        g2.setPaint(Color.blue);
        g2.draw(rect2);
        rotator.concatenate(at);
        g2.setFont(font.deriveFont(rotator));
        g2.setPaint(Color.red);
        g2.drawString(s, 0, 0);
        // Check scaled string bounds.
        // this was handled by the fractional metrics rendering hint
    public static void main(String[] args) {
        STF test = new STF();
        test.setPreferredSize(new Dimension(800,600));
        JFrame f = new JFrame();
        f.getContentPane().add(test);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
}