A Rotated Square Panel in Java Gui

A rotated square panel in Java GUI

The critical thing seems to be painting the components after rotating the graphics context. Here's an example:

Addendum 1:As @Atreys comments, the rotated components are drawn, but interact poorly. If the components must remain usable, event coordinates should also be transformed. Compare this (considerably) more complex example that mirrors components.

Addendum 2: If you also need to transform the mouse coordinates, this example may be helpful.

Addendum 3: Alternatively, consider the drawString() examples examined here.

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/** @see https://stackoverflow.com/questions/6333464 */
public class RotatePanel extends JPanel {

    public RotatePanel() {
        this.setPreferredSize(new Dimension(320, 240));
        this.add(new JLabel("Hello World!", JLabel.CENTER));
    }

    @Override
    public void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g;
        int w2 = getWidth() / 2;
        int h2 = getHeight() / 2;
        g2d.rotate(-Math.PI / 2, w2, h2);
        super.paintComponent(g);
    }

    private void display() {
        JFrame f = new JFrame("RotatePanel");
        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 RotatePanel().display();
            }
        });
    }
}

How to make a rotated panel in java

Yes, rotate the image around its center, as shown in this example.

Rotate what is painted in a JPanel keeping the centroid's location

Found. This example helped me. I updated the paintComponent(Graphics gr) method like this:

    @Override
    public void paintComponent(Graphics gr) {
        super.paintComponent(gr);
        Graphics2D g2 = (Graphics2D) gr;
        if (angle != 0) {
            // Moving to centroid
            g2.translate(getWidth()/2, getHeight()/2);
            g2.rotate(angle);
            // Moving back but using the string's dimensions
            // instead of the bounds (which have been changed)
            g2.translate(-stringWidth/2, -stringHeight/2);
        }
        g2.drawString("Hello World", 2, 12);
        if (angle != 0) {
            // Revert the transformation matrix back to its initial state
            g2.translate(stringWidth/2, stringHeight/2);
            g2.rotate(-angle);
            g2.translate(-getWidth()/2, -getHeight()/2);
        }
    }

The key is that the Graphics2D#rotate() executes the following calls:

translate(x, y);
rotate(theta);
translate(-x, -y);

But in my case I didn't want to translate back exactly the same amount as the original translation. I had to use the string's dimensions.

How to draw and rotate square inside center of other square?

You could first draw your figure around the origin (that's easy) and then translate:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setSize(400, 400);
        frame.setVisible(true);

        frame.add(new JPanel() {

            @Override
            protected void paintComponent(Graphics g) {
                Graphics2D g2d = (Graphics2D) g;

                double alpha = Math.toRadians(5);
                double factor = 1 / (Math.sin(alpha) + Math.cos(alpha));
                double size = 200;

                g2d.translate(size, size);

                for (int i = 0; i < 20; i++) {
                    g2d.setColor(i % 2 == 0 ? Color.black : Color.green);

                    int intSize = (int) Math.round(size);

                    g2d.fillRect(-intSize / 2, -intSize / 2, intSize, intSize);

                    size = size * factor;

                    g2d.rotate(alpha);
                }
            }
        });
    }
}

Rotate BufferedImage Inside JPanel

I solved my own issue. The problem lay in the code:

myPicture.getType()

Since there is a lot of variability in the types of images you could put in to the program, the results are going to be unpredictable when you start drawing into the new BufferedImage. I solved the problem by setting the type explicitly, which in my case required

BufferedImage.TYPE_INT_ARGB

so the full statement read:

BufferedImage newImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

Rotating a JTextField vertically

You can't usefully rotate interactive components without also transforming the mouse coordinates, but you can rotate the graphics context to render non-interactive components like JLabel, as shown here.

In your example, 1/2 * Math.PI != Math.PI / 2.

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