Rotating an image

[Unnar Björnsson]

Is it possible to have java rotate an imageIcon x degrees? The only way I can think of is to use paintshop to rotate the image for me and store 360 images for each degree of rotation. If so how?

[Michael Dunn]

use a JLabel, and in the label's paintComponent()
Graphics2D.rotate(..);
Graphics2D.drawImage(..);

http://java.sun.com/j2se/1.5.0/docs/api/java/awt/Graphics2D.html
[ December 22, 2006: Message edited by: Michael Dunn ]

[Unnar Björnsson]

Could you explain a little more, I have my code here so far:

import java.awt.*;
import javax.swing.*;
 
public class Test extends JPanel
{
ImageIcon image = new ImageIcon("Image.gif");
JLabel label = new JLabel(image);
 
public Test()
{
setPreferredSize(new Dimension(800,600));
setBackground(Color.lightGray);
setFocusable(true);
add(label);
}
public void paintComponent (Graphics page)
{
super.paintComponent(page);
}
public static void main(String[] args)
{
Test test = new Test();
JFrame frame = new JFrame();
frame.setContentPane(test);
    frame.pack();
frame.setVisible(true);
   }
}    

[Michael Dunn]

use the search facility, keywords
Graphics2D rotate
and you'll find working examples

if you still have problems, post what you've tried
(the posted code doesn't try anything regarding rotate)

[Unnar Björnsson]

Ok I got it now and it works perfectly except for one thing. The whole canvas rotates, I don�t want that I only want to rotate the image on the canvas, I therefore made JPanel of same size as the image and made it into a drawing canvas and added upon the old canvas. The other images which are now not part of the same canvas are not affected by the rotation but because the rotation canvas obscures the other one, there is always a solid square that turns regardless of the shape of the image.
Let me give an example to explain, lets say I wanted to make a windmill, the blades should rotate but not the mill itself however you should be able to see the mill between the blades as they turn. In my example the rotationCanvas obscures the non-rotating canvas instead of only the windmill blades.
I hope you understand what I mean, I�ll include my code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class Test extends JPanel
{
ImageIcon image = new ImageIcon("Image.gif");
ImageIcon apple1 = new ImageIcon("Apple.gif");
ImageIcon apple2 = new ImageIcon("Apple.gif");
JLabel label = new JLabel(image);
JPanel rotationPanel;
final int WIDTH = 800;
final int HEIGHT = 600;
double degrees;
 
public Test()
{
setPreferredSize(new Dimension(WIDTH,HEIGHT));
setBackground(Color.lightGray);
setLayout(null);
setFocusable(true);
addKeyListener(new KeyboardListener());
rotationPanel = new JPanel();
rotationPanel = new turningCanvas();
rotationPanel.setPreferredSize(new Dimension(image.getIconWidth(),image.getIconHeight()));
add(rotationPanel);
rotationPanel.setBounds(WIDTH/2, HEIGHT/2, rotationPanel.getPreferredSize().width, rotationPanel.getPreferredSize().height);
degrees = 0;
}
public void paintComponent (Graphics g)
{
super.paintComponent(g);
apple1.paintIcon(this, g, 100, 75);
apple2.paintIcon(this, g, WIDTH-100, HEIGHT-75);
 
}
public class turningCanvas extends JPanel
{
public void paintComponent (Graphics g)
{
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.rotate(Math.toRadians(degrees),image.getIconWidth()/2,image.getIconHeight()/2);
image.paintIcon(this, g2d, 0, 0);
 
}
}
    public class KeyboardListener implements KeyListener
    {
       public void keyPressed (KeyEvent event)
       {
   if(event.getKeyCode() == KeyEvent.VK_LEFT)
   {
   degrees--;
   repaint();
   }
   if(event.getKeyCode() == KeyEvent.VK_RIGHT)
   {
   degrees++;
   repaint();
   }
   }
       public void keyTyped (KeyEvent event) {}
       public void keyReleased (KeyEvent event) {}
    }
public static void main(String[] args)
{
Test test = new Test();
JFrame frame = new JFrame();
frame.setContentPane(test);
    frame.pack();
frame.setVisible(true);
   }
}    

[Michael Dunn]

just ran your code and the square (white background) remained whilst the image
rotated inside - java 1.5.0_05, winxp

I got rid of the white background with
rotationPanel.setOpaque(false);

one problem with the code you have adapted is the image is not really sharp.

here's a version using a label - note the rendering hints
(only used a label because it was easier to copy existing code into your code)

    
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
class Test extends JPanel
{
  //ImageIcon image = new ImageIcon("test.gif");
  ImageIcon apple1 = new ImageIcon("test1.gif");
  ImageIcon apple2 = new ImageIcon("test1.gif");
  //JLabel label = new JLabel(image);
  JPanel rotationPanel;
  final int WIDTH = 800;
  final int HEIGHT = 600;
  double degrees;
 
  public Test()
  {
    setPreferredSize(new Dimension(WIDTH,HEIGHT));
    setBackground(Color.lightGray);
    setLayout(null);
    setFocusable(true);
    addKeyListener(new KeyboardListener());
    rotationPanel = new JPanel();
    rotationPanel = new turningCanvas();
    //rotationPanel.setPreferredSize(new Dimension(image.getIconWidth(),image.getIconHeight()));
    add(rotationPanel);
    rotationPanel.setBounds(WIDTH/2, HEIGHT/2, rotationPanel.getPreferredSize().width, rotationPanel.getPreferredSize().height);
    degrees = 0;
  }
  public void paintComponent (Graphics g)
  {
    super.paintComponent(g);
    apple1.paintIcon(this, g, 100, 75);
    apple2.paintIcon(this, g, WIDTH-100, HEIGHT-75);
 
  }
  public class turningCanvas extends JPanel
  {
 
    public turningCanvas()
    {
      setOpaque(false);
      add(new TurningImage());
    }
    class TurningImage extends JLabel
    {
      ImageIcon image = new ImageIcon("Test.gif");
      int  w  = image.getIconWidth();
      int  h  = image.getIconHeight();
      public TurningImage(){setPreferredSize(new Dimension(w,h));}
      public void paintComponent(Graphics g)
      {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        RenderingHints hints = new RenderingHints(null);
        hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        hints.put(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
        hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        g2.setRenderingHints(hints);
        g2.rotate (Math.toRadians(degrees),w/2, h/2);
        g2.drawImage(image.getImage(), 0, 0, this);
        g2.dispose();
      }
    }
 
    //public void paintComponent (Graphics g)
    //{
      //super.paintComponent(g);
      //Graphics2D g2d = (Graphics2D)g;
      //g2d.rotate(Math.toRadians(degrees),image.getIconWidth()/2,image.getIconHeight()/2);
      //image.paintIcon(this, g2d, 0, 0);
    //}
  }
    public class KeyboardListener implements KeyListener
    {
       public void keyPressed (KeyEvent event)
       {
       if(event.getKeyCode() == KeyEvent.VK_LEFT)
       {
         degrees--;
         repaint();
       }
       if(event.getKeyCode() == KeyEvent.VK_RIGHT)
       {
         degrees++;
         repaint();
       }
     }
       public void keyTyped (KeyEvent event) {}
       public void keyReleased (KeyEvent event) {}
    }
  public static void main(String[] args)
  {
    Test test = new Test();
    JFrame frame = new JFrame();
    frame.setContentPane(test);
      frame.pack();
    frame.setVisible(true);
    }
}

[Unnar Björnsson]

Sorry if this sounds dumb but why is your version better?
The problem I described still remains for example if I add a rectangle behind the turningPanel, only the image should block the rectangle not the whole panel.

  public void paintComponent (Graphics g)
{
super.paintComponent(g);
g.setColor(Color.red);
g.fillRect(WIDTH/2-30, HEIGHT/2-30, 50, 50);
apple1.paintIcon(this, g, 100, 75);
apple2.paintIcon(this, g, WIDTH-100, HEIGHT-75);
 
}  

[Michael Dunn]

I think I understand the problem now, about the transparency between the 'blades'.
(my test.gif was a round logo, so it had no such problem)

This is not something I've had to do before, but a (very) quick search
indicates this looks like what you would need to experiment with
g2.setComposite( AlphaComposite.getInstance(...))

I'll play around with it (after the break) and see if I can get something to
work OK