AffineTransform make an image move

[Mauricio Lopes]

I've been trying to make an image rotate in a panel. I did it. But also i want the image to make a translation.

Here is the code i tryed at paintComponent() :

//////////////////////////

Graphics2D g2 = (Graphics2D) g ;
AffineTransform at = new AffineTransform() ;

// at.rotate ( angle in radians ) ;
at.rotate( this.getAngulo(1, 1) ) ;

g2.drawImage(imgemFlecha, at, this);

/////////////////////////////


I cant change image x,y doing this drawImage(). I want to make that change.

Any suggestions ?

[Mauricio Lopes]

??

[Craig Wood]

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.swing.*;

public class Mobility extends JPanel {
    BufferedImage image;

    public Mobility(BufferedImage image) {
        this.image = image;
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        int iw = image.getWidth();
        int ih = image.getHeight();
        double x = 50;
        double y = 50;
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);
        at.rotate(Math.PI/6, iw/2, ih/2);
        g2.drawRenderedImage(image, at);
        x = 150;
        y = 150;
        at.setToTranslation(x, y);
        at.rotate(Math.PI/4, iw/2, ih/2);
        g2.drawRenderedImage(image, at);
        x = 250;
        y = 250;
        at.setToTranslation(x, y);
        at.rotate(Math.PI/3, iw/2, ih/2);
        g2.drawRenderedImage(image, at);
    }

    public static void main(String[] args) throws IOException {
        File file = new File("images/geek/geek-----.gif");
        BufferedImage image = javax.imageio.ImageIO.read(file);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new Mobility(image));
        f.setSize(400,400);
        f.setLocation(100,100);
        f.setVisible(true);
    }
}

[Rob Spoor]

Mauricio Lopes wrote:??

http://faq.javaranch.com/java/PatienceIsAVirtue

[Cathy McDuff]

Hi,

I just wanted to say thank you to Craig for posting that class, it's one of the few that actually makes sense and is easy to follow. Other classes using Affine Transform have been horrific to understand. So yeah, thank you very much, you've been a big help )

[Campbell Ritchie]

Always start paintComponent with a super call and it has protected access, as in Craig Wood's post.
Don't use AffineTransforms on a Graphics object and then reuse the Graphics object. Take a defensive copy. What happens is that the calculations for the transform may be impossible to undo exactly, because of the imprecision of floating‑point arithmetic. Scale and translate usually can be undone and I have not had problems with rotate, but shear causes problems. The affine transforms also seem to be built into the Graphics2D object, so you have simpler ways to access them

@Override
potected void paintComponent(Graphics d)
{
   super.paintCompoennt(g);
   Graphics2D g2 = (Graphics2D)g.create();
   g2.rotate(...);
   // etc
   g2.shear(...);
   g2 = (Graphics2D)g.create(): // Defensive copy with original settings
   // etc
}

[Rob Spoor]

+1 on using Graphics.create. However, you should also dispose it manually:

Graphics2D g2 = (Graphics2D) g.create();
try {
    ...
} finally {
    g2.dispose();
}

[Campbell Ritchie]

Rob Spoor wrote: . . . you should also dispose it manually . . .

I never knew that. Thank you.

[Campbell Ritchie]

More about Graphics#dispose here.