Oval drawn is jagged instead of smooth

[VernonDozier]

OK, this is a follow-up to this thread, which I have marked solved.

http://www.daniweb.com/forums/thread152797.html

I changed things from GIF to PNG and that seems to solve the saving issue, but there is a new issue. I'm trying to create a semi-transparent circle as an image, which can be saved. The saving and retrieving seems to work, but the semi-transparent red circle is drawn rough/jagged instead of smooth. Lines 92 - 101 create an image of a circle. Compare the smoothness of that circle and the white circle drawn in paintComponent. The white circle is much smoother. Does anyone know why the red circle is so much rougher and how to fix it? Here is the code. The relevant lines are lines 92 - 101. The semi-transparent circle image is created there. Thanks.

package ColorForms;

import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.swing.*;
import java.util.*;
import javax.imageio.ImageIO;



public class ColorForms extends JFrame
{
    LeftPanel leftPanel;
    TopPanel topPanel;
    CanvasPanel canvasPanel;
    JSplitPane wholePanel, bottomPanel;
    
    public static void main (String args[])
    {
        ColorForms cf = new ColorForms ();
    }
    
    
    public ColorForms ()
    {
        this.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        this.setSize (400, 400);
        
        leftPanel = new LeftPanel ();
        canvasPanel = new CanvasPanel ();
        topPanel = new TopPanel (canvasPanel);
        
        bottomPanel = new JSplitPane (JSplitPane.HORIZONTAL_SPLIT, leftPanel, canvasPanel);
        bottomPanel.setDividerLocation (50);
        wholePanel = new JSplitPane (JSplitPane.VERTICAL_SPLIT, topPanel, bottomPanel);
        wholePanel.setDividerLocation (70);

        this.getContentPane ().add (wholePanel);
        this.setVisible (true);
        canvasPanel.repaint ();
    }
}


class LeftPanel extends JPanel
{
    public LeftPanel ()
    {        
    }
}


class TopPanel extends JPanel implements ActionListener
{
    JButton createNewImageButton;
    JButton saveImageToFileButton;
    JButton retrieveImageFromFileButton;
    CanvasPanel cp;
    
    public TopPanel (CanvasPanel canPan)
    {
        cp = canPan;
        createNewImageButton = new JButton ("Create New Image");
        saveImageToFileButton = new JButton ("Save Image To File");
        retrieveImageFromFileButton = new JButton ("Retrieve Image From File");
        this.add (createNewImageButton);
        this.add (saveImageToFileButton);
        this.add (retrieveImageFromFileButton);
        createNewImageButton.addActionListener(this);
        saveImageToFileButton.addActionListener(this);
        retrieveImageFromFileButton.addActionListener(this);
    }

    
    public void actionPerformed(ActionEvent e) 
    {
        if (e.getSource () == createNewImageButton)
            CreateNewImage ();
        else if (e.getSource () == saveImageToFileButton)
            SaveImageToFile();
        else if (e.getSource () == retrieveImageFromFileButton)
            RetrieveImageFromFile ();
        
        cp.repaint ();
    }
    
    
    public void CreateNewImage ()
    {
        cp.bi = new BufferedImage (200, 200, BufferedImage.TYPE_INT_ARGB_PRE);
        Graphics g = cp.bi.createGraphics();
        Graphics2D g2 = (Graphics2D) g;
        Color color1 = new Color(255, 0, 0, 100);
        g2.setColor (color1);
        g2.fillOval (30, 30, 80, 80);
        g2.dispose ();
    }
    
    
    public void SaveImageToFile ()
    {
        try
        {
             File saveFile = new File("SemiTransparentCircle.png");
             System.out.println ("Got this far");
             if (saveFile == null)
                 System.out.println ("saveFile is null");
             if (cp == null)
                 System.out.println ("cp is null");                 
             if (cp.bi == null)
                 System.out.println ("cp.bi is null");
             ImageIO.write(cp.bi, "png", saveFile);           
        }
        catch (IllegalArgumentException ex)
        {
            System.out.print ("Caught an illegal argument exception - ");
            System.out.println (ex.toString());            
        }
        catch (IOException ex)
        {
            System.out.print ("Caught an IO exception - ");
            System.out.println (ex.toString());            
        }
        catch (NullPointerException ex)
        {
            System.out.print ("Caught a null pointer exception - ");
            System.out.println (ex.toString());            
        }
        catch (Exception ex)
        {
            System.out.print ("Caught an exception - ");
            System.out.println (ex.toString());
        }
    }
    
    
    public void RetrieveImageFromFile ()
    {
        try 
        {
            File biFile = new File("SemiTransparentCircle.png");
            cp.bi = ImageIO.read(biFile);
        } 
        catch (IOException ex) 
        {
            System.out.println ("Problem opening file");
        }        
    }
}


class CanvasPanel extends JPanel
{
    BufferedImage bi;
    
    
    public CanvasPanel ()
    {
    }


    public void paintComponent (Graphics g)
    {
        super.paintComponent (g);        
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint (RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        setBackground(Color.GREEN);
        g2.setColor(Color.WHITE);
        g2.fillOval (50, 50, 75, 75);
        g2.drawImage (bi, 50, 50, null);
    }
}

[Ezzaral]

I would just guess it stems from the fact you created a fixed size buffer image and rendered the red circle on it without anti-aliasing. You then draw that image in paintComponent. The image itself will be unchanged and I don't think turning on anti-aliasing in paintComponent will affect that image.

[VernonDozier]

I would just guess it stems from the fact you created a fixed size buffer image and rendered the red circle on it without anti-aliasing. You then draw that image in paintComponent. The image itself will be unchanged and I don't think turning on anti-aliasing in paintComponent will affect that image.

Yes, I think that was it. I added the line in red below:

public void CreateNewImage ()
    {
        cp.bi = new BufferedImage (200, 200, BufferedImage.TYPE_INT_ARGB_PRE);
        Graphics g = cp.bi.createGraphics();
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint (RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        Color color1 = new Color(255, 0, 0, 100);
        g2.setColor (color1);
        g2.fillOval (30, 30, 80, 80);
        g2.dispose ();
    }

and the new image is much smoother. Thanks Ezzaral!