Fix jagged edges of a BufferedImage made from 2D array

Question

I am trying to make BufferedImages with color data stored in a 2D array. It works, but I was wondering if there was a simple way to fix the jagged, saw-tooth-like, edges.

I am guessing there may be an API or a simple trick this, but I been looking at numerous Java Docs to no avail. Vector Magic does do what I am looking for, but I want to learn how to code this on my own.

Answer 1

If you're interested in a quick way to just "turn on" anti-aliasing capabilities, then you may be able to take advantage of the Java2D APIs for Controlling Rendering Quality. You can pass options in the form of RenderingHints by calling Graphics2D#setRenderingHints. One of the available hints is to request anti-aliasing.

The following code sample displays 2 windows that both draw the same circle, one with the anti-aliasing option off, and the other with the anti-aliasing option on. If you look closely, you'll see that the one generated with the anti-aliasing rendering hint is less jaggy.

TestAntiAliasing.java

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;

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

public class TestAntiAliasingPanel extends JPanel {

    private final RenderingHints rh;

    private TestAntiAliasingPanel(RenderingHints rh) {
        this.rh = rh;
    }

    @Override
    public void paint(Graphics g) {
        BufferedImage bufferedImage = new BufferedImage(400, 400, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = (Graphics2D)bufferedImage.getGraphics();
        g2.setRenderingHints(rh);
        g2.setColor(Color.BLUE);
        g2.fillOval(50, 50, 300, 300);
        g.drawImage(bufferedImage, 50, 50, this);
    }

    public static void main(String[] args) {
        createFrameWithAntiAliasingOption(false);
        createFrameWithAntiAliasingOption(true);
    }

    private static void createFrameWithAntiAliasingOption(boolean antiAliasingOption) {
        RenderingHints rh = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
                antiAliasingOption ? RenderingHints.VALUE_ANTIALIAS_ON :
                RenderingHints.VALUE_ANTIALIAS_OFF);
        JFrame frame = new JFrame();
        frame.getContentPane().add(new TestAntiAliasingPanel(rh));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500, 500);
        frame.setVisible(true);
    }
}

Compile with javac TestAntiAliasingPanel.java and then run with java TestAntiAliasingPanel.

...but I want to learn how to code this on my own.

If you're really interested in learning how to code the buffer manipulations to do the anti-aliasing yourself directly, then this is a big topic that would require external research. As a starting point, Wikipedia has articles on several anti-aliasing algorithms.