How to color a pixel?

Question

I have to create a simple 2D animation without using various primitives for drawing line, circle etc for the purpose. It has to be done by manipulating pixels and implementing one of the algorithms for drawing line, circle etc by coloring pixels.

I thought of using Turbo C for the purpose, but I use ubuntu. So I tried using dosbox to install and run turbo C but to no avail.

Now my only option is Java. Is it possible to manipulate pixels in Java? I couldn't find myself any good tutorials for the same. It would be great if a sample code for the same can be given.

Answer 1

The class java.awt.BufferedImage has a method setRGB(int x, int y, int rgb) which sets the color of an individual pixel. Additionally, you might want to look at java.awt.Color, especially its getRGB() method, which can convert Colors into integers that you can put into the int rgb parameter of setRGB.

Answer 2

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class DirectDrawDemo extends JPanel {

    private BufferedImage canvas;

    public DirectDrawDemo(int width, int height) {
        canvas = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
        fillCanvas(Color.BLUE);
        drawRect(Color.RED, 0, 0, width/2, height/2);
    }

    public Dimension getPreferredSize() {
        return new Dimension(canvas.getWidth(), canvas.getHeight());
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.drawImage(canvas, null, null);
    }


    public void fillCanvas(Color c) {
        int color = c.getRGB();
        for (int x = 0; x < canvas.getWidth(); x++) {
            for (int y = 0; y < canvas.getHeight(); y++) {
                canvas.setRGB(x, y, color);
            }
        }
        repaint();
    }


    public void drawLine(Color c, int x1, int y1, int x2, int y2) {
        // Implement line drawing
        repaint();
    }

    public void drawRect(Color c, int x1, int y1, int width, int height) {
        int color = c.getRGB();
        // Implement rectangle drawing
        for (int x = x1; x < x1 + width; x++) {
            for (int y = y1; y < y1 + height; y++) {
                canvas.setRGB(x, y, color);
            }
        }
        repaint();
    }

    public void drawOval(Color c, int x1, int y1, int width, int height) {
        // Implement oval drawing
        repaint();
    }



    public static void main(String[] args) {
        int width = 640;
        int height = 480;
        JFrame frame = new JFrame("Direct draw demo");

        DirectDrawDemo panel = new DirectDrawDemo(width, height);

        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }


}

alt text http://grab.by/grabs/39416148962d1da3de12bc0d95745341.png

Answer 3

Another bit of fun I had today where I used #Jave Cavas, Color, Graphics and #Swing JFrame to create a simply colouring pixels class all we are doing is creating square a JFrame 400×400 pixels (few extra pixels required for the frame it self) and then we extend the Canvas and colour the pixels symmetrically.

package gcclinux.co.uk;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JFrame;

public class ColouringPixels extends Canvas {

    private static final long serialVersionUID = 1L;
    private static final int WIDTH = 407; // Additional pixels needed for the frame
    private static final int HEIGHT = 427; // Additional pixels needed for the frame


    @Override
    public void paint(Graphics g) {
        super.paint(g);

        for (int r = 0; r <= 2; r++) {

        for(int y = 0; y < HEIGHT; y++) { 
            for(int x = 0; x < WIDTH; x++) { 
                if (x >= 1 && x <= 100 && y >= 1 && y <=100){
                    g.setColor(Color.WHITE);
                } else if (x >= 101 && x <= 200 && y >= 101 && y <=200){
                    g.setColor(Color.RED);
                } else if (x >= 201 && x <= 300 && y >= 201 && y <=300){
                    g.setColor(Color.WHITE);
                } else if (x >= 301 && x <= 399 && y >= 301 && y <=400){
                    g.setColor(Color.RED);
                } else              
                {
                    g.setColor(Color.BLUE);
                }
                g.drawLine(x, y, x, y);
            }
        }
            for(int x = 0; x < HEIGHT; x++) {
                for(int y = 0; y < WIDTH; y++) {
                    if (x >= 1 && x <= 100 && y >= 1 && y <=100){
                        g.setColor(Color.RED);
                    } else if (x >= 101 && x <= 200 && y >= 101 && y <=200){
                        g.setColor(Color.WHITE);
                    } else if (x >= 201 && x <= 300 && y >= 201 && y <=300){
                        g.setColor(Color.RED);
                    } else if (x >= 301 && x <= 399 && y >= 301 && y <=400){
                        g.setColor(Color.WHITE);
                    } else              
                    {
                        g.setColor(Color.BLUE);
                    }
                    g.drawLine(x, y, x, y);
                }
            }
        }
        try {
            Thread.sleep(2000);             // Sleep for 2 seconds
            System.exit(0);             // Closed the program
        }catch(InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("ColouringPixels - Lesson 9");
        frame.setSize(WIDTH, HEIGHT);
        frame.setResizable(false);
        frame.add(new ColouringPixels());
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Answer 4

You can accomplish this using java's builtin 2D Graphics package.