Painting App

import acm.graphics.*;
import acm.util.*;
import acm.program.*;
import java.awt.*;


public class Seurat extends GraphicsProgram{

    private static final int NUM_PICTURES = 4;
    private static final int SPLOTCH_DIAMETER = 6;
    private static final int WAIT_TIME = 1;
    private RandomGenerator rgen = new RandomGenerator();

    public static void main(String[] args) {
        new Seurat().start(args);
    }

    public void run() {
        setBackground(Color.black);
        GImage image = new GImage(getRandomImage());
        int imageLeft = (int) ((getWidth() - image.getWidth())/2);
        int imageTop = (int)  ((getHeight() - image.getHeight())/2);

        while(true) {
            int pixelX = rgen.nextInt((int) image.getWidth());
            int pixelY = rgen.nextInt((int) image.getHeight());
            Color pixelColor = getColorAt(image, pixelX, pixelY);
            int xPos = imageLeft + pixelX;
            int yPos = imageTop + pixelY;
            drawSplotch(xPos, yPos, pixelColor);
            pause(WAIT_TIME);

        }

    }

    private void drawSplotch(int xPos, int yPos, Color pixelColor) {
        xPos = xPos - SPLOTCH_DIAMETER/2;
        yPos = yPos - SPLOTCH_DIAMETER/2;
        GOval circle = new GOval (xPos, yPos, SPLOTCH_DIAMETER, SPLOTCH_DIAMETER);
        circle.setColor(pixelColor);
        circle.setFilled(true);
        add(circle);
    }

    /**
     *
     * @param image
     * @param x of a pixel
     * @param y of a pixel
     * @return the color found at a specific pixel
     */
    private Color getColorAt(GImage image, int x, int y) {
        // feel free to ignore how the program is looking up the pixel color
        // this syntax is not very nice and you don't need to understand it.
        return new Color(image.getPixelArray()[y][x]);
    }

    private String getRandomImage() {
        switch(rgen.nextInt(NUM_PICTURES)) {
        case 0: return "vangogh.jpg";
        case 1: return "magritte.jpg";
        case 2: return "seurat.jpg";
        case 3: return "henson.jpg";
        case 4: return "firefox.jpg";
        default: return null;

        }
    }

}