CS1 Standard Demo Page

/*
 * A program to paint, centered on the canvas, a circle of randomly colored, black-framed squares.
 */

package npw;

import painter.SPainter;
import shapes.SCircle;
import shapes.SSquare;

import javax.swing.*;
import java.awt.*;
import java.util.Random;
import java.util.Scanner;

public class CircleOfSquares {

    private void paintTheImage(){
        // Get the input information
        int radius = getNumber("circle radius");
        int side = getNumber("square side length");

        // Establish the painter
        SPainter painter = new SPainter("Circle of Squares", radius*2+50, radius*2+50);
        painter.setBrushWidth(3);
        SCircle circle = new SCircle(radius);
        SSquare square = new SSquare(side);

        // Paint the squares
        paintCircleOfSquares(painter, circle, square);
    }

    private void paintCircleOfSquares(SPainter painter, SCircle circle, SSquare square){
        // Position the painter to begin drawing the rows
        painter.mfd(circle.radius());
        painter.tr();
        // Paint the circle of squares
        double moved = 0;
        while (moved < circle.diameter()) {
            double chord = chordLength(circle.radius() - moved, circle);
            int squares = squaresOnLineCount(chord, square.side());
            paintRow(painter, square, squares);
            nextRow(painter, square.side());
            moved = moved + square.side();
        }
        // Make the method invariant with respect to painter position
        painter.tl();
        painter.mfd(circle.radius());
    }

    // Move to the next row
    private void nextRow(SPainter painter, double rowHeight){
        painter.tr();
        painter.mfd(rowHeight);
        painter.tl();
    }

    // Assumes the painter is at the center of the row to paint, facing right.
    private void paintRow(SPainter painter, SSquare square, int squaresToPaint){
        // Move backward 1/2 of the length we're painting to get ready to paint the row.
        double centerOffset = ( (squaresToPaint * square.side()) / 2) - square.side()/2;
        painter.mbk(centerOffset);

        // Paint the row of squares.
        int painted = 0;
        while (painted < squaresToPaint){
            paintOneSquare(painter, square);
            painter.mfd(square.side());
            painted = painted + 1;
        }

        // Make the method invariant with respect to painter position.
        painter.mbk(centerOffset + square.side());
    }

    private void paintOneSquare(SPainter painter, SSquare square){
        painter.setColor(randomColor());
        painter.paint(square);
        painter.setColor(Color.BLACK);
        painter.draw(square);
    }

    private static int squaresOnLineCount(double lineLength, double sideLength){
        int squares = ( (int)Math.ceil( ( lineLength - sideLength ) / sideLength ) + 1);
        return squares;
    }

    private double chordLength(double yOffset, SCircle circle){
        double xLength = Math.sqrt(Math.pow(circle.radius(), 2) - Math.pow(yOffset, 2));
        double chordLength = xLength * 2;
        return chordLength;
    }

    private static int getNumber(String prompt) {
        String nss = JOptionPane.showInputDialog(null,prompt+"?");
        Scanner scanner = new Scanner(nss);
        return scanner.nextInt();
    }

    private static Color randomColor() {
        Random rgen = new Random();
        int r = rgen.nextInt(256);
        int g = rgen.nextInt(256);
        int b = rgen.nextInt(256);
        return new Color(r,g,b);
    }

    public CircleOfSquares() {
        paintTheImage();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new CircleOfSquares();
            }
        });
    }
}