1    /* 
2     * A program to paint, centered on the canvas, a circle of randomly colored, black-framed squares. 
3     */
4    
5    package npw;
6    
7    import painter.SPainter;
8    import shapes.SCircle;
9    import shapes.SSquare;
10   
11   import javax.swing.*;
12   import java.awt.*;
13   import java.util.Random;
14   import java.util.Scanner;
15   
16   public class HirstDots {
17   
18       private void paintTheImage(){
19           // Get the input information
20           int radius = getNumber("circle radius");
21           int side = getNumber("circle radius length");
22   
23           // Establish the painter
24           SPainter painter = new SPainter("Hirst Dots", radius*2+50, radius*2+50);
25           painter.setBrushWidth(3);
26           SCircle circle = new SCircle(radius);
27           SCircle dot = new SCircle(side);
28   
29           // Paint the dots
30           paintCircleOfDots(painter, circle, dot);
31       }
32   
33       private void paintCircleOfDots(SPainter painter, SCircle circle, SCircle dot){
34           // Position the painter to begin drawing the rows
35           painter.mfd(circle.radius());
36           painter.tr();
37           // Paint the circle of dots
38           double moved = 0;
39           while (moved < circle.diameter()) {
40               double chord = chordLength(circle.radius() - moved, circle);
41               int dots = dotsOnLineCount(chord, dot.radius());
42               paintRow(painter, dot, dots);
43               nextRow(painter, dot.radius());
44               moved = moved + dot.radius();
45           }
46           // Make the method invariant with respect to painter position
47           painter.tl();
48           painter.mfd(circle.radius());
49       }
50   
51       // Move to the next row
52       private void nextRow(SPainter painter, double rowHeight){
53           painter.tr();
54           painter.mfd(rowHeight);
55           painter.tl();
56       }
57   
58       // Assumes the painter is at the center of the row to paint, facing right.
59       private void paintRow(SPainter painter, SCircle dot, int dotsToPaint){
60           // Move backward 1/2 of the length we're painting to get ready to paint the row.
61           double centerOffset = ( (dotsToPaint * dot.radius()) / 2) - dot.radius()/2;
62           painter.mbk(centerOffset);
63   
64           // Paint the row of dots.
65           int painted = 0;
66           while (painted < dotsToPaint){
67               paintOneDot(painter, dot);
68               painter.mfd(dot.radius());
69               painted = painted + 1;
70           }
71   
72           // Make the method invariant with respect to painter position.
73           painter.mbk(centerOffset + dot.radius());
74       }
75   
76       private void paintOneDot(SPainter painter, SCircle dot){
77           painter.setColor(randomColor());
78           dot.s3();
79           painter.paint(dot);
80           painter.setColor(Color.BLACK);
81   
82           dot.x3();
83       }
84   
85       private static int dotsOnLineCount(double lineLength, double sideLength){
86           int dots = ( (int)Math.ceil( ( lineLength - sideLength ) / sideLength ) + 1);
87           return dots;
88       }
89   
90       private double chordLength(double yOffset, SCircle circle){
91           double xLength = Math.sqrt(Math.pow(circle.radius(), 2) - Math.pow(yOffset, 2));
92           double chordLength = xLength * 2;
93           return chordLength;
94       }
95   
96       private static int getNumber(String prompt) {
97           String nss = JOptionPane.showInputDialog(null,prompt+"?");
98           Scanner scanner = new Scanner(nss);
99           return scanner.nextInt();
100      }
101  
102      private static Color randomColor() {
103          Random rgen = new Random();
104          int r = rgen.nextInt(256);
105          int g = rgen.nextInt(256);
106          int b = rgen.nextInt(256);
107          return new Color(r,g,b);
108      }
109  
110      public HirstDots() {
111          paintTheImage();
112      }
113  
114      public static void main(String[] args) {
115          SwingUtilities.invokeLater(new Runnable() {
116              public void run() {
117                  new HirstDots();
118              }
119          });
120      }
121  }