1    /* 
2     * A program to paint, centered on the canvas, a circle of randomly colored, circles. 
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   
17   public class HirstDots {
18   
19       private void paintTheImage() {
20           // Get the input information
21           int radius = getNumber("circle radius");
22           int radius1 = getNumber("dot radius");
23   
24           // Establish the painter
25           SPainter painter = new SPainter("Circle of Dots", radius * 2 + 50, radius * 2 + 50);
26           painter.setBrushWidth(3);
27           SCircle circle = new SCircle(radius);
28           SCircle dot = new SCircle(radius1);
29   
30           // Paint the squares
31           paintCircleOfDots(painter, circle, dot);
32       }
33   
34       private void paintCircleOfDots(SPainter painter, SCircle circle, SCircle dot) {
35           // Position the painter to begin drawing the rows
36           painter.mfd(circle.radius());
37           painter.tr();
38           // Paint the circle of dots
39           double moved = 0;
40           while (moved < circle.diameter()) {
41               double chord = chordLength(circle.radius() - moved, circle);
42               int dots = dotsOnLineCount(chord, dot.radius());
43               paintRow(painter, dot, dots);
44               nextRow(painter, dot.radius());
45               moved = moved + dot.radius();
46           }
47           // Make the method invariant with respect to painter position
48           painter.tl();
49           painter.mfd(circle.radius());
50       }
51   
52       // Move to the next row
53       private void nextRow(SPainter painter, double rowHeight) {
54           painter.tr();
55           painter.mfd(rowHeight);
56           painter.tl();
57       }
58   
59       // Assumes the painter is at the center of the row to paint, facing right.
60       private void paintRow(SPainter painter, SCircle dot, int dotsToPaint) {
61           // Move backward 1/2 of the length we're painting to get ready to paint the row.
62           double centerOffset = ((dotsToPaint * dot.radius()) / 2) - dot.radius() / 2;
63           painter.mbk(centerOffset);
64   
65           // Paint the row of dots.
66           int painted = 0;
67           while (painted < dotsToPaint) {
68               paintOneDot(painter, dot);
69               painter.mfd(dot.radius());
70               painted = painted + 1;
71           }
72   
73           // Make the method invariant with respect to painter position.
74           painter.mbk(centerOffset + dot.radius());
75       }
76   
77       private void paintOneDot(SPainter painter, SCircle dot) {
78           dot.s3();
79   
80   
81   
82           painter.setColor(randomColor());
83           painter.paint(dot);
84   
85   
86   
87           dot.x3();
88   
89   
90       }
91   
92       private static int dotsOnLineCount(double lineLength, double sideLength) {
93           int dots = ((int) Math.ceil((lineLength - sideLength) / sideLength) + 1);
94           return dots;
95       }
96   
97       private double chordLength(double yOffset, SCircle circle) {
98           double xLength = Math.sqrt(Math.pow(circle.radius(), 2) - Math.pow(yOffset, 2));
99           double chordLength = xLength * 2;
100          return chordLength;
101      }
102  
103      private static int getNumber(String prompt) {
104          String nss = JOptionPane.showInputDialog(null, prompt + "?");
105          Scanner scanner = new Scanner(nss);
106          return scanner.nextInt();
107      }
108  
109      private static Color randomColor() {
110          Random rgen = new Random();
111          int r = rgen.nextInt(256);
112          int g = rgen.nextInt(256);
113          int b = rgen.nextInt(256);
114          return new Color(r, g, b);
115      }
116  
117      public HirstDots() {
118          paintTheImage();
119      }
120  
121      public static void main(String[] args) {
122          SwingUtilities.invokeLater(new Runnable() {
123              public void run() {
124                  new HirstDots();
125              }
126          });
127      }
128  }