1    /* 
2     * A program to paint, centered on the canvas, a circle of colored, unframed dots 
3     * that are separated. 
4     * */
5    
6    package npw;
7    
8    import painter.SPainter;
9    import shapes.SCircle;
10   
11   import javax.swing.*;
12   import java.awt.*;
13   import java.util.Random;
14   import java.util.Scanner;
15   
16   
17   public class SimpleDots {
18   
19   
20       private void paintTheImage() {
21           // Get the input information
22   
23           int radius = getNumber("circle radius");
24           int dotRadius = getNumber("dot radius");
25   
26   
27           // Establish the painter
28           SPainter painter = new SPainter("Simple Dots", radius * 2 + 50, radius * 2 + 50);
29           painter.setBrushWidth(3);
30           SCircle circle = new SCircle(radius);
31           SCircle dot = new SCircle(dotRadius);
32   
33           while (true) {
34               String command = JOptionPane.showInputDialog(null, "Color?");
35               if (command == null) {
36                   command = "exit";
37                   break;
38               } // user clicked on Cancel
39               if (command.equalsIgnoreCase("red")) {
40                   painter.setColor(Color.RED);
41                   break;
42               } else if (command.equalsIgnoreCase("green")) {
43                   painter.setColor(Color.GREEN);
44                   break;
45               } else if (command.equalsIgnoreCase("blue")) {
46                   painter.setColor(Color.BLUE);
47                   break;
48               } else {
49                   painter.setColor(Color.BLACK);
50                   break;
51               }
52           }
53   
54           // Paint the dots
55           paintSimpleDots(painter, circle, dot);
56       }
57   
58       private void paintSimpleDots(SPainter painter, SCircle circle, SCircle dot) {
59           // Position the painter to begin drawing the rows
60           painter.mfd(circle.radius());
61           painter.tr();
62           // Paint the circle of squares
63           double moved = 0;
64           while (moved < circle.diameter()) {
65               double chord = chordLength(circle.radius() - moved, circle);
66               int dots = dotsOnLineCount(chord, dot.diameter());
67               paintRow(painter, dot, dots);
68               nextRow(painter, dot.diameter());
69               moved = moved + dot.diameter();
70           }
71           // Make the method invariant with respect to painter position
72           painter.tl();
73           painter.mfd(circle.radius());
74       }
75   
76       // Move to the next row
77       private void nextRow(SPainter painter, double rowHeight) {
78           painter.tr();
79           painter.mfd(rowHeight);
80           painter.tl();
81       }
82   
83       // Assumes the painter is at the center of the row to paint, facing right.
84       private void paintRow(SPainter painter, SCircle dot, int dotsToPaint) {
85           // Move backward 1/2 of the length we're painting to get ready to paint the row.
86           double centerOffset = ((dotsToPaint * dot.diameter()) / 2) - dot.diameter() / 2;
87           painter.mbk(centerOffset);
88   
89           // Paint the row of squares.
90           int painted = 0;
91           while (painted < dotsToPaint) {
92               paintOneDot(painter, dot);
93               painter.mfd(dot.diameter());
94               painted = painted + 1;
95           }
96   
97           // Make the method invariant with respect to painter position.
98           painter.mbk(centerOffset + dot.diameter());
99       }
100  
101      private void paintOneDot(SPainter painter, SCircle dot) {
102      dot.s2();
103      painter.paint(dot);
104      dot.x2();
105      }
106  
107  
108      private static int dotsOnLineCount(double lineLength, double diameterLength) {
109          int dots = ((int) Math.ceil((lineLength - diameterLength) / diameterLength) + 1);
110          return dots;
111      }
112  
113      private double chordLength(double yOffset, SCircle circle) {
114          double xLength = Math.sqrt(Math.pow(circle.radius(), 2) - Math.pow(yOffset, 2));
115          double chordLength = xLength * 2;
116          return chordLength;
117      }
118  
119      private static int getNumber(String prompt) {
120          String nss = JOptionPane.showInputDialog(null, prompt + "?");
121          Scanner scanner = new Scanner(nss);
122          return scanner.nextInt();
123      }
124  
125  
126      private static Color randomColor() {
127          Random rgen = new Random();
128          int r = rgen.nextInt(256);
129          int g = rgen.nextInt(256);
130          int b = rgen.nextInt(256);
131          return new Color(r, g, b);
132      }
133  
134      public SimpleDots() {
135          paintTheImage();
136      }
137  
138      public static void main(String[] args) {
139          SwingUtilities.invokeLater(new Runnable() {
140              public void run() {
141                  new SimpleDots();
142              }
143          });
144      }
145  }
146