1    /* 
2     * A program to paint an abstract gradient in the vertical direction. 
3     */
4    
5    package npw;
6    
7    import painter.SPainter;
8    import shapes.SCircle;
9    
10   import javax.swing.*;
11   import java.awt.*;
12   import java.util.Random;
13   import java.util.Scanner;
14   
15   import static javax.swing.SwingUtilities.invokeLater;
16   
17   public class HirstDots {
18        private int spacingFactor = getNumber(" Dot Spacing");
19        private int width = getNumber("Canvas Width in Pixels");
20        private int height = getNumber("Canvas Height in Pixels ");
21   
22        private HirstDots() {
23           paintTheImage();
24       }
25   
26       public static void main(String[] args) {
27           invokeLater( HirstDots::new );
28       }
29   
30       private void paintTheImage(){
31           // Establish the painter
32           SPainter painter = new SPainter("SimpleDots", width, height);
33           SCircle dot = new SCircle(5);
34           // Move the painter to the upper left corner to get ready to paint the gradient
35           painter.mfd(height/2);
36           painter.tl(90);
37           painter.mfd(width/2 - 10);
38           painter.tl(90);
39           // Paint it!
40           paintGradient(painter, dot, height, width, spacingFactor);
41       }
42   
43       private static int getNumber(String prompt) {
44           String nss = JOptionPane.showInputDialog(null,prompt+"?");
45           Scanner scanner = new Scanner(nss);
46           return scanner.nextInt();
47       }
48   
49       // Supports double precision floating point numbers as spacingFactor values
50       private void paintGradient(SPainter painter, SCircle dot, int height, int width, int verticalSpacing){
51           // Calculate the number of columns. We want to fill the screen, but we don't want
52           // any dots only half on the canvas, so we subtract some space.
53           int nrOfCols = ( width / verticalSpacing ) - 2;
54           int columnCount = 0;
55           while (columnCount < nrOfCols){
56               nextCol(painter, verticalSpacing);
57               columnCount = columnCount + 1;
58               paintColumn(painter, dot, height);
59           }
60       }
61   
62       private void paintOneDot(SPainter painter, SCircle dot){
63           painter.setColor(randomColor());
64           painter.paint(dot);
65       }
66   
67       private void paintColumn(SPainter painter, SCircle dot, int height) {
68           int horizontalSpacing = spacingFactor;
69           int displacement = 0;
70   
71           while(displacement < height) {
72               displacement = displacement + horizontalSpacing;
73               painter.mfd(horizontalSpacing);
74               paintOneDot(painter, dot);
75           }
76               // Make the method invariant with respect to painter position.
77               painter.mbk(displacement);
78           }
79           // Moves the painter to the next column.
80       private void nextCol(SPainter painter, double colWidth){
81           painter.tl(90);
82           painter.mfd(colWidth);
83           painter.tr(90);
84       }
85       private Color randomColor(){
86           Random rgen = new Random();
87           int r = rgen.nextInt(255);
88           int g = rgen.nextInt(255);
89           int b = rgen.nextInt(255);
90           return new Color(r,g,b);
91       }
92   }
93