Recursion - Data Structures and Problem Solving Using Java - page 310

(a) (b)

figure 7.14
(a) A fractal star outline drawn by the code shown in Figure 7.15; (b) The same star immediately before the last square is added.

As with the previous example, the method drawFractal uses a Java library
routine. In this case, fillRect draws a rectangle; its upper left-hand corner
and dimensions must be specified. The code is shown in Figure 7.15. The

figure 7.15
Code for drawing the
fractal star outline
shown in Figure 7.14

1 // Draw picture in Figure 7.14.
2 void drawFractal( Graphics g, int xCenter,
3 int yCenter, int boundingDim )
4 {
5 int side = boundingDim / 2;
6
7 if( side < 1 )
8 return;
9
10 // Compute corners.
11 int left = xCenter - side / 2;
12 int top = yCenter - side / 2;
13 int right = xCenter + side / 2;
14 int bottom = yCenter + side / 2;
15
16 // Recursively draw four quadrants.
17 drawFractal( g, left, top, boundingDim / 2 );
18 drawFractal( g, left, bottom, boundingDim / 2 );
19 drawFractal( g, right, top, boundingDim / 2 );
20 drawFractal( g, right, bottom, boundingDim / 2 );
21
22 // Draw central square, overlapping quadrants.
23 g.fillRect( left, top, right - left, bottom - top );
24 }