JuliaSet1public class JuliaSet1 extends JComponent | This class is a Swing component that computes and displays a fractal image
known as a "Julia set". The print() method demonstrates printing with the
Java 1.1 printing API, and is the main point of the example. The code
that computes the Julia set uses complex numbers, and you don't need to
understand it. |
| Fields Summary |
|---|
| double | x1 | | double | y1 | | double | x2 | | double | y2 | | int | width | | int | height | | double | cx | | double | cy | | BufferedImage | image | | static int[] | colors |
| Constructors Summary |
|---|
public JuliaSet1()
// Static initializer for the colors[] array.
colors = new int[64];
for(int i = 0; i < colors.length; i++) {
colors[63-i] = (i*4 << 16) + (i*4 << 8) + i*4; // grayscale
// (i*4) ^ ((i * 3)<<6) ^ ((i * 7)<<13); // crazy technicolor
}
this(-1, 0);
| public JuliaSet1(double cx, double cy)
this.cx = cx;
this.cy = cy;
setPreferredSize(new Dimension(width, height));
computeImage();
|
| Methods Summary |
|---|
| void | computeImage()
// Create the image
image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// Now loop through the pixels
int i,j;
double x, y;
double dx = (x2 - x1)/width;
double dy = (y2 - y1)/height;
for(j = 0, y = y1; j < height; j++, y += dy) {
for(i = 0, x = x1; i < width; i++, x += dx) {
// For each pixel, call testPoint() to determine a value.
// Then map that value to a color and set it in the image.
// If testPoint() returns 0, the point is part of the Julia set
// and is displayed in black. If it returns 63, the point is
// displayed in white. Values in-between are displayed in
// varying shades of gray.
image.setRGB(i, j, colors[testPoint(x,y)]);
}
}
| | public void | paintComponent(java.awt.Graphics g)
g.drawImage(image,0,0,getWidth(), getHeight(),this);
| | public void | print()
// Create some attributes objects. This is Java 1.3 stuff.
// In Java 1.1, we'd use a java.util.Preferences object instead.
JobAttributes jattrs = new JobAttributes();
PageAttributes pattrs = new PageAttributes();
// Set some example attributes: monochrome, landscape mode
pattrs.setColor(PageAttributes.ColorType.MONOCHROME);
pattrs.setOrientationRequested(
PageAttributes.OrientationRequestedType.LANDSCAPE);
// Print to file by default
jattrs.setDestination(JobAttributes.DestinationType.FILE);
jattrs.setFileName("juliaset.ps");
// Look up the Frame that holds this component
Component frame = this;
while(!(frame instanceof Frame)) frame = frame.getParent();
// Get a PrintJob object to print the Julia set with.
// The getPrintJob() method displays a print dialog and allows the user
// to override and modify the default JobAttributes and PageAttributes
Toolkit toolkit = this.getToolkit();
PrintJob job = toolkit.getPrintJob((Frame)frame, "JuliaSet1",
jattrs, pattrs);
// We get a null PrintJob if the user clicked cancel
if (job == null) return;
// Get a Graphics object from the PrintJob.
// We print simply by drawing to this Graphics object.
Graphics g = job.getGraphics();
// Center the image on the page
Dimension pagesize = job.getPageDimension(); // how big is page?
Dimension panesize = this.getSize(); // how big is image?
g.translate((pagesize.width-panesize.width)/2, // center it
(pagesize.height-panesize.height)/2);
// Draw a box around the Julia Set and label it
g.drawRect(-1, -1, panesize.width+2, panesize.height+2);
g.drawString("Julia Set for c={" + cx + "," + cy + "}",
0, -15);
// Set a clipping region
g.setClip(0, 0, panesize.width, panesize.height);
// Now print the component by calling its paint method
this.paint(g);
// Finally tell the printer we're done with the page.
// No output will be generated if we don't call dispose() here.
g.dispose();
| | public int | testPoint(double zx, double zy)
for(int i = 0; i < colors.length; i++) {
// Compute z = z*z + c;
double newx = zx*zx - zy*zy + cx;
double newy = 2*zx*zy + cy;
zx = newx;
zy = newy;
// Check magnitude of z and return iteration number
if (zx*zx + zy*zy > 4) return i;
}
return colors.length-1;
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