ch14.htm

JAVA Developing Professional JavaApplets

         } // end
if<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return false;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
}</TT>
</BLOCKQUOTE>
<HR>
<H2><A NAME="TheMandelZoomAppClass"><FONT SIZE=5 COLOR=#FF0000>The
MandelZoomApp Class</FONT></A></H2>
<P>
Listing 14.7 shows the MandelZoomApp class, which represents this
chapter's main applet; its function was described earlier, in
the section &quot;Using the Applets.&quot; See this section and
Table 14.1 for how to use the applet.
<P>
The most interesting features in the code are the routines for
marking the region to be highlighted. Each pixel on the displayed
Mandelbrot image maps an x-y value to a real-imaginary value of
the <TT>c</TT> value of the Mandelbrot
formula shown in Formula 14.1. Whenever you move the cursor, the
current real-imaginary values are shown in the browser's status
bar. When you highlight an area to zoom in on, you are really
picking a range of <TT>c</TT> values
to be explored. All the double variables are used for tracking
this range of values. These values are read in at initialization
by the <TT>loadParameters()</TT> method
to match the bitmap that's displayed. You can specify other Mandelbrot
BMP files and corresponding data files by changing the <TT>filename</TT>
parameter of the applet's <TT>&lt;APPLET&gt;</TT>
tag.
<P>
The <TT>Zoom()</TT> method takes the
currently highlighted range and brings up a new Mandelbrot image
that corresponds to this range. It uses the same calculation-image
filtering techniques that the MandelApp class does.
<HR>
<BLOCKQUOTE>
<B>Listing 14.7. The MandelZoomApp class.<BR>
</B>
</BLOCKQUOTE>
<BLOCKQUOTE>
<TT>// This applet displays the Mandelbrot
set bitmap specified<BR>
// in the APPLET tag parameters.&nbsp;&nbsp;You can then zoom
and in<BR>
// and out of the bitmap by dragging a region to paint.<BR>
// And then clicking on the appropriate option...<BR>
// Z or z - Zoom<BR>
// S or s - Save.<BR>
public class MandelZoomApp extends Applet&nbsp;&nbsp;{<BR>
&nbsp;&nbsp;&nbsp;Image img;<BR>
&nbsp;&nbsp;&nbsp;boolean zoomOn = false;<BR>
&nbsp;&nbsp;&nbsp;double XLeft,XRight,YTop,YBottom,XDelta,YDelta;
<BR>
&nbsp;&nbsp;&nbsp;double currentX,currentY;<BR>
&nbsp;&nbsp;&nbsp;double startX,startY,endX,endY;&nbsp;&nbsp;//
Zooming coordinates...<BR>
&nbsp;&nbsp;&nbsp;Rectangle markingRectangle;&nbsp;&nbsp;// Zooming
rectangle...<BR>
&nbsp;&nbsp;&nbsp;Mandelbrot m; // Creates the Mandelbrot image...
<BR>
&nbsp;&nbsp;&nbsp;int NUMCOLS = 640;&nbsp;&nbsp;&nbsp;// Dimensions
image display...<BR>
&nbsp;&nbsp;&nbsp;int NUMROWS = 350;<BR>
&nbsp;&nbsp;&nbsp;boolean complete = false;<BR>
&nbsp;&nbsp;&nbsp;// Array for keeping track of Mandelbrot entries...
<BR>
&nbsp;&nbsp;&nbsp;MandelEntry me[];<BR>
&nbsp;&nbsp;&nbsp;int lastIndex;&nbsp;&nbsp;// Top of array...
<BR>
&nbsp;&nbsp;&nbsp;int currentIndex;<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Set up the Mandelbrot set specified in the
parameters...<BR>
&nbsp;&nbsp;&nbsp;public void init() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;img = null;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;m = null;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Get parameter of bitmap
to display...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;String filename;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if ((filename = getParameter(&quot;filename&quot;))
== null)<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;filename
= &quot;mandel1&quot;;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Load the bitmap...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;loadBitmap(filename);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Initialize Mandelbrot array...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;me = new MandelEntry[40];
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;me[0] = new MandelEntry(null,img,XLeft,XRight,YTop,YBottom);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;lastIndex = 0;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;currentIndex = 0;<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
<BR>
&nbsp;&nbsp;&nbsp;// ZOOM onto Mandelbrot set if all is good...
<BR>
&nbsp;&nbsp;&nbsp;void Zoom() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// No Zooming if off or no
rectangle...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if ((!zoomOn) || (markingRectangle
== null)) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Nothing
marked or Zooming disable...&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} // end if<BR>
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// See if Mandelbrot table
is full...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if ((lastIndex + 1) &gt;=
me.length) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Mandelbrot
table full. Clear with C before zooming&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;ZOOM: SX=&quot;
+ startX + &quot; SY=&quot; + startY + &quot; EX=&quot; + endX
+ &quot; EY=&quot; + endY);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Load new Mandelbrot...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;complete = false;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;zoomOn = false;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;markingRectangle = null; //
Reset marking rectangle...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;m = new Mandelbrot(NUMCOLS,NUMROWS,endX,startX,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;endY,startY);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;img = m.getImage();<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Store in Mandelbrot table...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;XLeft = startX;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;XRight = endX;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;YTop = startY;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;YBottom = endY;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;XDelta = Math.abs(XRight -
XLeft);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;YDelta = Math.abs(YBottom
- YTop);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;++lastIndex;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;me[lastIndex] = new MandelEntry(m,img,startX,endX,startY,endY);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;currentIndex = lastIndex;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Calculating...&quot;);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;repaint();<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Paint on update...<BR>
&nbsp;&nbsp;&nbsp;public void update(Graphics g) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;paint(g);<BR>
&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;public synchronized void paint(Graphics g) {
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (img == null)<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Show image...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;g.drawImage(img,0,0,this);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Show marking rectangle
if exists...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (markingRectangle != null)
{<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;g.drawRect(markingRectangle.x,markingRectangle.y,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;markingRectangle.width,markingRectangle.height);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} // end if<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Will get updates as set is being created.
<BR>
&nbsp;&nbsp;&nbsp;// Repaint when they occur...<BR>
&nbsp;&nbsp;&nbsp;public boolean imageUpdate(Image im,int flags,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;int x, int y, int w, int h)
{<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if ((flags &amp; FRAMEBITS)
!= 0) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;repaint();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return true;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if ((flags &amp; ALLBITS)
!= 0) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Image
Complete!&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;repaint();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;complete
= true;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;zoomOn =
true;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return false;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return true;<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Load a bitmap and accompanying data file...
<BR>
&nbsp;&nbsp;&nbsp;void loadBitmap(String filename) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Zoom is false unless both
succeed...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;zoomOn = false;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;markingRectangle = null; //
Reset marking rectangle...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Load the bitmap...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;try&nbsp;&nbsp;{<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Load
image...&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ImageProducer
producer = BmpImage.getImageProducer(<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;getDocumentBase(),
filename + &quot;.bmp&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;img = createImage(producer);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Image
loaded...&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;catch (AWTException e){<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;img = null;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Cannot
open file &quot; + filename);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Load the zoom parameters.
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Turn Zoom on if all works...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;try {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;loadParameters(filename);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;zoomOn =
true;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;complete
= true;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;catch (IOException e){<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Cannot
load parameter data. &quot; + e.getMessage());<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Load the parameters.&nbsp;&nbsp;Throw IO
Exception...<BR>
&nbsp;&nbsp;&nbsp;public void loadParameters(String filename)
throws IOException {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;// Create URL for data...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;URL u;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;try {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;u = new URL(getDocumentBase(),filename
+ &quot;.dat&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;catch (MalformedURLException e) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showMsg(&quot;Bad Data URL&quot;);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;throw new IOException(&quot;Bad
URL&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;// Now load the data by opening up a stream
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;// to the URL...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;DataInputStream dis = new DataInputStream(
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;new BufferedInputStream(u.openStream()
) );<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Read only the first line...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; String param = dis.readLine();<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Tokenize out the boundary values....
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; StringTokenizer s = new StringTokenizer(param,&quot;,&quot;);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; try {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; XLeft = Double.valueOf(s.nextToken()).doubleValue();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; XRight = Double.valueOf(s.nextToken()).doubleValue();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; YTop = Double.valueOf(s.nextToken()).doubleValue();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; YBottom = Double.valueOf(s.nextToken()).doubleValue();
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; XDelta = Math.abs(XRight
- XLeft);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&n