ch14.htm

JAVA Developing Professional JavaApplets

&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;public void imageComplete(int status) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp; if (!cpStart) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;cpStart = true;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dataUpdate();&nbsp;&nbsp;//
Show empty pixels...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;cp.start(pix,this);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; } // end if<BR>
&nbsp;&nbsp;&nbsp;&nbsp; if (complete)<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;consumer.imageComplete(ImageConsumer.STATICIMAGEDONE);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Called externally to notify that more data
has been created<BR>
&nbsp;&nbsp;&nbsp;// Notify consumer so they can repaint...<BR>
&nbsp;&nbsp;&nbsp;public void dataUpdate() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.setPixels(0,0,width,height,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;defaultRGBModel,pix,0,width);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.imageComplete(ImageConsumer.SINGLEFRAMEDONE);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// External call to update a specific pixel
row...<BR>
&nbsp;&nbsp;&nbsp;public void dataUpdateRow(int row) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // The key thing here is the second to
last parameter (offset)<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // which states where to start getting
data from the pix array...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.setPixels(0,row,width,1,<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;defaultRGBModel,pix,(width
* row),width);<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.imageComplete(ImageConsumer.SINGLEFRAMEDONE);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// External call to update a specific pixel
column...<BR>
&nbsp;&nbsp;&nbsp;public void dataUpdateColumn(int col,int pixdata[])
{<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // The key thing here is the second to
last parameter (offset)<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // which states where to start getting
data from the pix array...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.setPixels(col,0,1,height,<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;defaultRGBModel,pixdata,0,1);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; consumer.imageComplete(ImageConsumer.SINGLEFRAMEDONE);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Called from external calculating program
when data has<BR>
&nbsp;&nbsp;&nbsp;// finished being calculated...<BR>
&nbsp;&nbsp;&nbsp;public void setComplete() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;complete = true;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;consumer.setPixels(0,0,width,height,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;defaultRGBModel,pix,0,width);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;consumer.imageComplete(ImageConsumer.STATICIMAGEDONE);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
}</TT>
</BLOCKQUOTE>
<HR>
<H2><A NAME="TheCalculatorImageClass"><FONT SIZE=5 COLOR=#FF0000>The
CalculatorImage Class</FONT></A></H2>
<P>
The CalculatorImage class, shown in Listing 14.5, is the glue
between the CalculatorProducer class that produces the image data
and the CalculatorFilter that manages it. When an image is requested
with the <TT>getImage()</TT> method,
the CalculatorImage creates a color palette through an instance
of the ImageColorModel class, then creates a MemoryImageSource
object. This ImageProducer object produces an image initialized
to all zeros (black). It is combined with an instance of the CalculatorFilter
class to produce a FilteredImageSource. When the <TT>createImage()</TT>
method of the Toolkit is called, production of the calculated
image begins.
<P>
The color palette is a randomly generated series of pixel values.
Depending on your luck, these colors can be attractive or uninspiring.
The <TT>createPalette()</TT> method
is a good place to create a custom set of colors for this applet,
if you want to have some control over its appearance. You should
replace the random colors with hard-coded RGB values, and you
might want to download a URL file that specifies a special color
mapping.
<HR>
<BLOCKQUOTE>
<B>Listing 14.5. The CalculatorImage class.<BR>
</B>
</BLOCKQUOTE>
<BLOCKQUOTE>
<TT>// This class takes a CalculatorProducer
and sets up the<BR>
// environment for creating a calculated image.&nbsp;&nbsp;Ties
the<BR>
// producer to the CalculatorFilter so incremental updates can
<BR>
// be made...<BR>
public class CalculatorImage {<BR>
&nbsp;&nbsp;&nbsp;int width;&nbsp;&nbsp;// The dimensions of the
image...<BR>
&nbsp;&nbsp;&nbsp;int height;<BR>
&nbsp;&nbsp;&nbsp;CalculatorProducer cp;&nbsp;&nbsp;// What produces
the image data...<BR>
&nbsp;&nbsp;&nbsp;IndexColorModel palette;&nbsp;&nbsp;// The colors
of the image...<BR>
&nbsp;&nbsp;&nbsp;// Create Palette only once per session...<BR>
&nbsp;&nbsp;&nbsp;static IndexColorModel prvPalette = null;<BR>
&nbsp;&nbsp;&nbsp;int numColors = 256;&nbsp;&nbsp;// Number of
colors in palette...<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Use defines how big of an image they want...
<BR>
&nbsp;&nbsp;&nbsp;public CalculatorImage(int width,int height,CalculatorProducer
cp) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;this.width = width;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;this.height = height;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;this.cp = cp;<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Start producing the Calculator image...<BR>
&nbsp;&nbsp;&nbsp;public synchronized Image getImage() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Hook into the filter...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;createPalette();<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ImageProducer p = new FilteredImageSource(
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; new MemoryImageSource(width,height,palette,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(new
int[width * height]),0,width),<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;new
CalculatorFilter(palette,cp));<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// Return the image...<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return Toolkit.getDefaultToolkit().createImage(p);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Create a 256 color palette...<BR>
&nbsp;&nbsp;&nbsp;// Use Default color model...<BR>
&nbsp;&nbsp;&nbsp;void createPalette() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Create palette only once per session...
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; if (prvPalette != null) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;palette
= prvPalette;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; }<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Create a palette out of random RGB
combinations...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; byte blues[], reds[], greens[];<BR>
&nbsp;&nbsp;&nbsp;&nbsp; reds = new byte[numColors];<BR>
&nbsp;&nbsp;&nbsp;&nbsp; blues = new byte[numColors];<BR>
&nbsp;&nbsp;&nbsp;&nbsp; greens = new byte[numColors];<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // First and last entries are black and
white...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; blues[0] = reds[0] = greens[0] = (byte)0;
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; blues[255] = reds[255] = greens[255]
= (byte)255;<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Fill in other entries...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; for ( int x = 1; x &lt; 254; x++ ){<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;reds[x] = (byte)(255 * Math.random());
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;blues[x] = (byte)(255 * Math.random());
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;greens[x] = (byte)(255 * Math.random());
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; }<BR>
&nbsp;&nbsp;&nbsp;&nbsp; // Create Index Color Model...<BR>
&nbsp;&nbsp;&nbsp;&nbsp; palette = new IndexColorModel(8,256,reds,greens,blues);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp; prvPalette = palette;<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Save the image set as a BMP file...<BR>
&nbsp;&nbsp;&nbsp;public void saveBMP(String filename,int pix[])
{<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;try {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;BmpImage.saveBitmap(filename,palette,
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;pix,width,height);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;catch (IOException ioe) {
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;System.out.println(&quot;Error
saving file!&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<BR>
&nbsp;&nbsp;&nbsp;}<BR>
}</TT>
</BLOCKQUOTE>
<HR>
<H2><A NAME="TheMandelAppClass"><FONT SIZE=5 COLOR=#FF0000>The
MandelApp Class</FONT></A></H2>
<P>
The MandelApp class, shown in Listing 14.6, creates and displays
the full Mandelbrot set; the end result is shown in Figure 14.2.
An instance of the Mandelbrot class is created in the <TT>init()</TT>
method. Whenever the Mandelbrot calculation has produced some
new data, it calls the ImageObserver-based method, <TT>imageUpdate()</TT>.
This will probably result in the applet being repainted to show
the new data. If the image is complete, an internal flag is set.
After this, if you click the mouse, the image will be saved to
a BMP formatted file called mandel.bmp.
<HR>
<BLOCKQUOTE>
<B>Listing 14.6. The MandelApp class.<BR>
</B>
</BLOCKQUOTE>
<BLOCKQUOTE>
<TT>import java.awt.*;<BR>
import java.lang.*;<BR>
import java.applet.Applet;<BR>
<BR>
// This applet displays the Mandlebrot set through<BR>
// use of the Mandelbrot class...<BR>
public class MandelApp extends Applet&nbsp;&nbsp;{<BR>
&nbsp;&nbsp;&nbsp;Image im;&nbsp;&nbsp;&nbsp;// Image that displays
Mandelbrot set...<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>
<BR>
&nbsp;&nbsp;&nbsp;// Set up the Mandelbrot set...<BR>
&nbsp;&nbsp;&nbsp;public void init() {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;m = new Mandelbrot(NUMCOLS,NUMROWS);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;im = m.getImage();<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;showStatus(&quot;Calculating...&quot;);
<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;showStatus(&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;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;// 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; g.drawImage(im,0,0,this);
<BR>
&nbsp;&nbsp;&nbsp;}<BR>
<BR>
&nbsp;&nbsp;&nbsp;// Save Bitmap on mouse down when image complete...
<BR>
&nbsp;&nbsp;&nbsp;public boolean mouseDown(Event evt,int x, int
y) {<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (complete)
{<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showStatus(&quot;Save
Bitmap...&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;m.saveBMP(&quot;mandel.bmp&quot;);
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;showStatus(&quot;Bitmap
saved!&quot;);<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return
true;<BR>