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<TITLE>Creating an Image from an Array of Color-Indexed Pixel Values (Java Developers Almanac Example)
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<META CONTENT="Patrick Chan" NAME="AUTHOR">
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<h1>The Java Developers Almanac 1.4</h1>
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<A HREF="../java.awt.image/pkg.html">java.awt.image</A><font color="#666666" class="xsmall-font">
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<B><A HREF="../java.awt.image/pkg.html#Images">Images</A></B><font color="#666666" class="xsmall-font">
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<h3>e660. Creating an Image from an Array of Color-Indexed Pixel Values</h3>
This example demonstrates how to convert a byte array of pixel values
that are indices to a color table into an <code>Image</code>. In particular,
the example generates the Mandelbrot set in a byte buffer and uses the
<code>MemoryImageSource</code> image producer to create an image from the
pixel data in the byte buffer. A 16-color index color model is used to
represent the pixel colors.
<pre> import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
// Instantiate this class and then use the draw() method to draw the
// generated on the graphics context.
public class Mandelbrot {
// Holds the generated image
Image image;
// 16-color model
ColorModel colorModel = generateColorModel();
public Mandelbrot(int width, int height) {
// Initialize with default location
this(width, height, new Rectangle2D.Float(-2.0f, -1.2f, 3.2f, 2.4f));
}
public Mandelbrot(int width, int height, Rectangle2D.Float loc) {
image = Toolkit.getDefaultToolkit().createImage(
new MemoryImageSource(width, height,
colorModel, generatePixels(width, height, loc), 0, width));
}
public void draw(Graphics g, int x, int y) {
g.drawImage(image, x, y, null);
}
private byte[] generatePixels(int w, int h, Rectangle2D.Float loc) {
float xmin = loc.x;
float ymin = loc.y;
float xmax = loc.x+loc.width;
float ymax = loc.y+loc.height;
byte[] pixels = new byte[w * h];
int pIx = 0;
float[] p = new float[w];
float q = ymin;
float dp = (xmax-xmin)/w;
float dq = (ymax-ymin)/h;
p[0] = xmin;
for (int i=1; i<w; i++) {
p[i] = p[i-1] + dp;
}
for (int r=0; r<h; r++) {
for (int c=0; c<w; c++) {
int color = 1;
float x = 0.0f;
float y = 0.0f;
float xsqr = 0.0f;
float ysqr = 0.0f;
do {
xsqr = x*x;
ysqr = y*y;
y = 2*x*y + q;
x = xsqr - ysqr + p[c];
color++;
} while (color < 512 && xsqr + ysqr < 4);
pixels[pIx++] = (byte)(color % 16);
}
q += dq;
}
return pixels;
}
private static ColorModel generateColorModel() {
// Generate 16-color model
byte[] r = new byte[16];
byte[] g = new byte[16];
byte[] b = new byte[16];
r[0] = 0; g[0] = 0; b[0] = 0;
r[1] = 0; g[1] = 0; b[1] = (byte)192;
r[2] = 0; g[2] = 0; b[2] = (byte)255;
r[3] = 0; g[3] = (byte)192; b[3] = 0;
r[4] = 0; g[4] = (byte)255; b[4] = 0;
r[5] = 0; g[5] = (byte)192; b[5] = (byte)192;
r[6] = 0; g[6] = (byte)255; b[6] = (byte)255;
r[7] = (byte)192; g[7] = 0; b[7] = 0;
r[8] = (byte)255; g[8] = 0; b[8] = 0;
r[9] = (byte)192; g[9] = 0; b[9] = (byte)192;
r[10] = (byte)255; g[10] = 0; b[10] = (byte)255;
r[11] = (byte)192; g[11] = (byte)192; b[11] = 0;
r[12] = (byte)255; g[12] = (byte)255; b[12] = 0;
r[13] = (byte)80; g[13] = (byte)80; b[13] = (byte)80;
r[14] = (byte)192; g[14] = (byte)192; b[14] = (byte)192;
r[15] = (byte)255; g[15] = (byte)255; b[15] = (byte)255;
return new IndexColorModel(4, 16, r, g, b);
}
}
</pre>
Here's some code that uses the <code>Mandelbrot</code> class:
<pre> class RunMandelbrot {
static public void main(String[] args) {
new RunMandelbrot();
}
RunMandelbrot() {
Frame frame = new Frame("Mandelbrot Set");
frame.add(new MyCanvas());
frame.setSize(<font color="#0066ff"><i>300</i></font>, <font color="#0066ff"><i>200</i></font>);
frame.setVisible(true);
}
class MyCanvas extends Canvas {
Mandelbrot mandelbrot;
MyCanvas() {
// Add a listener for resize events
addComponentListener(new ComponentAdapter() {
// This method is called when the component's size changes
public void componentResized(ComponentEvent evt) {
Component c = (Component)evt.getSource();
// Get new size
Dimension newSize = c.getSize();
// Regenerate the image
mandelbrot = new Mandelbrot(newSize.width, newSize.height);
c.repaint();
}
});
}
public void paint(Graphics g) {
if (mandelbrot != null) {
mandelbrot.draw(g, 0, 0);
}
}
}
}
</pre>
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<b>Related Examples</b></font></td>
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</table>
e661. <a class="eglink" href="HasAlpha.html?l=rel">
Determining If an Image Has Transparent Pixels
</a>
<br>
e662. <a class="eglink" href="GetColorModel.html?l=rel">
Getting the Color Model of an Image
</a>
<br>
e663. <a class="eglink" href="GetGifColors.html?l=rel">
Getting the Transparent Pixel and Number of Colors Used in a GIF Image
</a>
<br>
e664. <a class="eglink" href="CropImage.html?l=rel">
Getting a Sub-Image of an Image
</a>
<br>
e665. <a class="eglink" href="FilterRgb.html?l=rel">
Filtering the RGB Values in an Image
</a>
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See also:
<a class="eglink" href="/egs/java.awt.image/pkg.html?l=rel#Buffered%20Images">
Buffered Images
</a>
<a class="eglink" href="/egs/java.awt.image/pkg.html?l=rel#Effects">
Effects
</a>
<a class="eglink" href="/egs/java.awt.image/pkg.html?l=rel#Volatile%20Images">
Volatile Images
</a>
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