First Swing steps - Gradient

12

Gradient

// <applet code="Gradient" width="200" height="160"></applet>
import java.applet.Applet;
import java.awt.*;
import java.awt.image.*;
public class Gradient extends Applet {
private Image image;
public void init() {
int w = 100;
int h = 100;
int[] pixs = new int[w * h];
for (int y = 0; y < h; y++)
for (int x = 0; x < w; x++) {
pixs[y * w + x] = 255 << 24 // alpha
| ((x * 255 / w) << 16) // red
| ((y * 255 / h) << 8) // green
| 0; // blue
}
image = createImage(new MemoryImageSource(w, h, pixs, 0, w));
}
public void paint(Graphics g) {
Dimension size = getSize();
int w = size.width / 3, h = size.height / 3;
g.drawImage(image, 0, 0, w, h, this);
g.drawImage(image, w, 0, w * 2, h, this);
g.drawImage(image, 0, h, w, h * 2, this);
g.drawImage(image, w, h, w * 2, h * 2, this);
}
}

$ javac Gradient.java
$ appletviewer Gradient.java

Incidentally, this graphics illustrates the identity (a+b)² = a² + b² + 2ab.

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