import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ColorBlocks extends JPanel{
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D)g;
Dimension d = getSize();
g2.translate(d.width / 2, d.height / 2);
Color[] colors = {
Color.white, Color.lightGray, Color.gray, Color.darkGray,
Color.black, Color.red, Color.pink, Color.orange,
Color.yellow, Color.green, Color.magenta, Color.cyan, Color.blue
};
float size = 25;
float x = -size * colors.length / 2;
float y = -size * 3 / 2;
// Show all the predefined colors.
for (int i = 0; i < colors.length; i++) {
Rectangle2D r = new Rectangle2D.Float(
x + size * (float)i, y, size, size);
g2.setPaint(colors[i]);
g2.fill(r);
}
//a linear gradient.
y += size;
Color c1 = Color.yellow;
Color c2 = Color.blue;
for (int i = 0; i < colors.length; i++) {
float ratio = (float)i / (float)colors.length;
int red = (int)(c2.getRed() * ratio + c1.getRed() * (1 - ratio));
int green = (int)(c2.getGreen() * ratio +
c1.getGreen() * (1 - ratio));
int blue = (int)(c2.getBlue() * ratio +
c1.getBlue() * (1 - ratio));
Color c = new Color(red, green, blue);
Rectangle2D r = new Rectangle2D.Float(
x + size * (float)i, y, size, size);
g2.setPaint(c);
g2.fill(r);
}
// Show an alpha gradient.
y += size;
c1 = Color.red;
for (int i = 0; i < colors.length; i++) {
int alpha = (int)(255 * (float)i / (float)colors.length);
Color c = new Color(c1.getRed(), c1.getGreen(),
c1.getBlue(), alpha);
Rectangle2D r = new Rectangle2D.Float(
x + size * (float)i, y, size, size);
g2.setPaint(c);
g2.fill(r);
}
// Draw a frame around the whole thing.
y -= size * 2;
Rectangle2D frame = new Rectangle2D.Float(x, y, size * colors.length, size * 3);
g2.setPaint(Color.black);
g2.draw(frame);
}
public static void main(String[] args) {
JFrame f = new JFrame();
f.getContentPane().add(new ColorBlocks());
f.setSize(350, 250);
f.show();
}
}