Composite demo
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import javax.swing.JApplet;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Composite extends JApplet implements ItemListener {
CompPanel comp;
JLabel alphaLabel = new JLabel("Alphas");
JLabel rulesLabel = new JLabel("Rules");
JComboBox alphas = new JComboBox();
JComboBox rules = new JComboBox();
String alpha = "1.0";
int rule = 0;
public void init() {
getContentPane().setLayout(new FlowLayout());
getContentPane().add(alphaLabel);
getContentPane().add(rulesLabel);
alphas.addItem("1.0");
alphas.addItem("0.75");
alphas.addItem("0.50");
alphas.addItem("0.25");
alphas.addItem("0.0");
alphas.addItemListener(this);
getContentPane().add(alphas);
rules.addItem("SRC");
rules.addItem("DST_IN");
rules.addItem("DST_OUT");
rules.addItem("DST_OVER");
rules.addItem("SRC_IN");
rules.addItem("SRC_OVER");
rules.addItem("SRC_OUT");
rules.addItem("CLEAR");
rules.addItemListener(this);
getContentPane().add(rules);
comp = new CompPanel();
getContentPane().add(comp);
validate();
}
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() != ItemEvent.SELECTED) {
return;
}
Object choice = e.getSource();
if (choice == alphas) {
alpha = (String) alphas.getSelectedItem();
} else {
rule = rules.getSelectedIndex();
}
comp.changeRule(alpha, rule);
}
public static void main(String s[]) {
JFrame f = new JFrame("Composite");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
JApplet applet = new Composite();
f.getContentPane().add("Center", applet);
applet.init();
f.pack();
f.setSize(new Dimension(300, 300));
f.show();
}
}
class CompPanel extends JPanel {
AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC);
float alpha = 1.0f;
public CompPanel() {
setPreferredSize(new Dimension(250, 250));
}
public void changeRule(String a, int rule) {
alpha = Float.valueOf(a).floatValue();
ac = AlphaComposite.getInstance(getRule(rule), alpha);
repaint();
}
public int getRule(int rule) {
int alphaComp = 0;
switch (rule) {
case 0:
alphaComp = AlphaComposite.SRC;
break;
case 1:
alphaComp = AlphaComposite.DST_IN;
break;
case 2:
alphaComp = AlphaComposite.DST_OUT;
break;
case 3:
alphaComp = AlphaComposite.DST_OVER;
break;
case 4:
alphaComp = AlphaComposite.SRC_IN;
break;
case 5:
alphaComp = AlphaComposite.SRC_OVER;
break;
case 6:
alphaComp = AlphaComposite.SRC_OUT;
break;
case 7:
alphaComp = AlphaComposite.CLEAR;
break;
}
return alphaComp;
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
int w = d.width;
int h = d.height;
BufferedImage buffImg = new BufferedImage(w, h,
BufferedImage.TYPE_INT_ARGB);
Graphics2D gbi = buffImg.createGraphics();
g2.setColor(Color.white);
g2.fillRect(0, 0, d.width, d.height);
int rectx = w / 4;
int recty = h / 4;
gbi.setColor(new Color(0.0f, 0.0f, 1.0f, 1.0f));
gbi.fill(new Rectangle2D.Double(rectx, recty, 150, 100));
gbi.setColor(new Color(1.0f, 0.0f, 0.0f, 1.0f));
gbi.setComposite(ac);
gbi.fill(new Ellipse2D.Double(rectx + rectx / 2, recty + recty / 2,
150, 100));
g2.drawImage(buffImg, null, 0, 0);
}
}
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