Java tutorial
/* * Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Sun Microsystems nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; 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; /* * This applet renders an ellipse overlapping a rectangle with the compositing * rule and alpha value selected by the user. */ public class Composite extends JApplet implements ItemListener { CompPanel comp; JLabel alphaLabel, rulesLabel; JComboBox alphas, rules; String alpha = "1.0"; int rule = 0; // Initializes the layout of the components. public void init() { GridBagLayout layOut = new GridBagLayout(); getContentPane().setLayout(layOut); GridBagConstraints l = new GridBagConstraints(); l.weightx = 1.0; l.fill = GridBagConstraints.BOTH; l.gridwidth = GridBagConstraints.RELATIVE; alphaLabel = new JLabel(); alphaLabel.setText("Alphas"); Font newFont = getFont().deriveFont(1); alphaLabel.setFont(newFont); alphaLabel.setHorizontalAlignment(JLabel.CENTER); layOut.setConstraints(alphaLabel, l); getContentPane().add(alphaLabel); GridBagConstraints c = new GridBagConstraints(); getContentPane().setLayout(layOut); l.gridwidth = GridBagConstraints.REMAINDER; rulesLabel = new JLabel(); rulesLabel.setText("Rules"); newFont = getFont().deriveFont(1); rulesLabel.setFont(newFont); rulesLabel.setHorizontalAlignment(JLabel.CENTER); layOut.setConstraints(rulesLabel, l); getContentPane().add(rulesLabel); GridBagConstraints a = new GridBagConstraints(); a.gridwidth = GridBagConstraints.RELATIVE; a.weightx = 1.0; a.fill = GridBagConstraints.BOTH; alphas = new JComboBox(); layOut.setConstraints(alphas, a); 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); a.gridwidth = GridBagConstraints.REMAINDER; rules = new JComboBox(); layOut.setConstraints(rules, a); 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); GridBagConstraints fC = new GridBagConstraints(); fC.fill = GridBagConstraints.BOTH; fC.weightx = 1.0; fC.weighty = 1.0; fC.gridwidth = GridBagConstraints.REMAINDER; comp = new CompPanel(); layOut.setConstraints(comp, fC); getContentPane().add(comp); validate(); } /* * Detects a change in either of the Choice components. Resets the variable * corresponding to the Choice whose state is changed. Invokes changeRule in * CompPanel with the current alpha and composite rules. */ 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.setVisible(true); } } class CompPanel extends JPanel { AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC); float alpha = 1.0f; public CompPanel() { } // Resets the alpha and composite rules with selected items. public void changeRule(String a, int rule) { alpha = Float.valueOf(a).floatValue(); ac = AlphaComposite.getInstance(getRule(rule), alpha); repaint(); } // Gets the requested compositing rule. 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; // Creates the buffered image. BufferedImage buffImg = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB); Graphics2D gbi = buffImg.createGraphics(); // Clears the previously drawn image. g2.setColor(Color.white); g2.fillRect(0, 0, d.width, d.height); int rectx = w / 4; int recty = h / 4; // Draws the rectangle and ellipse into the buffered image. 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)); // Draws the buffered image. g2.drawImage(buffImg, null, 0, 0); } }