一个JApplet的例子_ide



import java.lang.Integer;
import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;

/*
* This applet renders a shape, selected by the user, with a paint,stroke, and rendering method,
* also selected by the user.
*/

public class Transform extends JApplet implements ItemListener,
ActionListener {
JLabel primLabel, lineLabel, paintLabel, transLabel, strokeLabel;
TransPanel display;
static JComboBox primitive, line, paint, trans, stroke;
JButton redraw;
public static boolean no2D = false;

public void init() {
GridBagLayout layOut = new GridBagLayout();
getContentPane().setLayout(layOut);
GridBagConstraints c = new GridBagConstraints();

c.weightx = 1.0;
c.fill = GridBagConstraints.BOTH;
primLabel = new JLabel();
primLabel.setText("Primitive");
Font newFont = getFont().deriveFont(1);
primLabel.setFont(newFont);
primLabel.setHorizontalAlignment(JLabel.CENTER);
layOut.setConstraints(primLabel, c);
getContentPane().add(primLabel);

lineLabel = new JLabel();
lineLabel.setText("Lines");
lineLabel.setFont(newFont);
lineLabel.setHorizontalAlignment(JLabel.CENTER);
layOut.setConstraints(lineLabel, c);
getContentPane().add(lineLabel);

paintLabel = new JLabel();
paintLabel.setText("Paints");
paintLabel.setFont(newFont);
paintLabel.setHorizontalAlignment(JLabel.CENTER);
layOut.setConstraints(paintLabel, c);
getContentPane().add(paintLabel);

c.gridwidth = GridBagConstraints.RELATIVE;
transLabel = new JLabel();
transLabel.setText("Transforms");
transLabel.setFont(newFont);
transLabel.setHorizontalAlignment(JLabel.CENTER);
layOut.setConstraints(transLabel, c);
getContentPane().add(transLabel);

c.gridwidth = GridBagConstraints.REMAINDER;
strokeLabel = new JLabel();
strokeLabel.setText("Rendering");
strokeLabel.setFont(newFont);
strokeLabel.setHorizontalAlignment(JLabel.CENTER);
layOut.setConstraints(strokeLabel, c);
getContentPane().add(strokeLabel);

GridBagConstraints ls = new GridBagConstraints();
ls.weightx = 1.0;
ls.fill = GridBagConstraints.BOTH;
primitive = new JComboBox( new Object []{
"rectangle",
"ellipse",
"text"});
primitive.addItemListener(this);
newFont = newFont.deriveFont(0, 14.0f);
primitive.setFont(newFont);
layOut.setConstraints(primitive, ls);
getContentPane().add(primitive);

line = new JComboBox( new Object []{
"thin",
"thick",
"dashed"});
line.addItemListener(this);
line.setFont(newFont);
layOut.setConstraints(line, ls);
getContentPane().add(line);

paint = new JComboBox( new Object[]{
"solid",
"gradient",
"polka"});
paint.addItemListener(this);
paint.setFont(newFont);
layOut.setConstraints(paint, ls);
getContentPane().add(paint);

ls.gridwidth = GridBagConstraints.RELATIVE;

trans = new JComboBox( new Object[]{
"Identity",
"rotate",
"scale",
"shear"});
trans.addItemListener(this);
trans.setFont(newFont);
layOut.setConstraints(trans, ls);
getContentPane().add(trans);

ls.gridwidth = GridBagConstraints.REMAINDER;
stroke = new JComboBox( new Object[]{
"Stroke",
"Fill",
"Stroke & Fill"});
stroke.addItemListener(this);
stroke.setFont(newFont);
layOut.setConstraints(stroke, ls);
getContentPane().add(stroke);

GridBagConstraints button = new GridBagConstraints();
button.gridwidth = GridBagConstraints.REMAINDER;
redraw = new JButton("Redraw");
redraw.addActionListener(this);
redraw.setFont(newFont);
layOut.setConstraints(redraw, button);
getContentPane().add(redraw);

GridBagConstraints tP = new GridBagConstraints();
tP.fill = GridBagConstraints.BOTH;
tP.weightx = 1.0;
tP.weighty = 1.0;
tP.gridwidth = GridBagConstraints.REMAINDER;
display = new TransPanel();
layOut.setConstraints(display, tP);
display.setBackground(Color.white);
getContentPane().add(display);

validate();

}

public void itemStateChanged(ItemEvent e){}

public void actionPerformed(ActionEvent e) {
display.setTrans(trans.getSelectedIndex());
display.renderShape();
}


public static void main( String[] argv ) {
if ( argv.length > 0 && argv[0].equals( "-no2d" ) ) {
Transform.no2D = true;
}

JFrame frame = new JFrame( "Transform" );
frame.addWindowListener( new WindowAdapter(){
public void windowClosing( WindowEvent e ){
System.exit( 0 );
}
});

JApplet applet = new Transform();
frame.getContentPane().add( BorderLayout.CENTER, applet );

applet.init();

frame.setSize( 550, 400 );
frame.show();
}

}

class TransPanel extends JPanel {
AffineTransform at = new AffineTransform();
int w, h;
Shape shapes[] = new Shape[3];
BufferedImage bi;
boolean firstTime = true;

public TransPanel(){
setBackground(Color.white);
shapes[0] = new Rectangle(0, 0, 100, 100);
shapes[1] = new Ellipse2D.Double(0.0, 0.0, 100.0, 100.0);
TextLayout textTl = new TextLayout("Text", new Font("Helvetica", 1, 96), new FontRenderContext(null, false, false));
AffineTransform textAt = new AffineTransform();
textAt.translate(0, (float)textTl.getBounds().getHeight());
shapes[2] = textTl.getOutline(textAt);
}

public void setTrans(int transIndex) {
// Sets the AffineTransform.
switch ( transIndex ) {
case 0 : at.setToIdentity();
at.translate(w/2, h/2); break;
case 1 : at.rotate(Math.toRadians(45)); break;
case 2 : at.scale(0.5, 0.5); break;
case 3 : at.shear(0.5, 0.0); break;
}
}

public void renderShape() {
repaint();
}

public void paintComponent(Graphics g) {
super.paintComponent(g);

if ( !Transform.no2D ) {
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
w = d.width;
h = d.height;


// Prints out the intructions.
String instruct = "Pick a primitive, line style, paint, transform,";
TextLayout thisTl = new TextLayout(instruct, new Font("Helvetica", 0, 10), g2.getFontRenderContext());
float width = (float)thisTl.getBounds().getWidth();
float height = (float)thisTl.getBounds().getHeight();
thisTl.draw(g2, w/2-width/2, 15);

instruct = "and rendering method and click the Redraw button.";
thisTl = new TextLayout(instruct, new Font("Helvetica", 0, 10), g2.getFontRenderContext());
width = (float)thisTl.getBounds().getWidth();
thisTl.draw(g2, w/2-width/2, height + 17);

// Initialize the transform.
if (firstTime) {
at.setToIdentity();
at.translate(w/2, h/2);
firstTime = false;
}

// Sets the Stroke.
Stroke oldStroke = g2.getStroke();

switch ( Transform.line.getSelectedIndex() ) {
case 0 : g2.setStroke(new BasicStroke(3.0f)); break;
case 1 : g2.setStroke(new BasicStroke(8.0f)); break;
case 2 : float dash[] = {10.0f};
g2.setStroke(new BasicStroke(3.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f));
break;
}

// Sets the Paint.
Paint oldPaint = g2.getPaint();

switch ( Transform.paint.getSelectedIndex() ) {
case 0 : g2.setPaint(Color.blue);break;
case 1 : g2.setPaint(new GradientPaint(0, 0, Color.lightGray, w-250, h, Color.blue, false));
break;
case 2 : BufferedImage buffi = new BufferedImage(15, 15, BufferedImage.TYPE_INT_RGB);
Graphics2D buffig = buffi.createGraphics();
buffig.setColor(Color.blue);
buffig.fillRect(0, 0, 15, 15);
buffig.setColor(Color.lightGray);
buffig.translate((15/2)-(5/2), (15/2)-(5/2));
buffig.fillOval(0, 0, 7, 7);
Rectangle r = new Rectangle(0,0,25,25);
g2.setPaint(new TexturePaint(buffi, r));
break;
}



// Sets the Shape.
Shape shape = shapes[Transform.primitive.getSelectedIndex()];
Rectangle r = shape.getBounds();

// Sets the selected Shape to the center of the Canvas.
AffineTransform saveXform = g2.getTransform();
AffineTransform toCenterAt = new AffineTransform();
toCenterAt.concatenate(at);
toCenterAt.translate(-(r.width/2), -(r.height/2));

g2.transform(toCenterAt);

// Sets the rendering method.
switch ( Transform.stroke.getSelectedIndex() ) {
case 0 : g2.draw(shape); break;
case 1 : g2.fill(shape); break;
case 2 : Graphics2D tempg2 = g2;
g2.fill(shape);
g2.setColor(Color.darkGray);
g2.draw(shape);
g2.setPaint(tempg2.getPaint()); break;
}

g2.setStroke(oldStroke);
g2.setPaint(oldPaint);
g2.setTransform(saveXform);

}
}
}