GAMES LESSON Nineteen: Hiding and Unhiding Menus
The code for this sample applet is a little long because of all the
components we crown into it, but the basic ideas are quite simple. Take some
time to play with each of the buttons to make sure that you are quite
familiar with how it works.
There are panels used in this applet. The first panel is called menuSpace
and it contains three buttons: pauseB, resetB, and config B. The second
panel is called configSpace and it contains a label, a panel,
and a button: dirT, midSpace, and okayB. The panel called midSpace contains
two labels and two textfields: pauseT, resetT, pauseF, resetF. Here is the
applet up to the point where all these components are declared and
initialized.
<![CDATA[
public class SHOW extends Applet implements Runnable, ActionListener, KeyListener{
Dimension d;
Image offI;
Thread tt;
int y,x,cc;
double speed, xspeed;
final static double dec=1.2;
final static double acc=.9;
final static double xdec=.001;
boolean up, not_pause, left;
int floor;
Panel menuSpace, configSpace, midSpace;
Button resetB, pauseB, configB;
Label dirT, pauseT, resetT;
TextField pauseF, resetF;
Button okayB;
String pauseL = "p";
String resetL = "r";
public void init(){
d = getSize();
floor = d.height-20;
addKeyListener(this);
resetB = new Button("RESET");
resetB.setBackground(Color.white);
resetB.addActionListener(this);
pauseB = new Button("PAUSE");
pauseB.setBackground(Color.white);
pauseB.addActionListener(this);
configB = new Button("CONFIGURE");
configB.setBackground(Color.white);
configB.addActionListener(this);
menuSpace=new Panel();
menuSpace.setBackground(Color.green);
menuSpace.add(resetB);
menuSpace.add(pauseB);
menuSpace.add(configB);
add(menuSpace);
dirT = new Label("Enter single letter shortcut.");
pauseT = new Label("pause");
resetT = new Label("reset");
pauseF = new TextField(8);
pauseF.setBackground(Color.white);
resetF = new TextField(8);
resetF.setBackground(Color.white);
okayB = new Button("OK");
okayB.setBackground(Color.white);
okayB.addActionListener(this);
configSpace = new Panel();
configSpace.setBackground(Color.green);
configSpace.setLayout(new BorderLayout());
midSpace = new Panel();
midSpace.setBackground(Color.green);
midSpace.setLayout(new GridLayout(2,2));
midSpace.add(pauseT);
midSpace.add(pauseF);
midSpace.add(resetT);
midSpace.add(resetF);
configSpace.add(dirT, BorderLayout.NORTH);
configSpace.add(midSpace, BorderLayout.CENTER);
configSpace.add(okayB, BorderLayout.SOUTH);
add(configSpace);
reset();
offI=createImage(d.width,d.height);
tt = new Thread(this);
tt.start();
}
...
]]>
You probably noticed that configSpace was set to BorderLayout and that
midSpace was set to GridLayout. You will have to look up the particulars on
these two layouts if you don't already know them!
You should also have noticed that this applet implements both the
actionListener and keyListener interfaces. Here are the methods which must
be implemented as a result of this:
<![CDATA[
public void keyPressed(KeyEvent k) {
if(k.getKeyChar() == pauseL.charAt(0)){
System.out.println("PAUSE LETTER: " + pauseL.charAt(0));
not_pause=!not_pause;
}
else if(k.getKeyChar() == resetL.charAt(0)){
System.out.println("RESET LETTER: " + resetL.charAt(0));
reset();
}
System.out.println("KEYEVENT TRIGGERED");
}
public void keyReleased(KeyEvent k){
System.out.println("Key Released");
}
public void keyTyped(KeyEvent k){
System.out.println("Key Typed");
}
public void actionPerformed(ActionEvent e) {
Object src = e.getSource();
if(src == resetB){
reset();
}
else if(src == pauseB){
not_pause=!not_pause;
}
else if(src == configB){
configSpace.setVisible(true);
}
else if(src == okayB){
pauseL = pauseF.getText();
resetL = resetF.getText();
if(pauseL.equals("") || pauseL.charAt(0) == ' ') pauseL="p";
if(resetL.equals("") || resetL.charAt(0) == ' ') resetL="r";
System.out.println("PAUSE: " + pauseL + ", RESET: " + resetL);
configSpace.setVisible(false);
}
requestFocus(); //very important!!!
}
]]>
Notice that at the end of the actionPerformed method a call to requestFocus
us made. This is pretty important. Without it, the user's keystrokes will be
ignored!
SHOW.java
<![CDATA[
import java.awt.*;
import java.applet.*;
import java.util.*;
import java.awt.event.*;
public class SHOW extends Applet implements Runnable, ActionListener, KeyListener{
Dimension d;
Image offI;
Thread tt;
int y,x,cc;
double speed, xspeed;
final static double dec=1.2;
final static double acc=.9;
final static double xdec=.001;
boolean up, not_pause, left;
int floor;
Panel menuSpace, configSpace, midSpace;
Button resetB, pauseB, configB;
Label dirT, pauseT, resetT;
TextField pauseF, resetF;
Button okayB;
String pauseL = "p";
String resetL = "r";
public void init(){
d = getSize();
floor = d.height-20;
addKeyListener(this);
resetB = new Button("RESET");
resetB.setBackground(Color.white);
resetB.addActionListener(this);
pauseB = new Button("PAUSE");
pauseB.setBackground(Color.white);
pauseB.addActionListener(this);
configB = new Button("CONFIGURE");
configB.setBackground(Color.white);
configB.addActionListener(this);
menuSpace=new Panel();
menuSpace.setBackground(Color.green);
menuSpace.add(resetB);
menuSpace.add(pauseB);
menuSpace.add(configB);
add(menuSpace);
dirT = new Label("Enter single letter shortcut.");
pauseT = new Label("pause");
resetT = new Label("reset");
pauseF = new TextField(8);
pauseF.setBackground(Color.white);
resetF = new TextField(8);
resetF.setBackground(Color.white);
okayB = new Button("OK");
okayB.setBackground(Color.white);
okayB.addActionListener(this);
configSpace = new Panel();
configSpace.setBackground(Color.green);
configSpace.setLayout(new BorderLayout());
midSpace = new Panel();
midSpace.setBackground(Color.green);
midSpace.setLayout(new GridLayout(2,2));
midSpace.add(pauseT);
midSpace.add(pauseF);
midSpace.add(resetT);
midSpace.add(resetF);
configSpace.add(dirT, BorderLayout.NORTH);
configSpace.add(midSpace, BorderLayout.CENTER);
configSpace.add(okayB, BorderLayout.SOUTH);
add(configSpace);
reset();
offI=createImage(d.width,d.height);
tt = new Thread(this);
tt.start();
}
public void keyPressed(KeyEvent k) {
if(k.getKeyChar() == pauseL.charAt(0)){
System.out.println("PAUSE LETTER: " + pauseL.charAt(0));
not_pause=!not_pause;
}
else if(k.getKeyChar() == resetL.charAt(0)){
System.out.println("RESET LETTER: " + resetL.charAt(0));
reset();
}
System.out.println("KEYEVENT TRIGGERED");
}
public void keyReleased(KeyEvent k){
System.out.println("Key Released");
}
public void keyTyped(KeyEvent k){
System.out.println("Key Typed");
}
public void actionPerformed(ActionEvent e) {
Object src = e.getSource();
if(src == resetB){
reset();
}
else if(src == pauseB){
not_pause=!not_pause;
}
else if(src == configB){
configSpace.setVisible(true);
}
else if(src == okayB){
pauseL = pauseF.getText();
resetL = resetF.getText();
if(pauseL.equals("") || pauseL.charAt(0) == ' ') pauseL="p";
if(resetL.equals("") || resetL.charAt(0) == ' ') resetL="r";
System.out.println("PAUSE: " + pauseL + ", RESET: " + resetL);
configSpace.setVisible(false);
}
requestFocus();
}
public void reset(){
not_pause = true;
y = 0;
x = 0;
speed=1;
xspeed=4;
}
public void run(){
while(true){
if(not_pause){
if(up){
y-=(int)speed;
speed-=dec;
}
else{
y+=(int)speed;
speed+=acc;
}
if(left){
x-=(int)xspeed;
}
else{
x+=(int)xspeed;
}
if(xspeed>0) xspeed -= xdec;
if(!up && y>floor-5) up=true;
else if(up && y<0) up=false;
else if(speed<=0) up=false;
if(!left && x>d.width) left=true;
else if(left && x<0) left=false;
repaint();
}
try{
Thread.sleep(30);
}catch(InterruptedException ie){ }
}
}
public void update(Graphics g){
paint(g);
}
public void paint(Graphics g){
Graphics offG = offI.getGraphics();
offG.setColor(Color.yellow);
offG.fillRect(0,0,d.width,d.height);
offG.setColor(Color.red);
offG.fillOval(x,y,10,10);
offG.drawLine(0,floor,d.width,floor);
g.drawImage(offI, 0,0, this);
}
}
]]>
ASSIGNMENT: