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This page contains an archived post to the Java Answers Forum made prior to February 25, 2002.
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Message:
Store the line co-ordinates in a vector
Posted by Kishori Sharan on July 16, 2001 at 10:47 PM
Hi
The only way to keep all lines on screen is we store all lines co-ordinates somewhere and we draw all lines in paint() method. The following Line.java file content does the same. I have added a Vector in Line class and now it also has an inner class which is used to represent a line co-ordinates. In paint() method first I am checking if the line current being drawn is in vector then don't add this line in vector else add the line in vector and then draw all lines. Note that I haven't overridden update method. This way you have all your lines even if you resize you frame or minimize and maximize it.
Thanks
Kishori
//////////// Line.java
import java.awt.*;
import java.awt.event.*;
import java.util.* ;
public class Line extends Frame implements MouseListener{
int x1=-1;
int x2=-1;
int y1=-1;
int y2=-1;
private Vector lines = new Vector ( ) ;
// Start of inner class
private class ALine {
int x1 ;
int x2 ;
int y1 ;
int y2 ;
public ALine ( int x1, int y1, int x2, int y2 ) {
this.x1 = x1 ;
this.x2 = x2 ;
this.y1 = y1 ;
this.y2 = y2 ;
}
public int getX1 ( ) {
return x1;
}
public int getY1 ( ) {
return y1;
}
public int getX2 ( ) {
return x2;
}
public int getY2 ( ) {
return y2;
}
public void draw ( Graphics g ) {
g.drawLine ( x1, y1, x2, y2 );
}
public boolean equals ( ALine al ) {
return ( x1 == al.getX1() && y1 == al.getY1() && x2 == getX2() && y2 == getY2() ) ;
}
}
// end of inner class
// this method will draw all lines
private void draw ( Graphics g ) {
Enumeration e = lines.elements() ;
ALine ll ;
while ( e.hasMoreElements ( ) ) {
ll = ( ALine )e.nextElement() ;
ll.draw ( g ) ;
}
}
public Line() {
setVisible(true);
setSize(200,200);
addMouseListener(this);
aa();
}
public void aa() {
x1=0;
x2=100;
for(int i =0; i < 100; i = i + 10 ){
y1 = i;
y2 = i;
repaint();
}
}
public void mousePressed (MouseEvent e) {
x1=e.getX();
y1=e.getY();
}
public void mouseReleased(MouseEvent e) {
x2=e.getX();
y2=e.getY();
repaint();
}
public void mouseClicked(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseExited(MouseEvent e){}
public void paint(Graphics g) {
System.out.println("paint : " + new Date ( ) );
// If the last line in vector stored is not the same being drawn then
// append this line in vector and then draw all lines
if ( lines.size ( ) > 0 ) {
ALine a2 = new ALine (x1, y1, x2, y2 ) ;
if ( !lines.contains( a2 ) ) {
lines.add ( a2 ) ;
}
}
else {
// First time there won't be any element
lines.add ( new ALine ( x1, y1, x2, y2 ) ) ;
}
// Draw all lines
this.draw ( g ) ;
}
public static void main(String[] args) {
Line l = new Line();
}
}
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