a problem when creating a text marquee
Hi,
I am making a text marquee class which extends JPanel and implements Runnable. Now here is the description of the problem, this class is being put on another JPanel which has a background. In the paintComponent method of the marquee class, if I don't call clearRect, the moving text will remain on the screen every time it is paint, but if I use clearRect or fillRect, the background of the other JPanel will be cleared or filled by a new color. So is there a way, that I can move the text on a "transparent" background?
Here is part of the code in the marquee class:
publicvoid paintComponent(Graphics g){
//super.paintComponent(g);
//g.clearRect(0,0,getWidth(),getHeight());
//g.setColor(getBackground());
//g.fillRect(0,0,getSize().width,getSize().height);
g.setColor(this.getForeground());
g.drawString(text,x,10);
//g.clearRect(0,0,getWidth(),getHeight());
x-=speed;
speed/=accelaration;
if (speed<1)
speed=1;
if (x<15){
x=15;
done=true;
}
}
Thanks in advance!
# 1
Make the panel non-opaque.
If you need further help then you need to create a "Short, Self Contained, Compilable and Executable, Example Program (SSCCE)",
see http://homepage1.nifty.com/algafield/sscce.html,
that demonstrates the incorrect behaviour, because I can't guess exactly what you are doing based on the information provided.
Don't forget to use the "Code Formatting Tags",
see http://forum.java.sun.com/help.jspa?sec=formatting,
so the posted code retains its original formatting.
# 2
Thanks for your reply. Here is the SSCCE, I hope this could help explain my question. The background of the text marquee is white in this case, but I really want to see the background /border of the other jPanel. Thanks again!
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class test extends JFrame{
/** Creates a new instance of test */
public test() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setBackground(new java.awt.Color(0, 51, 51));
setSize(700,100);
JPanel panel=new JPanel();
panel.setBorder(javax.swing.BorderFactory.createEtchedBorder());
panel.setBackground(new java.awt.Color(242, 213, 22));
Marquee marquee=new Marquee();
add(panel);
panel.setLayout(new javax.swing.GroupLayout(panel));
panel.add(marquee);
}
public static void main(String[] args){
JFrame frame=new test();
//frame.pack();
frame.setVisible(true);
}
public class Marquee extends JPanel implements Runnable{
int x;
String text;
boolean done=false;
/** Creates a new instance of Marquee */
public Marquee() {
this.setSize(600,20);
this.setOpaque(false);
setText("Hello Marquee!");
}
public void setText(String t){
text=t;
start();
}
public void start(){
Thread thread=new Thread(this);
thread.start();
}
public void run() {
x=getWidth();
while(true){
try {
Thread.sleep(10);
repaint();
if(done){
return;
}
} catch (InterruptedException ex) {
ex.printStackTrace();
return;
}
}
}
public void paintComponent(Graphics g){
super.paintComponent(g);
//g.clearRect(0,0,getWidth(),getHeight());
g.setColor(getBackground());
g.fillRect(0,0,getSize().width,getSize().height);
g.setColor(this.getForeground());
g.drawString(text,x--,10);
if (x<15){
x=15;
done=true;
}
}
}
}
# 3
After fixing the compile errors (GroupLayout is not standard) and fixing the code (you don't set the size of a component, you set the preferred size so the Layout Manager can use that informaion). I just commented out these lines:
//g.clearRect(0,0,getWidth(),getHeight());
//g.setColor(getBackground());
//g.fillRect(0,0,getSize().width,getSize().height);
