Solved

Applet reloads with old information

Posted on 2006-10-22
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Last Modified: 2010-03-31
Hello experts,

I have a Java applet that allows users to draw onto a background. When the Applet is reloaded to use a different background, all the user's previous drawings remain and overlay the new background.

How do I get my Applet to refresh the graphics when it initializes?

Thanks,
Matt.
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Question by:mb2297
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9 Comments
 
LVL 14

Expert Comment

by:hoomanv
ID: 17784001
Clear the drawings
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 17784003
Actually that's simple. The difficult thing is to make them stick ;-). Just make sure that no drawing takes place in the paint method at that time
0
 

Author Comment

by:mb2297
ID: 17784102
Sorry, I don't quite follow you.

Is there a method I can call that clears all graphics?
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LVL 14

Accepted Solution

by:
hoomanv earned 250 total points
ID: 17784166
Depends on how you store them
If they are just painted on the Canvas or an ImageBuffer
Then clear them by filling it by background color
But if they are stored as individual elements like lines and circles
So you might want to remove them to not being painted anymore
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 17784175
If custom drawing is occurring, you need to flag it 'on or off'
0
 
LVL 92

Assisted Solution

by:objects
objects earned 250 total points
ID: 17785640
As hoomanv has siad you need to clear all your stored drawing.
you can do this in the start() method of your applet.
0
 

Author Comment

by:mb2297
ID: 17803961
This might be more complicated than I first thought.

What I really want to do is completely reset the Applet. No information should transfer when the Applet reloads - it should be as if I was running it for the first time. At the moment, I have some Singletons which all behave as they were before the reload.

Is there a simple way to reset everything, or do I have to build that functionality into all my classes?

Thanks,
Matt.
0
 

Author Comment

by:mb2297
ID: 17804404
I have the additional problem that the panel which holds the background image gets autosized according to the image loaded into it. Once the background image is changed, the image panel does not re-adjust it's size.

Isn't there some kind of reinitialize function built in to Swing components?

Thanks,
Matt.
0
 

Author Comment

by:mb2297
ID: 17859739
All the problems I was having here are explained in the accepted answer to this question: http://www.experts-exchange.com/Programming/Programming_Languages/Java/Q_22039366.html

In the end I used the destroy() method of the Applet to manually clear my drawings, and the start() method to resize the image panel.
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