How is it possible ? (paint problem)

[metalcam]

Hi all !!

I'm trying to execute this code

	protected void paint(Graphics g) {
		g.setColor(255,255,255);
		g.fillRect(0, 0, this.getWidth(), this.getHeight());
		g.setColor(0,0,0);
		g.drawString("Loading...", this.getHeight()/3, this.getWidth()/3, Graphics.TOP | Graphics.LEFT);
		StreamConnection connection = null;
		InputStream in = null;
		StringBuffer buffer = new StringBuffer();	
        try {
			connection = (StreamConnection)
			Connector.open("http://metalcam.free.fr/brut.php");
...

It's weird because, when I call the class wich extends the canvas... I'm still seeing the "old canvas", with the message "do you accept the request" (because of the Connector), and AFTER accepted, I see that the fillRect has been executed (le background is white).

Is it normal ? What can I do ?

[grahamhughes]

Yes, this is perfectly normal. It's because painting occurs to a buffer, and not to the screen until the paint() method ends.

My advice is: don't do anything in paint(), except paint. Don't access the network, don't access RMS, don't load anything from the JAR, don't access the file system, don't send text messages, and don't change the state of your application (that is, don't change the values of any non-local variables).

More generally, don't do anything time consuming (network access, RMS, sleep(), etc.) in any event handler method (like keyPress(), commandAction(), startApp(), etc.) Event methods should always return as quickly as possible.

Network access needs to happen in a separate thread.

Graham.

[metalcam]

Ok thanks I'll try this...

[im2amit]

Yes, this is normal.

You should not do any blocking operation in your paint() method as paint will finally be visible to you only after the complete paint method is executed.

Try to move the connection code to a thread, and if you need start the thread from your paint method.

thanks,
~Amitabh
(Poster of the Month -Aug'09)
Follow me on my blog for Innovative Mobile Apps

[grahamhughes]

Is there an echo in here...?

[im2amit]

Sorry, I did'nt saw your reply - I dont know why... may be some network delay/problem on my end.

thanks,
~Amitabh
(Poster of the Month -Aug'09)
Follow me on my blog for Innovative Mobile Apps