🚀 go-pugleaf

Alan:

All the samples for image loading for applets that i have use a media
tracker.  It's de rigeur under Java, it's just that sometimes it works
without one and everyone gets confused.

The examples are at:

http://www.got.net/~rwilkman/java  hop into samples.  First sample on
the left, source included.

-Rich

Alan McDonald wrote:
> 
> Wow, thanks for that lengthy answer. I'll certainly do some more work on
> this. Is there any sample code of how MediaTracker is used? And you are
> right I am calling it from a jar on th 98 machine. But caled from a jar on
> my linux box causes no problems. I don't understand why a jar container is
> such aproblem when it's supposed to the standard method of distribution.
> Alan McDonald
> 
> John P. McGrath wrote in message ...
> >Alan McDonald <alan@meta.com.au> wrote:
> >
> >> Thanks for your input but what's a media tracker and why does
> >> exactly the same code bring up an imagecontrol init exception
> >> on Windows 98? I'd love to deliver just one thing with java
> >> which appears to be platform independent.  Why don't I need
> >> a media tracker on my NT? Why does my NT not "use" the image
> >> before it's loaded?
> >
> >MediaTracker is a class defined in the java.awt package that can be
> >used to track the loading of images.
> >
> >The AWT was designed to be used over a (possibly slow) network, so
> >given that images are often very large, the image loading is done in
> >the background.  This allows programs to display windows containing
> >images, and fill in the images as the data arrives, as we have all
> >seen done in web pages.
> >
> >The AWT defines a number of interfaces for dealing with this.  See the
> >ImageObserver, ImageConsumer, and ImageProducer interfaces in the
> >package java.awt.image.  The actual implementation of these interfaces
> >may vary from platform to platform, and from toolkit to toolkit.  As a
> >result, the behavior may vary when your code is not written correctly.
> >
> >My guess is that your code tries to use the image attributes or data
> >without making certain that they are available, or arranging to do the
> >appropriate updates when the data is available.  But it may be that,
> >given the implementation under NT, the image is always loaded in time,
> >so it appears to work correctly.
> >
> >I am somewhat surprised that you see a different behavior between
> >Windows NT and Windows 98.  Could it be that when you deployed the
> >application on Windows 98, your image was in a file contained within a
> >JAR file, but when you ran it on NT, it was in a separate file?  The
> >first time I noticed this kind of behavior was when I moved everything
> >into a JAR.
> >
> >As Rich pointed out, using the java.awt.MediaTracker class will solve
> >this problem.  Before I moved to Swing (and started using ImageIcon),
> >I added a simple loadImage() method to one of my utility classes, that
> >would get an image and wait for it to complete loading.  I never ran
> >into the problem after that.
> >
> >IMHO, a method like this should have been in the JDK from the start.
> >Clearly JavaSoft violated the principle that the simplest cases should
> >be easy to use in this case.
> >
> >--
> >Regards,
> >
> >John P. McGrath
> ><mcgrath@enter.net>
> ><jpm@nscs.fast.net>

-- 

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Rich Wilkman
Senior Quality Assurance Engineer
Borland JBuilder Team

If you see something that looks like an opinion up there,
it's mine and mine alone.

Mail sent to me from the newsgroups won't bounce but will
be ignored.  If I have time, I'll respond, but you  have
a better chance if you confine your posts to the newsgroups
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