Hi,
I am using Java SDK 2 on Redhat 6.0. I have
a Java GUI on a C++ library and have hit the
following problem.
The GUI includes a component like this for
displaying images,
class DisplayPanel extends JPanel
{
public void paintComponent (Graphics g)
{
super. paintComponent (g); // paint background
// route 1
g. drawImage (image, 0, 0, this);
... OR ...
// route 2
_interface_to_c++. display_image (g, this);
}
}
If I use route 1, everything is fine, the
image is displayed whenever it is required.
Route 2 involves a call to a C++ routine, which
takes an image from memory, wraps it up in the
required Java format (using MemoryImageSource),
then does a drawImage. However, the following
problem occurs -
paintComponent is invoked in the usual way,
it calls the C++ routine, the image is
displayed (correctly), the processing terminates,
but then something causes paintComponent
to be invoked again. It goes into a loop
in which paintComponent is repeatedly invoked,
and the C++ routine is continually drawing
the image.
Well the basic logic is ok on the Java side because
route 1 works fine. So something in the C++ routine
causes Java to think the DiplayPanel component
needs to be updated. And it all hinges on the
call to drawImage from C++ (if I remove that,
no looping).
I almost began to think it's a bug, that you can't use
the JNI when displaying images. Any thoughts?
Thanks,
Paul.
p.s. I tried things like "markCompletelyClean" on the component
after return from C++ to try to disable the repaint but no luck.
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Paul Beardsley email: [EMAIL PROTECTED]
MERL - A Mitsubishi Electric Research Laboratory, tel: +(617) 621 7569
201 Broadway, Cambridge, MA 02139, USA fax: +(617) 621 7550
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