Hi Curtis, thanks for the followup.
The quickest and dirtiest fix for me was to add the following changes,
both in VisADCanvasJ2D.java. I add the 0 value for the alpha channel of
the background, in the call to setBackgroundColor:
public void setBackgroundColor(float r, float g, float b) {
// setBackground(new Color(r, g, b));
setBackground(new Color(r, g, b, 0));
}
The better way to go would be to offer a transparency arg along with the
r,g,b in classes such as DisplayRenderer, RendererControl, but just
looking through the code I can see that this is quite a few changes.
Obviously my quick fix is not suitable for a release, since it hard
wires all images to be transparent.
The other major change is the BufferedImage construction:
//new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
I replaced the TYPE_INT_RGB with the ARGB version in all calls to build
new BufferedImages in VisADCanvasJ2D.
I am using visad in offscreen mode by the way. As I said, my changes
just reflect my needs. I can well imagine there are some delicate
issues in adding transparency support.
On an unrelated note, I am still planning to add an Ant build.xml to the
visad distro, just havent found time so far.
Let me know if I can help further.
If you're interested, you can check out an inprogress web site, which
uses visad on the back end to produce the transparent images. The
actual UI is the browser.
The url is
http://metoc.apl.washington.edu/glmpc/browser/routebuilding.html. For
route composition, you go into 'add route mode', then clicking on the
canvas builds up a 'route', just a list of joined points.
Stuart Maclean
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