MultiView

So, I just made my first multiview component. It was easier than I expected, and the source code in the minicomposer example was particularly helpful.

In fact, too helpful. Or, rather, it was so precisely what I needed, that I wonder why it was necessary for me to copy so much source code verbatim, rather than just invoking some higher level API.

If you have a file type that can be edited in 2 ways (text and some other GUI), and you've already written TopComponents for both, you can pretty much just paste in a big chunk of the minicomposer ScoreEditorSupport to your own EditorSupport, and pull in a little code from ScorePanel to your own GUI TopComponent. You may want to change the names of the buttons ("compose", for me, became "graph"). But that's about it.

Extremely simple, but not exactly the best example of code reuse.

code snippets in blogger.com?

That last post was a pain, to get the whitespace to work. Anyone know of a better way to get spaces or tabs at the beginning of lines, besides inserting a bunch of   tokens?

TopComponentGroup semantics

I've been struggling with TopComponentGroup semantics. Basically, I have a TopComponent class A, and a singleton TopComponent B that displays property sheets relating to A. So, in my window system delcarations, I make a group containing the singleton B.

The trick is, when do I call open() and close() on the TopComponentGroup? The conventional wisdom is to have:

protected void componentActivated() {
 super.componentActivated();
 TopComponentGroup group = WindowManager.getDefault().findTopComponentGroup(TC_GROUP);
 if (group != null) {
  group.open();
 }
}

protected void componentDeactivated() {
 TopComponentGroup group = WindowManager.getDefault().findTopComponentGroup(TC_GROUP);
 if (group != null) {
  group.close();
 }
}

This, however, doesn't work. For one thing, when I click on B, I am deactivating A. Therefore, clicking on B makes it disappear! My next thought was to use componentShowing() and componentHidden() instead of activated/deactivated. But, if I have 2 A's showing in different modes, that paradigm breaks down. Long story short(er), this is what I ended up with, and it seems to work:

protected void componentActivated() {
 super.componentActivated();

 TopComponentGroup group = WindowManager.getDefault().findTopComponentGroup(TC_GROUP);
 if (group != null) {
  group.open();
 }
}

protected void componentHidden() {
 Mode m = WindowManager.getDefault().findMode(this);
 if (m == null) {
  // if the component is hiding because it is being closed,
  // we must back off to assuming the editor mode
  m = WindowManager.getDefault().findMode(EDITOR_MODE);
 }

 TopComponent selected = m.getSelectedTopComponent();
 if (selected == null || !(selected instanceof PageEditor)) {
  // close the TC_GROUP
  TopComponentGroup group = WindowManager.getDefault().findTopComponentGroup(TC_GROUP);
  if (group != null)
   group.close();
 }
}

New NetBeans Platform Tutorial

I've finished my entry for the netbeans tutorial contest. Of course, they then extended the deadline. However, they've allowed me to post it anyway, so folks get get use out of it right away. Check it out at http://www.cs.wustl.edu/~rbu1/feedreader/.

My office-mate has already (correctly) pointed out that there's no reason for SiteListComponent to subclass CloneableTopComponent, as it's a singleton. Oops.

While I was at it, I added an explorer module to the cluster build harness. It was a rush job, but people have been asking for a while for some simple sample code that adds node-exploring capability to the bare platform. Right now, it's just got a hidden root node with children gathered from java.io.File.listRoots().

Hopefully, all this will help some folks get their work done.

...and maybe the tutorial will turn out to be ipod-worthy :)