CODEWITHSUNDEEP
javaswingawt
Craig Smilovitz
Craig Smilovitz

Reputation: 23

Swing: Determining containing object for end of drag

I'd like to know what object a swing MouseMotionEvent (or MouseReleased) ends in. The problem is that both the MousePressed and MouseReleased events go to the object that was under the "press", not the release.

Here's a contrived example that may explain better:

The user sees a screen with some balls and some baskets and is told to drag a ball to a basket. Each ball represents some entity in the application space and each basket represents some action to take in the application space. From the Swing point of view, the balls and baskets are implemented separately as highly-overridden JButtons. On mousePressed the ball stores its identity in a known place. I'd like mouseReleased to be caught by a MouseListener in the basket which checks up the balls identity in the known place and then goes off into program logic and do the task represented by that basket.

But as I understand Swing (actually the AWT) the mouseReleased event goes to the component that contained the mousePressed event (ie the ball). Other than looking at X and Y (which seems an atrocious kludge) how do I figure out which basket the mouseReleased happened in? (If the mouseRelease happened outside of any basket, I'll need to take some sort of default reset action. Than can be done by a mouseEvent handler in the underlying JPanel).

(Please don't tell me this is a poor interface. The example I've given is not real. It abstracts out the problem I have in a way that I think is easy to visualize and understand.)

Upvotes: 0

Views: 94

Answers (1)

camickr
camickr

Reputation: 324207

If the mouseRelease happened outside of any basket, I'll need to take some sort of default reset action -

Use the Drag and Drop API and then you will only be able to drop on components that support your drop.

Other than looking at X and Y (which seems an atrocious kludge)

Why? The event doesn't have the information so you need to get it somehow. So if you don't want to use the DnD API then you need to do this yourself.

There are methods in the API to help you do this:

Window window = SwingUtilities.windowForComponent( e.getComponent() );
Point dropPoint = SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), window);
Component dropComponent = SwingUtilities.getDeepestComponentAt(window, dropPoint.x, dropPoint.y);

Upvotes: 2

Related Questions