The simplest approach probably is to use an Embedded image behind the draggable objects that is generated server-side with a StreamResource. Just use normal Java drawing functionality to draw the lines. You could have one embedded image for each line or a big one where you draw all the lines.
If you want it on the fly while the user is dragging an object, you have to do it on the client-side and it could get hairy. There’s the
GWT Graphics add-on that might help you.
Well, you
could do it on the server-side while dragging with a ServerSideCriterion, but the server requests would get rather intensive.
As this has been asked before and was an interesting question, I wrote a
simpl-ish example that shows how to draw connectors between dragged components.
Hello Marko,
I followed your advice of using StreamResource but I putted the generated images in the same layer with the other components and this lead to some inconvenients. (Draggable elements being hidden by non-draggable images ).
I’m studing your solution and it looks way more cleaner.
Thank you,
Dani