# Catch mouse events on a drawn object (say a Polygon)

Hi,

I have drawn 4 polygons on a JPanel. I wish to capture mouse events so as to say which polygon has been clicked. I can see three possible solutions, could you please tell me which are feasable and which solution you consider best ?

Solution 1 : very conveniently, Java has enabled listeners of some sort for 2D Graphic objects ... how do I catch them ?

Solution 2 : ok, Solution 1 doesn't exist : I have to extend a Swing clickable object (such as a JButton for example) and make it look like my polygon ... how do I go about this ?

Solution 3 : none of the above are possible, I therefore have to check the coordinates of the mouse click and see if it belongs to any of my polygons. I'm kind of hoping this isn't the only solution ;-)

Thanks,

Stephane.
LVL 4
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Author Commented:
PS : any unthought of solution will be more than welcome of course !

Stephane.
0
Commented:
I always go for solution 3 ;-)
0
Commented:
Gui components enabled for the capture of mouse events are based on windowed peers and are therefore rectangular, which is why no solution other than 3 exists. This is trivial though:

public void mouseClicked(MouseEvent e) {
boolean inPoly = poly.contains(e.getPoint());
}
});
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Commented:
Polygon[] polygons;

public void mouseClicked(MouseEvent event)
{
Polygon inside = null;
for (int i=0; i<polygons.length; i++)
{
if (polygons[i].contains(event.getPoint()))
{
inside = polygons[i];
}
}
if (inside!=null)
{
// do whatever
}
}
0
Author Commented:
Hi,

Thanks to all for your participation.

However, I have done some of my own research yesterday and it does seem that solution 2 is implementable : wouldn't it be possible for me to extend the JComponent class in order to draw clickable polygons ? I haven't been able to achieve that yet but it sure looks possible. Any ideas ?

Thanks,

Stephane.
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Commented:
I'm not sure where you'd think the distinction is going to lie between that and the suggested solution
0
Author Commented:
Hi CEHJ,

The way I see it, solution 2 means I just add a component (say JPolygonComponent, which extends JComponent) : the polygon becomes visible and I can add MouseListeners to it at any time.

The solution 3 on the other hand consisted in drawing 2D objects on a JPanel and catching all mouse events on the JPanel *then* trying to figure out to which polygon the event is applicable.

I would much prefer implementing solution2 (which means I don't need to keep an array of polygons to check every one each time an event is triggered). You said in your post "no solution other than 3 exists" : if your solution applied to a solution2 architecture, please show me how.

Thanks,

Stephane.
0
Commented:
All JComponents are rectangular...

You can make them look polygonal, but they will be rectangular

So you will end up doing a load of work to see if they component has been clicked on...

Option 3 is a much easier solution, as you then control things like Z-Ordering, and painting yourself
0
Commented:
>>
I would much prefer implementing solution2 (which means I don't need to keep an array of polygons to check every one each time an event is triggered).
>>

Then have each polygon on a separate component. You'd still be using 3 though
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Author Commented:
Ok, i'll try solution 3. thanks to all,

Stephane.
0
Commented:
Good luck!

Tim
0
Commented:
8-)
0
Commented:
(:
0
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