Question

How can I copy a polygon to a new location. I use e.isPopupTrigger() to select the polygon, but I dont know how to copy it. Is the function of copy similar to the function of translate?
e.g. polygon.translate(x,y)?

Thanks.

EDITED:

//this code doesnt work 🙁

if(e.getSource() == Copy){  
  Polygon copyPolygon = new Polygon();
  copyPolygon = selectedTriangle;
  copyPolygon.translate(2, 2);
  repaint();
}

The problem has been solved with these code 🙂

if(e.getSource() == Copy){    
  Polygon copyPolygon = new Polygon(selectedTriangle.xpoints,selectedTriangle.ypoints,selectedTriangle.npoints);
  copyPolygon.translate(10,10);
  triangles.add(copyPolygon);
  repaint();
}           

Answer 1

You could construct a new polygon from the old one, then move that polygon to a new location

Polygon newPolygon = new Polygon(oldPolygon.xpoints, oldPolygon.ypoints, oldPolygon.npoints);
newPolygon.translate(newXPos, newYPos);

Your code doesn’t work because the line

copyPolygon = selectedTriangle;

Doesn’t make a copy of selectedTriangle, it just makes copyPolygon point to the same object. So you need to construct a new polygon that is identical to the original, which is what the first line in my suggestion does.