Java Slick2d - how to keep a shape allways inside a window?

Question

I'm moving a circle across the window by dragging it with the mouse. I'm supposed to make it always inside the window.

So by the default, when you drag the circle in a way that your mouse exits the frame, half of the circle will disappear (because it exits the frame), and half of it won't. I need to make it visible whole all the time, even if your cursor exits the frame. Here's the code:

if(draggingcircle)
{
  g.drawString("Dragging circle = " + draggingcircle, 50, 110);
  circle.setCenterX( gc.getInput().getMouseX() );
  circle.setCenterY( gc.getInput().getMouseY() );
}

Answer 1

whatever the circle is contained in, lets call id , you can keep it in the container with simple math if you know the radius or the diameter (i forget which)

so

if(draggingcircle)
{
  g.drawString("Dragging circle = " + draggingcircle, 50, 110);
  circle.setCenterX( gc.getInput().getMouseX() );
  circle.setCenterY( gc.getInput().getMouseY() );
}

becomes

var width = $('#container').width();
var height = $('#container').height();
var radius = 2;

if(draggingcircle)
{
  g.drawString("Dragging circle = " + draggingcircle, 50, 110);
  if (gc.getInput().getMouseX() > radius && gc.getInput().getMouseX() < width - radius)
  {
    circle.setCenterX( gc.getInput().getMouseX() );
  }
  if (gc.getInput().getMouseY() > radius && gc.getInput().getMouseY() < height - radius)
  {
    circle.setCenterY( gc.getInput().getMouseY() );
  }
}

Sorry for my poor syntax, I am not familiar with Slick2d, but something along these lines should work.