Rectangle roi from ImageStack

Posted by Michael Doube on Mar 18, 2009; 1:09pm
URL: http://imagej.273.s1.nabble.com/Rectangle-roi-from-ImageStack-tp3693215.html

Hi all

I want to get the Rectangle ROI from an ImageStack that I have passed to
a method, as in

public void myMethod(ImageStack stack){
        Rectangle r = stack.getRoi();
        //do something with r
        return;
}

This is fine when there is a rectangle drawn, but if there is not an ROI
drawn, I get a null pointer exception.

Interestingly, if I set r to be a class variable

Public Rectangle r;

Then in the run() method set it with

r = ip.getRoi();

All the 'r's in my other methods behave sensibly and I don't get a null
pointer exception when I haven't drawn an ROI on my stack.

What is going on here?

Mike