Scaling Graphics

I'm creating a program that basically draws an nxn matrix of ellipses. The program enables the user to change the distance between the ellipses. I want to let the user change the size of the ellipses without changing the relative distance between them. I already have a zoom function in place using the scaletransform method but want to be able to scale the graphics without throwing off the distances between the ellipses. I tried simply multiplying the w,h,x,y dimensions and locations of the ellipses, but found that it throws off the spacing between them. Is there any way to go about this???? Any help greatly appreciated. thanks, Brian