You can calculate the dimensions of an inclusive-exclusive rectangle as follows:

    cx = rcl.xRight - rcl.xLeft; /* width  */
    cy = rcl.yTop - rcl.yBottom; /* height */

You can calculate the dimensions of an inclusive-inclusive rectangle as follows:

    cx = (rcl.xRight - rcl.xLeft) + 1; /* width  */
    cy = (rcl.yTop - rcl.yBottom) + 1; /* height */