Dimensions between blocks insertion point and outer points of a block

[Anonymous]

Hello everyone,

I am attempting to create a lisp similar to QDIM that will:

1. Allow the user to select a block (A). or pick two outside points.

2. Allow the user select multiple blocks (B).

3. Draw dimension lines on the chosen side of Block (A) from the farthest point of block (A) to the fist block (B) and then to the farthest point on block (A).  This should repeat for each block selected.

 I would appreciate any assistance that can be provided. If possible, I would like as detailed as possible explanation how to write this lisp.  I am new to lisp and this task is a little over my head. Ideally, I would be able to dimension something similar to the image below as fast as possible. Also include is the current code I am working with. I found it and am trying to edit it to to fit my needs.  Thank you.