Index: vg-test.scm
==================================================================
--- vg-test.scm
+++ vg-test.scm
@@ -1,35 +1,51 @@
 (use canvas-draw iup)
 (import canvas-draw-iup)
 
 (load "vg.scm")
 
+(use trace)
+(trace vg:draw-rect)
 (define d1 (vg:drawing-new))
 (define l1 (vg:lib-new))
 (define c1 (vg:comp-new))
+(define c2 (vg:comp-new))
 (let ((r1 (vg:make-rect 20 20 40 40))
       (r2 (vg:make-rect 40 40 80 80)))
   (vg:add-objs-to-comp c1 r1 r2))
 
 ;; add the c1 component to lib l1 with name firstcomp
 (vg:add-comp-to-lib l1 "firstcomp" c1)
+(vg:add-comp-to-lib l1 "secondcomp" c2)
 
 ;; add the l1 lib to drawing with name firstlib
 (vg:add-lib d1 "firstlib" l1)
 
 ;; instantiate firstlib/firstcomp as inst1 in drawing d1 at 0,0
 (vg:instantiate d1 "firstlib" "firstcomp" "inst1" 0 0)
 (vg:instantiate d1 "firstlib" "firstcomp" "inst2" 200 200)
-(vg:drawing-scalex-set! d1 1.1)
-(vg:drawing-scaley-set! d1 0.5)
+
+;; (vg:drawing-scalex-set! d1 1.1)
+;; (vg:drawing-scaley-set! d1 0.5)
 
 ;; (define xtnts (vg:scale-offset-xy 
 ;; 	       (vg:component-get-extents c1)
 ;; 	       1.1 1.1 -2 -2))
 
+;; get extents of c1 and put a rectange around it
+;;
 (define xtnts (apply vg:grow-rect 10 10 (vg:components-get-extents c1)))
 (vg:add-objs-to-comp c1 (apply vg:make-rect xtnts))
+
+;; get extents of all objects and put rectangle around it
+;;
+(define big-xtnts (vg:instances-get-extents d1))
+(vg:add-objs-to-comp c2 (apply vg:make-rect big-xtnts))
+(vg:instantiate d1 "firstlib" "secondcomp" "inst3" 0 0)
+
+(vg:drawing-scalex-set! d1 1.8)
+(vg:drawing-scaley-set! d1 1.1)
 
 (define cnv #f)
 (define the-cnv (canvas 
 		 #:size "500x400"
 		 #:expand "YES"
@@ -44,10 +60,10 @@
  (dialog
   (vbox
    the-cnv)))
 
 (vg:drawing-cnv-set! d1 cnv)
-(vg:draw d1)
+(vg:draw d1 #t)
 
 ;; (canvas-rectangle! cnv  10 100 10 80)
 
 (main-loop)

Index: vg.scm
==================================================================
--- vg.scm
+++ vg.scm
@@ -8,11 +8,11 @@
 ;;  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 ;;  PURPOSE.
 
 ;;  strftime('%m/%d/%Y %H:%M:%S','now','localtime')
 
-(use defstruct)
+(use defstruct srfi-1)
 
 (declare (unit vg))
 (use canvas-draw iup)
 (import canvas-draw-iup)
 ;; structs
@@ -213,44 +213,76 @@
 			  font:       (vg:obj-font       obj)))
 	(pts (vg:obj-pts obj)))
     (vg:obj-pts-set! res (vg:drawing-inst-apply-scale-offset drawing inst pts))
     (vg:drawing-cache-set! drawing (cons res (vg:drawing-cache drawing) ))
     res))
+
+;;======================================================================
+;; instances
+;;======================================================================
+
+(define (vg:instances-get-extents drawing . instance-names)
+  (let ((xtnt-lst (vg:draw drawing #f))
+	(llx   #f)
+	(lly   #f)
+	(ulx   #f)
+	(uly   #f))
+    (for-each
+     (lambda (extents)
+       (let* ((ollx      (list-ref extents 0))
+	      (olly      (list-ref extents 1))
+	      (oulx      (list-ref extents 2))
+	      (ouly      (list-ref extents 3)))
+	 (if (or (not llx)(< ollx llx))(set! llx ollx))
+	 (if (or (not lly)(< olly lly))(set! lly olly))
+	 (if (or (not ulx)(> oulx ulx))(set! ulx oulx))
+	 (if (or (not uly)(> ouly uly))(set! uly ouly))))
+     xtnt-lst)
+    (list llx lly ulx uly)))
+
 
 ;;======================================================================
 ;; Unravel and draw the objects
 ;;======================================================================
 
-(define (vg:draw-obj drawing obj)
+;; with get-extents = #t return the extents
+;; with draw = #f don't actually draw the object
+;;
+(define (vg:draw-obj drawing obj #!key (draw #t))
   (print "obj type: " (vg:obj-type obj))
   (case (vg:obj-type obj)
-    ((r)(vg:draw-rect drawing obj))))
+    ((r)(vg:draw-rect drawing obj draw: draw))))
 
 ;; given a rect obj draw it on the canvas applying first the drawing
 ;; scale and offset
 ;;
-(define (vg:draw-rect drawing obj)
+(define (vg:draw-rect drawing obj #!key (draw #t))
   (let* ((cnv (vg:drawing-cnv drawing))
 	 (pts (vg:drawing-apply-scale drawing (vg:obj-pts obj)))
 	 (llx (car pts))
 	 (lly (cadr pts))
 	 (ulx (caddr pts))
 	 (uly (cadddr pts)))
-    (print "pts: " pts)
-    (canvas-rectangle! cnv llx ulx lly uly)))
-
-(define (vg:draw drawing)
-  (let ((insts (vg:drawing-insts drawing)))
-    (for-each 
-     (lambda (inst)
-       (let* ((libname  (vg:inst-libname inst))
+    (if draw (canvas-rectangle! cnv llx ulx lly uly))
+    pts)) ;; return extents
+
+(define (vg:draw drawing draw-mode . instnames)
+  (let ((insts (vg:drawing-insts drawing))
+	(res   '()))
+    (for-each 
+     (lambda (instname)
+       (let* ((inst     (hash-table-ref insts instname))
+	      (libname  (vg:inst-libname inst))
 	      (compname (vg:inst-compname inst))
 	      (comp     (vg:get-component drawing libname compname)))
 	 (print "comp: " comp)
 	 (for-each
 	  (lambda (obj)
 	    (print "obj: " (vg:obj-pts obj))
 	    (let ((obj-xfrmd (vg:map-obj drawing inst obj)))
 	      (print "obj-xfrmd: " (vg:obj-pts obj-xfrmd))
-	      (vg:draw-obj drawing obj-xfrmd))) ;;
+	      (set! res (cons (vg:draw-obj drawing obj-xfrmd draw: draw-mode) res)))) ;;
 	  (vg:comp-objs comp))))
-    (hash-table-values insts))))
+     (if (null? instnames)
+	 (hash-table-keys insts)
+	 instnames))
+    res)) ;;  (hash-table-values insts))))