2012

■ The DIMSCALE variable is set to the drawing's scale factor (that is, a drawing
to be plotted at a scale of 1" = 10' would have a scale factor of 120, or a
1/4" = 1' scale drawing would have a scale factor of 48).
If you load and execute the sample AutoLISP routine, AutoCAD inserts the
symbol at the size and location you have specified. When plotted, the symbols
are the specified size (if the drawing is plotted at the same scale as that specified
by DIMSCALE).
The following is a sample AutoLISP routine.
(defun C:SYMIN ( )
(setq sym
(getstring
"\nEnter symbol name: ") ; Prompts for a symbol name
)
; Display the custom toolbar named Symsize
(command "._-toolbar" "SymSize" "_show")
(setq
siz (getreal
"\nSelect symbol size: ") ; Prompts for a symbol size
p1 (getpoint
"\nInsertion point: ") ; Prompts for insertion point
)
(command "._insert" ; Issues the INSERT command
sym ; using the desired symbol
p1 siz siz 0) ; insertion point, and size
; Hide the custom toolbar named Symsize
(command "._-toolbar" "SymSize" "_hide")
(princ) ; Exits quietly
)
NOTE An AutoLISP routine that you use regularly should include error checking
to verify the validity of user input.
The DIESEL expressions in the following example multiply the current value
of DIMSCALE by the specified value, and return an appropriate scale factor.
This cannot be done with similar AutoLISP code; a value returned by an
AutoLISP expression cannot typically be used as a response to a getxxx function
call (such as, the getreal function in the preceding sample).
$M=$(*,$(getvar,dimscale),0.375)
$M=$(*,$(getvar,dimscale),0.5)
$M=$(*,$(getvar,dimscale),0.625)
394 | Chapter 5 DIESEL