source: trunk/SRC/Colors/color24.pro @ 155

;+
;
; @file_comments 
; The purpose of this function is to convert a RGB color triple
; into the equivalent 24-big long integer. 
;
; @categories Graphics, Color
;
; @param rgb_triple {in}{required} 
; A three-element column or row array representing 
; a color triple. The values of the elements must be between 0 and 255.
;
; @returns 
; a 24-bit long integer that is equivalent the input color. 
; The color is described in terms of a hexadecimal number (e.g., FF206A)
; where the left two digits represent the blue color, the 
; middle two digits represent the green color, and the right 
; two digits represent the red color.
;
; @examples 
; To convert the color triple for the color YELLOW, 
; (255, 255, 0), to the hexadecimal value '00FFFF'x 
; or the decimal number 65535, type:
;
; IDL> color = COLOR24([255, 255, 0])
;       
; This routine was written to be used with routines like COLORS or GETCOLOR
;
; @history
;       Written by:     David Fanning, 3 February 96.
;
; @version $Id$
;
;-
FUNCTION COLOR24, rgb_triple
;
  compile_opt idl2, strictarrsubs
;   
ON_ERROR, 1

IF N_ELEMENTS(rgb_triple) NE 3 THEN $
   MESSAGE, 'Argument must be a three-element vector.'

IF MAX(rgb_triple) GT 255 OR MIN(rgb_triple) LT 0 THEN $
   MESSAGE, 'Argument values must be in range of 0-255'

base16 = [[1L, 16L], [256L, 4096L], [65536L, 1048576L]]

num24bit = 0L

FOR j=0,2 DO num24bit = num24bit + ((rgb_triple[j] MOD 16) * base16[0,j]) + $
   (Fix(rgb_triple[j]/16) * base16[1,j])
   
RETURN, num24bit
END