;+
; NAME: 
;	xhelp
;
; PURPOSE:
;	Display an IDL procedure header using widgets and the widget manager.
;
; CATEGORY:
;	Widgets.
;
; CALLING SEQUENCE:
;	xhelp, Filename,_extra=ex
;
; INPUTS:
;     Filename:	A scalar string that contains the filename of the file
;		to display.  If FILENAME does not include a complete path
;               specification, xhelp will search for the file in
;               the current working directory and then each of the
;               directories listed in !PATH environment variable.  The
;               ".pro" file suffix will be appended if it is not supplied.
;
; KEYWORD PARAMETERS:
;       Ceux de xdisplayfile
;
; OUTPUTS:
;	No explicit outputs.  A file viewing widget is created.
;
; SIDE EFFECTS:
;	Triggers the XMANAGER if it is not already in use.
;
; RESTRICTIONS:
;	None.
;
; PROCEDURE:
;	Open a file and create a widget to display its contents.
;
; MODIFICATION HISTORY:
;	Written By Steve Richards, December 1990
;	Graceful error recovery, DMS, Feb, 1992.
;       Modified to extract .pro documentation headers, PJR/ESRG mar94
;
;  author:  Paul Ricchiazzi                            jun93
;           Institute for Computational Earth System Science
;           University of California, Santa Barbara
;
;  7/1/99 : legeres mofification par Sebastien Masson : utilisation de
;  xdisplayfile, de findfile et de _extra.
;  6/7/1999: compatibilite mac et windows
;-
PRO xhelp, filename, _extra=ex

; filename est bien un string?
   cquoidonc = size(filename, /type)
   if cquoidonc NE 7 then begin
      ras = report('Input parameter must be a string and not a '+size(filename, /tname))
      return
   endif
; il faut trouver le nom complet 
   pfile=FILENAME
   if strpos(pfile,".pro") lt 0 then pfile=pfile+".pro" 
   thisOS = strupcase(strmid(!version.os_family, 0, 3))
   CASE thisOS of
      'MAC':BEGIN & sep = ':' & pathsep = ',' & end
      'WIN':BEGIN & sep = '\' & pathsep = ';' & end
      ELSE: BEGIN & sep = '/' & pathsep = ':' & end
   ENDCASE
   cd, current = current
   if strpos(pfile,sep) lt 0 then BEGIN
      if rstrpos(current,sep) NE strlen(current)-1 then current = current+sep
      multipath = str_sep(!path,pathsep)
      if rstrpos(multipath[0],sep) NE strlen(multipath[0])-1 then multipath = multipath +sep
      pfile = [current, multipath]+ pfile
   ENDIF
; on test tous les noms possibles pour trouver ou est le fichier
   nfile=n_elements(pfile)
   n = 0
   repeat begin
      res = findfile(pfile[n]) 
      n = n+1
   endrep until res[0] NE '' OR n EQ n_elements(pfile) 
   if res[0] NE '' then BEGIN
      openr, unit,pfile[n-1], /get_lun ; ouverture du fichier
; on selectionne le morceaux en-tete     
      a = strarr(1000)          ;Maximum # of lines
      xsize=0
      i = 0
      c = ''
      readon=0
      while not eof(unit) do begin
         readf,unit,c
         if strpos(c,';-') eq 0 then readon=0
         if readon then begin
            dum=where(byte(c) eq 9b,ntab) ; count tab characters
            xsize=xsize > (strlen(c)+8*ntab)
            a(i) = strmid(c,1,200)
            i = i + 1
         endif
         if strpos(c,';+') eq 0 then readon=1
      endwhile
      if i EQ 0 then $
         ras = report('le programme a etait mal ecrit, il n''y a pas d''en-tete... utiliser xfile.pro.') ELSE BEGIN 
         a = a(0:i-1)
; on ecrit le contenu de a ds un widget
         xdisplayfile,'toto',text = a,title=pfile[n-1], _extra = ex
      ENDELSE 
      FREE_LUN, unit         ;free the file unit.
   ENDIF ELSE ras = report('le fichier demande n''existe pas...')

   return
end