PRO bscan, datafile, start_at, end_at = end_at, average = average, $
    max_scale = max_scale, min_scale = min_scale, $
    range = range, altitude = altitude
;=========================================================================
; Reads fixed-record-length binary data files with 30 word headers.
; This program runs on a DOS-PC or Unix-workstation, under PV-WAVE
; or IDL, and makes color images of any airborne or ground-based 
; lidar field in a time-versus-range or time-versus-altitude style.
; Please report bugs and suggestions for improvement to Shane Mayor, 
; University of Wisconsin-Madison, shane@lidar.ssec.wisc.edu,
; office: 608-263-6847
;=========================================================================

;=========================================================================
; First, determine what os running and where to get BSCAN 
; supporting files (i.e. color tables, etc.) if Unix.
;=========================================================================

print,'BSCAN Version 1.060 (18 November 97)'

bscan_files = '' 
if ((!Version.os eq 'sunos') OR (!Version.os eq 'solaris') OR $
    (!version.os eq 'AIX')) then begin
   bscan_files = getenv('BSCAN_FILES')
   if (bscan_files eq '') then begin
      print,'Sorry, BSCAN cannot find BSCAN_FILES in your environment.'
      print,'Please exit PV-WAVE or IDL and set the BSCAN_FILES '+$
      ' environment variable:'
      print,'At NCAR-ATD:  BSCAN_FILES=/local/lib/bscan/'
      print,'At NOAA-ETL:  BSCAN_FILES=/opt/local/shane/'
      print,'At Wisconsin: BSCAN_FILES=/usr6/shane/bscan/code/'
      return
   endif else begin
      bscan_files = bscan_files + '/'
      print,'BSCAN_FILES = ',bscan_files
   endelse
endif else if (!Version.os eq 'Win32') then begin
;  PC version of PV-WAVE
   path = !Path
;  Search through the !Path variable and locate the subdir with the word
;  bscan in it. Then set bscan_files to that subdir.
   result = strpos(strupcase(path),'BSCAN')
   if (result gt -1) then begin
	path_chars = strarr(strlen(path))
	for i = 0,n_elements(path_chars)-1 do begin
	    path_chars(i) = strmid(path,i,1)
	endfor
	semi_locs = where(path_chars eq ';')
	lt_result = where(semi_locs lt result)
	gt_result = where(semi_locs gt result)
	if (lt_result(0) ne -1) then begin
	   start_pos = semi_locs(max(lt_result))+1
	endif else begin
	   start_pos = 0
	endelse
	if (gt_result(0) ne -1) then begin
	   end_pos = semi_locs(min(gt_result))
	endif else begin
	   end_pos = n_elements(path_chars)
	endelse
	chars = end_pos - start_pos
	print,start_pos, end_pos, chars
	bscan_files = strmid(path,start_pos,chars)
	; Append backslash if necessary (for DOS systems)
	if (strmid(bscan_files,strlen(bscan_files)-1,1) ne '\') then begin
	       bscan_files = bscan_files + '\'
	endif
	print,'BSCAN_FILES = ',bscan_files   
   endif else begin
	print,'Sorry, reference to BSCAN was not found in your !Path.'
	print,'Please set your !Path to include location of BSCAN files.'
	print,'The subdirectory name must contain the word BSCAN.'
	return
   endelse
endif else begin
   print,'Running on non-Unix and non-win32 platform.'
   print,'Not sure how to proceed.  Program ending.'
   return
endelse 

;======================================================================
; Check to make sure we can find the data file.
;======================================================================
err = findfile(datafile,count=count)
if (count eq 0) then begin
   print,'Data file: '+datafile+' cannot be found.'
   return
endif

;======================================================================
; Check to make sure we can find the color tables
; This essentially checks to make sure BSCAN_FILES is correct.
;======================================================================
err = findfile(bscan_files+'browell_.27',count=count)
if (count eq 0) then begin
   print,'Color table: '+bscan_files+'browell_.27 cannot be found.'
   return
endif
err = findfile(bscan_files+'velocity.32',count=count)
if (count eq 0) then begin
   print,'Color table: '+bscan_files+'velocity.32 cannot be found.'
   return
endif

;======================================================================
; Set some initial conditions here
;======================================================================
loop = 1
set_file = 'BSCAN.SET'
eps_option = 0
ps_image = 1
ps_color_option = 2    ; 1 for no-color, 2 for color
ps_fn = ''
ps_path = ''
pretitle= ''
platform= ''
instrument=''
field=''
project = ''
supplement1 = ''
supplement2 = ''
lr_flag = 1
flag = -999.0
screen_type = !d.name
dual_time = 0b
upper_row_time_label = ''
lower_row_time_label = ''
upper_row_hour_adj = 0
lower_row_hour_adj = 0
landscape = 0b
transects = 0
range_shift = 0.
alt_shift = 0.
paper_size = 0.
custom_xsize = 0.
custom_ysize = 0.
custom_xoffset = 0.
custom_yoffset = 0.
x_dim = 500.
y_dim = 300.
first_loop = 0.
range_extend_flag=0     ; 1 = user wants to display beyond range of data
altitude_extend_flag=0  ; 1 = user wants to display beyond altitude of data.     

;======================================================================
; Check out the first header in the data file.
; Determine file size and if byteswapping is required.
;======================================================================
openr,lun,datafile,/get_lun
stats = fstat(lun)
record = assoc(lun,fltarr(30))
first_header = record(0)
close,lun
free_lun,lun
byteswap=0b
if ((first_header(11) ne flag) and (first_header(11) lt 1)) then begin
	byteswap = 1b
	print,'Byteswapping required.'
	stop
endif
if (byteswap) then byteorder,first_header,/Lswap

prof_len = first_header(28)

if (prof_len le 0) then begin
   print,'Sorry. First header of '+datafile
   print,'says that profile length is less than or equal to 0.'
   print,'This header element must be positive number.'
   print,'BSCAN stopping.'
   stop
endif

rec_len = prof_len + 30 
data_id = first_header(16)
platform_id = first_header(22)
recs_in_file = long(stats.size/(rec_len*4))
mb_in_file = long(stats.size)/(1024.*1024)

; Check out the last header in the data file.
openr,lun,datafile,/get_lun
record = assoc(lun,fltarr(rec_len))
last_record = record(recs_in_file-1)
last_header = last_record(0:29)
close,lun
free_lun,lun
if (byteswap) then byteorder,last_header,/Lswap

lookups,data_id,platform_id,$
	instrument,field,platform,$
	cfile,mns,mxs

hours = strtrim(string(fix(first_header(0))),2)
minutes = strtrim(string(fix(first_header(1))),2)
if (strlen(minutes) eq 1) then minutes='0'+minutes
seconds = strtrim(string(fix(first_header(2))),2)
if (strlen(seconds) eq 1) then seconds='0'+seconds
first_file_time = hours+':'+minutes+':'+seconds

hours =   strtrim(string(fix(last_header(0))),2)
maj_tim_tic = (hours/6)+1
minutes = strtrim(string(fix(last_header(1))),2)
if (strlen(minutes) eq 1) then minutes='0'+minutes
seconds = strtrim(string(fix(last_header(2))),2)
if (strlen(seconds) eq 1) then seconds='0'+seconds
last_file_time = hours+':'+minutes+':'+seconds

print,'File name = '+datafile+', Date: '+$
      strtrim(string(fix(first_header(11))),2)+'-'+$
      strtrim(string(fix(first_header(12))),2)+'-'+$
      strtrim(string(fix(first_header(13))),2)

print,strtrim(recs_in_file,2),' records, ',strtrim(mb_in_file,2),' MB, ',$
first_file_time,' to ',last_file_time,', data ID = ',$ 
strtrim(fix(first_header(16)),2)

start_at_size = size(start_at)

openr,lun,datafile,/get_lun

if (start_at_size(1) eq 7) then begin
;  string detected
   if (strpos(strupcase(start_at),'T') ne -1) then begin
;    transect number detected
     findtran,fix(start_at),lun,rec_len,recs_in_file,first_rec,tran2
   endif else if (strpos(start_at,':') ne -1) then begin
;    time detected
     findtime,start_at,lun,rec_len,recs_in_file,first_rec
   endif else begin
     print,'Use of string for start position requires : '+$
     '(for time) or T (for transect).'
     return
   endelse
endif else begin
;  record number detected
   first_rec = long(start_at)
endelse

if (not keyword_set(average)) then average = 1

if (keyword_set(end_at)) then begin 
   end_at_size = size(end_at)
   if (end_at_size(1) eq 7) then begin
;    string detected
     if (strpos(strupcase(end_at),'T') ne -1) then begin
;      transect number detected
       findtran,fix(end_at),lun,rec_len,recs_in_file,tran3,last_rec
     endif else if (strpos(end_at,':') ne -1) then begin
;      time detected
       findtime,end_at,lun,rec_len,recs_in_file,last_rec
     endif else begin
       print,'Use of string for end_at requires : '+$
       '(for time) or T (for transect).'
       return
     endelse
   endif else begin
;    record number detected
     last_rec = long(end_at)
   endelse
endif else begin
   if (strpos(strupcase(start_at),'T') ne -1) then begin
      last_rec = tran2
   endif else begin
      last_rec = first_rec + (512*average) - 1
   endelse
endelse
close,lun
free_lun,lun

if (first_rec ge recs_in_file-1) then begin
   print,'Sorry, there are only ',strtrim(recs_in_file,2),' records in ',datafile
   print,'and you asked to start reading at record ',strtrim(first_rec,2),'.'
   return
endif

the_most_recs = (512*average)
if (((last_rec-first_rec) GT the_most_recs) and (average GT 1)) then begin 
  last_rec = first_rec + the_most_recs - 1
  if (last_rec lt recs_in_file-1) then begin
    print,'Due to the average keyword and the limit of 512 averaged profiles,' 
    print,'the last record that will be read is '+ $ 
    strtrim(last_rec,2)
  endif
endif

if ((last_rec gt recs_in_file-1) or (last_rec lt 0)) then $
last_rec = recs_in_file-1

if (first_rec lt 0) then first_rec = 0
num_recs = last_rec - first_rec + 1

read_data_entry:

if (average gt 1) then begin
   print,'Reading records '+strtrim(first_rec,2)+' to '+$
   strtrim(last_rec,2)+' ('+strtrim(num_recs,2)+' records, averaging every '+$ 
   strtrim(average,2)+' together.)'
endif else begin
   print,'Reading records '+strtrim(first_rec,2)+' to '+$
   strtrim(last_rec,2)+' ('+strtrim(num_recs,2)+' records, with no averaging.)'
endelse

data_recs = num_recs/average

print,'The resulting data array will contain '+strtrim(data_recs,2)+' profiles.'
data = fltarr(prof_len,data_recs) 
header = fltarr(30,data_recs)

openr,lun,datafile,/get_lun
record=assoc(lun,fltarr(rec_len))

if (last_rec gt (recs_in_file-1)) then begin
    last_rec = recs_in_file - average
endif
   
if (byteswap) then begin
; Read with byteswapping
  if (average gt 1) then begin
; accumulate and average while reading
    data_rec = 0
    sum=fltarr(rec_len)
    for i=first_rec,last_rec-average+1,average do begin
      for j=1,average do begin
	k = i + j - 1
;        print,'data_rec,j,k = ',data_rec,j,k
	z=record(k)
	byteorder,z,/Lswap
	sum=sum+z(30:rec_len-1)
      endfor
      header(*,data_rec) = z(0:29)
      data(*,data_rec) = sum(*)/average
      sum(*)=0.
      data_rec = data_rec + 1
    endfor
  endif else begin
;   straight read of every record with no averaging
    for i=first_rec,last_rec do begin
       z=record(i)
       byteorder,z,/Lswap
       header(*,i-first_rec) = z(0:29)
       data(*,i-first_rec) = z(30:rec_len-1)
    endfor
  endelse
endif else begin
; Read with no byteswapping
  if (average gt 1) then begin
;   accumulate and average while reading
    data_rec = 0
    sum=fltarr(rec_len)
    for i=first_rec,last_rec-average+1,average do begin
      for j=1,average do begin
	k = i + j - 1
;        print,'data_rec,j,k = ',data_rec,j,k
	z=record(k)
	sum=sum+z(30:rec_len-1)
      endfor
      header(*,data_rec) = z(0:29)
      data(*,data_rec) = sum(*)/average
      sum(*)=0.
      data_rec = data_rec + 1
    endfor
  endif else begin
;   straight read of every record with no averaging
    for i=first_rec,last_rec do begin
       z=record(i)
       header(*,i-first_rec) = z(0:29)
       data(*,i-first_rec) = z(30:rec_len-1)
    endfor
  endelse
endelse

this_transect = z(29)

close,lun
free_lun,lun

;==============================================================
; Check to make sure some variables in the header are constant
;==============================================================
const_test = header(21,*) - shift(header(21,*),1)
delta_locs = where(const_test ne 0)
if (delta_locs(0) ne -1) then begin
   print
   print,'Warning: Header element number 21 (range-resolution of data)'
   print,'is not constant through this segment of data.'
   print,'Program cannot continue.'
   print,'Please check reduced data file.'
   stop
   return
endif
const_test = header(23,*) - shift(header(23,*),1)
delta_locs = where(const_test ne 0)
if (delta_locs(0) ne -1) then begin
   print
   print,'Warning: Header element number 23 (number of header words per record)'
   print,'is not constant through this segment of data.  Program cannot continue.'  
   print,'Please check reduced data file.'
   stop
   return
endif
const_test = header(28,*) - shift(header(28,*),1)
delta_locs = where(const_test ne 0)
if (delta_locs(0) ne -1) then begin
   print
   print,'Warning: Header element number 28 (number of profile words per record)'
   print,'is not constant through this segment of data.  Program cannot continue.'  
   print,'Please check reduced data file.'
   stop
   return
endif
const_test = 0b
delta_locs = 0b

;=============================================================
; Check to see how many transects this segment spans
;=============================================================
transects = max(header(29))-min(header(29))+1

;=============================================================
; Check to see how many hours of data the scene spans
;=============================================================
delta_scene_hours = max(header(0)) - min(header(0))

data_size = size(data)
;print,data_size

; Now check some things that only need to be done the 
; first time through.

if (loop eq 1) then begin
; Flag sample style
  screen_sample_style=flag
  PS_sample_style=flag
; First, check to see if data is ground-based or airborne
  airborne = -1
  if (fix(first_header(22)) eq 9) then airborne = 0
  if (fix(first_header(22)) eq 8) then airborne = 1
  if (airborne lt 0) then begin
    ask1:
    print,''
    print,'Is this airborne or ground-based data?'
    print,'1) airborne'
    print,'2) ground-based'
    answer = 0
    read,answer
    if ((answer lt 1) or (answer gt 2)) then begin
	   print,'You must reply with either 1 or 2.'
	   goto,ask1
    endif
    if (answer eq 1) then begin
	   airborne = 1
	   print,'Airborne selected.'
    endif
    if (answer eq 2) then begin
	   airborne = 0
	   print,'Ground-based selected.'
    endif
  endif
; Make sure header element 21 has a non-zero value in it.
  if (header(21,0) le 0.) then begin
	print,'Warning: header element 21 is: '+strtrim(header(21,0),2)
	print,'This value is not allowed for range resolution of data.'
	ask9:
	print,'Enter new value (meters per word).'
	metpwd = 0.
	read,metpwd
	if (metpwd le 0.) then begin
	    print,strtrim(metpwd,2)+' is not valid.'
	    print,'Please enter a positive number.'
	    goto,ask9
	endif
	ask10:
	print,'Would you like to update the data file?'
	print,'1) yes'
	print,'2) no'
	answer=-1
	read,answer
	if ((answer lt 1) or (answer gt 2)) then begin
	   print,'You may only answer 1 or 2.'
	   goto, ask10
	endif
	if (answer eq 1) then begin
	   fixhdr,datafile,21,metpwd
	endif
  endif
;===================================================================
; Images can be made with the platform at the bottom with range 
; increasing up **OR** platform at the top with range increasing down.
; The default is platform at the bottom with range increasing up.
;===================================================================
  updn = 1
;====================================================================
; If the data are airborne, find out if nadir or zenith image.
; If it is not obvious (i.e. not + or - 90.) then ask the user.
;====================================================================
  if (airborne eq 1) then begin
    if (header(7,0) eq 90.) then updn = 1
    if (header(7,0) eq -90.) then updn = -1
    if ((header(7,0) ne 90.) and (header(7,0) ne -90.)) then begin
	ask_updn:
	print,'Beam elevation is not + or - 90.'
	print,'Do want the image to appear as:'
	print,'1) nadir (platform at the top, lidar looking down)'
	print,'2) zenith (platform at the bottom, lidar looking up)'
	updn=0.
	read,updn
	if ((updn ne 1) and (updn ne 2)) then begin
		print,'You may choose 1 or 2 only.'
		print,'(Even if the data are not zenith or nadir.)'
		goto,ask_updn
	endif
	if (updn eq 1) then begin
		updn=-1
		print,'Nadir selected'
	endif
	if (updn eq 2) then begin
		updn=1
		print,'Zenith selected'
	endif
    endif else begin
	if (updn eq 1) then begin
	   print,'This appears to be zenith data.'
	endif
	if (updn eq -1) then begin
	   print,'This appears to be nadir data.'
	endif
    endelse
  endif
;==================================================================
; Set the min and max scale for the color bar here
;==================================================================
  if (not keyword_set(max_scale)) then max_scale = mxs
  if (not keyword_set(min_scale)) then min_scale = mns

  load_ct,bscan_files + cfile,bins,RGB_array

  if (max_scale eq flag) then begin
     find_mag,max(data),mag
     max_scale = .50 * 10^(mag)
  endif
  if (min_scale eq flag) then begin
	 min_scale = 0.
  endif

  max_scale = float(max_scale)
  min_scale = float(min_scale)
;=========================================================================
; Decide on whether the image will be altitude aligned or not.
; If altitude-aligned, then altitude (m ASL) will be the vertical coordinate
; If not altitude-aligned, then range (m from platform) will
; be the vertical coordinate.
;=========================================================================
  range_flag = 1b
  altitude_flag = 0b
  if (airborne) then begin
	range_flag = 0b
	altitude_flag = 1b
  endif
  if (keyword_set(range)) then begin
    print,'Time versus RANGE plot requested.'
    range_flag = 1b
    altitude_flag = 0b
  endif else begin
    range = 1
  endelse
  if (keyword_set(altitude)) then begin
    print,'Time versus ALTITUDE plot requested.'
    range_flag = 0b
    altitude_flag = 1b
  endif else begin
    altitude = 1
  endelse
;======================================================
; Find out if user wants a new window for each image.
;======================================================
  ask05:
  print,''
  window_prompt=-1
  print,'Would you like to:'
  print,'1) Keep all images on the screen (do not prompt again)' 
  print,'2) Delete recent image before creating new one (do not prompt again)'
  print,'3) Be prompted with a choice each time an image is created.'
  print,'4) Quit BSCAN now and return to WAVE prompt.'
  read,window_prompt
  if ((window_prompt lt 1) or (window_prompt gt 4)) then begin
     print,'You may only answer 1, 2, 3, or 4. Please try again.'
     goto,ask05
  endif
  if (window_prompt eq 1) then new_window = 1
  if (window_prompt ge 2) then new_window = -1
  if (window_prompt eq 4) then return
endif

min_alt = min(header(3,*))
max_alt = max(header(3,*))
alt_range = max_alt - min_alt
if (updn eq 1) then start_alt = min_alt
if (updn eq -1) then start_alt = max_alt

sampling_inquiry:
if ((!d.name ne 'PS') and (screen_sample_style eq flag)) then begin
;        X or WIN32 device
	 print,''
	 print,'Subsampling required for this device: '+strtrim(!d.name)
	 print,'Which do you want? (This will set the default for this run.)'
	 ask_screen_sample_style:
	 print,'1) bilinear interpolation'
	 print,'2) nearest neighbor'
         print,'3) bilinear interpolation(skip flagged values)'
	 read,screen_sample_style
	 if (screen_sample_style lt 1) or (screen_sample_style gt 3) then begin
	    print,'Please choose 1, 2, or 3 only.'
	    goto,ask_screen_sample_style
	 endif else begin
	    print,''
	    if (screen_sample_style eq 1) then $
	    print,'Bilinear interpolation subsampling selected for screen display.'
	    if (screen_sample_style eq 2) then $
	    print,'Nearest neighbor subsampling selected for screen display.' 
	    if (screen_sample_style eq 3) then begin
	        print,'Bilinear interpolation subsampling selected for screen display (skip flagged values).'
                if(flag eq 0.0)then begin
                   print,'What value do you want to represent bad data?'
                   read,flag
	        endif
            endif
	 endelse
endif else if ((!d.name eq 'PS') and (PS_sample_style eq flag)) then begin
;       PS device
	print,'Options for PS display.'
	print,'Which do you want? (This will set the default for this run.)'
	ask_PS_sample_style:
	print,'1) subsampling using bilinear interpolation'
	print,'2) subsampling using nearest neighbor method'
        print,'3) subsampling using bilinear interpolation(skip flagged values)'
;        print,'3) no subsampling (plot all data as read)'
	read,PS_sample_style
	if (PS_sample_style lt 1) or (PS_sample_style gt 3) then begin
	   print,'Please choose 1, 2, or 3 only.'
	   goto,ask_PS_sample_style
	endif else begin
	   print,''
	   if (PS_sample_style eq 1) then $
	   print,'Bilinear interpolation subsampling selected for PS output.'
	   if (PS_sample_style eq 2) then $
	   print,'Nearest neighbor subsampling selected for PS output.'
	   if (PS_sample_style eq 3) then begin
	       print,'Bilinear interpolation subsampling selected for PS output (skip flagged values).'
               if(flag eq 0.0)then begin
                  print,'What value do you want to represent bad data?'
                  read,flag
	       endif
           endif
;
;check for bad user values for the image size
;
           if (x_dim le 0) then x_dim = 500
           if (y_dim le 0) then y_dim = 300
	endelse
	goto, sample_entry
endif

vertical_alignment_entry:
if (altitude_flag) then begin
  print,'Altitude range of platform during this segment: ',$
  strtrim(min_alt,2)+' - '+strtrim(max_alt,2)+' m'
  print,'Platform altitude changes '+strtrim(alt_range,2)+$
  ' m during this segment'
  if (alt_range ne 0.) then begin
    print,'Altitude alignment required.'
    expanded_range = fix((alt_range / header(21,0)) + header(28,0))
;    print,'Expanded vertical range '+strtrim(expanded_range,2)+' words'
    data1 = fltarr(expanded_range,data_recs)
    data1(*) = flag
    ref_alt = max_alt
;    print,'Reference altitude = '+strtrim(ref_alt,2)
    for i = 0,(data_recs-1) do begin
	start_word = fix((ref_alt-header(3,i))/header(21,i))
	stop_word = fix(start_word + header(28,i) - 1)
;       print,header(3,i),' 0-'+strtrim((expanded_range-1),2)+' ',$
;       strtrim(start_word,2)+'-'+strtrim(stop_word,2),stop_word-start_word+1
;       stop
	data1(start_word:stop_word,i) = data(*,i)
    endfor
  endif else begin
    data1 = data
  endelse
  data1_size=size(data1)
  vertical1 = (findgen(data1_size(1))*header(21,0)*float(updn)) + $
	      start_alt + (first_header(20)*float(updn)) + alt_shift
endif else begin
  data1 = data
  data1_size=size(data1)
  vertical1 = (findgen(data1_size(1))*header(21,0)) + $
	       first_header(20) + range_shift
endelse
;print,data1_size

vertical_extend_entry:
; This section is under developement by S Mayor as of 11/18/97
; If the user specifies a range or altitude above/below the max/min
; altitude or range of the data, then we have to make an oversized
; array and place the existing data into it at the right spot.
; This is essentially padding with flags.
if (altitude_flag) then begin
; altitude display requested
    if ((min(altitude) lt min(vertical1)) or $
        (max(altitude) gt max(vertical1))) then altitude_extend_flag=1
    if ((min(altitude) gt min(vertical1)) and $
	(max(altitude) lt max(vertical1))) then altitude_extend_flag=0
    print,'altitude_extend_flag=',altitude_extend_flag
    if (altitude_extend_flag eq 1) then begin
       extend_alt_up = max(altitude)-max(vertical1)
       extend_alt_dn = min(vertical1)-min(altitude)
       if (extend_alt_up lt 0) then extend_alt_up=0.
       if (extend_alt_dn lt 0) then extend_alt_dn=0.
       extend_dim = (extend_alt_up/header(21,0)) + $
		    (extend_alt_dn/header(21,0)) + data1_size(1)
       print,'extend_alt_up=',extend_alt_up,' m'
       print,'extend_alt_dn=',extend_alt_dn,' m'
       print,'data1_size=',data1_size
       print,'extend_dim=',extend_dim,' words'
       exp_data = fltarr(fix(extend_dim+1),data1_size(2))
       print,'size(exp_data)=',size(exp_data)
    endif
endif else begin
; range display requested
    if ((min(range) lt min(vertical1)) or $
        (max(range) gt max(vertical1))) then range_extend_flag=1
    if ((min(range) gt min(vertical1)) and $
	(max(range) lt max(vertical1))) then range_extend_flag=0
    if (range_extend_flag eq 1) then begin
       extend_range_up = max(altitude)-max(vertical1)
       extend_range_dn = min(vertical1)-min(altitude)
       if (extend_range_up lt 0) then extend_range_up=0.
       if (extend_range_dn lt 0) then extend_range_dn=0.
       extend_dim = (extend_range_up/header(21,0)) + $
		    (extend_range_dn/header(21,0)) + data1_size(1)
       print,'extend_range_up=',extend_range_up,' m'
       print,'extend_range_dn=',extend_range_dn,' m'
       print,'data1_size=',data1_size
       print,'extend_dim=',extend_dim,' words'
       exp_data = fltarr(fix(extend_dim+1),data1_size(2))
       print,'size(exp_data)=',size(exp_data)
    endif
endelse

vertical_extract_entry:
; Extract a swath across the data array for display
; This will restrict the vertical dimension of the data being displayed.
;print,'altitude_flag=',altitude_flag
if (altitude_flag) then begin
  if (n_elements(altitude) eq 1) then begin
;   no altitudes specified by user.  Take all.
    levels = where(vertical1 gt (-500.))
  endif else begin
;   altitudes specified by user.  
    levels = where((vertical1 ge min(altitude)) and (vertical1 le max(altitude)))
  endelse
endif else begin
  if (n_elements(range) eq 1) then begin
;   no ranges specified by user.  Take all.
    levels = indgen(n_elements(vertical1))
  endif else begin
;   ranges specified by user.  
    levels = where((vertical1 ge min(range)) and (vertical1 le max(range)))
  endelse
endelse
data2 = data1(levels,*)
data2_size = size(data2)
;print,data2_size
vertical2 = vertical1(levels)
if(first_loop eq 0) then goto, first_loop_jump_point

sample_entry:
;if ((!d.name eq 'PS') and (screen_sample_style eq ps_sample_style)) then goto,color_entry
if (!d.name eq screen_type) then begin
;  This image going to the screen   
   if (screen_sample_style eq 1) then begin
;       print,'Bilinear congridding...'
       data3 = congrid(data2,y_dim,x_dim,/Interp) 
   endif else if (screen_sample_style eq 2) then begin
;       print,'Nearest-neighbor congridding...'
       data3 = congrid(data2,y_dim,x_dim)
   endif else if (screen_sample_style eq 3) then begin
       s = size(data2)
       dx = double((s(1)-1)/(y_dim-1))
       dy = double((s(2)-1)/(x_dim-1))
       my_x = fltarr(y_dim)
       my_y = fltarr(x_dim)
       j = 0
       for i=0.0, s(1)-1, dx DO BEGIN
         my_x(j) = i
         j = j + 1
       endfor
       my_x(y_dim-1)=s(1)-1
       j = 0
       for i=0.0, s(2)-1, dy DO BEGIN
         my_y(j) = i
         j = j + 1
       endfor
       my_y(x_dim-1)=s(2)-1
       print,'Working...'        
       data3 = newbilinear(data2,my_x,my_y,flag)
   endif else begin
       print,'Screen sample style ',screen_sample_style,' not supported.'
       print,'BSCAN stopping.'
       stop
   endelse
endif else begin
;  This image going to a Postscript file
   if (PS_sample_style eq 0) then begin
       data3 = data2
   endif else if (PS_sample_style eq 1) then begin
;       print,'Bilinear congridding...'
       data3 = congrid(data2,y_dim,x_dim,/Interp)
   endif else if (PS_sample_style eq 2) then begin 
;       print,'Nearest-neighbor congridding...'
       data3 = congrid(data2,y_dim,x_dim)
   endif else if (screen_sample_style eq 3) then begin
       s = size(data2)
       dx = double((s(1)-1)/(y_dim-1))
       dy = double((s(2)-1)/(x_dim-1))
       my_x = fltarr(y_dim)
       my_y = fltarr(x_dim)
       j = 0
       for i=0.0, s(1)-1, dx DO BEGIN
         my_x(j) = i
         j = j + 1
       endfor
       my_x(y_dim-1)=s(1)-1
       j = 0
       for i=0.0, s(2)-1, dy DO BEGIN
         my_y(j) = i
         j = j + 1
       endfor
       my_y(x_dim-1)=s(2)-1
       print,'Working...'        
       data3 = newbilinear(data2,my_x,my_y,flag)
   endif else begin
       print,'PS sample style ',PS_sample_style,' not supported.'
       print,'BSCAN stopping.'
       stop
   endelse
endelse
vertical3 = interpol(vertical2,y_dim)
data3_size = size(data3)

color_entry:
scale_range = max_scale - min_scale
if (scale_range eq 0.) then begin
   print,'Warning: SCALE_RANGE = 0.'
   print,'BSCAN cannot continue.'
   stop
endif

bin_width = scale_range/float(bins-2)
;print,'bin_width = ',bin_width
elements = where(data3 eq max_scale)
if (elements(0) ge 0) then data3(elements)=data3(elements)-0.00001
data4 = fix((data3 - min_scale)/bin_width) + 1
elements = where(data4 lt 0.)
if (elements(0) ge 0) then data4(elements)=0.
elements = where(data4 gt (bins-2))
if (elements(0) ge 0) then data4(elements)=float(bins-1)
disp_arr=byte(data4)

if (!d.name eq 'PS') and (ps_color_option eq 1) then begin
   disp_arr=(byte(data4)*255)/bins
   !p.color = 0
endif

sx=x_dim + 200
sy=y_dim + 212
disp_size=size(disp_arr)
dx=float(disp_size(2))/sx
dy=float(disp_size(1))/sy
x0=(1.-dx)/2.
y0=(1.-dy)/3.5

data_id = header(16,0)

m = header(11,0)
if (m ne flag) then begin
   ascii_mo,m,month
endif else begin
   month = ' '
endelse
day = header(12,0)
year = header(13,0)
date_string=strtrim(string(fix(day)),2)+' '+month+' '+$
	    strtrim(string(fix(year)),2)

hours = strtrim(string(fix(header(0,0))),2)
minutes = strtrim(string(fix(header(1,0))),2)
if (strlen(minutes) eq 1) then minutes='0'+minutes
seconds = strtrim(string(fix(header(2,0))),2)
if (strlen(seconds) eq 1) then seconds='0'+seconds
first_rec_time = hours+':'+minutes+':'+seconds

hours =   strtrim(string(fix(header(0,data_recs-1))),2)
minutes = strtrim(string(fix(header(1,data_recs-1))),2)
if (strlen(minutes) eq 1) then minutes='0'+minutes
seconds = strtrim(string(fix(header(2,data_recs-1))),2)
if (strlen(seconds) eq 1) then seconds='0'+seconds
last_rec_time = hours+':'+minutes+':'+seconds

window_title = instrument+'  '+date_string+', '+first_rec_time+' to '+$
last_rec_time+' (records '+strtrim(string(long(first_rec)),2)+'-'+$
strtrim(string(long(last_rec )),2)+')'

start_graphics:

if ((!d.name ne 'PS') and (window_prompt eq 3)) then begin
   ask06:
   print,''
   new_window = -1
   print,'Open a new window?'
   print,'1) Yes (keep existing window and open a new one)'
   print,'2) No (delete existing window (if present) and open a new one) '
   read,new_window
   if ((new_window lt 1) or (new_window gt 2)) then begin
       print,'You may only answer 1 or 2.  Please try again.'
       goto, ask06
   endif
   if (new_window eq 2) then new_window = -1
endif

if (!d.name ne 'PS') then begin
;  print,'new_window = ',new_window
   if (new_window eq 1) then begin
;     Open a new window with the /free keyword
      window,xsize=sx,ysize=sy,title=window_title,colors=256,retain=2,/free
   endif else begin
;     Just kill the latest window then open a new one
      window,xsize=sx,ysize=sy,title=window_title,colors=256,retain=2
   endelse
endif

; WHITE white
!p.background=bins
erase

if ((updn eq -1) and (lr_flag gt 0)) then begin
  disp_rotate=3
  vertical4=rotate(vertical3,2)
endif
if ((updn eq 1) and (lr_flag gt 0)) then begin
  disp_rotate=4
  vertical4=vertical3
endif
if ((updn eq -1) and (lr_flag lt 0)) then begin
  disp_rotate=6
  vertical4=rotate(vertical3,2)
endif
if ((updn eq 1) and (lr_flag lt 0)) then begin
  disp_rotate=1
  vertical4=vertical3
endif

tv,rotate(disp_arr,disp_rotate),x0,y0,xsize=dx,ysize=dy,/normal

; Remember, screen_type is only set at the initialization.
; It does not tell you whether you are in PS mode or not.
; It only tells you whether you are X or win32.
; You must use !d.name to know whether you are writing to PS.

; BLACK black
if (ps_color_option eq 2) then begin
    !p.color = bins+1
endif else begin
    !p.color = 0
endelse

if (!d.name eq 'PS') then begin
  if (landscape) then begin
;    Use larger characters for Landscape 
     !p.charsize = 1.0
     !p.thick=3
  endif else begin
;    Use smaller characters for Portrait
     !p.charsize = 0.75
     !p.thick=2 
  endelse
endif else begin
; screen output
  !p.charsize = 1.0
  !p.thick=2
endelse
!p.font=0

y1=y0-.02
y2=y0-.04
y3=y0-.068
y4=y0-.093
y5=(y0+dy)+.02
y6=(y0+dy)+.04
y7=(y0+dy)+.048
y8=(y0+dy)+.076

y9=y0-.03
y10=(y0+dy)+.03

x1=x0-.015
x2=x0-.025
x3=x0-.040
x4=x0-.045
x5=(x0+dx)+.015
x6=(x0+dx)+.025
x7=(x0+dx)+.040
x8=(x0+dx)+.045
x9=x0-.072

plots,[x0,x0+dx],[y1,y1],/normal
plots,[x0,x0+dx],[y5,y5],/normal
plots,[x1,x1],[y0,y0+dy],/normal
plots,[x5,x5],[y0,y0+dy],/normal

;==============================================================================
;********  VERTICAL axes section starts here  *********************************
;==============================================================================
vertical_extent = max(vertical4) - min(vertical4)
if (vertical_extent gt 3000.) then begin
   maj_range_tic = 1000.
   min_range_tic = 250.
   frac = 0
endif else if (vertical_extent gt 1000.) then begin
   maj_range_tic = 500.
   min_range_tic = 100.
   frac = 1
endif else begin
   maj_range_tic = 250.
   min_range_tic = 50.
   frac = 2
endelse

remainder_thres = vertical_extent/y_dim

for i = 0,(n_elements(vertical4)-1) do begin
    if (vertical4(i) ge 0.) then begin
      maj_remainder = (vertical4(i) mod maj_range_tic)
      min_remainder = (vertical4(i) mod min_range_tic)
;      print,i,vertical4(i),maj_remainder,min_remainder
      if (maj_remainder le remainder_thres) then begin
	y = y0 + (float(i)/sy)
	plots,[x1,x3],[y,y],/normal
	plots,[x5,x7],[y,y],/normal
	if (frac eq 0) then begin
;         DO NOT display fraction of km in the vertical axes tic labels
	  vert_axes_string = strtrim(string(fix(vertical4(i)/1000.)),2)
	endif else if (frac eq 1) then begin
;         Display tenths of km (1 decimal place) in the vertical axes tic labels
	  vert_axes_string = strtrim(string((vertical4(i)/1000.),format='(f7.1)'),2)
	endif else begin
;         Display .25 km (2 decimal place) in the vertical axes tic labels
	  vert_axes_string = strtrim(string((vertical4(i)/1000.),format='(f7.2)'),2)
	endelse
	xyouts,x4,y-0.01,vert_axes_string,alignment=1,/normal
	xyouts,x8,y-0.01,vert_axes_string,alignment=0,/normal
      endif
      if (min_remainder le remainder_thres) then begin
	y = y0 + (float(i)/sy)
	plots,[x1,x2],[y,y],/normal
	plots,[x5,x6],[y,y],/normal
      endif
    endif
endfor

if ((!d.name eq 'X') or (!d.name eq 'PS')) then begin
  if (frac eq 0) then x = x0 - 0.072
  if (frac eq 1) then x = x0 - 0.083
  if (frac eq 2) then x = x0 - 0.096
  if (altitude_flag) then begin
	xyouts,x,y0+(dy/2),'Altitude (km ASL)',$
	orientation=90,alignment=.5,/normal
  endif else begin
	xyouts,x,y0+(dy/2),'Range (km)',$
	orientation=90,alignment=.5,/normal
  endelse       
endif

if (airborne) then begin
  xyouts,(1.-x9),y7,'N  LAT',/normal,alignment=.75
  xyouts,(1.-x9),y8,'E  LON',/normal,alignment=.75
endif else begin
  xyouts,(1.-x9),y7,'AZ',/normal,alignment=.75
  xyouts,(1.-x9),y8,'EL',/normal,alignment=.75
endelse

xyouts,(x6+x7)/2.,y3,upper_row_time_label,/normal,alignment=0.
if (dual_time) then xyouts,(x6+x7)/2.,y4,lower_row_time_label,/normal,alignment=0.

;==========================================================================
;******************** Horizontal axes section *****************************
;==========================================================================

;
;Added this if statement in case someone entered a bad tick mark value
;

if (maj_tim_tic le 0) then maj_tim_tic = 1.
header_size = size(header)
if (lr_flag gt 0) then begin
;  time increasing to the right
   start_horizontal_scan = 0
   end_horizontal_scan=header_size(2)-1
   step=1
endif else begin
;  time increasing to the left
   start_horizontal_scan=header_size(2)-1
   end_horizontal_scan=0
   step=-1
endelse
h_tick_count = 0
old_min = header(1,start_horizontal_scan)

; The following variables are 2-word arrays each.
; They define the starting and ending coordinates of horizontal axes tic label strings.
; pre refers to the most recent label.
; now refers to the one currently being considered.
pre_top_upper = [lr_flag*(-1.),lr_flag*(-1.)]
pre_bot_upper = [lr_flag*(-1.),lr_flag*(-1.)]
pre_top_lower = [lr_flag*(-1.),lr_flag*(-1.)]
pre_bot_lower = [lr_flag*(-1.),lr_flag*(-1.)]
now_top_upper = [lr_flag*(-1.),lr_flag*(-1.)]
now_bot_upper = [lr_flag*(-1.),lr_flag*(-1.)]
now_top_lower = [lr_flag*(-1.),lr_flag*(-1.)]
now_bot_lower = [lr_flag*(-1.),lr_flag*(-1.)]

for i=start_horizontal_scan,end_horizontal_scan,step do begin
	x=x0+((float(i)/float(header_size(2)))*dx)
	if ((header(1,i) mod maj_tim_tic) eq 0.) and (header(1,i) ne old_min) then begin

	     upper_hr = (header(0,i)+upper_row_hour_adj)
	     if (upper_hr lt 0) then upper_hr = 24 + upper_hr
	     if (upper_hr gt 23) then upper_hr = upper_hr - 24
	     lower_hr = (header(0,i)+lower_row_hour_adj)
	     if (lower_hr lt 0) then lower_hr = 24 + lower_hr
	     if (lower_hr gt 23) then lower_hr = lower_hr - 24

	     upper_hours = strtrim(string(fix(upper_hr)),2)
	     lower_hours = strtrim(string(fix(lower_hr)),2)
	     minutes = strtrim(string(fix(header(1,i))),2)
	     if (strlen(minutes) eq 1) then minutes = '0'+minutes
	     if (strlen(upper_hours) eq 1) then upper_hours = '0'+upper_hours
	     if (strlen(lower_hours) eq 1) then lower_hours = '0'+lower_hours
	     upper_time_string = upper_hours+':'+minutes
	     lower_time_string = lower_hours+':'+minutes

	     ; This part checks to see if the upper axis elements are flags and
	     ; if they are not, puts them into the string variables.
	     if (header(18,i) ne header(24,i)) then begin
	        lat_string = strtrim(string(header(18,i),format='(f7.2)'),2)
	     endif else begin
		lat_string = ' '
	     endelse
	     if (header(19,i) ne header(24,i)) then begin
	        lon_string = strtrim(string(header(19,i),format='(f7.2)'),2)
	     endif else begin
		lon_string = ' '
	     endelse
	     if (header(6,i) ne header(24,i)) then begin
	        beam_az_string = strtrim(string(header(6,i),format='(f7.2)'),2)
	     endif else begin
		beam_az_string = ' '
	     endelse
	     if (header(7,i) ne header(24,i)) then begin
	        beam_el_string = strtrim(string(header(7,i),format='(f7.2)'),2)
	     endif else begin
		beam_el_string = ' '
	     endelse 

	     now_top_lower(0)=x-((((strlen(upper_time_string)+2.)*!d.x_ch_size)/2.)/!d.x_size)
	     now_top_lower(1)=x+((((strlen(upper_time_string)+2.)*!d.x_ch_size)/2.)/!d.x_size)
	     now_bot_lower(0)=x-((((strlen(lower_time_string)+2.)*!d.x_ch_size)/2.)/!d.x_size)
	     now_bot_lower(1)=x+((((strlen(lower_time_string)+2.)*!d.x_ch_size)/2.)/!d.x_size)

	     if (airborne) then begin
		now_top_upper(0)=x-(((strlen(lat_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_top_upper(1)=x+(((strlen(lat_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_bot_upper(0)=x-(((strlen(lon_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_bot_upper(1)=x+(((strlen(lon_string)*!d.x_ch_size)/2.)/!d.x_size)
	     endif else begin
		now_top_upper(0)=x-(((strlen(beam_az_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_top_upper(1)=x+(((strlen(beam_az_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_bot_upper(0)=x-(((strlen(beam_el_string)*!d.x_ch_size)/2.)/!d.x_size)
		now_bot_upper(1)=x+(((strlen(beam_el_string)*!d.x_ch_size)/2.)/!d.x_size)
	     endelse

	     if (lr_flag gt 0) then begin
;              Time increasing to the right
	       if ((now_top_lower(0) gt pre_top_lower(1)) and $
		   (now_bot_lower(0) gt pre_bot_lower(1))) then begin 
;                  Full-tick marks and labels
	         plots,[x,x],[y1,y2],/normal
	         plots,[x,x],[y5,y6],/normal
		 xyouts,x,y3,upper_time_string,/normal,alignment=.5
		 h_tick_count = h_tick_count + 1
		 if (dual_time) then xyouts,x,y4,lower_time_string,/normal,alignment=.5
		 if (airborne) then begin
;                   If airborne then print lat and lon across the top
		    xyouts,x,y7,lat_string,/normal,alignment=.5
		    xyouts,x,y8,lon_string,/normal,alignment=.5
		 endif else begin
;                   If ground-based then print beam angles across the top
		    xyouts,x,y7,beam_az_string,/normal,alignment=.5
		    xyouts,x,y8,beam_el_string,/normal,alignment=.5
		 endelse
		 pre_top_upper = now_top_upper
		 pre_bot_upper = now_bot_upper
		 pre_top_lower = now_top_lower
		 pre_bot_lower = now_bot_lower
	       endif else begin
	       ; half tick marks with no labels
		 if (delta_scene_hours lt 2.) then begin
	            plots,[x,x],[y1,y9],/normal
	            plots,[x,x],[y5,y10],/normal
		 endif
	       endelse
	     endif else begin
;              Time decreasing to the right
	       if ((now_top_lower(1) lt pre_top_lower(0)) and $
		   (now_bot_lower(1) lt pre_bot_lower(0))) then begin 
	         plots,[x,x],[y1,y2],/normal
	         plots,[x,x],[y5,y6],/normal
		 xyouts,x,y3,upper_time_string,/normal,alignment=.5
		 h_tick_count = h_tick_count + 1
		 if (dual_time) then xyouts,x,y4,lower_time_string,/normal,alignment=.5
		 if (airborne) then begin
;                   If airborne then print lat and lon across the top
		    xyouts,x,y7,lat_string,/normal,alignment=.5
		    xyouts,x,y8,lon_string,/normal,alignment=.5
		 endif else begin
;                   If ground-based then print beam angles across the top
		    xyouts,x,y7,beam_az_string,/normal,alignment=.5
		    xyouts,x,y8,beam_el_string,/normal,alignment=.5
		 endelse
		 pre_top_upper = now_top_upper
		 pre_bot_upper = now_bot_upper
		 pre_top_lower = now_top_lower
		 pre_bot_lower = now_bot_lower
	       endif else begin
;                half tick marks with no labels
		 if (delta_scene_hours lt 2.) then begin
	            plots,[x,x],[y1,y9],/normal
	            plots,[x,x],[y5,y10],/normal
		 endif
	       endelse
	     endelse 
	endif
	old_min = header(1,i)
endfor

; If no time/lat/lon/az/el tick marks were drawn, mark the first and last time.
if (h_tick_count eq 0) then begin
  ; Compute the x-center of the first profile
  x = x0 + (dx/data_recs)/2.
  plots,[x,x],[y1,y2],/normal
  plots,[x,x],[y5,y6],/normal
  ; Compute the x-center of the last profile
  x = (x0 + dx) - (dx/data_recs)/2.
  plots,[x,x],[y1,y2],/normal
  plots,[x,x],[y5,y6],/normal
endif

;==========================================================================
;******************** Color bar and annotation ****************************
;==========================================================================

color_ba,bins,min_scale,max_scale,ps_color_option
xyouts,.5,.94,field,alignment=.5,/normal
xyouts,.05,.94,instrument,/normal
xyouts,.95,.94,date_string,alignment=1.,/normal

;==========================================================================
; If other optional annotations are available, write them on the image
;==========================================================================
if (strlen(pretitle) gt 0) then xyouts,.50,.97,pretitle,alignment=.5,/normal
if (strlen(project) gt 0)  then xyouts,.05,.97,project,/normal
if (strlen(platform) gt 0) then xyouts,.95,.97,platform,alignment=1.,/normal
if (strlen(supplement1) gt 0) then begin
   case (strupcase(supplement1)) of
   'TRANSECT': out_supp1 = supplement1 + ' ' + strtrim(fix(this_transect),2)
   'DURATION': begin
      header_size = size(header)
      first_dt = var_to_dt(header(13,0),header(11,0),header(12,0),$
			   header(0,0),header(1,0),header(2,0))
      last_dt = var_to_dt(header(13,header_size(2)-1),header(11,header_size(2)-1),$
			  header(12,header_size(2)-1),header(0,header_size(2)-1),$
			  header(1,header_size(2)-1),header(2,header_size(2)-1))
      dur = dt_duration(last_dt,first_dt)*24.*60.
      if (airborne) then begin
         append_String = ' MINUTES'
      endif else begin
         append_String = ' MIN STARE'
      endelse 
      out_supp1 = strtrim(string((dur),format='(f6.2)'),2) + append_String
      end
   else: out_supp1 = supplement1
   endcase
   xyouts,.05,.91,out_supp1,/normal
endif
if (strlen(supplement2) gt 0) then begin
   case (strupcase(supplement2)) of
   'TRANSECT': out_supp2 = supplement2 + ' ' + strtrim(fix(this_transect),2)
   'DURATION': begin
      header_size = size(header)
      first_dt = var_to_dt(header(13,0),header(11,0),header(12,0),$
			   header(0,0),header(1,0),header(2,0))
      last_dt = var_to_dt(header(13,header_size(2)-1),header(11,header_size(2)-1),$
			  header(12,header_size(2)-1),header(0,header_size(2)-1),$
			  header(1,header_size(2)-1),header(2,header_size(2)-1))
      dur = dt_duration(last_dt,first_dt)*24.*60.
      if (airborne) then begin
	 append_string = ' MINUTES'
      endif else begin
	 append_string = ' MIN STARE'
      endelse
      out_supp2 = strtrim(string((dur),format='(f6.2)'),2) + append_String
      end
   else: out_supp2 = supplement2
   endcase
   xyouts,.95,.91,out_supp2,alignment=1.,/normal
endif

;print,'=====MAKING IMAGE======================='
;print,'num_recs = ',num_recs
;print,'average = ',average
;print,'data_recs = ',data_recs
;print,'device name = ',!d.name
;print,'screen_sample_style = ',screen_sample_style
;print,'PS_sample_style = ',ps_sample_style
;print,'max_scale = ',max_scale
;print,'min_scale = ',min_scale
;print,'scale_range = ',scale_range
;print,'bins = ',bins
;print,'bin_width = ',bin_width
;print,'airborne = ',airborne
;print,'beam elevation = ',header(7,0)
;print,'========================================'

first_loop_jump_point:
first_loop = 1.
end_at_transect = 0b
if (keyword_set(end_at)) then begin
   if (strpos(strupcase(end_at),'T') ne -1) then end_at_transect = 1b
endif

if ((strpos(strupcase(start_at),'T') ne -1) OR (end_at_transect)) then begin
   final_transect=last_header(29)
   if (this_transect ne final_transect) then begin
	next_transect = this_transect + transects
   endif else begin
	next_transect = first_header(29)
   endelse
   option1 = 'a) Next transect (#'+strtrim(fix(next_transect),2)+', '
   openr,lun,datafile,/get_lun
   record=assoc(lun,fltarr(rec_len))
   findtran,next_transect,lun,rec_len,recs_in_file,next_first_rec,next_last_rec
   close,lun
   free_lun,lun
endif else begin
   option1 = 'a) Next image (#'+strtrim(fix(loop+1),2)+', '
   next_first_rec = last_rec + 1
   if (next_first_rec gt recs_in_file-1) then begin 
      next_first_rec=0
      num_recs = 512*average
   endif
   next_last_rec = next_first_rec + num_recs - 1
   if (next_last_rec gt recs_in_file-1) then next_last_rec = recs_in_file-1
   next_num_recs = next_last_rec - next_first_rec + 1
endelse
next_num_recs = next_last_rec - next_first_rec + 1

if (average gt 1) then begin
   next_string = strtrim(next_first_rec,2)+' to '+$
		 strtrim(next_last_rec,2)+', '+$ 
		 strtrim(next_num_recs,2)+' records, averaging every '+$
		 strtrim(average,2)+')' 
endif else begin
   next_string = strtrim(next_first_rec,2)+' to '+$
		 strtrim(next_last_rec,2)+', '+$ 
		 strtrim(next_num_recs,2)+' records, with no averaging.)'
endelse

if (!d.name eq 'PS') then begin
   print,'Closing PS file.'
   device,/close
   set_plot,screen_type
   ps_image = ps_image + 1
endif

main_menu:
print,' '
if (alt_shift ne 0.) then begin
   print,'WARNING: Altitude-axes shifting turned on! (',alt_shift,' m)'
endif
if (range_shift ne 0.) then begin
   print,'WARNING: Range-axes shifting turned on! (',range_shift,' m)'
endif
print,'BSCAN Main Menu Options:'
print,option1+' '+next_string
print,'x) Create image in X-window'
print,'b) Make PS file'
print,'c) Change color-bar scale limits'
print,'d) Left-right image reversal' 
print,'e) Change sampling method'
if (range_flag) then begin
  print,'f) Change the range swath of data being displayed'
  print,'g) Altitude align the data'
  print,'h) Move range axis up/down with respect to image' 
endif else begin
  print,'f) Change the altitude swath of data being displayed'
  print,'g) Remove altitude alignment'
  print,'h) Move altitude axis up/down with respect to image'
endelse
print,'i) Optional annotation'
print,'j) Time axis options'
print,'k) Delete most recent window from screen'
print,'l) Stop and make data available'
print,'m) Pointer
print,'n) Save/restore settings
print,'o) Compute/display mean profile'
print,'p) redraw current scene'
print,'q) use different color table'
print,'r) create a TIFF file'
print,'s) change image size'
print,'z) Quit BSCAN'

answer = ' '
print,'Please select a choice. Enter a letter.'
read,answer
if (strupcase(answer) eq 'A') then begin
  loop = loop + 1
  first_rec = next_first_rec
  last_rec = next_last_rec
  num_recs = next_num_recs
  print,''
  goto,read_data_entry
endif

if (strupcase(answer) eq 'B') then begin
  ask12:
  ps_color_option=2
  print,'Enter:
  print,'1) for no-color
  print,'2) for color
  read,ps_color_option
  if (ps_color_option lt 1) or (ps_color_option gt 2) then begin
     print,'You may only enter 1 or 2.'
     print,'Please try again.'
     goto,ask12
  endif

  ask15:
  eps_option=0
  print,'Enter:
  print,'1) for regular postscript
  print,'2) Encapsulated postscript
  read,eps_option
  if (eps_option lt 1) or (eps_option gt 2) then begin
     print,'You may only enter 1 or 2.'
     print,'Please try again.'
     goto,ask15
  endif

  ask20:
  ps_option = 0
  print,' '
  print,'Postscript options:'
  print,'1) Portrait, top-half of page'
  print,'2) Portrait, bottom-half of page'
  print,'3) Landscape, full page'
  print,'4) Portrait, custom location & size'
  print,'5) Landscape, custom location & size'
  read,ps_option
  if (ps_option lt 1) or (ps_option gt 5) then begin
	print,'You may only enter 1 to 5.'
	print,'Please try again.'
	goto,ask20
  endif
  if (ps_image eq 0) then begin
    ask21:
    answer = 0
    print,' '
    if (strlen(ps_path) eq 0) then begin
       print,'Currently, the PS file will be created in'
       print,'the directory you are running this from.'
    endif else begin
       print,'Current path: ',ps_path
    endelse
    print,'Keep this path?'
    print,'1) yes, keep the current path'
    print,'2) no, set a new path'
    read,answer
    if ((answer lt 1) or (answer gt 2)) then begin
       print,'You may only answer 1 or 2.'
       print,'Please try again.'
       goto,ask21
    endif
    if (answer eq 2) then begin
       print,'Enter a new path (location to create PS file).'
       read,ps_path
       if ((!Version.os eq 'sunos') OR (!Version.os eq 'solaris')) then begin
       ;  Append forward slash if necessary
          if (strmid(ps_path,strlen(ps_path)-1,1) ne '/') then begin
	       ps_path = ps_path + '/'
          endif
       endif else begin
       ;  Append backward slash if necessary
          if (strmid(ps_path,strlen(ps_path)-1,1) ne '\') then begin
	       ps_path = ps_path + '\'
          endif
       endelse
    endif
  endif
  print,' '
  if (strlen(ps_fn) gt 0) then begin
      print,'The last PS file you made was '+ps_fn
  endif else begin
      print,'This will be your first PS file this run of BSCAN.'
  endelse

  if (eps_option eq 2) then begin
      ps_file_exten = '.eps'
  endif else begin
      ps_file_exten = '.ps'
  endelse

  print,'This will be image number '+strtrim(ps_image,2)+' from this run.'
  if (strlen(strtrim(ps_image,2)) eq 1) then $
  default_ps_fn = 'bscan00' + string(strtrim(ps_image,2))+ps_file_exten
  if (strlen(strtrim(ps_image,2)) eq 2) then $
  default_ps_fn = 'bscan0' + string(strtrim(ps_image,2))+ps_file_exten
  if (strlen(strtrim(ps_image,2)) eq 3) then $
  default_ps_fn = 'bscan' + string(strtrim(ps_image,2))+ps_file_exten
  ps_fn = default_ps_fn
  print,'Enter PS file name. (Default is '+default_ps_fn+')'
  read,ps_fn
  if (strlen(ps_fn) le 0) then begin
     ps_fn = ps_path + default_ps_fn
  endif else begin
     ps_fn = ps_path + ps_fn
  endelse

  enter_paper_size:
  if ((paper_size lt 1) or (paper_size gt 2)) then begin
     print,' '
     print,'Select paper size.'
     print,'1) Letter'
     print,'2) Legal' 
     read,paper_size
     if ((paper_size lt 1) or (paper_size gt 2)) then begin
        print,'Sorry, you may choose only 1 or 2.'
        goto,enter_paper_size
     endif
  endif

  if (ps_color_option eq 2) then begin
    print,'Color PS'
    print,' '
    set_plot,'PS'
    device,filename=ps_fn
    if (eps_option eq 2) then begin
       print,'Set to Encapsulated postscript.'
       device,/color,/encapsulated,bits_per_pixel=8
    endif else begin
       device,/color,bits_per_pixel=8
    endelse
  endif else begin
    print,'non-Color PS'
    print,' '
    set_plot,'PS'
    device,filename=ps_fn
    if (eps_option eq 2) then begin
       print,'Set to Encapsulated postscript.'
       device,/encapsulated,bits_per_pixel=8
    endif else begin
;       device,bits_per_pixel=8
    endelse
  endelse

  print,'Creating PS file: ',ps_fn
  if ((ps_option eq 1) or (ps_option eq 2)) then begin
     device,/portrait
     landscape = 0b
     if (ps_option eq 1) then begin
;       PORTRAIT-TOP
	print,'Portrait, top-half.'
	if (paper_size eq 1) then begin
;          letter size
	   print,'For letter-size paper.'
	   device,yoffset=5.47,ysize=4.35,/inches
	endif else begin
;          legal size
	   print,'For legal-size paper.'
	   device,yoffset=6.97,ysize=4.35,/inches
	endelse
	device,xoffset=0.75,xsize=7.00,/inches
     endif else begin
;       PORTRAIT-BOTTOM
	print,'Portrait, bottom-half.'
	if (paper_size eq 1) then begin
;          letter size
	   print,'For letter-size paper.'
	   device,yoffset=1.15,ysize=4.35,/inches
	endif else begin
;          legal size
	   print,'For legal-size paper.'
           device,yoffset=2.65,ysize=4.35,/inches	
	endelse
	device,xoffset=0.75,xsize=7.00,/inches
     endelse
  endif else if (ps_option eq 3) then begin
     print,'Landscape, full-page.'
     device,/landscape
     landscape = 1b
     if (paper_size eq 1) then begin
	 print,'For letter-size paper.'
;         device,yoffset=10.425,/inches  3/7/96
         device,yoffset=10.005,xsize=8.5625,/inches
     endif else begin
	 print,'For legal-size paper.'
         device,yoffset=11.625,/inches
     endelse
  endif else if (ps_option eq 4) then begin
     print,'Portrait, custom location & sizing'
     device,/portrait
     landscape = 0b
     print,'Enter xsize in inches'
     read,custom_xsize
     print,'Enter ysize in inches '
     read,custom_ysize
     print,'Enter xoffset in inches'
     read,custom_xoffset
     print,'Enter yoffset in inches '
     read,custom_yoffset
     device,ysize=custom_ysize,xsize=custom_xsize,/inches
     device,yoffset=custom_yoffset,xoffset=custom_xoffset,/inches
  endif else if (ps_option eq 5) then begin
     print,'Landscape, custom location & sizing'
     device,/landscape
     landscape = 1b
     print,'Enter xsize in inches'
     read,custom_xsize
     print,'Enter ysize in inches '
     read,custom_ysize
     print,'Enter xoffset in inches'
     read,custom_xoffset
     print,'Enter yoffset in inches '
     read,custom_yoffset
     device,ysize=custom_ysize,xsize=custom_xsize,/inches
     device,yoffset=custom_yoffset,xoffset=custom_xoffset,/inches
  endif
  print,' '
  goto,sampling_inquiry
endif

if (strupcase(answer) eq 'C') then begin
   print,'Enter new min scale value.'
   read,min_scale
   print,'Enter new max scale value.'
   read,max_scale
;   wdelete
   goto,main_menu
endif

if (strupcase(answer) eq 'D') then begin
   lr_flag = lr_flag * (-1)
   header = rotate(header,7)
;   wdelete
   goto,sample_entry
endif

if (strupcase(answer) eq 'E') then begin
;  Flag sample style
   screen_sample_style=flag
   PS_sample_style=flag
   goto,sampling_inquiry
endif

if (strupcase(answer) eq 'F') then begin
   if (altitude_flag) then begin
      print,'Enter new min altitude value (in meters ASL).'
      read,min_altitude
      print,'Enter new max altitude value (in meters ASL).'
      read,max_altitude
      altitude = [min_altitude,max_altitude]
      if (min_altitude gt max_altitude) then altitude = shift(altitude,1)
   endif
   if (range_flag) then begin
      print,'Enter new min range value (in meters from platform).'
      read,min_range
      print,'Enter new max range value (in meters from platform).'
      read,max_range
      range = [min_range,max_range]
      if (min_range gt max_range) then range = shift(range,1)
   endif
;   wdelete
   goto,vertical_extract_entry
endif

if (strupcase(answer) eq 'G') then begin
   if (altitude_flag) then begin
      altitude_flag = 0b
      range_flag = 1b
   endif else begin
      altitude_flag = 1b
      range_flag = 0b
   endelse
   if (altitude_flag) then begin
      print,'Enter new min altitude value.'
      read,min_altitude
      print,'Enter new max altitude value.'
      read,max_altitude
      altitude = [min_altitude,max_altitude]
   endif
   if (range_flag) then begin
      print,'Enter new min range value.'
      read,min_range
      print,'Enter new max range value.'
      read,max_range
      range = [min_range,max_range]
   endif
;   wdelete
   goto,vertical_alignment_entry
endif

if (strupcase(answer) eq 'H') then begin
   if (altitude_flag) then begin
      print,' '
      print,'This option shifts altitude axes up or down with respect to'
      print,'the data.  Used when data file altitudes are in systematic error.'
      print,'Positive value moves axes down.  Negative value moves axes up.'
      print,'Current altitude axes shift = ',alt_shift,' m'
      print,'Enter number of meters to shift altitude axes.'
      read,alt_shift
   endif
   if (range_flag) then begin
      print,' '
      print,'This option shifts range axes toward or away from the platform '
      print,'and data.  Used when data file altitudes are in systematic error.'
      print,'Positive value increases distance to platform.  Negative value '
      print,'moves data closer to platform.'
      print,'Current range axes shift = ',alt_shift,' m'
      print,'Enter number of meters to shift range axes.'
      read,range_shift
   endif
   goto,vertical_alignment_entry
endif

if (strupcase(answer) eq 'I') then begin
   supp_text_menu:
   print,' '
   print,'                                            CURRENT SETTING'
   print,'                                            ==============='
   print,'1) Pre-title (top-center)                  '+pretitle
   print,'2) Project name (top-left)                 '+project
   print,'3) Platform name (top-right)               '+platform 
   print,'4) Supplement 1 (below lidar name on left) '+supplement1
   print,'5) Supplement 2 (below date on right)      '+supplement2
   print,'6) Field (color bar title)                 '+field
   print,'7) Instrument name                         '+instrument
   print,'8) Return to BSCAN main menu
   print,'Please select 1 - 8.'
   read,answer
   if ((answer lt 1) or (answer gt 8)) then begin
      print,'You may answer only 1 - 8.'
      print,'Please try again'
      goto,supp_text_menu
   endif
   if (answer eq 1) then begin
      print,'Enter the pre-title (top-center)'
      read,pretitle
   endif
   if (answer eq 2) then begin
      print,'Enter the project name (top-left)'
      read,project
   endif
   if (answer eq 3) then begin
      print,'Enter the platform name (top-right)'
      read,platform
   endif
   if (answer eq 4) then begin
      print,'Enter supplement 1 (bottom-left)'
      read,supplement1
   endif
   if (answer eq 5) then begin
      print,'Enter supplement 2 (bottom-right)'
      read,supplement2
   endif
   if (answer eq 6) then begin 
      print,'Enter field name and units for color-bar ' 
      read,field
   endif
   if (answer eq 7) then begin 
      print,'Enter instrument name '
      read,instrument
   endif
   if (answer eq 8) then goto,main_menu
   goto,start_graphics
endif

if (strupcase(answer) eq 'J') then begin
   time_questions:
   answer=0
   print,' '
   print,'The time axis is always below the image.'
   print,'and can have two rows of labels below it.'
   if (dual_time) then begin
      print,'1) Dual-time on lower axis: on'
   endif else begin
      print,'1) Dual-time on lower axis: off'
   endelse
   print,'2) Upper-row time-tic axis label (right-side) : ',upper_row_time_label
   print,'3) Lower-row time-tic axis label (right-side) : ',lower_row_time_label
   print,'4) Upper-row time-tic hour-adjustment: ',upper_row_hour_adj
   print,'5) Lower-row time-tic hour-adjustment: ',lower_row_hour_adj
   print,'6) Number of seconds between tick marks: ',maj_tim_tic*60
   print,'Please enter 1-6.'
   read,answer
   if ((answer ge 1) or (answer le 5)) then begin
   if (answer eq 1) then begin
      if (dual_time) then begin
	 dual_time = 0b
      endif else begin
	 dual_time = 1b
      endelse
   endif
   if (answer eq 2) then begin
      print,'Enter upper-row time-tic axis label (i.e. UTC, CDT, MST).'
      read,upper_row_time_label
   endif
   if (answer eq 3) then begin
      print,'Enter lower-row time-tic axis label (i.e. UTC, CDT, MST).'
      read,lower_row_time_label
   endif
   if (answer eq 4) then begin
      print,'Enter upper-row time-tic hour adjustment (a + or - whole number).'
      read,upper_row_hour_adj
   endif
   if (answer eq 5) then begin
      print,'Enter lower-row time-tic hour adjustment (a + or - whole number).'
      read,lower_row_hour_adj
   endif
   if (answer eq 6) then begin
      print, "How many seconds would you like between tick marks?"
      read, maj_tim_tic
      maj_tim_tic = maj_tim_tic/60
   endif
;   wdelete
   goto, start_graphics
   endif
   goto, main_menu
endif

if (strupcase(answer) eq 'K') then begin
;  Remove most recent window from screen
   wdelete
   goto,main_menu
endif

if (strupcase(answer) eq 'L') then begin
;  Stop and make data available
   print,''
   print,'You may now work with BSCAN variables interactively.'
   print,''
   print,'In IDL type help,header'
   print,'            help,data'
   print,''
   print,'In PV-WAVE type info,header'
   print,'                info,data'
   print,''
   print,'In either IDL or PV-WAVE type .con to continue BSCAN.'
   print,''
   !p.thick=1
   stop
   !p.thick=2
   goto,main_menu
endif

if (strupcase(answer) eq 'M') then begin
;  pointer
   print,''
   print,'Sorry, this option installed yet.'
   goto,main_menu
endif

if (strupcase(answer) eq 'N') then begin
;  save/restore settings
   ask13:
   print
   print,'1) Save current settings'
   print,'2) Restore other settings'
   print,'3) Return to main menu'
   print,'4) Tell me about save/restore settings'
   print,'Please choose 1, 2, 3 or 4'
   read,answer
   if ((answer lt 1) or (answer gt 4)) then begin
      print,'You may choose only 1, 2, 3 or 4.'
      print,'Please try again.'
      goto,ask13
   endif
   if (answer eq 1) then begin
   ; SAVE SETTINGS
     altitude = [min(vertical2),max(vertical2)]
     range = [min(vertical2),max(vertical2)]
     print
     print,'Please choose'
     print,'1) to write to BSCAN.SET'
     print,'2) to specify your own set file name'
     print,'3) return to main menu without saving settings'
     answer = '0'
     read,answer
     if (answer eq 1) then set_file='BSCAN.SET'
     if (answer eq 2) then begin
	print
	print,'Please enter set file name:'
	read,set_file
     endif
     if ((answer lt 1) or (answer gt 2)) then goto,main_menu
     print
     print,'Writing: ',set_file
     openw,lun,set_file,/get_lun
     printf,lun,pretitle 
     printf,lun,ps_path
     printf,lun,platform
     printf,lun,project
     printf,lun,supplement1
     printf,lun,supplement2
     printf,lun,dual_time
     printf,lun,upper_row_time_label
     printf,lun,lower_row_time_label
     printf,lun,upper_row_hour_adj
     printf,lun,lower_row_hour_adj
     printf,lun,min_scale
     printf,lun,max_scale
     printf,lun,altitude_flag
     printf,lun,altitude
     printf,lun,range_flag
     printf,lun,range
     printf,lun,screen_sample_style
     printf,lun,PS_sample_style
     printf,lun,range_shift
     printf,lun,alt_shift
     printf,lun,color_table_filename
     close,lun
     free_lun,lun
     goto,main_menu
   endif
   if (answer eq 2) then begin
   ; RESTORE SETTINGS
     print
     print,'Please choose '
     print,'1) to read from BSCAN.SET'
     print,'2) to read from a set file you specify'
     print,'3) to return to the main menu'
     answer = 'x'
     read,answer
     if (answer eq 1) then set_file='BSCAN.SET'
     if (answer eq 2) then begin
	print
	print,'Please enter a set file name'
	read,set_file
     endif
     if ((answer lt 1) or (answer gt 2)) then goto,main_menu
     err = findfile(set_file,count=count)
     if (count eq 0) then begin
        print,'Set file: '+set_file+' cannot be found.'
        goto,main_menu
     endif
     altitude = [min(vertical2),max(vertical2)]
     range = [min(vertical2),max(vertical2)]
     color_table_filename=' '
     print,'Reading '+set_file
     openr,lun,set_file,/get_lun
     readf,lun,pretitle 
     readf,lun,ps_path
     readf,lun,platform
     readf,lun,project
     readf,lun,supplement1
     readf,lun,supplement2
     readf,lun,dual_time
     readf,lun,upper_row_time_label
     readf,lun,lower_row_time_label
     readf,lun,upper_row_hour_adj
     readf,lun,lower_row_hour_adj
     readf,lun,min_scale
     readf,lun,max_scale
     readf,lun,altitude_flag
     readf,lun,altitude
     readf,lun,range_flag
     readf,lun,range
     readf,lun,screen_sample_style
     readf,lun,PS_sample_style
     readf,lun,range_shift
     readf,lun,alt_shift
     readf,lun,color_table_filename
     close,lun
     free_lun,lun
     goto,vertical_alignment_entry
   endif
   if (answer eq 4) then begin
      print,''
      print,'Currently, BSCAN saves 13 scene settings into an ASCII'
      print,'file named '+set_file+' in your current directory.'
      print,'The settings include: PS path; pre-title; platform; project;'
      print,'supplement1; supplement2; dual time flag (on or off); upper'
      print,'and lower row time label and hour adjustment; max and min
      print,'color bar scale.'
      print,''
      print,'Press return to continue...'
      answer = ''
      read,answer
      goto,main_menu
   endif
endif

if (strupcase(answer) eq 'O') then begin
;   meanprof,header,data
   print,'Sorry, this option not installed yet.'
   goto,main_menu
endif

if (strupcase(answer) eq 'P') then begin
   goto,start_graphics
endif

if (strupcase(answer) eq 'Q') then begin
    color_table_filename = ' '
    print,'Enter color table file name.
    print,'(Include path if file is not in current directory.)'
    read,color_table_filename

    err = findfile(color_table_filename,count=count)
    if (count eq 0) then begin
        print,'Color table file: '+color_table_filename+' cannot be found.'
	goto,main_menu
    endif
    load_ct,color_table_filename,bins,RGB_array
    goto,main_menu
endif

if (strupcase(answer) eq 'R') then begin
    byte_array = TVRD(0,0,sx,sy)
    RGB_array=RGB_array*256L
;===================================================
;    red_bytes = byte_array
;    grn_bytes = byte_array
;    blu_bytes = byte_array
;    for i = 0,(n_elements(byte_array)-1) do begin
;        red_bytes(i)=RGB_array(0,byte_array(i))
;        grn_bytes(i)=RGB_array(1,byte_array(i))
;        blu_bytes(i)=RGB_array(2,byte_array(i))
;    endfor
;    RGB_bytes = bytarr(sx,sy,3)
;    RGB_bytes(*,*,0)=red_bytes
;    RGB_bytes(*,*,1)=grn_bytes
;    RGB_bytes(*,*,2)=blu_bytes
;    tiff_status = DC_WRITE_TIFF('test.tif',RGB_bytes,$
;     Class='RGB Full Color')
;=================================================
    tiff_status = DC_WRITE_TIFF('test.tif',byte_array,$
    Palette=RGB_array,Class='Palette Color',Compress='None')
    if (tiff_status ne 0) then begin
       print,'tiff write status = ',tiff_status
    endif else begin
       print,'Successful TIFF write.'
    endelse
   goto,main_menu
endif

if (strupcase(answer) eq 'S') then begin
   print,'What do you what the X dimension of the resulting image to be?'
   read,x_dim
   print,'What do you what the Y dimension of the resulting image to be?'
   read,y_dim
   goto,main_menu
endif

if (strupcase(answer) eq 'X') then goto,sample_entry 

if (strupcase(answer) ne 'Z') then begin
   print,'Sorry, that is not a main menu option.'
   print,' '
   goto,main_menu
endif

retall
end