1 Language
                             GTVL\ Language Summary

    CHANGE      : Change some attributes of the plot.
    CLEAR Arg   : Clear some (parts of) the plot or windows.
    COMPRESS    : Remove invisible parts of the plot.
    CORNERS     : Display corners of the plotting surface.
    CREATE Arg  : Create directory, windows or LUTs.
    DEVICE      : Open the graphic device.
    DISPLAY     : List some parameters of the plot.
    GTV SEARCH  : Search for a GTV directory.
    HARDCOPY    : Get a printed copy of the plot.
    LUT [arg]   : Change the color Look‐Up‐Table.
    METACODE    : Save or load part of the plot to/from metacode file.
    REPLICATE   : Copy a directory to another place.
    ZOOM        : Zoom or refreshes the plot (possibly in another window).
1 CHANGE
        [GTVL\]CHANGE Item SegName Value [Val2 [Val3]]
        [GTVL\]CHANGE Behaviour Value

    Changes  some  attribute of the Graphic Library. Three items concern the
    current directory and active windows:
      ‐ CHANGE DIRECTORY DirName [WinNum]
          changes the default directory to DirName, and optionally  the  ac‐
          tive window number to WinNum (instead of 0) within this directory.
      ‐ CHANGE WINDOW WinNum [NOREFRESH|REFRESH]
          changes the active window number to WinNum, and optionally changes
          its automatic refresh behaviour.
      ‐ CHANGE ZOOM NEW|CURRENT
          changes the default ZOOM command behaviour.
      ‐ CHANGE CLEAR TREE|WHOLE
          changes the default CLEAR PLOT command behaviour.

    Some other items are image segment attributes:
      ‐ CHANGE SCALING    SegName LIN|LOG [Lcut [Hcut]]
          will change the transfer function for the specified image segment.
      ‐ CHANGE BLANKING   SegName BLACK|WHITE|Colour
          will change the colour of blanked pixels (if any) in the displayed
          image. Colour is a colour value as in PENCIL command (1‐8).
      ‐ CHANGE COLOUR     SegName Value
      ‐ CHANGE DASH       SegName Value
      ‐ CHANGE DEPTH      SegName Value
      ‐ CHANGE VISIBILITY SegName ON|OFF
      ‐ CHANGE WEIGHT     SegName Value
    The  last  five items are general segment attributes. For these, if Seg‐
    Name is a segment, only that segment is modified, but if it is a  direc‐
    tory,  all segments attached to this directory are modified accordingly.
    See subtopic SEGMENT_NAMES for details on naming segments.

    And finally, some general behaviours can be changed will  the  following
    keywords:
      ‐ CHANGE DRAW ON|OFF
          toggles  the  drawing  state  to ’active’ (ON) or ’sleeping’ (OFF)
          mode, i.e., if the current mode is ’sleeping’, the plot  will  not
          be  updated  until the drawing state is switched again to ’active’
          mode. Default value is ON.
      ‐ CHANGE LUT STATIC|DYNAMIC
          toggles the Look‐Up‐Tables to STATIC or DYNAMIC mode.  Default  is
          DYNAMIC. See subtopic LUT for details.
      ‐ CHANGE PENCIL HARD|SOFT
          specifies  whether  the  GTV library should use the (output depen‐
          dent) hardware generator for dashes and thickness, or  whether  it
          should  use its own (output independent) software emulation. Hard‐
          ware generator may (or may not) produce nicer output, and  may  be
          faster...
      ‐ CHANGE POSITION Num
          moves  current  window  to the specified position, where Num is in
          the range 1‐9. The 9 most remarkable points of  the  screen  (cor‐
          ners, middle of the sides, and center) are numbered according to a
          VT100 numeric keypad notation.
2 LUT

        Specifies whether the color Look‐Up‐Tables (LUT and PEN) are static,
    i.e.  associated with each graphic segment, or Dynamic, i.e.  controlled
    by the terminal colors. This changes the behaviour of the  LUT  and  PEN
    commands.

    In  STATIC  mode, each graphic segment has its own LUT, so that this al‐
    lows to display complex plots with many colors. The LUT  and  PEN  which
    are stored with each segment must be set before the segment creation. It
    cannot be changed after. In this mode, the display may differ  from  the
    hardcopy  output, because not all interactive displays support many col‐
    ors.

    In DYNAMIC mode, one single LUT its associated to the plot.  It  can  be
    changed  dynamically  afterwards using the LUT (and PEN) commands. It is
    appropriate for interactive visualisation. The hardcopy output  will  be
    identical to the display.

    The default is DYNAMIC.
2 SEGMENT_NAMES

        The  ’SegName’  used in all the CHANGE commands is formed by a name,
    given by the calling high‐level program (usually a reminder of the  com‐
    mand  used), followed by an unique, incremental, number. To refer a par‐
    ticular segment, one uses the full name  (as  in  CHANGE VISIBILITY CON‐
    TOUR:46 OFF).  To refer to ALL the segments with the same name, omit the
    number (as in CHANGE VISIBILITY CONTOUR OFF). To refer  to  a  range  of
    segments,  use a ’minus’ sign in the range (as in CHANGE VISIBILITY CON‐
    TOUR:32‐46 OFF).  Segments  names  can  be  the  segment  name,  as   in
    CHANGE VISIBILITY *TOUR OFF).

    Trick: A reverse range of segments (as in CLEAR SEGMENT 32‐12) is valid.
    In the particular case of the above example, it  is  equivalent  to  the
    command CHANGE VISIBILITY 32‐12 CLEAR which in turns tries to delete (as
    opposed to change the visibility) the segments  (which  is  possible  if
    segment 32 is the last segment plotted).
1 CLEAR
        [GTVL\]CLEAR [Arg]

    CLEAR  without  arguments  clears  the current plot and ask the user for
    confirmation. In non interactive session, it  clears  the  plot  without
    prompting.

    Please consult the following sections for the various CLEAR arguments:
2 ALPHA
         CLEAR ALPHA erases the alphanumeric screen alone, without affecting
    the plot on old graphic terminals. Under X‐Window,  the  graphic  screen
    created by the ’DEVICE’ command is raised up.
2 DIRECTORY
         CLEAR DIRECTORY [DirName]  makes the named directory (or by default
    the current directory) invisible. All the attached structure becomes in‐
    visible.  Under X, the graphic screen is updated, elsewhere use the com‐
    mand ZOOM REFRESH to do it. Note that the directory  is  not  destroyed:
    you can recover it by a CHANGE VISIBILITY command.
2 GRAPHIC
         CLEAR GRAPHIC  lowers  the  graphic  windows,  popping up the alpha
    screen (X window only).
2 PLOT
         CLEAR PLOT destroys the current tree or the whole plot, and  clears
    the  graphic screen accordingly. The default behaviour can be controlled
    by command CHANGE CLEAR.
2 SEGMENT
         CLEAR SEGMENT destroys the last graphic segment, i.e. the  part  of
    the  plot corresponding to the last graphic command. Can be used repeti‐
    tively. The Graphic screen is updated under X‐Window, elsewhere use com‐
    mand ZOOM REFRESH to do it.

    CLEAR SEGMENT SegName makes the named segment invisible.

    One  can erase a range of graphic segments in a single command by typing
    a range of segment numbers, as in CLEAR SEGMENT 24‐16. The  use  of  re‐
    verse  range  (24‐16)  forces the graphic library to actually delete the
    segment, if possible,  instead  of  making  it  invisible.  See  command
    GTVL\CHANGE for details.
2 TREE
         CLEAR TREE clears the current tree only, leaving all other parallel
    trees intact. All associated windows are  destroyed,  and  the  tree  is
    recreated empty, with a single attached window. If only one tree exists,
    a CLEAR WHOLE is performed.

    Programmer trick: In complex plots with more than one top plot  directo‐
    ry,  the CLEAR command does not necessarily free the plot memory, but in
    general marks part of the plot as invisible.   To  reclaim  unused  plot
    memory, one should use command COMPRESS.
2 WHOLE
         CLEAR WHOLE destroys the whole plot. On X‐Window displays, all win‐
    dows are destroyed, and a new window is recreated for  the  first  tree.
    Other trees are destroyed.
2 WINDOW
         CLEAR WINDOW WindowNumber  deletes  the  current graphic window (if
    possible). Only supported on multi‐window displays (X‐Window).
1 COMPRESS
        [GTVL\]COMPRESS

        Compress the internal metacode, by removing (definitely) all invisi‐
    ble segments and directories. It is useful to reclaim unused plot memory
    when frequent use of CLEAR TREE is made.
1 CORNERS
        [GTVL\]CORNERS

        Displays angles in corners indicating the  limits  of  the  plotting
    surface.
1 CREATE
        [GTVL\]CREATE Argum Value

      ‐ CREATE DIRECTORY PathName [/SIZE SizeX SizeY] [/PIXEL Px Py]
        Create  a  new  directory. PathName syntax follows "Unix‐like" path‐
        names, with the use of token ’<’ instead  of  ’/’.  Constructs  like
        ..<DIR are valid.

        To create a new directory tree (called e.g. NEWTOP), use the follow‐
        ing syntax:
            CREATE DIRECTORY <NEWTOP
        Option /SIZE can be used to specify the associated plot space  size.
        Option  /PIXEL can be used to specify the size of the window associ‐
        ated to this new tree.
      ‐ CREATE LUT
        Store the current Look Up Table into the internal  metacode.  Stored
        LUT  will be re‐used for PostScript hardcopies, allowing to use more
        than one color palette on PostScript printout.
      ‐ CREATE PENLUT
        Store the current pencil colors into the internal  metacode.  Stored
        pencil LUTs will be re‐used for PostScript hardcopies, allowing more
        than 16 filled colors on the same printout.
      ‐ CREATE WINDOW [BLACK|WHITE] [NOREFRESH] [NAME Name] [/PIXEL Px Py]
        Create a new window with the corresponding attributes of  background
        colour,  automatic  refresh behaviour and Name. Option /PIXEL speci‐
        fies the window size (in pixels); if not present, the cursor is used
        to define the zooming area.
2 /PIXEL
      ‐ CREATE WINDOW [BLACK|WHITE] [NOREFRESH] [NAME Name] /PIXEL Px Py
        Specifies the size in pixel of the window.
      ‐ CREATE DIRECTORY <NewTree /PIXEL Px Py [/SIZE Sx Sy]
        Specifies  the size in pixel of the default window associated to the
        new tree.
2 /SIZE
      ‐ CREATE DIRECTORY <NewTree /SIZE Sx Sy [/PIXEL Px Py]
        Specifies the workspace dimension of a new tree (one Plot  workspace
        unit  will equal one centimeter on hardcopies). It is usually a good
        practice to also specify a window with the same aspect ratio.
1 DEVICE
        [GTVL\]DEVICE Dev_Type [Mode] [/OUTPUT Dev_Name]

    Directs graphic output to the graphics device of the specified type  and
    sets  default  values  for  the plot region location and device physical
    limits. The basic unit is 1 cm for hardcopies. All plots to  interactive
    devices  are made with some pre‐computed factor to match the screen size
    to the Plot Page size, defined by command SET PLOT_PAGE (default size is
    an A4 format page, 30 by 21).

    Use  DEVICE  ?  to get the list of recognized graphics devices or DEVICE
    type ? to get the list of modes on a given device.

    /OUTPUT Dev_Name option allows you to direct the graphic output to some‐
    thing else than your own terminal (TT:). Note that some specific devices
    will not support this option: this is currently the  case  for  X‐Window
    devices.

    Bitmap color is only available with DEVICE IMAGE on X‐Window terminals.
1 DISPLAY
        [GTVL\]DISPLAY Item [Argument [s]] [/OUTPUT]

    List the internal parameters of the named item:
      DISPLAY CLEAR  shows the CLEAR command behaviour. See also CHANGE com‐
        mand help.
      DISPLAY DIRECTORY shows the working directory.  Symbol  PWD  does  the
        same.
      DISPLAY POINTER [SEGMENT|TREE] shows the internal values of the point‐
        ers.
      DISPLAY SEGMENT [SegName] shows the attributes of  input  segment,  or
        all  segments  attached  to  input macrosegment (directory). Default
        lists segments of current directory.
      DISPLAY TREE [DirName] shows the directory tree (default from  current
        point).
      DISPLAY WINDOW shows the list of windows and their associated directo‐
        ries.
    Used for debugging mostly.
1 GTV
        [GTVL\]GTV SEARCH DirName

    If the GTV directory DirName exists,  sets  the  variable  GTV%EXIST  to
    .TRUE. .
1 HARDCOPY
        [GTVL\]HARDCOPY  [File] [/DEVICE FirstName SecondName] [/PLOT Desti‐
    nation] [/LANDSCAPE] [/PORTRAIT] [/EXACT]

    Creates (and optionally plots) a "hardcopy" of  the  current  plot.  The
    plot  is  not  destroyed and can be appended later by new plot commands.
    The default behaviour is to scale the GreG PLOT_PAGE (centimeters)  into
    the output physical page. This behaviour can be overridden by the /EXACT
    option, and in a restricted manner by the /LANDSCAPE and  /PORTRAIT  op‐
    tions.

    The  /DEVICE  option first argument specifies which type of plotter will
    be used. The same devices recognized by command DEVICE are  allowed  for
    this option. PrimaryName usually indicates the graphic protocol support‐
    ed by the device, and SecondaryName a variant of this protocol. For  ex‐
    ample
                   HARDCOPY File /DEVICE PS COLOR
    is  used to create a Postscript file with full color support. The device
    First and Second names are defined in the  file  GAG_TERMINAL  that  de‐
    scribes,  in binary format, the protocol and options relative to all the
    devices locally supported. Changes to this file are done by  the  system
    manager using the gtvdef program.

    The /PLOT option is used to force immediate printing and, optionally, to
    control which printer should be used. Printer is the printer name, which
    defaults to the content of the logical name GAG_PRINTER. If no file name
    was specified for an immediate printing, the metacode  file  is  deleted
    after print completion, otherwise it is kept.

    Default type, printing command and destination can be controlled by log‐
    ical names GAG_HARDCOPY, GAG_LPR and GAG_PRINTER, in the user, local  or
    global dictionaries.
2 /DEVICE
        The  /DEVICE  option  first argument specifies which type of plotter
    will be used. The same devices recognized by command DEVICE are  allowed
    for this option. PrimaryName indicates the graphic protocol supported by
    the device, and SecondaryName a variant  of  this  protocol.  Among  the
    available device types are the following
       PS FAST         PostScript with hardware pen thickness handling
                       Clipping of wide pens may be inaccurate.
       PS GREY         PostScript with fixed greyscale transfer function for
                       bitmap. Clipping is accurate.
       PS COLOR        PostScript with user controlled color transfer
                       function. A greyscale with equivalent luminosity is
                       used on non‐color printers.

       EPS FAST, EPS GREY, EPS COLOR
                       As PS, but for "Encapsulated PostScript", in which
                       the BoundingBox is computed from the plot boundaries
                       rather than from the Plot Page size.

       HPGL            HPGL language for HP printers.
2 /EXACT
        The  EXACT  option is used to preserve the size of the plot (1 cm in
    GreG = 1 cm of the plotter). Available only on PostScript devices.
2 /LANDSCAPE
        The output plot will be in LANDSCAPE  mode.  Not  available  on  all
    types of hardcopy devices.
2 /PORTRAIT
        The output plot will be in PORTRAIT mode. Not available on all types
    of hardcopy devices.
1 LUT
        [GTVL\]LUT Argum [/PEN]

    Modify the bitmap or pen look up table. Option /PEN indicates to  modify
    the  value  of the 16 user‐controlled pen colors (colors 8 to 23) rather
    than the bitmap look‐up table.

    Possibles arguments are:
      ‐ COLOR  Load a default color table
      ‐ WHITE  Load a black and white color table (White  background,  black
        sources)
      ‐ BLACK  Load  a  black and white color table (Black background, white
        sources).
      ‐ LUT    Load the color table defined  by  an  HSV  color  model  (HSV
        stands  for  HUE, SATURATION and VALUE). There are three user‐write‐
        able SIC Variables of name HUE, SATURATION and VALUE,  that  contain
        the HSV model of the current LUT. These arrays values can be manipu‐
        lated using standard SIC mathematic functions to create new  Look‐Up
        Tables (see below).
      ‐ Any other LUT Argum will read Red Green Blue values from the format‐
        ted file named "Argum".

    The default argument is LUT. A convenient value for the HUE array is
            LET HUE[I] = 256‐2*I
    which is a "classical" color table from blue to red as used in AIPS  for
    example.

    Color  contours  can  be  obtained using variations around the following
    command:
            LET HUE[I] = 16*INT((256‐2*I)|16)
    and so on with the most funny functions you may invent.
    CAUTION: the HUE is a real number between 0 and 360.0

    Note that a similar behaviour is defined for the pen colors with the ar‐
    rays P_HUE, P_SATURATION and P_VALUE (the colors of the 16 contour‐fill‐
    ing pens), and for the BLANKING color (the color used to  paint  blanked
    pixels in images), with the 3 reals B_HUE, B_SATURATION and B_VALUE.
2 /PEN
        Same  behaviour  as  LUT,  but will update the colors of the 16 pens
    used for contour‐filling.
1 METACODE
        [GTVL\]METACODE EXPORT|IMPORT FileName [DirName] [/PATH PathName]

    Allow to save or load whole or parts of the current plot to  or  from  a
    metacode file.
2 EXPORT
        [GTVL\]EXPORT FileName [DirName]

    Export the current (or specified) directory tree to an external metacode
    file of name FileName. The default extension is .meta, and  these  files
    have  a different format than the old .vec files. The sub‐plot can later
    be reincorporated using command  IMPORT.  This  allows  merging  several
    plots together. This command does an implicit COMPRESS before saving the
    tree, so that invisible subtrees will be deleted.
2 IMPORT
        [GTVL\]IMPORT FileName [DirName] [/PATH PathName]

    Insert an external metacode file (type .meta, not the old .vec files) at
    the specified PathName into the current plot. The directory name DirName
    is derived from the filename by default.
1 REPLICATE
        [GTVL\]REPLICATE Dir1 Dir2

    Copy Dir1 subtree to Dir2 subtree. Not very useful now, but will  become
    interesting  when  shifting,  stretching, rotations, and user coordinate
    changes will be allowed for all segments.
1 ZOOM
        [GTVL\]ZOOM [Argument(s)] [/NEW] [/CURRENT] [/REGION]

    ZOOM can be used to modify the viewing window of the current plot.   The
    zooming does not affect the plot, but only the way it is displayed.
      ‐ ZOOM X1 X2 Y1 Y2  Defines the viewing window by its corners
      ‐ ZOOM OFF          Turns off zooming, i.e. defines the viewing window
        to be the plot page
      ‐ ZOOM REFRESH      Redraws the current plot (useful after CLEAR  SEG‐
        MENT)

    Without  arguments ZOOM calls the cursor to define a new viewing window.
    This new window will be defined by its center (at the  cursor  position)
    and a zooming factor (by steps of 1.414) :
       Z       Increase the zooming factor
       ‐       Decrease it
       B       Display the viewing window boundaries
    These commands do not produce effective zooming, press the space bar to
    do it. Additional commands:
       A       Clear alphanumeric screen
       0       Display the whole plot page (ZOOM OFF).
       <Space> Returns to previous zooming factor.
       E       Exits from the routine.
    For X11 displays, you may use the mouse buttons for the commands Z (left
    mouse button), <Space> (middle mouse button), and E  (right  mouse  but‐
    ton).

    Option  /NEW  and  /CURRENT  can be used to specified whether the zoomed
    area appears in the special zoom window (/NEW) or in the original window
    (/CURRENT).  Default  behaviour  is specified by CHANGE ZOOM NEW|CURRENT
    command.
2 /REGION
        This option uses a different ZOOM cursor, a rectangular  area  drawn
    using the middle button of the mouse. Clicking outside the area with the
    middle button will resize the rectangle. By keeping  the  middle  button
    pressed,  the  shape will follow the mouse. To drag the shape on another
    part of the screen, click with the middle button inside  the  shape  and
    keep  the button pressed while dragging the shape. Button 1 will perform
    the zoom (in an auxiliary zoom window), button 3 exits.
1 ENDOFHELP










































