Ubuntu Manpage: ctrans - a Computer Graphics Metafile ( CGM ) translator

NAME

       ctrans - a Computer Graphics Metafile ( CGM ) translator

SYNOPSIS

       ctrans  [ -bell ] [ -d device ] [ -f font ] [ -lmin min ] [ -lmax max ] [ -lscale scale ] [ -movie time ]
       [ -outfile file ] [ -pal pal_fname ] [ -pause ] [ -quiet ] [ -record  record_num  ...   ]  [  -soft  ]  [
       -verbose  ]  [  -Version ] [ -viewport llx:lly:urx:ury ] [ -wid window_id ] [ -window llx:lly:urx:ury ] [
       device-specific options ] [ - | metafile ...  ]

DESCRIPTION

ctrans is a metafile translator, taking metafile(s), a metafile stored in the NCAR Computer Graphics
Metafile (CGM) standard, and interpreting its instructions on the device defined by the GRAPHCAP
environment variable. Fonts are stroked according to specifications in the Fontcap file defined by the
FONTCAP environment variable. ctrans utilizes Graphcaps by default, see graphcap(5NCARG), while
providing optional processing by user provided libraries, if that is required by the device or desired by
the user. Thus, ctrans is capable of driving any device for which a Graphcap is available; with
programming modifications, ctrans can accommodate any device for which an external library of plotting
routines is available. Currently, the following Graphcap independent devices are supported: X11 under
release 4 and 5, version 11 of X.

ctrans can also translate metacode into the following raster formats: a60, avs, hdf, hppcl, nrif, sun and
xwd. The device specifier for these raster formats is the name of the format. For example "-d xwd"
specifies translation to an xwd formatted raster file. Additionally, a clear text driver, "-d CTXT", is
available on any terminal. Not all of the aforementioned devices may be supported by your particular
configuration of ctrans. For a list of supported devices see the gcaps(1NCARG) command.

ctrans will read from the standard input if no metafile name is specified or the the name specified is
`-'.

OPTIONS

-bell Ring the bell at the end of each frame. The default is to run in silent mode. This option is not
supported by all devices.

-d device
Device name. ctrans will use the Graphcap (if it exists) or the appropriate graphics library
indicated by device;

If device is preceded by a UNIX directory path then ctrans will look in that directory for the
specified graphcap. Otherwise ctrans searches the directory $NCARG_ROOT/lib/ncarg/graphcaps for
the graphcap.

For all device specifications except X11 output is directed to standard out. In the case of X11
translation results in appropriate calls to the X11 libraries. See graphcap(5NCARG) for a
description of supported devices. See gcaps(1NCARG) for a list of devices supported by your
particular configuration of ctrans.

This option overrides the GRAPHCAP environment variable.

-f fontcap
Fontcap file to be used for stroking text. When interpreting CGM TEXT command elements use
fontcap as the default font for textual translation. Note: CGMs may contain textual descriptions
which are not embedded in CGM TEXT elements. Hence they are not influenced by fontcap
specifications. Note also that a CGM may explicitly specify a named font which may override a
font provided on the command line. The environment variable FONTCAP may also be used to specify a
default fontcap.

If fontcap is preceded by a UNIX directory path then ctrans will look in that directory for the
specified fontcap. Otherwise ctrans searches the directory $NCARG_ROOT/lib/ncarg/fontcaps for the
fontcap.

See fontcap(5NCARG) for a description of the available fontcaps. See fcap(1NCARG) for a list of
the fontcaps installed on your system.

This option overrides the FONTCAP environment variable.

-lmin min
On devices which support line width scaling all lines are guaranteed to be scaled at least min
times the default line width for that device. This option effectively insures that the minimum
value for the CGM element "LINE WIDTH" is min.

-lmax max
On devices which support line width scaling all lines are guaranteed to be scaled at most max
times the default line width for that device. This option effectively insures that the maximum
value for the CGM element "LINE WIDTH" is max. The results of setting max less then min are
undefined.

-lscale scale
On devices which support line width scaling all line width specifications within the metafile will
be scaled by scale. This option is subject to modification by the -lmin and -lmax options.

-movie time
Set pause to time seconds. In normal operation mode the translator requires user interaction after
the display of each plot. ctrans will not proceed until the user responds. If movie mode is set
ctrans will wait time seconds after the display of each frame and then proceed automatically.
This option and the -pause option are mutually exclusive.

This option may not behave as expected on slower devices.

-outfile file
Direct translator output to file. By default translator output is written to the standard output.
This option has no effect for devices of which ctrans has a function-callable interface. e.g. X11
.

-pal pal_fname
Use the color palette defined in the file pal_fname for subsequent translation of the metafile.
This palette will override any color map defined by the CGM being translated. For a description of
the format of pal_fname see ras_palette(5NCARG).

-pause Pause after each frame in the metafile is displayed and wait for the user to type a newline before
proceding. This option is probably only useful when used in conjunction with the -wid option as
this is the normal behaviour for ctrans in most instances. This option and the -movie option are
mutually exclusive.

-quiet Suppress reporting of non-fatal (warning) error messages; only fatal error messages are reported.

-record
< record_number... >
If processing only single frames of the metafile is desired, this option specifies the record
number containing the start of that frame. ctrans assumes the processing is to start at the first
BEGIN PICTURE element in that record. The user must perform bookkeeping to determine the record
that contains the desired frame. Normally, a metafile editor (e.g., ictrans(1NCARG). may be used
as the actual user interface to perform this bookkeeping. Without a specified record number,
ctrans processes the entire metafile.

-soft Unconditionally perform software filling of all filled polygons. This option may be useful for
devices which do not support the filled polygon drawing primitive or have limits on the number of
vertices describing a polygon. On some devices this number is known and software filling is
performed, as appropriate, without user specification.

-verbose
Operate in verbose mode.

-Version
Print the version number and then exit.

-viewport llx:lly:urx:ury
Set the viewport of the output device. The viewport is the rectangular region of the output device
of which the virtual device coordinate system of the metafile is mapped onto. Normally this region
is the largest device-addressable square which fits in the center of the device address space. The
-viewport option may be used to change the default mapping. llx and lly specify the lower left
corner of the device in normalized coordinates. urx and ury specify the upper right corner of the
device in normalized coordinates. For example, -viewport 0.0 0.0 0.5 0.5, specifies the lower
left corner of the device.

-window llx:lly:urx:ury
Specify the workstation window (in the GKS sense). Four coordinates are specified which define a
rectangular window which is a subset of the normalized VDC rectangle with corner points (0,0) and
(1.0,1.0). llx and lly specify the lower left corner. urx and .ury specify the upper right
corner. The specified window is mapped onto the entire display viewport. For example, if the
workstation window is defined by the corner points (0,0) and (0.5 0.5) then the lower left quarter
of a plot would be blown up to fill the entire viewport. Specification of such a window can be
used for zooming and panning.

The range with which one may zoom in on a plot may be limited by the integer addressing precision
of the device.

DEVICE-SPECIFIC OPTIONS:

The following options are available when the device is graphcap-driven (See the gcaps(1NCARG) command for
a list of graphcap-driven devices):

-simulatebg
Simulate CGM background color requests by drawing a large filled rectangle of the appropriate
color. This option is useful for devices such as color PostScript printers which have no concept
of background color.

The following options are available when device is CTXT:

-Data Suppress display of CGM output primitive data. All other CGM element data is displayed. This may
substantially reduce the verbosity of the clear text driver.

-Para Suppress display of CGM element data except for output primitives. The -Data combined with the
-Para option permit the display of only the CGM element names.

The following options are available when device is X11:

-background color
Specifies the default window background color for color devices. If the metafile explicitly sets
color index 0 then this option is overridden.

-foreground color
Specifies the default foreground color for color devices. If the metafile explicitly sets color
index 1 then this option is overridden.

-geometry geometry
Specify the size and/or position of the graphics window in the format of an X11 Window System
geometry string.

-ignorebg
Ignore requests to change the background color. This option may be useful when ctrans renders into
a X window created by an application other than ctrans. As a side effect of this option the
rendering window is not cleared between frames.

-reverse
On monochrome devices reverse video is simulated by swapping the foreground and background colors.

-wid window_id
Render into the previously created X window specified by window_id. Normally ctrans creates its
own window for plotting. The window specified by window_id must be of type InputOutput. The
window must also have inherited its color map, depth and visual class from the root window.

Note also that when this option is used ctrans cannot receive X events from the drawing window.
Hence, ctrans cannot use "mouse clicks" as a signal to advance frames. For this reason the -pause
option is useful to prevent ctrans from processing the entire metafile without pausing between
frames.

window_id may be specified as a decimal or hexidecimal integer.

The following options apply to the X11 color map management of ctrans when device is X11:

ctrans supports three different methods of X11 color map management.

If the user specifies a shared color map (using the -scmap option), then ctrans will use the
default X color map for the screen, that is shared by all applications. If the metafile contains
more colors than there are available in the default X color map, then a color matching algorithm
is employed. The idea of the algorithm is that the color in the current color table that is
closest to the requested color will be selected. Closest is defined in terms of the normal
distance metric on the RGB cube. If the closest color is equal to or farther away than the
percentage error allowed ( -colerr ), then a warning message will be printed. The closest color
is still used.

If the user specifies a private color map (using the -pcmap option), then ctrans will create a
private color map for the graphics window. This will guarantee that 256 distinct colors are
available to the window. This means that the X window will have a different color map than all
the other windows on the screen. Therefore, you usually have to have the mouse pointer in the
window for the correct color table to be installed. One disadvantage to this option is that there
is usually a color flashing effect on the screen since the wrong color table will be installed for
the other windows on the screen.

The default color map management scheme attempts to take the best of the two previous models. It
starts out behaving like the shared model, in that it uses the default color map for the screen.
It differs in that, once it can't allocate any more colors from the default color map, in
allocates its own private color table and starts using it. This way, the color flashing is only
present if it absolutely needs to be so that ctrans can display the correct color.

-scmap Ask ctrans to use the shared default X color map only.

This is the option used if -wid is specified.

-colerr n
Specifies the percentage color error that is acceptable if the -scmap option is being used. If
the color being used is n percentage or more different from the color requested, a warning will be
reported by ctrans.

-pcmap Ask ctrans to create its own X color map and use it exclusively.

This option is ignored if the -wid option is present.

The following options are available when device is a60, avs, hdf, hppcl, nrif, sun, or xwd:

-dpi dpi
Specify the number of dots per inch. This option is only meaningful for the HP LaserJet, hppcl,
which ignores the -resolution option. dpi may be one of 75, 100, 150, or 300. The default is
150.

-direct
By default ctrans outputs raster imagery with 8-bit-indexed encoding. When this option is used, if
the raster file format supports it, raster imagery is output in a 24-bit-direct encoding scheme.
Be warned: the resultant file is three times the size of its 8-bit-indexed counterpart.

-landscape
Generate the image in landscape mode. This option is ignored by all raster devices except the HP
LaserJet, hppcl. By default the LaserJet uses portrait mode.

-resolution widthxheight
width and height specify the spatial resolution in pixels of the raster file to be created. The
default is 512x512.

EXAMPLES

       To process a metafile named gmeta and display its contents  on  the  TEKTRONIX  4107  terminal,  use  the
       following call:

            % ctrans -d t4107 gmeta

       If this device is already defined by the GRAPHCAP environment variable, simply call:

            % ctrans gmeta

       If you wish to display only the first frame starting in the third record, call:

            % ctrans -record 3 -d t4107 gmeta

       To examine the metafile gmeta's contents without CGM element data being displayed:

            % ctrans -d CTXT -Data -Para gmeta

       To  render  the  metafile  gmeta (under X Windows) in a window that is 512x512 pixels in dimension in the
       lower right corner of your screen

            % ctrans -d X11 -geometry 512x512-0-0 gmeta

       To rasterize the contents of the metafile gmeta at a resolution of 1024x1024 pixels, call:

            % ctrans -d xwd -res 1024x1024 > raster.xwd

       The raster output is in X11 "xwd" format and is sent to the file raster.xwd.

       To zoom in on the upper right quarter of the metafile gmeta and display it in an X window, call:

            % ctrans -d X11 -window 0.5:0.5:1.0:1.0

ENVIRONMENT

       FONTCAP
              Default fontcap specifier.

       GRAPHCAP
              Default output device specifier.

       NCARG_ROOT
              Path to root of NCAR Graphics installation.

       NCARG_LIB
              If set this variable contains the path  to  the  installed  NCAR  Graphics  libraries.   NCARG_LIB
              overrides NCARG_ROOT.

       NCARG_TMP
              If  set,  this  environment  variable contains a directory path to be used for temporary files. On
              most systems the default is /tmp.  On some systems the default is /usr/tmp.

FILES

       $NCARG_ROOT/lib/ncarg/graphcaps/*
                                     The binary NCAR Graphcap files

       $NCARG_ROOT/lib/ncarg/fontcaps/*
                                     The binary NCAR Fontcap files

CAVEATS

       Running  in  "movie"  mode  may give surprising results on slower devices, such as dumb terminals. If too
       short a time interval is specified slow devices may not have finished rendering before  the  movie  timer
       expires. This results in no pause between frames.

       Metafiles  which  reference color table indices that were not previously defined may have varying results
       from one device to the next.

       Using the -wid option to have ctrans display its output in a window created by another X application  may
       produce unexpected results, particularly with regard to color.

       At  ctrans' current level of implementation, the subset of CGM elements supported is closely approximated
       by the list provided in NCAR's Graphics Installer's Guide, Version 2.00 (August 1987).  However, the best
       way to determine whether a particular CGM element is supported by  the  translator  is  feed  a  metafile
       containing the element in question to ctrans.  Consult the aforementioned publication for a discussion of
       Graphcaps and Fontcaps as well.

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research

       The use of this Software is governed by a License Agreement.

NCARG                                             January 1993                                    CTRANS(1NCARG)