Provided by: xgterm_2.1+dfsg-1_amd64 
NAME
xgterm - terminal emulator for X with graphics and imaging capability
SYNOPSIS
xgterm [-toolkitoption ...] [-option ...]
DESCRIPTION
The xgterm program is a terminal emulator for the X Window System based largely on xterm
but with a completely new graphics and imaging widget. It provides DEC VT102 and Tektronix
4014 compatible terminals for programs that can't use the window system directly. XGterm
also serves as a prototype for the Widget Server being developed by the IRAF Project at
NOAO. The Object Manager Library it uses implements a window system toolkit as an
interpreted window-object language, allowing application GUIs to be defined and executed
at runtime without compiling any code, and with minimal dependence upon the underlying
window system toolkit library. We will concentrate here, however, on it's use as a
terminal emulator and a description of the new Gterm widget.
The Gterm graphics window operates almost identically to the xterm Tek window, however
there are extensions for implementing full-screen cursors, imaging, area fills, colors,
graphics erasure, a "status line" and so on. Any graphics application capable of running
under an xterm Tek window should also be able to use xgterm as well. Client programs
wishing to make use of the extended features, or those wishing to implement a GUI, are
advised to use the OBM (Object Manager) library supplied with the XGterm source as part of
the X11IRAF package. This provides a much better programmatic interface to all of the
features available; however, as of this writing it is not yet fully documented. Users are
referred to the XImtool task as an example of a more complex application using the OBM
Library and Gterm widget, as well as demo tasks in the guidemo directory of the X11IRAF
sources.
The VT102 text window is unchanged from the original xterm application. All of it's
resources, command-line options and operation are identical to that used by xterm. The
termcap(5) entry for xterm may be used for xgterm as well. See the xterm(1) man page for
details.
OPTIONS
All xterm(1) and X Toolkit command line options are supported, there are no additional
options.
RESOURCES
The program understands all of the core X Toolkit resource names and classes, all text
window resources known to xterm(1), as well as the Gterm (graphics and imaging widget)
resources. The proper Class name for all resources described here is Gterm. A table of
available Gterm resources and their defaults may be found below, some of the more
interesting resources are described here in detail:
basePixel
Base cell of the custom colormap. This essentially allows you to reserve basePixel
colors in the global colormap for other applications. The default is 38, if changed
you'll need to also enable the cmapInitialize resource to force the Gterm widget to
update it's global colormap resource in the X server.
cmapInitialize
Initialize the ximtool colormap at startup. When resetting the basePixel resource or
colormap this is required in order to force the Gterm widget to update it's global
colormap resource in the X server. The default is False.
cmapInterpolate
Interpolate the colormap to the number of display colors. The default is True.
cmapName
Name used for private colormap. The default for all IRAF imaging applications is
image. Gterm widget based imaging applications which have the same value of cmapName
will share the same colormap, minimizing colormap flashing and allowing multiple
applications to be run at the same time.
color0
The widget background color. The default is black.
color1
The widget foreground color. The default is white.
color2 thru color9
Optional drawing colors. The line color used for graphics is set using an escape
sequence to select the current color index. See Gterm I/O Escape Sequences below for
more details.
crosshairCursorColor
Color of the full screen crosshair cursor.
defaultMarker
Default marker type. Options include text, line, polyline, rectangle, box, circle,
ellipse, and polygon. The default is rectangle.
deiconifyWindow
De-iconify the Gterm graphics window when activated. The default is False.
dialogBgColor
Dialog box (i.e. the status line) background color. Dialog text is text which is
drawn into the dialog area at the bottom of the gterm window, it is transient and is
not a permanent part of the graphics being drawn. Dialog text is normally used to
interact with the user or to display messages during program operation, without
affecting the graphics being drawn.
dialogFgColor
Dialog box (i.e. status line) foreground color.
ginmodeBlinkInterval
Graphics cursor blink interval, time is specified in milliseconds. The default is 0.
ginmodeCursor
Graphics mode cursor type. The default is a full screen cursor custom to the widget.
height
Height of the Gterm window. The default is 480.
idleCursor
Cursor to use when not in graphics mode. The default is a plus sign.
markerHighlightColor
Highlight color for the active marker. When the pointer moves into a marker is it
marked "active", the highlight color and width change to which marker is active. The
default is green.
markerHighlightWidth
Highlight width for the active marker. The default is 2.
maxColors
The maximum number of colors to use in the private global colormap, the default is
216. Out of this number 10 colors (the color0 thru color9 values) are reserved by
the widget as static colors, the remainder may be allocated for images.
raiseWindow
Raise the window when active. The default is False.
warpCursor
Warp the cursor to the window when active. The default is False.
width
Width of the Gterm window. The default is 640.
GTERM WIDGET RESOURCES
Class Hierarchy
Core -> Gterm
Resources
When creating a Gterm widget instance, the following resources are retrieved from the
arguments list or from the resource database:
Name Class Type Default Description
─────────────────────────────────────────────────────────────────────────────────────────────────────────
markerFill Boolean False Flood fill marker area with markerFillColor
edge required for translation actions for be in
effect.
vertex (i.e. knot) required for translation
actions for be in effect.
GTERM WIDGET TRANSLATIONS AND ACTIONS
The default translations for a Gterm window are:
<Btn1Down>: m_create()
<Btn2Down>: crosshair(on)
<Btn2Motion>: crosshair(on)
<Btn2Up>: crosshair(off)
<EnterWindow>: enter-window()
<LeaveWindow>: leave-window()
<KeyPress>: graphics-input()
<Motion>: track-cursor()
The available action procedures for a Gterm window are:
ignore() Ignore an event.
graphics-input() Handle a graphics input request.
crosshair(on|off) Display a crosshair cursor.
track-cursor() Track crosshair cursor position.
enter-window() Handle an EnterWindow event.
leave-window() Handle an LeaveWindow event.
reset() Do a soft reset of the Gterm widget.
m_create() Create a new marker. Valid types include
text line polyline rectangle
box circle ellipse polygon
The default is rectangle, if no type is given the default type
specified by the markerType resource will be used.
GTERM MARKER TRANSLATIONS AND ACTIONS
The default translations for a marker are:
!Shift <Btn1Motion>: m_rotateResize()
<Btn1Motion>: m_moveResize()
!Shift <Btn1Down>: m_raise() m_markpos()
<Btn1Down>: m_raise() m_markposAdd()
<Btn1Up>: m_redraw() m_destroyNull()
<Btn2Down>: m_lower()
<Key>BackSpace: m_deleteDestroy()
<Key>Delete: m_deleteDestroy()
<KeyPress>: m_input()
<Motion>: track-cursor()
Translations affect only the currently active marker, the cursor must be within nearEdge
pixels of a marker edge, or nearVertex pixels of a marker vertex to take effect.
The available action procedures for a marker are
m_create(type) Create a new marker. Valid types include
text line polyline rectangle
box circle ellipse polygon
The default is rectangle, if no type is given the default type
specified by the markerType resource will be used.
m_destroy() Destroy the active marker.
m_destroyNull() Destroy the active marker if it is null sized.
m_set(attribute, value, ....)
Set a marker attribute. Valid attributes include
activated autoRedraw fill fillBgColor
fillColor fillPattern fillStyle font
height highlightColor imageText knotColor
knotSize lineColor lineStyle lineWidth
rotangle sensitive textBgColor textBorder
textColor translations type visible
width x y
m_raise() Raise the active marker to the top of the display list.
m_lower() Lower the active marker to the bottom of the display list.
m_notify(event, event, ....)
Notify any clients that have registered callbacks for the
specified type of events. Recognized events include
notify moveResize modify
redraw destroy input
focusIn focusOut constraint
m_input() Notify any clients that have registered a input callback that a
input event has occurred.
m_markpos() Mark the current position of the marker, e.g., so that it can
later be erased.
m_markposAdd() Execute either the markpos or add action, depending upon the
pointer location. If the pointer is over an active marker at a
location where the add action can be executed this is done,
otherwise the markpos action is executed.
m_redraw() Redraw the active marker.
m_addPt() Add a point (i.e. vertex knot). Polyline and polygon markers
only.
m_deletePt() Delete a point (i.e. vertex knot).
m_movePt() Move a point (i.e. vertex knot). Polyline and polygon markers
only.
m_deleteDestroy() Delete a point or destroy a marker, depending upon the pointer
position.
m_move() Move a marker.
m_resize() Resize a marker.
m_moveResize() Move a point or marker, or resize a marker, depending upon the
pointer position.
m_rotate() Rotate a marker.
m_rotateResize() Rotate or resize a marker. A marker is rotated if near a vertex
know, or resized if near an edge.
GTERM I/O ESCAPE SEQUENCES
XGterm uses escape sequences to provide graphics emulation. This protocol is an extension
of the Tektronix 4012 graphics protocol. The basic extensions are patterned after the
Retrographics VT640 graphics terminal, using GS (octal \035, aka Ctrl-]) and CAN (octal
\030, aka Ctrl-x) to switch between vt100 and graphics modes. Additional extensions are
defined to support advanced features such as color, area fills, graphics erasure, setting
the cursor location under program control, interactive dialog via the "status line", and
so on.
While these escape sequences can be used directly, the best programmatic interface is to
use the OBM (Object Manager) library supplied with the XGterm source as part of the
X11IRAF package. Any Tektronix-compatible graphics library will suffice for producing
vector graphics, the added escape sequences used by the Gterm widget are required to make
use of imaging, area fills, the status line, etc.
All escape sequences begin with an ESC character (octal \033), followed by up to three
characters defining the action to be taken. All strings in capital letters refer to the
ASCII code (e.g. LF is the ASCII linefeed code), a three digit number preceded by a '´
refers to an octal code (e.g. " 12" is octal 12) , all others are characters in the
escape code (e.g. "/bc" are the three characters '/', 'b', and 'c').
ESCAPE SEQUENCES
US
CR Switch to alpha mode. Characters are drawn in the graphics window
at the "current" position (normally set beforehand with a GS/US
vector move), using the alpha mode font. Receipt of any control code
causes alpha mode to be exited.
GS Switch to vector polyline mode.
FS Switch to vector polypoint mode.
RS Switch to vector mode, vertices are joined as a polygon.
With all three codes, vertices and points are accumulated in a
buffer and displayed when the buffer fills or when vector mode is
terminated by receipt of any control code. A workstation open will
be done if it hasn't already been opened, no-op sequences GS-CAN are
filtered out, since they would only cause a pointless switch to the
graphics frame and back without drawing. The open workstation
sequence is GS,US, or by the xterm graphics start escape sequence
"[?38h".
EM Enter message mode. In message mode input text is accumulated in a
buffer and eventually passed to the object manager, which delivers
the message to the referenced object. Messages are used to download
the user interface to be executed by the object manager. During
execution, messages are used to set the values of user interface
parameters to allow the UI to track the state of the client
application.
CAN Close workstation and enter command mode.
BEL Ring the screen bell.
ENQ Return terminal status. Returned values include the terminal mode,
and alpha cursor x and y position.
SUB Initiate a cursor read, values are returned in window coordinates.
/SUB Return window cursor position in raster coordinates.
FF Clear the screen.
/f Set current cursor position.
0 Set character size 0. (Currently ignored).
1 Set character size 1. (Currently ignored).
2 Set character size 2. (Currently ignored).
3 Set character size 3. (Currently ignored).
/0d Set color index.
/1d Clear graphics screen.
/2d Invert graphics screen
` Select line style 0. (Solid)
a Select line style 1. (Dashed)
b Select line style 2. (Dotted)
c Select line style 3. (DashDot)
d Select line style 4. (Dash3Dot)
/0w Select line width 0.
/1w Select line width 1.
/2w Select line width 2.
/nw Select line width 3.
/0c Select line color 0.
/1c Select line color 1.
/2c Select line color 2.
/3c Select line color 3.
/4c Select line color 4.
/5c Select line color 5.
/6c Select line color 6.
/7c Select line color 7.
/8c Select line color 8.
/9c Select line color 9.
IMAGING ESCAPE SEQUENCES
These are encoded as follows:
ESC <code> [ P ; P ; ... ] <data>
where code is a character sequence and P is an ASCII encoded parameter described below.
/nc Select line color. Parameter is the color number in the range 0-9.
sre Reset. Parameters are "reset-str".
ssz Resize. Parameters are "resize-str".
rir Initialize raster.
rcr Create a raster. Parameters are raster number, type, width, height,
and depth. Type is 1 for a normal (client) raster, 2 for cached in
server memory, or 0 if you don't care. Depth may be 1, 8, 16, or
32.
rde Destroy a raster. Parameter is raster number.
rqr Query a raster. Parameter is raster number. Output parameters are
status, type, width, height, and depth encoded in the string
""\033[5;%d;%d;%d;%d;%d]".
rsr Select a raster. Parameter is raster number.
rwr Write pixels to a rectangular region of a raster. Parameters are
raster number, encoding type (not used), x1, y1, nx, ny, and depth
followed by (nx*ny) data pixels.
rrd Read from a rectangular region of a raster. Parameters are raster
number, encoding type (not used), x1, y1, nx, ny, and depth followed
by (nx*ny) data pixels.
rrp Refresh raster pixels. Parameters are raster number, coordinate
type (0 for pixel, 1 for NDC), x1, y1, nx, ny.
rsp Set all the raster pixels in a region to a single color. Parameters
are raster number, coordinate type (0 for pixel, 1 for NDC), x1, y1,
nx, ny, color, and raster operand. If nx=ny=0 the entire raster
will be written. Raster operands include transient (octal 020),
refresh_all (octal 040), or refresh_none (octal 100).
rco Copy a region of the source raster to a region of the destination
raster. Parameters are raster operand, source raster number,
source type, source x coord, source y coord, source width, source
height, destination raster number, destination type, destination x
coord, destination y coord, destination width, destination height,
If the input and output regions are not the same size the subimage
is automatically scaled to fit the destination region. If the
destination extent DNX or DNY is negative, the image is flipped in
that axis. The type of spatial scaling performed is determined by
the scale factors (zoom, dezoom, or no scaling). The rasterop
argument is used to exercise fine control over how the mapping is
performed, e.g. to force a refresh, implement a transient mapping,
or in the case of a dezoom (many-to-one) mapping, select the
antialiasing technique to be used.
rwc Write a colormap. Parameters are colormap number, first color and
the number of colors followed by NC colors triples in the data.
rrc Return the color assignments for a region of the named colormap.
Parameters are colormap number, first color and the number of colors
followed by NC colors triples in the data.
rlc Load a colormap into the display, optionally scaling the colormap
via a linear transformation in the process. Parameters are the
colormap number, the offset value, and the cursor x and Y
coordinates in NDC units. The colormap is unaffected if offset=0.5,
scale=1.0. A negative scale inverts the image. If map=0 the linear
transformation is applied directly to the display colormap.
rfc Free a colormap. Parameter is the colormap number.
rwo Write the IOmap. Parameters are the first color and the number of
colors, followed by NC color triples in the data. An iomap is an
optional lookup table used to isolate the client application from
the color model used within the Gterm widget. To simplify color
allocation the Gterm widget defines a logical color space where
color 0 is the background, 1 the foreground, 2-N are statically
allocated standard colors, and colors N+1 and above are dynamically
allocated by the graphics application. Less-demanding applications
use only the statically allocated, shared colors. The widget
internally maps these logical colors to whatever the window system
requires, but providing a well-defined logical color space isolates
the client from the details of color allocation in the underlying
window system.
An iomap can be used to define a mapping between the color model of
the client application and the Gterm color model (when we say color
model here we mean color allocation schemes for 8 bit pseudocolor).
By default the iomap is one-to-one. The use of an iomap frees the
client from having to worry about color index translations, and
allows color tables to be combined in the widget for greater
efficiency when color tables are serially applied. The iomap
applies to all color indices or pixel values passed in i/o
operations between the client and the Gterm widget.
rro Read the IOmap. Return values are the first color and the number of
colors, followed by NC color triples in the data.
rim Delete all mappings and initialize the mapping subsystem.
rsm Define a new mapping function, or modify an old one. If a new
mapping is defined it is merely enabled, and no refreshing of the
screen takes place until either some mapped data is written to or
the mapping is explicitly refreshed. If an existing mapping is
modified the old and new mappings are examined and only those
portions of the destination rect for which the mapping changed are
updated. This permits minor changes to a mapping (e.g. moving an
edge) without having to redraw the entire region. Regions of the
destination drawable which were previously covered by the mapping
but which were exposed by modifying the mapping are redrawn.
rgm Return the external parameters of a mapping. Parameter is the
mapping number, values returned (in the string "\033[6;%d;%d
%d;%d;%d;%d;%d;%d %d;%d;%d;%d;%d;%d]") are the mapping number,
rasterop, source mapping, type, x, y, width, height, and destination
mapping, type, x, y, width and height.
rem Enable a mapping. Parameters are the mapping number and an integer
flag indicating whether to refresh the mapping.
rdm Disable a mapping. Disabling a mapping does not affect the mapping
definition, hence a disabled mapping may later be reenabled.
Parameters are the mapping number and an integer flag indicating
whether to erase the mapping.
rrm Refresh a mapping. Parameter is the mapping number.
rfm Free a mapping. Parameter is the mapping number.
MORE ON IMAGING
The imaging model of the Gterm widget defines the following key object or data types:
rasters, mappings, and colors.
raster A raster is a MxN array of pixels. At present pixels are 8 bits deep but hooks
are built into the widget to expand this in the future. Pixel values are
indices into the Gterm virtual colormap, with values starting at zero. A raster
may be any size. A raster is merely a two-dimensional array in the graphics
server; it is not displayed unless mapped. An exception is raster zero, which
is the graphics window. Rasters are referred to by number, starting with zero.
Initially only raster zero exists; new rasters are created with the create
raster escape code rcr. Space for rasters may be allocated either in the
graphics server, or in the X server. This has implications on performance but
is otherwise transparent to the client. By default rasters are allocated in the
graphics server, i.e., in the X client.
mapping A mapping defines a projection of a rectangle of the source raster onto a
rectangle of the destination raster. Mappings may be either enabled (active) or
disabled. When a mapping is enabled, any change to a pixel in the source rect
will cause the corresponding pixels in the destination rect to be updated.
Mappings are referred to by number starting with one. Initially no mappings are
defined. If the size of the input and output rect is not the same the input
rect will be scaled by pixel replication or subsampling to fill the output rect.
If the argument DW (destination width) or DH (destination height) of the
destination rect is negative, the image will be flipped around the corresponding
axis when copied to the destination; the region of the destination drawn into is
the same in either case. Multiple mappings may reference the same source or
destination raster. Mappings are refreshed in order by the mapping number.
Modifying a mapping causes the changed regions of the destination rect to be
refreshed.
color The Gterm widget provides a fixed number of preassigned colors corresponding to
pixel values 0 through 9. Zero is the background color, one is the foreground
color, and 2-9 (8 colors) are arbitrary colors defined by Gterm widget
resources. These static colors are normally used to draw the background, frame,
axes, titles, etc. of a plot, or to draw color graphics within the drawing area.
The advantage of static colors is that they are shared with other X clients, and
the values of these colors may be assigned by the user to personalize the way
plots look.
The Gterm widget also allows any number (up to about 200 or so) additional
colors to be defined at runtime by the client application. These color values
start at pixel value 10 and go up to the maximum pixel value assigned by the
client. The client application allocates colors with the write colormap escape
code rwc. Attempts to overwrite the values of the static colors are ignored.
The values of already allocated colors may be changed dynamically at runtime
using write colormap code to write the desired range of color values.
Applications should not assume that there are 10 static colors and 200 or so
allocatable colors. The IRAF graphcap entry for the logical device in use, and
resources set for the widget, defines these parameters for the device.
Alternatively, the read colormap code may be used to dynamically determine how
many colors the server has preallocated when the application starts up.
An image may use either static and dynamic pixel values or both types of values,
but in most cases imaging applications involve smoothly shaded surfaces hence
will require dynamically assigned private colors.
If for some reason the client application cannot use the Gterm widget color
model, the IOMAP feature can be used to make the widget appear to have some
externally defined (i.e., client defined) color model.
The maximum number of rasters and maximum number of mappings is defined by the Gterm
widget resources maxRaster and maxMappings (or in the GUI file) when the graphics
application starts up. The maximum values should be much larger than most applications
require. Applications should allocate raster or mapping numbers sequentially starting at
1 (more or less) to avoid running out of raster or mapping descriptors.
The {read|write}pixels escape codes operate directly on raster pixels. The mapping escape
codes support two alternative coordinate systems, raster pixels and NDC (normalized device
coordinates), as indicated by the ST or DT argument (source or destination coordinate
type). Note that the origin of the pixel coordinate system is the upper left corner of
the display window (consistent with most graphics systems), whereas the origin of the NDC
coordinate system is the lower left corner (consistent with IRAF).
Pixel coordinates allow precise control of imaging but require the application to know the
window size, and may result in complications e.g. if the window is resized. NDC
coordinates pretty much guarantee that a mapping will involve sampling, hence are not the
most efficient, but the graphics will be drawn correctly no matter how the window is
resized and for most applications the performance difference is negligible. Most
applications should use NDC coordinates for raster 0 (the display window), and pixel
coordinates for rasters 1-N.
Although the size of rasters 1 and higher are defined by the client application, the size
of raster zero, the actual gterm display window, is subject to the constraints of the
window system. The client can attempt to reset the size of the gterm window using create
raster escape with raster=0, however the Gterm widget, UI containing the Gterm widget, and
the window manager are all free to deny such a request. The query raster escape should be
called to determine the actual size of the window one will be drawing into.
AN EXAMPLE IMAGING APPLICATION
An example of a simple imaging application might be one that downloads an image and
displays it in the gterm window, filling the window. This could be done as follows
(following a graphics open and other escape codes to prepare the drawing surface).
create raster Create raster 1 the size of the pixel array to be displayed. This need not
be the same as the size of the gterm display window.
set mapping Define a mapping between raster 1 and raster 0, the display window, using
NDC coordinates to define the region of the display window to be filled.
The mapping number is arbitrary but mappings should normally be allocated
starting with 1. The mapping is automatically enabled when first defined.
write colormap (Optional). Define the pixel value to RGB color assignments for the image
pixels.
write pixels This escape is called one or more times to write pixels into raster 1. At
most 32K pixels can be written in each call. As each write is made the
affected region of the display window will be updated.
Alternatively, one could write the pixels and then define the mapping to cause the entire
image to be displayed at once.
Note that the imaging escape can be combined with normal graphics to draw text and
graphics around or on top of an image region. The order in which drawing operations occur
is important, e.g., to draw graphics or text on top of an image the image should be drawn
first.
MARKERS
Markers are a general feature of the Gterm widget and are used more extensively in other
programs (e.g. the prototype IRAF science GUI applications), but they have no real use in
xgterm when used as simply a graphics terminal. All markers share some of the same
characteristics, so it is worthwhile learning basic marker manipulation keystrokes (as
defined using the default marker translations), especially how to delete an accidentally
created marker:
o Delete or Backspace in a marker deletes it.
o MB1 anywhere inside a marker may be used to drag the marker.
o MB1 near a marker corner or edge, depending on the type of marker, resizes the
marker.
o Shift-MB1 on the corner of most markers will rotate the marker.
o Markers stack, if you have several markers and you put one on top of the other.
The active marker is highlighted to tell you which of the stacked markers is
active. If the markers overlap, this will be marker "on top" in the stacking
order.
o MB2 in the body of a marker "lowers" the marker, i.e. moves it to the bottom of
the stacking order.
ENVIRONMENT
XGterm sets the environment variables ``TERM'' and ``TERMCAP'' properly for the size
window you have created. It also uses and sets the environment variable ``DISPLAY'' to
specify which bit map display terminal to use. The environment variable ``WINDOWID'' is
set to the X window id number of the xgterm window.
SEE ALSO
xterm(1), resize(1), X(1), pty(4), tty(4)
Xterm Control Sequences (in the xterm source directory)
BUGS
Many of the same bugs affecting xterm also apply here.
Xgterm is not normally installed with setuid permissions. On some Linux systems, for
example, where the /dev/tty and /dev/pty devices have root ownership and permission 600
this can cause problems. Workarounds are to either install XGterm with setuid permissions
or modify the /dev/tty and /dev/pty devices to have permission 666.
COPYRIGHT
Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.