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diff --git a/unix/sun/Gterm.hlp b/unix/sun/Gterm.hlp new file mode 100644 index 00000000..d97b4407 --- /dev/null +++ b/unix/sun/Gterm.hlp @@ -0,0 +1,198 @@ +.help gterm Dec86 "Vector Graphics for the Sun Workstation" +.sp 2 +.ce +\fBVector Graphics for IRAF on the Sun Workstation\fR +.ce +Doug Tody +.ce +December, 1986 +.ce +(design document) +.sp 3 +.NH +Graphics Terminal Model + + The window based, native vector graphics facility for Sun/IRAF will be +implemented as a purely data driven interface based on the concept of an +intelligent virtual graphics terminal. The virtual graphics terminal will +be implemented in software as a process running under a window system such +as Sunview or X. + +A virtual terminal interface will allow the Sun workstation to be used as an +ordinary graphics terminal to access IRAF or other software on either the +local or a foreign host via any data stream interface, e.g., rlogin, telnet, +or a modem connection. For example, one will be able to use telnet running +in a GTERM window to login on a VMS machine, then run IRAF on the VMS machine +in the normal fashion. Conversely, since the IRAF software on the Sun node +will always think that it is talking to a conventional data driven graphics +terminal, the Sun/IRAF software may in fact be run from a conventional +graphics terminal, via either a direct or remote login. Finally, a pure data +stream TTY interface where all details of the windowing system are isolated +into a server process makes it possible for a single version of IRAF to support +multiple window systems on the same host. + +The graphics terminal to be implemented by GTERM shall consist of independent +text and graphics frames. These will be implemented as separate windows +(frames) under SunView, allowing them to be moved, resized, exposed, hidden, +open, closed, etc., independently of each other. Note however that since both +frames are connected to the controlling process via a single terminal i/o +connection, the controlling process (e.g., the CL) can only read from or +write to one frame at a time. + +In normal use, the user will work for a time in the text frame, issuing +commands to run tasks which do not require interactive graphics facilities. +When a graphics program is run the graphics frame will be opened or exposed +and the plot drawn. If the graphics program is interactive, i.e., uses +cursor input, the cursor will be moved to the center of the window and the +crosshairs turned on to indicate that cursor input is required. A sequence +of keystroke or mouse button triggered cursor reads will follow, and +eventually graphics mode will be exited by transmission of the close +workstation sequence to GTERM by GIO running in the applications program. + +When graphics mode is exited GTERM terminal i/o is redirected to the text +frame and the cursor is restored to its former position in the text frame, +automatically restoring interactive control to the text frame. The graphics +frame may or may not be closed or hidden, depending upon the GTERM defaults +set up by the user. If the graphics frame is to be closed or hidden this +should probably require interactive confirmation by the user, else the plot +might disappear immediately after being drawn. Since control naturally +toggles back and forth between the text and graphics frames and since screen +space is always limited and a large, high resolution graph is generally +desired, it is expected that the graphics frame will normally be displayed +only while in graphics mode. + +.NH +GTERM Graphics Language + + The tektronix graphics language is a simple and efficient standard language +for graphics terminal i/o which will work about as well as anything in our +application. In particular, the vector encoding scheme is simple, compact and +efficient, and well suited to use with a variety of terminal drivers and +modems (since binary data is avoided). The best approach to implementing the +GTERM graphics language would seem to be to take the tektronix language as a +starting point and add additional functionality by extending the language +with new control sequences. Some of the extensions defined here a taken from +the Retrographics vt640 and the Pericom. Others more specific to window based +applications will be added in the future in an upwards compatible fashion. + + +.ks +.nf + GS open workstation if not already open + open/expose graphics frame (icon -> full window) + direct terminal i/o to graphics frame + save cursor (mouse) position + issue GS dark vector command (see below) + CAN close workstation + restore control to text frame (restore cursor) + close/hide graphics frame (full window -> icon) + keystroke required to trigger close-window? + + + GS (workstation already opened) + enter vector drawing mode, dark vector + FS enter point plot mode + US,CR enter alpha mode + text is drawn in graphics frame + defaults to transparent text, erase permitted + ESC CR enter text mode + lines of text are drawn on status line in + nontransparent (overwrite) mode + + ESC SUB enter crosshair mode + ESC FF clear screen, initialize drawing modes + ESC/f [x,y] set crosshair position + GS [x,y] US sets alpha cursor position + + ESC[0123] set character size (normal,2x,3x,4x) + ESC[`abcd] set line drawing style (normal,dotted,dotdash,sd,ld) + ESC/[012]d set drawing mode (set, clear, toggle) + ESC/[0123]w set polyline linewidth (normal,2x,3x,4x) + + Standard screen resolution is 1024 by 780. + In graphics mode, chars are interpreted as [x,y] coordinate pairs. + In alpha mode, chars are interpreted as characters to be drawn. +.fi +.ke + + +A number of extensions to this basic language are being considered for future +implementation. Support for color, multiple text fonts, general polymarkers, +area fill, and possibly cell array are contemplated, as well as simple +extensions for window control and pop-down menus. Support for the standard +textronix features which have been omitted (vector point elimination, +incremental point mode, status enquiry) is possible. The interface is easily +extensible hence there is no need to attempt to define or support such features +in the initial interface. + +.NH +Implementation Notes + + The GTERM virtual terminal consists of two independent frames, the text +frame and the graphics frame. Selection of the frame to which output is to +be delivered is done at the lowest possible level, i.e., when the read system +call is issued by the terminal to accept terminal output from the pty +(pseudo-terminal driver) stream for the terminal. This is done by linking in +a custom version of the notify_read() primitive, the low level read primitive +for notifer based programs. Output is initially to the text frame. Output +is redirected to the graphics frame when GS is seen in the output stream, +and later restored to the text frame when CAN is seen. Input is controlled +independently by the two frames at a high level, hence does not have to be +switched. + +All terminal operations are event driven. Graphics data is deposited into a +circular input buffer by an event driven read routine, which can issue +<ctrl/s>/<ctrl/q> to the terminal driver to control the rate at which input +is accumulated. A separate drawing routine running off an interval timer +is used to process data appearing in the input buffer. The drawing code is +always in one of three modes: vector drawing mode, alpha mode (randomly +addressable character drawing), or text mode (textual output to the status +line). + +.SH +Appendix: Tektronix Graphics Language (Retrographics vt640) + +.ks +.nf + *GS enter graphics mode; dark vector + *FS enter point plot mode + RS enter incremental point mode + *US,CR enter alpha mode, graphics plane, tek font + CAN disable graphics mode, restore output to terminal plane + + ESC"0g alias for enter transparent mode + ESC"4g alias for enter crosshair mode + ESC"5g enter light pen mode + + *ESC SUB enter crosshair mode + *ESC FF clear screen, initialize drawing modes + *ESC ENQ return cursor position, other status + + ESC[0123] set character size (normal,2x,3x,4x) + ESC[`abcd] set line drawing style (normal,dotted,dotdash,sd,ld) + ESC/[012]d set drawing mode (set, clear, toggle) + + ESC/f set crosshair position + *GS [x,y] US sets alpha cursor position + + Vector coordinate encoding (max 10 bits = 1024 points res.): + + high y P01XXXXX + low y P11XXXXX + high x P01XXXXX + low x P10XXXXX + + Cursor return structure: + + key PXXXXXXX + high x P01XXXXX + low x P01XXXXX + high y P01XXXXX + low y P01XXXXX + trailer <cr> + + Standard 4010/4012 screen resolution is 1024 by 780. + In graphics mode, chars are interpreted as [x,y] coordinate pairs. + In alpha mode, chars are interpreted as characters to be drawn. +.fi +.ke |