1 /* This file is part of the GNU plotutils package. Copyright (C) 1995,
2 1996, 1997, 1998, 1999, 2000, 2005, 2008, Free Software Foundation, Inc.
3
4 The GNU plotutils package is free software. You may redistribute it
5 and/or modify it under the terms of the GNU General Public License as
6 published by the Free Software foundation; either version 2, or (at your
7 option) any later version.
8
9 The GNU plotutils package is distributed in the hope that it will be
10 useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with the GNU plotutils package; see the file COPYING. If not, write to
16 the Free Software Foundation, Inc., 51 Franklin St., Fifth Floor,
17 Boston, MA 02110-1301, USA. */
18
19 /* This file contains a low-level routine for shifting a Tektronix graphics
20 device to a specified display mode, by emitting an escape sequence if
21 necessary. */
22
23 /* Basic Tektronix modes are alpha mode (for drawing alphanumeric
24 characters in any of four character sizes), ``graph mode'' i.e. vector
25 plot mode (for drawing line segments), and GIN (graphics input) mode,
26 which requests a cursor location from the user. The EGM (enhanced
27 graphics module), besides increasing the addressable point from 0..1023
28 x 0..1023 to 0..4095 x 0..4095, added three additional modes: point plot
29 mode, special point plot mode, and incremental plot mode.
30
31 Switching among the three basic modes is accomplished thus:
32
33 US, CR, or ESC FF: enter alpha mode (CR repositions cursor to left edge,
34 and ESC FF homes it)
35 GS: enter graph mode
36 ESC ENQ: enquire cursor location (works in both alpha, graph mode),
37 i.e. temporarily enter GIN mode and back out. In alpha mode
38 cursor location is lower left corner of flickerint 8x9 cursor.
39 ESC SUB: enter GIN mode, turn on positionable crosshair cursor
40 and send address in response to ESC ENQ. Thumbwheels
41 (potentiometers located on the keyboard) were used for positioning.
42
43 Getting back to alpha / graph mode from GIN is complicated; it's
44 best to send a US or GS to ensure this happens.
45
46 A genuine 4014 doesn't normally plot the first vector drawn after graph
47 mode is entered via GS (it's ``dark vector''). To get it plotted, you
48 need to issue a BEL, VT, HT, LF, CR or BS immediately after issuing the
49 GS. Only the first of these (BEL) won't disturb the location of the
50 graphics cursor.
51
52 If the EGM is present, we also have:
53
54 FS: enter point plot mode
55 RS: enter incremental mode
56 ESC FS: enter special point plot mode
57
58 Point plot commands are identical to vector plot commands (the endpoint
59 of the vector is drawn). Incremental plot mode allows motion by one
60 unit in any of 8 directions, on receipt of a single byte. First byte
61 after RS must be a beam-off or beam-on command.
62
63 In special point plot mode, the byte after the ESC FS (and the byte
64 which precedes every point address thereafter) is interpreted as an
65 intensity character, which determines the on-time of the beam. It is
66 loaded into an intensity register. This allows control of the dot size
67 (focused vs. unfocused), and brightness, in any of these three new
68 modes.
69
70 The user can also control the trichotomy normal z-axis (i.e. focused
71 beam) / defocused z-axis (i.e. defocused beam) / write-thru mode (see
72 tek2plot.c for the control codes used for this). Write-thru simply
73 means that written data, whether alpha characters or vectors, are
74 written to screen but are not refreshed. So they appear briefly and
75 then vanish (unless they are refreshed under user control, by drawing
76 them repeatedly).
77
78 WARNING: it is a peculiarity of the 4014 that in the following list,
79 one can mode-switch only _downward_, not upward! The exception is
80 that one can always switch up to alpha mode.
81
82 alpha mode
83 vector mode
84 point plot mode
85 special point plot mode
86 incremental plot mode.
87
88 Control codes that would switch `upward' are ignored. GIN mode can be
89 switched into from any mode, however.
90 */
91
92 #include "sys-defines.h"
93 #include "extern.h"
94
95 void
_pl_t_tek_mode(R___ (Plotter * _plotter)int newmode)96 _pl_t_tek_mode(R___(Plotter *_plotter) int newmode)
97 {
98 if (_plotter->tek_mode_is_unknown || _plotter->tek_mode != newmode)
99 /* need to emit escape sequence */
100 {
101 switch (newmode)
102 {
103 case TEK_MODE_ALPHA:
104 /* ASCII US, i.e. ^_ (enter alpha mode) */
105 _write_byte (_plotter->data, '\037');
106 break;
107 case TEK_MODE_PLOT:
108 if ((_plotter->tek_mode_is_unknown)
109 || (_plotter->tek_mode == TEK_MODE_POINT)
110 || (_plotter->tek_mode == TEK_MODE_INCREMENTAL))
111 /* ASCII US, i.e. ^_ (enter alpha) */
112 _write_byte (_plotter->data, '\037');
113 /* ASCII GS, i.e. ^] (enter vector mode)*/
114 _write_byte (_plotter->data, '\035');
115 break;
116 case TEK_MODE_POINT:
117 if ((_plotter->tek_mode_is_unknown) ||
118 (_plotter->tek_mode == TEK_MODE_INCREMENTAL))
119 /* ASCII US, i.e. ^_ (enter alpha) */
120 _write_byte (_plotter->data, '\037');
121 /* ASCII FS, i.e. ^\ (enter point mode) */
122 _write_byte (_plotter->data, '\034');
123 break;
124 case TEK_MODE_INCREMENTAL:
125 /* ASCII RS, i.e. ^^ (enter incplot mode)*/
126 _write_byte (_plotter->data, '\036');
127 break;
128 default:
129 break;
130 }
131
132 /* Tektronix is now in specified internal state */
133 _plotter->tek_mode = newmode;
134 _plotter->tek_mode_is_unknown = false;
135 }
136 }
137