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 the internal path_is_flushable() method, which is
20 invoked after any path segment is added to the segment list, provided
21 (0) the segment list has become greater than or equal to the
22 `max_unfilled_path_length' Plotter parameter, (1) the path isn't to be
23 filled. In most Plotters, this operation simply returns true. */
24
25 /* This file also contains the internal maybe_prepaint_segments() method.
26 It is called immediately after any segment is added to a path. Some
27 Plotters, at least under some circumstances, treat endpath() as a no-op.
28 Instead, they plot the segments of a path in real time. */
29
30 /**********************************************************************/
31
32 /* This version of the internal method path_is_flushable() is for Tektronix
33 Plotters, which (1) reduce all paths to line segments as they are
34 constructed, and (2) plot the resulting line segments ("vectors") in
35 real time. Unlike the generic version, which returns true, this version
36 returns false. */
37
38 #include "sys-defines.h"
39 #include "extern.h"
40
41 bool
_pl_t_path_is_flushable(S___ (Plotter * _plotter))42 _pl_t_path_is_flushable (S___(Plotter *_plotter))
43 {
44 return false;
45 }
46
47 /**********************************************************************/
48
49 /* This version of the internal method maybe_prepaint_segments() is for
50 Tektronix Plotters, which (1) reduce all paths to line segments as they
51 are constructed, and (2) plot the resulting line segments ("vectors") in
52 real time. This is what does all the painting of line segments on a
53 Tektronix display. */
54
55 /* for Cohen-Sutherland clipper, see g_clipper.c */
56 enum { ACCEPTED = 0x1, CLIPPED_FIRST = 0x2, CLIPPED_SECOND = 0x4 };
57
58 void
_pl_t_maybe_prepaint_segments(R___ (Plotter * _plotter)int prev_num_segments)59 _pl_t_maybe_prepaint_segments (R___(Plotter *_plotter) int prev_num_segments)
60 {
61 int i;
62
63 /* sanity check */
64 if (_plotter->drawstate->path->num_segments < 2)
65 return;
66
67 if (_plotter->drawstate->path->num_segments == prev_num_segments)
68 /* nothing to paint */
69 return;
70
71 /* skip drawing if pen level is set to `0' */
72 if (_plotter->drawstate->pen_type == 0)
73 return;
74
75 /* Skip drawing if the pen color is white. Since our TekPlotter class
76 doesn't support filling, this is ok to do if the Tektronix isn't a
77 kermit emulator (the kermit emulator supports color). */
78 if (_plotter->tek_display_type != TEK_DPY_KERMIT
79 && _plotter->drawstate->fgcolor.red == 0xffff
80 && _plotter->drawstate->fgcolor.green == 0xffff
81 && _plotter->drawstate->fgcolor.blue == 0xffff)
82 return;
83
84 /* iterate over all new segments, i.e. segments to be painted */
85
86 for (i = IMAX(1, prev_num_segments);
87 i < _plotter->drawstate->path->num_segments;
88 i++)
89 {
90 plPoint start, end; /* endpoints of line seg. (in device coors) */
91 plIntPoint istart, iend; /* same, quantized to integer Tek coors */
92 int clipval;
93 bool same_point, force;
94
95 /* nominal starting point and ending point for new line segment, in
96 floating point device coordinates */
97 start.x = XD(_plotter->drawstate->path->segments[i-1].p.x,
98 _plotter->drawstate->path->segments[i-1].p.y);
99 start.y = YD(_plotter->drawstate->path->segments[i-1].p.x,
100 _plotter->drawstate->path->segments[i-1].p.y);
101 end.x = XD(_plotter->drawstate->path->segments[i].p.x,
102 _plotter->drawstate->path->segments[i].p.y);
103 end.y = YD(_plotter->drawstate->path->segments[i].p.x,
104 _plotter->drawstate->path->segments[i].p.y);
105 same_point = (start.x == end.x && start.y == end.y) ? true : false;
106
107 /* clip line segment to rectangular clipping region in device frame */
108 clipval = _clip_line (&start.x, &start.y, &end.x, &end.y,
109 TEK_DEVICE_X_MIN_CLIP, TEK_DEVICE_X_MAX_CLIP,
110 TEK_DEVICE_Y_MIN_CLIP, TEK_DEVICE_Y_MAX_CLIP);
111 if (!(clipval & ACCEPTED)) /* line segment is OOB */
112 continue;
113
114 /* convert clipped starting point, ending point to integer Tek coors */
115 istart.x = IROUND(start.x);
116 istart.y = IROUND(start.y);
117 iend.x = IROUND(end.x);
118 iend.y = IROUND(end.y);
119
120 if (i == 1)
121 /* New polyline is beginning, so start to draw it on the display:
122 move to starting point of the first line segment, in Tek space.
123 As a side-effect, the escape sequence emitted by _pl_t_tek_move()
124 will shift the Tektronix to the desired mode, either PLOT or
125 POINT. Note that if we are already in the desired mode,
126 emitting the escape sequence will prevent a line being drawn at
127 the time of the move (the "dark vector" concept). That is of
128 course what we want. */
129 _pl_t_tek_move (R___(_plotter) istart.x, istart.y);
130 else
131 /* A polyline is underway, >=1 line segments already. So check
132 whether the position on the Tektronix is the same as the
133 starting point of the new line segment; if it differs, move to
134 the latter. Such a difference can occur on account of clipping.
135 Also the Tektronix position could have changed on us if a
136 savestate()...restorestate() occurred since the last call to
137 cont(). */
138 {
139 int correct_tek_mode =
140 _plotter->drawstate->points_are_connected ? TEK_MODE_PLOT : TEK_MODE_POINT;
141
142 if (_plotter->tek_position_is_unknown
143 || _plotter->tek_pos.x != istart.x
144 || _plotter->tek_pos.y != istart.y
145 || _plotter->tek_mode_is_unknown
146 || _plotter->tek_mode != correct_tek_mode)
147 /* Move to desired position. This automatically shifts the
148 Tektronix to correct mode, PLOT or POINT; see comment
149 above. */
150 _pl_t_tek_move (R___(_plotter) istart.x, istart.y);
151 }
152
153 /* Sync Tek's linestyle with ours; an escape sequence is emitted only
154 if necessary. Linestyle could have changed on us if a
155 savestate()...restorestate() occurred since the last call to
156 cont(). Sync Tek's color and background color too (significant
157 only for kermit Tek emulator). */
158 _pl_t_set_attributes (S___(_plotter));
159 _pl_t_set_pen_color (S___(_plotter));
160 _pl_t_set_bg_color (S___(_plotter));
161
162 /* If this is initial line segment of a polyline, force output of a
163 vector even if line segment has zero length, so that something
164 visible will appear on the display. We do this only if (1) the
165 line segment in the user frame was of nonzero length, or (2) it
166 was of zero length but the cap mode is "round". This more or less
167 agrees with our convention, on bitmap Plotters (X, PNM, GIF,
168 etc.), for dealing with device-frame vectors that are of
169 (quantized) zero length. */
170 if (i == 1
171 && (same_point == false
172 || (same_point == true
173 && _plotter->drawstate->cap_type == PL_CAP_ROUND)))
174 force = true;
175 else
176 force = false;
177
178 /* continue polyline by drawing vector on Tek display */
179 _pl_t_tek_vector_compressed (R___(_plotter)
180 iend.x, iend.y, istart.x, istart.y, force);
181
182 /* update our notion of Tek's notion of position */
183 _plotter->tek_pos.x = iend.x;
184 _plotter->tek_pos.y = iend.y;
185 }
186 }
187