1 /* PSPP - draws pie charts of sample statistics
3 Copyright (C) 2004 Free Software Foundation, Inc.
4 Written by John Darrington <john@darrington.wattle.id.au>
6 This program is free software; you can redistribute it and/or
7 modify it under the terms of the GNU General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 This program is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
30 #include "value-labels.h"
32 #include "plot-chart.h"
34 /* Pie charts of course need to know Pi :) */
36 #define M_PI ( 22.0 / 7.0 )
41 /* Draw a single slice of the pie */
43 draw_segment(struct chart *ch,
44 double centre_x, double centre_y,
46 double start_angle, double segment_angle,
53 piechart_plot(const char *title, const struct slice *slices, int n_slices)
56 double total_magnetude=0;
58 struct chart *ch = chart_create();
60 const double left_label = ch->data_left +
61 (ch->data_right - ch->data_left)/10.0;
63 const double right_label = ch->data_right -
64 (ch->data_right - ch->data_left)/10.0;
66 const double centre_x = (ch->data_right + ch->data_left ) / 2.0 ;
67 const double centre_y = (ch->data_top + ch->data_bottom ) / 2.0 ;
69 const double radius = min(
70 5.0 / 12.0 * (ch->data_top - ch->data_bottom),
71 1.0 / 4.0 * (ch->data_right - ch->data_left)
75 chart_write_title(ch, title);
77 for (i = 0 ; i < n_slices ; ++i )
78 total_magnetude += slices[i].magnetude;
80 for (i = 0 ; i < n_slices ; ++i )
82 static double angle=0.0;
84 const double segment_angle =
85 slices[i].magnetude / total_magnetude * 2 * M_PI ;
87 const double label_x = centre_x -
88 radius * sin(angle + segment_angle/2.0);
90 const double label_y = centre_y +
91 radius * cos(angle + segment_angle/2.0);
93 /* Fill the segment */
95 centre_x, centre_y, radius,
99 /* Now add the labels */
100 if ( label_x < centre_x )
102 pl_line_r(ch->lp, label_x, label_y,
103 left_label, label_y );
104 pl_moverel_r(ch->lp,0,5);
105 pl_alabel_r(ch->lp,0,0,slices[i].label);
113 pl_moverel_r(ch->lp,0,5);
114 pl_alabel_r(ch->lp,'r',0,slices[i].label);
117 angle += segment_angle;
121 /* Draw an outline to the pie */
122 pl_filltype_r(ch->lp,0);
123 pl_fcircle_r (ch->lp, centre_x, centre_y, radius);
129 fill_segment(struct chart *ch,
130 double x0, double y0,
132 double start_angle, double segment_angle) ;
135 /* Fill a segment with the current fill colour */
137 fill_segment(struct chart *ch,
138 double x0, double y0,
140 double start_angle, double segment_angle)
143 const double start_x = x0 - radius * sin(start_angle);
144 const double start_y = y0 + radius * cos(start_angle);
146 const double stop_x =
147 x0 - radius * sin(start_angle + segment_angle);
149 const double stop_y =
150 y0 + radius * cos(start_angle + segment_angle);
152 assert(segment_angle <= 2 * M_PI);
153 assert(segment_angle >= 0);
155 if ( segment_angle > M_PI )
157 /* Then we must draw it in two halves */
158 fill_segment(ch, x0, y0, radius, start_angle, segment_angle / 2.0 );
159 fill_segment(ch, x0, y0, radius, start_angle + segment_angle / 2.0,
160 segment_angle / 2.0 );
164 pl_move_r(ch->lp, x0, y0);
166 pl_cont_r(ch->lp, stop_x, stop_y);
167 pl_cont_r(ch->lp, start_x, start_y);
175 pl_endpath_r(ch->lp);
181 /* Draw a single slice of the pie */
183 draw_segment(struct chart *ch,
184 double x0, double y0,
186 double start_angle, double segment_angle,
189 const double start_x = x0 - radius * sin(start_angle);
190 const double start_y = y0 + radius * cos(start_angle);
192 pl_savestate_r(ch->lp);
194 pl_savestate_r(ch->lp);
195 pl_colorname_r(ch->lp, colour);
197 pl_pentype_r(ch->lp,1);
198 pl_filltype_r(ch->lp,1);
200 fill_segment(ch, x0, y0, radius, start_angle, segment_angle);
201 pl_restorestate_r(ch->lp);
203 /* Draw line dividing segments */
204 pl_pentype_r(ch->lp, 1);
205 pl_fline_r(ch->lp, x0, y0, start_x, start_y);
208 pl_restorestate_r(ch->lp);