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., 59 Temple Place - Suite 330, Boston, MA
29 #include "value-labels.h"
32 /* Pie charts of course need to know Pi :) */
34 #define M_PI ( 22.0 / 7.0 )
38 #define min(A,B) ((A>B)?B:A)
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;
60 chart_initialise(&ch);
62 const double left_label = ch.data_left +
63 (ch.data_right - ch.data_left)/10.0;
65 const double right_label = ch.data_right -
66 (ch.data_right - ch.data_left)/10.0;
68 const double centre_x = (ch.data_right + ch.data_left ) / 2.0 ;
69 const double centre_y = (ch.data_top + ch.data_bottom ) / 2.0 ;
71 const double radius = min(
72 5.0 / 12.0 * (ch.data_top - ch.data_bottom),
73 1.0 / 4.0 * (ch.data_right - ch.data_left)
77 chart_write_title(&ch, title);
79 for (i = 0 ; i < n_slices ; ++i )
80 total_magnetude += slices[i].magnetude;
82 for (i = 0 ; i < n_slices ; ++i )
84 static double angle=0.0;
86 const double segment_angle =
87 slices[i].magnetude / total_magnetude * 2 * M_PI ;
89 const double label_x = centre_x -
90 radius * sin(angle + segment_angle/2.0);
92 const double label_y = centre_y +
93 radius * cos(angle + segment_angle/2.0);
95 /* Fill the segment */
97 centre_x, centre_y, radius,
101 /* Now add the labels */
102 if ( label_x < centre_x )
104 pl_line_r(ch.lp, label_x, label_y,
105 left_label, label_y );
106 pl_moverel_r(ch.lp,0,5);
107 pl_alabel_r(ch.lp,0,0,slices[i].label);
115 pl_moverel_r(ch.lp,0,5);
116 pl_alabel_r(ch.lp,'r',0,slices[i].label);
119 angle += segment_angle;
123 /* Draw an outline to the pie */
124 pl_filltype_r(ch.lp,0);
125 pl_fcircle_r (ch.lp, centre_x, centre_y, radius);
131 fill_segment(struct chart *ch,
132 double x0, double y0,
134 double start_angle, double segment_angle) ;
137 /* Fill a segment with the current fill colour */
139 fill_segment(struct chart *ch,
140 double x0, double y0,
142 double start_angle, double segment_angle)
145 const double start_x = x0 - radius * sin(start_angle);
146 const double start_y = y0 + radius * cos(start_angle);
148 const double stop_x =
149 x0 - radius * sin(start_angle + segment_angle);
151 const double stop_y =
152 y0 + radius * cos(start_angle + segment_angle);
154 assert(segment_angle <= 2 * M_PI);
155 assert(segment_angle >= 0);
157 if ( segment_angle > M_PI )
159 /* Then we must draw it in two halves */
160 fill_segment(ch, x0, y0, radius, start_angle, segment_angle / 2.0 );
161 fill_segment(ch, x0, y0, radius, start_angle + segment_angle / 2.0,
162 segment_angle / 2.0 );
166 pl_move_r(ch->lp, x0, y0);
168 pl_cont_r(ch->lp, stop_x, stop_y);
169 pl_cont_r(ch->lp, start_x, start_y);
177 pl_endpath_r(ch->lp);
183 /* Draw a single slice of the pie */
185 draw_segment(struct chart *ch,
186 double x0, double y0,
188 double start_angle, double segment_angle,
191 const double start_x = x0 - radius * sin(start_angle);
192 const double start_y = y0 + radius * cos(start_angle);
194 pl_savestate_r(ch->lp);
196 pl_savestate_r(ch->lp);
197 pl_colorname_r(ch->lp, colour);
199 pl_pentype_r(ch->lp,1);
200 pl_filltype_r(ch->lp,1);
202 fill_segment(ch, x0, y0, radius, start_angle, segment_angle);
203 pl_restorestate_r(ch->lp);
205 /* Draw line dividing segments */
206 pl_pentype_r(ch->lp, 1);
207 pl_fline_r(ch->lp, x0, y0, start_x, start_y);
210 pl_restorestate_r(ch->lp);