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"
33 /* Pie charts of course need to know Pi :) */
35 #define M_PI ( 22.0 / 7.0 )
40 /* Draw a single slice of the pie */
42 draw_segment(struct chart *ch,
43 double centre_x, double centre_y,
45 double start_angle, double segment_angle,
54 piechart_plot(const char *title, const struct slice *slices, int n_slices)
57 double total_magnetude=0;
61 chart_initialise(&ch);
63 const double left_label = ch.data_left +
64 (ch.data_right - ch.data_left)/10.0;
66 const double right_label = ch.data_right -
67 (ch.data_right - ch.data_left)/10.0;
69 const double centre_x = (ch.data_right + ch.data_left ) / 2.0 ;
70 const double centre_y = (ch.data_top + ch.data_bottom ) / 2.0 ;
72 const double radius = min(
73 5.0 / 12.0 * (ch.data_top - ch.data_bottom),
74 1.0 / 4.0 * (ch.data_right - ch.data_left)
78 chart_write_title(&ch, title);
80 for (i = 0 ; i < n_slices ; ++i )
81 total_magnetude += slices[i].magnetude;
83 for (i = 0 ; i < n_slices ; ++i )
85 static double angle=0.0;
87 const double segment_angle =
88 slices[i].magnetude / total_magnetude * 2 * M_PI ;
90 const double label_x = centre_x -
91 radius * sin(angle + segment_angle/2.0);
93 const double label_y = centre_y +
94 radius * cos(angle + segment_angle/2.0);
96 /* Fill the segment */
98 centre_x, centre_y, radius,
102 /* Now add the labels */
103 if ( label_x < centre_x )
105 pl_line_r(ch.lp, label_x, label_y,
106 left_label, label_y );
107 pl_moverel_r(ch.lp,0,5);
108 pl_alabel_r(ch.lp,0,0,slices[i].label);
116 pl_moverel_r(ch.lp,0,5);
117 pl_alabel_r(ch.lp,'r',0,slices[i].label);
120 angle += segment_angle;
124 /* Draw an outline to the pie */
125 pl_filltype_r(ch.lp,0);
126 pl_fcircle_r (ch.lp, centre_x, centre_y, radius);
132 fill_segment(struct chart *ch,
133 double x0, double y0,
135 double start_angle, double segment_angle) ;
138 /* Fill a segment with the current fill colour */
140 fill_segment(struct chart *ch,
141 double x0, double y0,
143 double start_angle, double segment_angle)
146 const double start_x = x0 - radius * sin(start_angle);
147 const double start_y = y0 + radius * cos(start_angle);
149 const double stop_x =
150 x0 - radius * sin(start_angle + segment_angle);
152 const double stop_y =
153 y0 + radius * cos(start_angle + segment_angle);
155 assert(segment_angle <= 2 * M_PI);
156 assert(segment_angle >= 0);
158 if ( segment_angle > M_PI )
160 /* Then we must draw it in two halves */
161 fill_segment(ch, x0, y0, radius, start_angle, segment_angle / 2.0 );
162 fill_segment(ch, x0, y0, radius, start_angle + segment_angle / 2.0,
163 segment_angle / 2.0 );
167 pl_move_r(ch->lp, x0, y0);
169 pl_cont_r(ch->lp, stop_x, stop_y);
170 pl_cont_r(ch->lp, start_x, start_y);
178 pl_endpath_r(ch->lp);
184 /* Draw a single slice of the pie */
186 draw_segment(struct chart *ch,
187 double x0, double y0,
189 double start_angle, double segment_angle,
192 const double start_x = x0 - radius * sin(start_angle);
193 const double start_y = y0 + radius * cos(start_angle);
195 pl_savestate_r(ch->lp);
197 pl_savestate_r(ch->lp);
198 pl_colorname_r(ch->lp, colour);
200 pl_pentype_r(ch->lp,1);
201 pl_filltype_r(ch->lp,1);
203 fill_segment(ch, x0, y0, radius, start_angle, segment_angle);
204 pl_restorestate_r(ch->lp);
206 /* Draw line dividing segments */
207 pl_pentype_r(ch->lp, 1);
208 pl_fline_r(ch->lp, x0, y0, start_x, start_y);
211 pl_restorestate_r(ch->lp);
218 piechart_plot(const char *title, const struct slice *slices, int n_slices)