1 #define INKSCAPE_HELPER_GEOM_CPP\r
2 \r
3 /**\r
4 * Specific geometry functions for Inkscape, not provided my lib2geom.\r
5 *\r
6 * Author:\r
7 * Johan Engelen <goejendaagh@zonnet.nl>\r
8 *\r
9 * Copyright (C) 2008 Johan Engelen\r
10 *\r
11 * Released under GNU GPL\r
12 */\r
13 \r
14 #include "helper/geom.h"\r
15 \r
16 #include <2geom/pathvector.h>\r
17 #include <2geom/transforms.h>\r
18 #include <2geom/rect.h>\r
19 #include <2geom/coord.h>\r
20 \r
21 /* Fast bbox calculation */\r
22 /* Thanks to Nathan Hurst for suggesting it */\r
23 static void\r
24 cubic_bbox (Geom::Coord x000, Geom::Coord y000, Geom::Coord x001, Geom::Coord y001, Geom::Coord x011, Geom::Coord y011, Geom::Coord x111, Geom::Coord y111, Geom::Rect &bbox)\r
25 {\r
26 Geom::Coord a, b, c, D;\r
27 \r
28 bbox[0].extendTo(x111);\r
29 bbox[1].extendTo(y111);\r
30 \r
31 /*\r
32 * xttt = s * (s * (s * x000 + t * x001) + t * (s * x001 + t * x011)) + t * (s * (s * x001 + t * x011) + t * (s * x011 + t * x111))\r
33 * xttt = s * (s2 * x000 + s * t * x001 + t * s * x001 + t2 * x011) + t * (s2 * x001 + s * t * x011 + t * s * x011 + t2 * x111)\r
34 * xttt = s * (s2 * x000 + 2 * st * x001 + t2 * x011) + t * (s2 * x001 + 2 * st * x011 + t2 * x111)\r
35 * xttt = s3 * x000 + 2 * s2t * x001 + st2 * x011 + s2t * x001 + 2st2 * x011 + t3 * x111\r
36 * xttt = s3 * x000 + 3s2t * x001 + 3st2 * x011 + t3 * x111\r
37 * xttt = s3 * x000 + (1 - s) 3s2 * x001 + (1 - s) * (1 - s) * 3s * x011 + (1 - s) * (1 - s) * (1 - s) * x111\r
38 * xttt = s3 * x000 + (3s2 - 3s3) * x001 + (3s - 6s2 + 3s3) * x011 + (1 - 2s + s2 - s + 2s2 - s3) * x111\r
39 * xttt = (x000 - 3 * x001 + 3 * x011 - x111) * s3 +\r
40 * ( 3 * x001 - 6 * x011 + 3 * x111) * s2 +\r
41 * ( 3 * x011 - 3 * x111) * s +\r
42 * ( x111)\r
43 * xttt' = (3 * x000 - 9 * x001 + 9 * x011 - 3 * x111) * s2 +\r
44 * ( 6 * x001 - 12 * x011 + 6 * x111) * s +\r
45 * ( 3 * x011 - 3 * x111)\r
46 */\r
47 \r
48 a = 3 * x000 - 9 * x001 + 9 * x011 - 3 * x111;\r
49 b = 6 * x001 - 12 * x011 + 6 * x111;\r
50 c = 3 * x011 - 3 * x111;\r
51 \r
52 /*\r
53 * s = (-b +/- sqrt (b * b - 4 * a * c)) / 2 * a;\r
54 */\r
55 if (fabs (a) < Geom::EPSILON) {\r
56 /* s = -c / b */\r
57 if (fabs (b) > Geom::EPSILON) {\r
58 double s, t, xttt;\r
59 s = -c / b;\r
60 if ((s > 0.0) && (s < 1.0)) {\r
61 t = 1.0 - s;\r
62 xttt = s * s * s * x000 + 3 * s * s * t * x001 + 3 * s * t * t * x011 + t * t * t * x111;\r
63 bbox[0].extendTo(xttt);\r
64 }\r
65 }\r
66 } else {\r
67 /* s = (-b +/- sqrt (b * b - 4 * a * c)) / 2 * a; */\r
68 D = b * b - 4 * a * c;\r
69 if (D >= 0.0) {\r
70 Geom::Coord d, s, t, xttt;\r
71 /* Have solution */\r
72 d = sqrt (D);\r
73 s = (-b + d) / (2 * a);\r
74 if ((s > 0.0) && (s < 1.0)) {\r
75 t = 1.0 - s;\r
76 xttt = s * s * s * x000 + 3 * s * s * t * x001 + 3 * s * t * t * x011 + t * t * t * x111;\r
77 bbox[0].extendTo(xttt);\r
78 }\r
79 s = (-b - d) / (2 * a);\r
80 if ((s > 0.0) && (s < 1.0)) {\r
81 t = 1.0 - s;\r
82 xttt = s * s * s * x000 + 3 * s * s * t * x001 + 3 * s * t * t * x011 + t * t * t * x111;\r
83 bbox[0].extendTo(xttt);\r
84 }\r
85 }\r
86 }\r
87 \r
88 a = 3 * y000 - 9 * y001 + 9 * y011 - 3 * y111;\r
89 b = 6 * y001 - 12 * y011 + 6 * y111;\r
90 c = 3 * y011 - 3 * y111;\r
91 \r
92 if (fabs (a) < Geom::EPSILON) {\r
93 /* s = -c / b */\r
94 if (fabs (b) > Geom::EPSILON) {\r
95 double s, t, yttt;\r
96 s = -c / b;\r
97 if ((s > 0.0) && (s < 1.0)) {\r
98 t = 1.0 - s;\r
99 yttt = s * s * s * y000 + 3 * s * s * t * y001 + 3 * s * t * t * y011 + t * t * t * y111;\r
100 bbox[1].extendTo(yttt);\r
101 }\r
102 }\r
103 } else {\r
104 /* s = (-b +/- sqrt (b * b - 4 * a * c)) / 2 * a; */\r
105 D = b * b - 4 * a * c;\r
106 if (D >= 0.0) {\r
107 Geom::Coord d, s, t, yttt;\r
108 /* Have solution */\r
109 d = sqrt (D);\r
110 s = (-b + d) / (2 * a);\r
111 if ((s > 0.0) && (s < 1.0)) {\r
112 t = 1.0 - s;\r
113 yttt = s * s * s * y000 + 3 * s * s * t * y001 + 3 * s * t * t * y011 + t * t * t * y111;\r
114 bbox[1].extendTo(yttt);\r
115 }\r
116 s = (-b - d) / (2 * a);\r
117 if ((s > 0.0) && (s < 1.0)) {\r
118 t = 1.0 - s;\r
119 yttt = s * s * s * y000 + 3 * s * s * t * y001 + 3 * s * t * t * y011 + t * t * t * y111;\r
120 bbox[1].extendTo(yttt);\r
121 }\r
122 }\r
123 }\r
124 }\r
125 \r
126 Geom::Rect\r
127 bounds_fast_transformed(Geom::PathVector const & pv, Geom::Matrix const & t)\r
128 {\r
129 return bounds_exact_transformed(pv, t); //use this as it is faster for now! :)\r
130 // return Geom::bounds_fast(pv * t);\r
131 }\r
132 \r
133 Geom::Rect\r
134 bounds_exact_transformed(Geom::PathVector const & pv, Geom::Matrix const & t)\r
135 {\r
136 Geom::Rect bbox;\r
137 \r
138 if (pv.empty())\r
139 return bbox;\r
140 \r
141 Geom::Curve *temp = pv.front().front().transformed(t);\r
142 bbox = temp->boundsExact();\r
143 delete temp;\r
144 \r
145 for (Geom::PathVector::const_iterator it = pv.begin(); it != pv.end(); ++it) {\r
146 bbox.expandTo(it->initialPoint() * t);\r
147 \r
148 // don't loop including closing segment, since that segment can never increase the bbox\r
149 for (Geom::Path::const_iterator cit = it->begin(); cit != it->end_open(); ++cit) {\r
150 Geom::Curve const *c = &*cit;\r
151 \r
152 if(Geom::LineSegment const *line_segment = dynamic_cast<Geom::LineSegment const *>(c))\r
153 {\r
154 bbox.expandTo( (*line_segment)[1] * t );\r
155 }\r
156 else if(Geom::CubicBezier const *cubic_bezier = dynamic_cast<Geom::CubicBezier const *>(c))\r
157 {\r
158 Geom::Point c0 = (*cubic_bezier)[0] * t;\r
159 Geom::Point c1 = (*cubic_bezier)[1] * t;\r
160 Geom::Point c2 = (*cubic_bezier)[2] * t;\r
161 Geom::Point c3 = (*cubic_bezier)[3] * t;\r
162 cubic_bbox( c0[0], c0[1],\r
163 c1[0], c1[1],\r
164 c2[0], c2[1],\r
165 c3[0], c3[1],\r
166 bbox );\r
167 }\r
168 else\r
169 {\r
170 // should handle all not-so-easy curves:\r
171 Geom::Curve *ctemp = cit->transformed(t);\r
172 bbox.unionWith( ctemp->boundsExact());\r
173 delete ctemp;\r
174 }\r
175 }\r
176 }\r
177 //return Geom::bounds_exact(pv * t);\r
178 return bbox;\r
179 }\r
180 \r
181 /*\r
182 Local Variables:\r
183 mode:c++\r
184 c-file-style:"stroustrup"\r
185 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))\r
186 indent-tabs-mode:nil\r
187 fill-column:99\r
188 End:\r
189 */\r
190 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :\r