1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1998-2000 Raph Levien
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20 /* Basic constructors and operations for vector paths */
21
22 #include "config.h"
23 #include "art_vpath.h"
24
25 #include <math.h>
26 #include <stdlib.h>
27
28 #include "art_misc.h"
29
30 #include "art_rect.h"
31
32 /**
33 * art_vpath_add_point: Add point to vpath.
34 * @p_vpath: Where the pointer to the #ArtVpath structure is stored.
35 * @pn_points: Pointer to the number of points in *@p_vpath.
36 * @pn_points_max: Pointer to the number of points allocated.
37 * @code: The pathcode for the new point.
38 * @x: The X coordinate of the new point.
39 * @y: The Y coordinate of the new point.
40 *
41 * Adds a new point to *@p_vpath, reallocating and updating *@p_vpath
42 * and *@pn_points_max as necessary. *@pn_points is incremented.
43 *
44 * This routine always adds the point after all points already in the
45 * vpath. Thus, it should be called in the order the points are
46 * desired.
47 **/
48 void
art_vpath_add_point(ArtVpath ** p_vpath,int * pn_points,int * pn_points_max,ArtPathcode code,double x,double y)49 art_vpath_add_point (ArtVpath **p_vpath, int *pn_points, int *pn_points_max,
50 ArtPathcode code, double x, double y)
51 {
52 int i;
53
54 i = (*pn_points)++;
55 if (i == *pn_points_max)
56 art_expand (*p_vpath, ArtVpath, *pn_points_max);
57 (*p_vpath)[i].code = code;
58 (*p_vpath)[i].x = x;
59 (*p_vpath)[i].y = y;
60 }
61
62 /* number of steps should really depend on radius. */
63 #define CIRCLE_STEPS 128
64
65 /**
66 * art_vpath_new_circle: Create a new circle.
67 * @x: X coordinate of center.
68 * @y: Y coordinate of center.
69 * @r: radius.
70 *
71 * Creates a new polygon closely approximating a circle with center
72 * (@x, @y) and radius @r. Currently, the number of points used in the
73 * approximation is fixed, but that will probably change.
74 *
75 * Return value: The newly created #ArtVpath.
76 **/
77 ArtVpath *
art_vpath_new_circle(double x,double y,double r)78 art_vpath_new_circle (double x, double y, double r)
79 {
80 int i;
81 ArtVpath *vec;
82 double theta;
83
84 vec = art_new (ArtVpath, CIRCLE_STEPS + 2);
85
86 for (i = 0; i < CIRCLE_STEPS + 1; i++)
87 {
88 vec[i].code = i ? ART_LINETO : ART_MOVETO;
89 theta = (i & (CIRCLE_STEPS - 1)) * (M_PI * 2.0 / CIRCLE_STEPS);
90 vec[i].x = x + r * cos (theta);
91 vec[i].y = y - r * sin (theta);
92 }
93 vec[i].code = ART_END;
94
95 return vec;
96 }
97
98 /**
99 * art_vpath_affine_transform: Affine transform a vpath.
100 * @src: Source vpath to transform.
101 * @matrix: Affine transform.
102 *
103 * Computes the affine transform of the vpath, using @matrix as the
104 * transform. @matrix is stored in the same format as PostScript, ie.
105 * x' = @matrix[0] * x + @matrix[2] * y + @matrix[4]
106 * y' = @matrix[1] * x + @matrix[3] * y + @matrix[5]
107 *
108 * Return value: the newly allocated vpath resulting from the transform.
109 **/
110 ArtVpath *
art_vpath_affine_transform(const ArtVpath * src,const double matrix[6])111 art_vpath_affine_transform (const ArtVpath *src, const double matrix[6])
112 {
113 int i;
114 int size;
115 ArtVpath *new;
116 double x, y;
117
118 for (i = 0; src[i].code != ART_END; i++);
119 size = i;
120
121 new = art_new (ArtVpath, size + 1);
122
123 for (i = 0; i < size; i++)
124 {
125 new[i].code = src[i].code;
126 x = src[i].x;
127 y = src[i].y;
128 new[i].x = matrix[0] * x + matrix[2] * y + matrix[4];
129 new[i].y = matrix[1] * x + matrix[3] * y + matrix[5];
130 }
131 new[i].code = ART_END;
132
133 return new;
134 }
135
136 /**
137 * art_vpath_bbox_drect: Determine bounding box of vpath.
138 * @vec: Source vpath.
139 * @drect: Where to store bounding box.
140 *
141 * Determines bounding box of @vec, and stores it in @drect.
142 **/
143 void
art_vpath_bbox_drect(const ArtVpath * vec,ArtDRect * drect)144 art_vpath_bbox_drect (const ArtVpath *vec, ArtDRect *drect)
145 {
146 int i;
147 double x0, y0, x1, y1;
148
149 if (vec[0].code == ART_END)
150 {
151 x0 = y0 = x1 = y1 = 0;
152 }
153 else
154 {
155 x0 = x1 = vec[0].x;
156 y0 = y1 = vec[0].y;
157 for (i = 1; vec[i].code != ART_END; i++)
158 {
159 if (vec[i].x < x0) x0 = vec[i].x;
160 if (vec[i].x > x1) x1 = vec[i].x;
161 if (vec[i].y < y0) y0 = vec[i].y;
162 if (vec[i].y > y1) y1 = vec[i].y;
163 }
164 }
165 drect->x0 = x0;
166 drect->y0 = y0;
167 drect->x1 = x1;
168 drect->y1 = y1;
169 }
170
171 /**
172 * art_vpath_bbox_irect: Determine integer bounding box of vpath.
173 * @vec: Source vpath.
174 * idrect: Where to store bounding box.
175 *
176 * Determines integer bounding box of @vec, and stores it in @irect.
177 **/
178 void
art_vpath_bbox_irect(const ArtVpath * vec,ArtIRect * irect)179 art_vpath_bbox_irect (const ArtVpath *vec, ArtIRect *irect)
180 {
181 ArtDRect drect;
182
183 art_vpath_bbox_drect (vec, &drect);
184 art_drect_to_irect (irect, &drect);
185 }
186
187 #define PERTURBATION 2e-3
188
189 /**
190 * art_vpath_perturb: Perturb each point in vpath by small random amount.
191 * @src: Source vpath.
192 *
193 * Perturbs each of the points by a small random amount. This is
194 * helpful for cheating in cases when algorithms haven't attained
195 * numerical stability yet.
196 *
197 * Return value: Newly allocated vpath containing perturbed @src.
198 **/
199 ArtVpath *
art_vpath_perturb(ArtVpath * src)200 art_vpath_perturb (ArtVpath *src)
201 {
202 int i;
203 int size;
204 ArtVpath *new;
205 double x, y;
206 double x_start, y_start;
207 int open;
208
209 for (i = 0; src[i].code != ART_END; i++);
210 size = i;
211
212 new = art_new (ArtVpath, size + 1);
213
214 x_start = 0;
215 y_start = 0;
216 open = 0;
217 for (i = 0; i < size; i++)
218 {
219 new[i].code = src[i].code;
220 x = src[i].x + (PERTURBATION * rand ()) / RAND_MAX - PERTURBATION * 0.5;
221 y = src[i].y + (PERTURBATION * rand ()) / RAND_MAX - PERTURBATION * 0.5;
222 if (src[i].code == ART_MOVETO)
223 {
224 x_start = x;
225 y_start = y;
226 open = 0;
227 }
228 else if (src[i].code == ART_MOVETO_OPEN)
229 open = 1;
230 if (!open && (i + 1 == size || src[i + 1].code != ART_LINETO))
231 {
232 x = x_start;
233 y = y_start;
234 }
235 new[i].x = x;
236 new[i].y = y;
237 }
238 new[i].code = ART_END;
239
240 return new;
241 }
242