1 /* CPML - Cairo Path Manipulation Library
2 * Copyright (C) 2008, 2009 Nicola Fontana <ntd at entidi.it>
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser 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.
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 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
23 * @short_description: Contiguous lines
25 * A segment is a single contiguous line got from a cairo path.
27 * Every #CpmlPath struct can contain more than one segment:
28 * the CPML library provides iteration APIs to browse these segments.
29 * The <structname>CpmlSegment</structname> struct internally keeps
30 * a reference to the source #CpmlPath so it can be used both
31 * for getting data from the current segment, browsing the next and
32 * reset to the first (it is used also as a forward iterator).
34 * Use cpml_segment_reset() to reset the iterator at the start of the
35 * cairo path (will point the first segment) and cpml_segment_next()
36 * to get the next segment. When initialized,
37 * <structname>CpmlSegment</structname> yet refers to the first
38 * segment, so the initial reset is useless.
40 * Getting the previous segment is not provided, as the underlying
41 * cairo struct is not accessible in reverse order.
47 * This is another name for the #cairo_path_t type. Although phisically
48 * they are the same struct, #CpmlPath conceptually embodies an important
49 * difference: it is a cairo path that can embed %CAIRO_PATH_ARC_TO
50 * primitives. This is not a native cairo primitive and having two
51 * different data types is a good way to make clear when a function
52 * expect or not embedded arc-to primitives.
57 * @path: the source #CpmlPath struct
58 * @data: the segment data
59 * @num_data: size of @data
61 * This is an unobtrusive struct to identify a segment inside a
62 * cairo path. Unobtrusive means that the real coordinates are
63 * still stored in @source: CpmlSegment only provides a way to
64 * access the underlying cairo path.
67 #include "cpml-segment.h"
68 #include "cpml-primitive.h"
69 #include "cpml-line.h"
70 #include "cpml-curve.h"
71 #include "cpml-pair.h"
72 #include "cpml-alloca.h"
77 static cairo_bool_t
normalize (CpmlSegment
*segment
);
78 static cairo_bool_t
ensure_one_move_to (CpmlSegment
*segment
);
79 static void reshape (CpmlSegment
*segment
);
83 * cpml_segment_from_cairo:
84 * @segment: a #CpmlSegment
85 * @path: the source #CpmlPath
87 * Builds a CpmlSegment from a #CpmlPath structure. This operation
88 * involves stripping the leading %CAIRO_PATH_MOVE_TO primitives and
89 * setting the internal segment structure accordling. A pointer to the
90 * source cairo path is kept.
92 * This function will fail if @path is null, empty or if its
93 * <structfield>status</structfield> member is not %CAIRO_STATUS_SUCCESS.
94 * Also, the first primitive must be a %CAIRO_PATH_MOVE_TO, so no
95 * dependency on the cairo context is needed.
97 * Return value: 1 on success, 0 on errors
100 cpml_segment_from_cairo(CpmlSegment
*segment
, CpmlPath
*path
)
102 /* The cairo path should be defined and in a perfect state */
103 if (path
== NULL
|| path
->num_data
== 0 ||
104 path
->status
!= CAIRO_STATUS_SUCCESS
)
107 segment
->path
= path
;
108 segment
->data
= path
->data
;
109 segment
->num_data
= path
->num_data
;
111 return normalize(segment
);
116 * @segment: a #CpmlSegment
117 * @src: the source segment to copy
119 * Makes a shallow copy of @src into @segment.
121 * Return value: @segment or %NULL on errors
124 cpml_segment_copy(CpmlSegment
*segment
, const CpmlSegment
*src
)
126 if (segment
== NULL
|| src
== NULL
)
129 return memcpy(segment
, src
, sizeof(CpmlSegment
));
134 * cpml_segment_reset:
135 * @segment: a #CpmlSegment
137 * Modifies @segment to point to the first segment of the source cairo path.
140 cpml_segment_reset(CpmlSegment
*segment
)
142 segment
->data
= segment
->path
->data
;
143 segment
->num_data
= segment
->path
->num_data
;
149 * @segment: a #CpmlSegment
151 * Modifies @segment to point to the next segment of the source cairo path.
153 * Return value: 1 on success, 0 if no next segment found or errors
156 cpml_segment_next(CpmlSegment
*segment
)
158 int rest
= segment
->path
->num_data
- segment
->num_data
+
159 segment
->path
->data
- segment
->data
;
164 segment
->data
+= segment
->num_data
;
165 segment
->num_data
= rest
;
167 return normalize(segment
);
172 * cpml_segment_to_cairo:
173 * @segment: a #CpmlSegment
174 * @cr: the destination cairo context
176 * Appends the path of @segment to @cr. The segment is "flattened",
177 * that is %CAIRO_PATH_ARC_TO primitives are approximated by one
178 * or more %CAIRO_PATH_CURVE_TO using cpml_arc_to_cairo(). Check
179 * its documentation for further details.
182 cpml_segment_to_cairo(const CpmlSegment
*segment
, cairo_t
*cr
)
184 CpmlPrimitive primitive
;
186 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
189 cpml_primitive_to_cairo(&primitive
, cr
);
190 } while (cpml_primitive_next(&primitive
));
195 * @segment: a #CpmlSegment
197 * Dumps the specified @segment to stdout. Useful for debugging purposes.
200 cpml_segment_dump(const CpmlSegment
*segment
)
202 CpmlPrimitive primitive
;
203 cairo_bool_t first_call
= 1;
205 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
208 cpml_primitive_dump(&primitive
, first_call
);
210 } while (cpml_primitive_next(&primitive
));
215 * cpml_segment_reverse:
216 * @segment: a #CpmlSegment
218 * Reverses @segment in-place. The resulting rendering will be the same,
219 * but with the primitives generated in reverse order.
222 cpml_segment_reverse(CpmlSegment
*segment
)
224 cairo_path_data_t
*data
, *dst_data
;
227 int n
, num_points
, n_point
;
228 const cairo_path_data_t
*src_data
;
230 data_size
= sizeof(cairo_path_data_t
) * segment
->num_data
;
231 data
= cpml_alloca(data_size
);
232 end_x
= segment
->data
[1].point
.x
;
233 end_y
= segment
->data
[1].point
.y
;
235 for (n
= 2; n
< segment
->num_data
; ++n
) {
236 src_data
= segment
->data
+ n
;
237 num_points
= src_data
->header
.length
;
239 dst_data
= data
+ segment
->num_data
- n
- num_points
+ 2;
240 dst_data
->header
.type
= src_data
->header
.type
;
241 dst_data
->header
.length
= num_points
;
243 for (n_point
= 1; n_point
< num_points
; ++n_point
) {
244 dst_data
[num_points
- n_point
].point
.x
= end_x
;
245 dst_data
[num_points
- n_point
].point
.y
= end_y
;
246 end_x
= src_data
[n_point
].point
.x
;
247 end_y
= src_data
[n_point
].point
.y
;
253 data
[0].header
.type
= CAIRO_PATH_MOVE_TO
;
254 data
[0].header
.length
= 2;
255 data
[1].point
.x
= end_x
;
256 data
[1].point
.y
= end_y
;
257 memcpy(segment
->data
, data
, data_size
);
261 * cpml_segment_transform:
262 * @segment: a #CpmlSegment
263 * @matrix: the matrix to be applied
265 * Applies @matrix on all the points of @segment.
268 cpml_segment_transform(CpmlSegment
*segment
, const cairo_matrix_t
*matrix
)
270 cairo_path_data_t
*data
;
271 int n
, n_point
, num_points
;
273 data
= segment
->data
;
275 for (n
= 0; n
< segment
->num_data
; n
+= num_points
) {
276 num_points
= data
->header
.length
;
278 for (n_point
= 1; n_point
< num_points
; ++n_point
) {
279 cairo_matrix_transform_point(matrix
, &data
->point
.x
, &data
->point
.y
);
286 * cpml_segment_intersection:
287 * @segment: the first #CpmlSegment
288 * @segment2: the second #CpmlSegment
289 * @dest: the destination vector of #CpmlPair
290 * @max: maximum number of intersections to return
292 * Computes the intersections between @segment and @segment2 and
293 * returns the found points in @dest. If the intersections are more
294 * than @max, only the first @max pairs are stored in @dest.
296 * To get the job done, the primitives of @segment are sequentially
297 * scanned for intersections with any primitive in @segment2. This
298 * means @segment has a higher precedence over @segment2.
300 * Return value: the number of intersections found
303 cpml_segment_intersection(const CpmlSegment
*segment
,
304 const CpmlSegment
*segment2
,
305 CpmlPair
*dest
, int max
)
307 CpmlPrimitive portion
;
310 cpml_primitive_from_segment(&portion
, (CpmlSegment
*) segment
);
314 partial
= cpml_primitive_intersection_with_segment(&portion
,
319 } while (total
< max
&& cpml_primitive_next(&portion
));
325 * cpml_segment_offset:
326 * @segment: a #CpmlSegment
327 * @offset: the offset distance
329 * Offsets a segment of the specified amount, that is builds a "parallel"
330 * segment at the @offset distance from the original one and returns the
331 * result by replacing the original @segment.
334 * <title>TODO</title>
336 * <listitem>Closed path are not yet managed: an elegant solution is not
337 * so obvious: use cpml_close_offset() when available.</listitem>
338 * <listitem>Degenerated primitives, such as lines of length 0, are not
339 * managed properly.</listitem>
344 cpml_segment_offset(CpmlSegment
*segment
, double offset
)
346 CpmlPrimitive primitive
;
347 CpmlPrimitive last_primitive
;
348 cairo_path_data_t org
, old_end
;
349 cairo_bool_t first_cycle
;
351 cpml_primitive_from_segment(&primitive
, segment
);
357 primitive
.org
= &org
;
360 old_end
= *cpml_primitive_get_point(&primitive
, -1);
361 cpml_primitive_offset(&primitive
, offset
);
364 cpml_primitive_join(&last_primitive
, &primitive
);
365 primitive
.org
= cpml_primitive_get_point(&last_primitive
, -1);
368 cpml_primitive_copy(&last_primitive
, &primitive
);
370 } while (cpml_primitive_next(&primitive
));
375 * @segment: a #CpmlSegment
377 * Strips the leading %CAIRO_PATH_MOVE_TO primitives, updating
378 * the CpmlSegment structure accordling. One, and only one,
379 * %CAIRO_PATH_MOVE_TO primitive is left.
381 * Return value: 1 on success, 0 on no leading MOVE_TOs or on errors
384 normalize(CpmlSegment
*segment
)
386 if (!ensure_one_move_to(segment
))
394 * ensure_one_move_to:
395 * @segment: a #CpmlSegment
397 * Strips the leading %CAIRO_PATH_MOVE_TO primitives, updating
398 * the <structname>CpmlSegment</structname> structure accordling.
399 * One, and only one, %CAIRO_PATH_MOVE_TO primitive is left.
401 * Return value: 1 on success, 0 on no leading MOVE_TOs or on empty path
404 ensure_one_move_to(CpmlSegment
*segment
)
406 cairo_path_data_t
*new_data
;
407 int new_num_data
, length
;
409 new_data
= segment
->data
;
411 /* Check for at least one move to */
412 if (new_data
->header
.type
!= CAIRO_PATH_MOVE_TO
)
415 new_num_data
= segment
->num_data
;
418 /* Strip the leading CAIRO_PATH_MOVE_TO, leaving only the last one */
421 new_num_data
-= length
;
422 length
= new_data
->header
.length
;
424 /* Check for end of cairo path data */
425 if (length
>= new_num_data
)
427 } while (new_data
[length
].header
.type
== CAIRO_PATH_MOVE_TO
);
429 segment
->data
= new_data
;
430 segment
->num_data
= new_num_data
;
437 * @segment: a #CpmlSegment
439 * Looks for the segment termination and modify the
440 * <structfield>num_data</structfield> field of @segment accordling.
441 * @segment must have only one leading %CAIRO_PATH_MOVE_TO and
442 * it is supposed to be non-empty, conditions yet imposed by the
443 * ensure_one_move_to() function.
446 reshape(CpmlSegment
*segment
)
448 cairo_path_data_t
*data
;
449 int num_data
, new_num_data
, length
;
451 /* Skip the leading move to */
453 data
= segment
->data
+ new_num_data
;
455 /* Calculate the remaining data in the cairo path */
456 num_data
= segment
->path
->num_data
-
457 (segment
->data
- segment
->path
->data
);
459 while (new_num_data
< num_data
) {
460 /* A primitive is considered valid if it has implemented
461 * its own type_get_npoints() */
462 if (cpml_primitive_type_get_npoints(data
->header
.type
) < 0)
465 length
= data
->header
.length
;
467 new_num_data
+= length
;
470 segment
->num_data
= new_num_data
;