1 /* CPML - Cairo Path Manipulation Library
2 * Copyright (C) 2008,2009,2010 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.
22 * SECTION:cpml-segment
23 * @Section_Id:CpmlSegment
25 * @short_description: Contiguous segment that can be a fragment
26 * or a whole cairo path
28 * A segment is a single contiguous line got from a cairo path. The
29 * CPML library relies on one assumption to let the data be independent
30 * from the current point (and thus from the cairo context): any segment
31 * MUST be preceded by at least one %CPML_MOVE primitive.
32 * This means a valid segment in cairo could be rejected by CPML.
34 * #CpmlSegment provides an unobtrusive way to access a cairo path.
35 * This means #CpmlSegment itsself does not hold any coordinates but
36 * instead a bunch of pointers to the original #cairo_path_t struct:
37 * modifying data throught this struct also changes the original path.
39 * Every #CpmlPath struct can contain more than one segment: the CPML
40 * library provides iteration APIs to browse the segments of a path.
41 * Use cpml_segment_reset() to reset the iterator at the start of the
42 * cairo path (will point the first segment) and cpml_segment_next()
43 * to get the next segment. Getting the previous segment is not provided
44 * as the underlying cairo struct is not accessible in reverse order.
46 * When initialized, #CpmlSegment yet refers to the first segment so
47 * the initial reset is not required.
53 * This is another name for the #cairo_path_t type. Although phisically
54 * they are the same struct, #CpmlPath conceptually embodies an important
55 * difference: it is a cairo path that can embed %CPML_ARC primitives.
56 * This is not a native cairo primitive and having two different data
57 * types is a good way to make clear when a function expect or not
58 * embedded arc-to primitives.
63 * @path: the source #CpmlPath struct
64 * @data: the data points of the segment; the first primitive
65 * will always be a %CPML_MOVE
66 * @num_data: size of @data
68 * This is an unobtrusive struct to identify a segment inside a
69 * cairo path. Unobtrusive means that the real coordinates are
70 * still stored in @path: CpmlSegment only provides a way to
75 #include "cpml-internal.h"
76 #include "cpml-extents.h"
77 #include "cpml-segment.h"
78 #include "cpml-primitive.h"
79 #include "cpml-curve.h"
82 static cairo_bool_t
normalize (CpmlSegment
*segment
);
83 static cairo_bool_t
ensure_one_leading_move (CpmlSegment
*segment
);
84 static cairo_bool_t
reshape (CpmlSegment
*segment
);
88 * cpml_segment_from_cairo:
89 * @segment: a #CpmlSegment
90 * @path: the source #CpmlPath
92 * Builds a CpmlSegment from a #CpmlPath structure. This operation
93 * involves stripping the duplicate %CPML_MOVE primitives at the
94 * start of the path and setting <structfield>num_data</structfield>
95 * field to the end of the contiguous line, that is when another
96 * %CPML_MOVE primitive is found or at the end of the path.
97 * A pointer to the source cairo path is kept though.
99 * This function will fail if @path is null, empty or if its
100 * <structfield>status</structfield> member is not %CAIRO_STATUS_SUCCESS.
101 * Also, the first primitive must be a %CPML_MOVE, so no
102 * dependency on the cairo context is needed.
104 * Returns: 1 on success, 0 on errors
107 cpml_segment_from_cairo(CpmlSegment
*segment
, CpmlPath
*path
)
109 /* The cairo path should be defined and in a perfect state */
110 if (path
== NULL
|| path
->num_data
== 0 ||
111 path
->status
!= CAIRO_STATUS_SUCCESS
)
114 segment
->path
= path
;
115 segment
->data
= path
->data
;
116 segment
->num_data
= path
->num_data
;
118 return normalize(segment
);
123 * @segment: a #CpmlSegment
124 * @src: the source segment to copy
126 * Makes a shallow copy of @src into @segment.
129 cpml_segment_copy(CpmlSegment
*segment
, const CpmlSegment
*src
)
131 memcpy(segment
, src
, sizeof(CpmlSegment
));
135 * cpml_path_is_empty:
136 * @cpml_path: a #CpmlPath (or a #cairo_path_t) pointer
138 * Checks if @cpml_path is empty. An invalid path is considered empty.
140 * Returns: %1 if the path is empty or invalid, %0 otherwise
144 * cpml_segment_reset:
145 * @segment: a #CpmlSegment
147 * Modifies @segment to point to the first segment of the source cairo path.
150 cpml_segment_reset(CpmlSegment
*segment
)
152 segment
->data
= segment
->path
->data
;
153 segment
->num_data
= segment
->path
->num_data
;
159 * @segment: a #CpmlSegment
161 * Modifies @segment to point to the next segment of the source cairo path.
163 * Returns: 1 on success, 0 if no next segment found or errors
166 cpml_segment_next(CpmlSegment
*segment
)
168 cairo_path_data_t
*new_data
;
169 const cairo_path_data_t
*end_data
;
171 new_data
= segment
->data
+ segment
->num_data
;
172 end_data
= segment
->path
->data
+ segment
->path
->num_data
;
174 if (new_data
>= end_data
)
177 segment
->data
= new_data
;
178 segment
->num_data
= end_data
- new_data
;
180 return normalize(segment
);
184 * cpml_segment_get_length:
185 * @segment: a #CpmlSegment
187 * Gets the whole length of @segment.
189 * Returns: the requested length
192 cpml_segment_get_length(const CpmlSegment
*segment
)
194 CpmlPrimitive primitive
;
197 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
201 length
+= cpml_primitive_get_length(&primitive
);
202 } while (cpml_primitive_next(&primitive
));
208 * cpml_segment_put_extents:
209 * @segment: a #CpmlSegment
210 * @extents: where to store the extents
212 * Gets the whole extents of @segment.
215 cpml_segment_put_extents(const CpmlSegment
*segment
, CpmlExtents
*extents
)
217 CpmlPrimitive primitive
;
218 CpmlExtents primitive_extents
;
220 extents
->is_defined
= 0;
222 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
225 cpml_primitive_put_extents(&primitive
, &primitive_extents
);
226 cpml_extents_add(extents
, &primitive_extents
);
227 } while (cpml_primitive_next(&primitive
));
231 * cpml_segment_put_pair_at:
232 * @segment: a #CpmlSegment
233 * @pos: the position value
234 * @pair: the destination #CpmlPair
236 * Gets the coordinates of the point lying on @segment at position
237 * @pos. @pos is an homogeneous factor where %0 is the start point,
238 * %1 the end point, %0.5 the mid point and so on.
239 * The relation %0 < @pos < %1 should be satisfied, although some
240 * cases accept value outside this range.
243 * <title>TODO</title>
245 * <listitem>The actual implementation returns only the start and end points,
246 * that is only when @pos is %0 or %1.</listitem>
251 cpml_segment_put_pair_at(const CpmlSegment
*segment
, double pos
,
254 CpmlPrimitive primitive
;
256 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
258 /* Handle the common cases: start and end points */
260 return cpml_primitive_put_pair_at(&primitive
, 0, pair
);
263 while (cpml_primitive_next(&primitive
))
265 return cpml_primitive_put_pair_at(&primitive
, 1, pair
);
270 * cpml_segment_put_vector_at:
271 * @segment: a #CpmlSegment
272 * @pos: the position value
273 * @vector: the destination #CpmlVector
275 * Gets the steepness of the point lying on @segment at position
276 * @pos. @pos is an homogeneous factor where %0 is the start point,
277 * %1 the end point, %0.5 the mid point and so on.
278 * The relation %0 < @pos < %1 should be satisfied, although some
279 * cases accept value outside this range.
282 * <title>TODO</title>
284 * <listitem>The actual implementation returns only the start and end
285 * steepness, that is only when @pos is %0 or %1.</listitem>
290 cpml_segment_put_vector_at(const CpmlSegment
*segment
, double pos
,
293 CpmlPrimitive primitive
;
295 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
297 /* Handle the common cases: start and end points */
299 cpml_primitive_put_vector_at(&primitive
, 0, vector
);
304 while (cpml_primitive_next(&primitive
))
306 cpml_primitive_put_vector_at(&primitive
, 1, vector
);
312 * cpml_segment_put_intersections:
313 * @segment: the first #CpmlSegment
314 * @segment2: the second #CpmlSegment
315 * @n_dest: maximum number of intersections to return
316 * @dest: the destination vector of #CpmlPair
318 * Computes the intersections between @segment and @segment2 and
319 * returns the found points in @dest. If the intersections are more
320 * than @n_dest, only the first @n_dest pairs are stored in @dest.
322 * To get the job done, the primitives of @segment are sequentially
323 * scanned for intersections with any primitive in @segment2. This
324 * means @segment has a higher precedence over @segment2.
326 * Returns: the number of intersections found
329 cpml_segment_put_intersections(const CpmlSegment
*segment
,
330 const CpmlSegment
*segment2
,
331 size_t n_dest
, CpmlPair
*dest
)
333 CpmlPrimitive portion
;
334 size_t partial
, total
;
336 cpml_primitive_from_segment(&portion
, (CpmlSegment
*) segment
);
340 partial
= cpml_primitive_put_intersections_with_segment(&portion
,
345 } while (total
< n_dest
&& cpml_primitive_next(&portion
));
351 * cpml_segment_offset:
352 * @segment: a #CpmlSegment
353 * @offset: the offset distance
355 * Offsets a segment of the specified amount, that is builds a "parallel"
356 * segment at the @offset distance from the original one and returns the
357 * result by replacing the original @segment.
360 * <title>TODO</title>
362 * <listitem>Closed path are not yet managed: an elegant solution is not
363 * so obvious: use cpml_close_offset() when available.</listitem>
364 * <listitem>Degenerated primitives, such as lines of length 0, are not
365 * managed properly.</listitem>
370 cpml_segment_offset(CpmlSegment
*segment
, double offset
)
372 CpmlPrimitive primitive
;
373 CpmlPrimitive last_primitive
;
374 cairo_path_data_t org
, old_end
;
375 cairo_bool_t first_cycle
;
377 cpml_primitive_from_segment(&primitive
, segment
);
383 primitive
.org
= &org
;
386 old_end
= *cpml_primitive_get_point(&primitive
, -1);
387 cpml_primitive_offset(&primitive
, offset
);
390 cpml_primitive_join(&last_primitive
, &primitive
);
391 primitive
.org
= cpml_primitive_get_point(&last_primitive
, -1);
394 cpml_primitive_copy(&last_primitive
, &primitive
);
396 } while (cpml_primitive_next(&primitive
));
400 * cpml_segment_transform:
401 * @segment: a #CpmlSegment
402 * @matrix: the matrix to be applied
404 * Applies @matrix on all the points of @segment.
407 cpml_segment_transform(CpmlSegment
*segment
, const cairo_matrix_t
*matrix
)
409 CpmlPrimitive primitive
;
410 cairo_path_data_t
*data
;
413 cpml_primitive_from_segment(&primitive
, segment
);
414 cairo_matrix_transform_point(matrix
, &(primitive
.org
)->point
.x
,
415 &(primitive
.org
)->point
.y
);
418 data
= primitive
.data
;
419 if (data
->header
.type
!= CAIRO_PATH_CLOSE_PATH
) {
420 n_points
= cpml_primitive_get_n_points(&primitive
);
422 while (--n_points
> 0) {
424 cairo_matrix_transform_point(matrix
,
425 &data
->point
.x
, &data
->point
.y
);
428 } while (cpml_primitive_next(&primitive
));
432 * cpml_segment_reverse:
433 * @segment: a #CpmlSegment
435 * Reverses @segment in-place. The resulting rendering will be the same,
436 * but with the primitives generated in reverse order.
438 * It is assumed that @segment has yet been sanitized, that is returned
439 * by some CPML API function or it is a path yet conforming to the
440 * segment rules described by the cpml_segment_from_cairo() function.
443 cpml_segment_reverse(CpmlSegment
*segment
)
445 cairo_path_data_t
*data
, *dst_data
;
449 size_t n_points
, n_point
;
450 const cairo_path_data_t
*src_data
;
452 data_size
= sizeof(cairo_path_data_t
) * segment
->num_data
;
453 data
= malloc(data_size
);
454 end_x
= segment
->data
[1].point
.x
;
455 end_y
= segment
->data
[1].point
.y
;
457 n
= segment
->data
->header
.length
;
458 data
->header
.type
= CAIRO_PATH_CLOSE_PATH
;
459 data
->header
.length
= n
;
461 while (n
< segment
->num_data
) {
462 src_data
= segment
->data
+ n
;
463 n_points
= cpml_primitive_type_get_n_points(src_data
->header
.type
);
464 length
= src_data
->header
.length
;
466 dst_data
= data
+ segment
->num_data
- n
+ data
->header
.length
;
467 dst_data
->header
.type
= src_data
->header
.type
;
468 dst_data
->header
.length
= length
;
470 for (n_point
= 1; n_point
< n_points
; ++n_point
) {
471 dst_data
[n_points
- n_point
].point
.x
= end_x
;
472 dst_data
[n_points
- n_point
].point
.y
= end_y
;
473 end_x
= src_data
[n_point
].point
.x
;
474 end_y
= src_data
[n_point
].point
.y
;
477 /* Copy also the embedded data, if any */
478 if (n_points
< length
) {
479 size_t size
= (length
- n_points
) * sizeof(cairo_path_data_t
);
480 memcpy(dst_data
+ n_points
, src_data
+ n_points
, size
);
484 data
[1].point
.x
= end_x
;
485 data
[1].point
.y
= end_y
;
486 memcpy(segment
->data
, data
, data_size
);
492 * cpml_segment_to_cairo:
493 * @segment: a #CpmlSegment
494 * @cr: the destination cairo context
496 * Appends the path of @segment to @cr. The segment is "flattened",
497 * that is %CPML_ARC primitives are approximated by one or more
498 * %CPML_CURVE using cpml_arc_to_cairo(). Check its documentation
499 * for further details.
502 cpml_segment_to_cairo(const CpmlSegment
*segment
, cairo_t
*cr
)
504 CpmlPrimitive primitive
;
506 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
509 cpml_primitive_to_cairo(&primitive
, cr
);
510 } while (cpml_primitive_next(&primitive
));
515 * @segment: a #CpmlSegment
517 * Dumps the specified @segment to stdout. Useful for debugging purposes.
520 cpml_segment_dump(const CpmlSegment
*segment
)
522 CpmlPrimitive primitive
;
523 cairo_bool_t first_call
= 1;
525 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
528 cpml_primitive_dump(&primitive
, first_call
);
530 } while (cpml_primitive_next(&primitive
));
536 * @segment: a #CpmlSegment
538 * Sanitizes @segment by calling ensure_one_leading_move() and reshape().
540 * Returns: 1 on success, 0 on no leading MOVE_TOs or on errors
543 normalize(CpmlSegment
*segment
)
545 if (!ensure_one_leading_move(segment
))
548 return reshape(segment
);
552 * ensure_one_leading_move:
553 * @segment: a #CpmlSegment
555 * Strips the leading %CPML_MOVE primitives, updating the
556 * <structname>CpmlSegment</structname> structure accordingly.
557 * One, and only one, %CPML_MOVE primitive is left.
559 * Returns: 1 on success, 0 on no leading MOVE_TOs or on empty path
562 ensure_one_leading_move(CpmlSegment
*segment
)
564 cairo_path_data_t
*new_data
;
565 int new_num_data
, move_length
;
567 /* Check for at least one move to */
568 if (segment
->data
->header
.type
!= CAIRO_PATH_MOVE_TO
)
571 new_data
= segment
->data
;
572 new_num_data
= segment
->num_data
;
575 move_length
= new_data
->header
.length
;
577 /* Check for the end of cairo path data, that is when
578 * @segment is composed by only CAIRO_PATH_MOVE_TO */
579 if (new_num_data
<= move_length
)
582 /* Check if this is the last CAIRO_PATH_MOVE_TO */
583 if (new_data
[move_length
].header
.type
!= CAIRO_PATH_MOVE_TO
)
586 new_data
+= move_length
;
587 new_num_data
-= move_length
;
590 segment
->data
= new_data
;
591 segment
->num_data
= new_num_data
;
598 * @segment: a #CpmlSegment
600 * Looks for the segment termination, that is the end of the underlying
601 * cairo path or a %CPML_MOVE operation. <structfield>num_data</structfield>
602 * field is modified to properly point to the end of @segment.
603 * @segment must have only one leading %CPML_MOVE and it is supposed
604 * to be non-empty, conditions yet imposed by the ensure_one_leading_move().
606 * This function also checks that all the components of @segment
607 * are valid primitives.
609 * Returns: 1 on success, 0 on invalid primitive found
612 reshape(CpmlSegment
*segment
)
614 const cairo_path_data_t
*data
;
615 int trailing_data
, new_num_data
, length
;
617 data
= segment
->data
;
619 trailing_data
= segment
->num_data
;
622 length
= data
->header
.length
;
623 new_num_data
+= length
;
624 trailing_data
-= length
;
627 /* Check for invalid data size */
628 if (trailing_data
< 0)
631 if (trailing_data
== 0 || data
->header
.type
== CAIRO_PATH_MOVE_TO
)
634 /* Ensure that all the components are valid primitives */
635 if (cpml_primitive_type_get_n_points(data
->header
.type
) == 0)
639 segment
->num_data
= new_num_data
;