1 /* CPML - Cairo Path Manipulation Library
2 * Copyright (C) 2007-2015 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
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 #cairo_path_t 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.
54 * @path: the source #cairo_path_t struct
55 * @data: the data points of the segment; the first primitive
56 * will always be a %CPML_MOVE
57 * @num_data: size of @data
59 * This is an unobtrusive struct to identify a segment inside a
60 * cairo path. Unobtrusive means that the real coordinates are
61 * still stored in @path: CpmlSegment only provides a way to
68 #include "cpml-internal.h"
69 #include "cpml-extents.h"
70 #include "cpml-segment.h"
71 #include "cpml-primitive.h"
72 #include "cpml-curve.h"
76 static int normalize (CpmlSegment
*segment
);
77 static int ensure_one_leading_move (CpmlSegment
*segment
);
78 static int reshape (CpmlSegment
*segment
);
82 * cpml_segment_from_cairo:
83 * @segment: a #CpmlSegment
84 * @path: (type gpointer): the source #cairo_path_t
86 * Builds a CpmlSegment from a #cairo_path_t structure. This operation
87 * involves stripping the duplicate %CPML_MOVE primitives at the
88 * start of the path and setting <structfield>num_data</structfield>
89 * field to the end of the contiguous line, that is when another
90 * %CPML_MOVE primitive is found or at the end of the path.
91 * A pointer to the source cairo path is kept though.
93 * This function will fail if @path is null, empty or if its
94 * <structfield>status</structfield> member is not %CAIRO_STATUS_SUCCESS.
95 * Also, the first primitive must be a %CPML_MOVE, so no
96 * dependency on the cairo context is needed.
98 * Returns: (type gboolean): 1 if @segment has been succesfully computed, 0 on errors.
103 cpml_segment_from_cairo(CpmlSegment
*segment
, cairo_path_t
*path
)
105 /* segment and path must be non-NULL and path must be valid */
106 if (path
== NULL
|| segment
== NULL
||
107 path
->num_data
== 0 || path
->status
!= CAIRO_STATUS_SUCCESS
)
110 segment
->path
= path
;
111 segment
->data
= path
->data
;
112 segment
->num_data
= path
->num_data
;
114 return normalize(segment
);
119 * @segment: a #CpmlSegment
120 * @src: the source segment to copy
122 * Makes a shallow copy of @src into @segment.
127 cpml_segment_copy(CpmlSegment
*segment
, const CpmlSegment
*src
)
129 memcpy(segment
, src
, sizeof(CpmlSegment
));
133 * cpml_segment_reset:
134 * @segment: a #CpmlSegment
136 * Modifies @segment to point to the first segment of the source cairo path.
141 cpml_segment_reset(CpmlSegment
*segment
)
143 segment
->data
= segment
->path
->data
;
144 segment
->num_data
= segment
->path
->num_data
;
150 * @segment: a #CpmlSegment
152 * Modifies @segment to point to the next segment of the source cairo path.
154 * Returns: (type gboolean): 1 on success, 0 if no next segment found or errors.
159 cpml_segment_next(CpmlSegment
*segment
)
161 cairo_path_data_t
*new_data
;
162 const cairo_path_data_t
*end_data
;
164 new_data
= segment
->data
+ segment
->num_data
;
165 end_data
= segment
->path
->data
+ segment
->path
->num_data
;
167 if (new_data
>= end_data
)
170 segment
->data
= new_data
;
171 segment
->num_data
= end_data
- new_data
;
173 return normalize(segment
);
177 * cpml_segment_get_length:
178 * @segment: a #CpmlSegment
180 * Gets the whole length of @segment.
182 * Returns: the requested length
187 cpml_segment_get_length(const CpmlSegment
*segment
)
189 CpmlPrimitive primitive
;
195 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
199 length
+= cpml_primitive_get_length(&primitive
);
200 } while (cpml_primitive_next(&primitive
));
206 * cpml_segment_put_extents:
207 * @segment: a #CpmlSegment
208 * @extents: where to store the extents
210 * 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 <constant>0 < @pos < 1</constant> should be satisfied,
240 * although some 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>
253 cpml_segment_put_pair_at(const CpmlSegment
*segment
, double pos
,
256 CpmlPrimitive primitive
;
258 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
260 /* Handle the common cases: start and end points */
262 cpml_primitive_put_pair_at(&primitive
, 0, pair
);
264 while (cpml_primitive_next(&primitive
))
266 cpml_primitive_put_pair_at(&primitive
, 1, pair
);
271 * cpml_segment_put_vector_at:
272 * @segment: a #CpmlSegment
273 * @pos: the position value
274 * @vector: the destination #CpmlVector
276 * Gets the steepness of the point lying on @segment at position
277 * @pos. @pos is an homogeneous factor where 0 is the start point,
278 * 1 the end point, 0.5 the mid point and so on.
279 * The relation <constant>0 < @pos < 1</constant> should be satisfied,
280 * although some cases accept value outside this range.
283 * <title>TODO</title>
285 * <listitem>The actual implementation returns only the start and end
286 * steepness, that is only when @pos is 0 or 1.</listitem>
293 cpml_segment_put_vector_at(const CpmlSegment
*segment
, double pos
,
296 CpmlPrimitive primitive
;
298 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
300 /* Handle the common cases: start and end points */
302 cpml_primitive_put_vector_at(&primitive
, 0, vector
);
307 while (cpml_primitive_next(&primitive
))
309 cpml_primitive_put_vector_at(&primitive
, 1, vector
);
315 * cpml_segment_put_intersections:
316 * @segment: the first #CpmlSegment
317 * @segment2: the second #CpmlSegment
318 * @n_dest: maximum number of intersections to return
319 * @dest: the destination vector of #CpmlPair
321 * Computes the intersections between @segment and @segment2 and
322 * returns the found points in @dest. If the intersections are more
323 * than @n_dest, only the first @n_dest pairs are stored in @dest.
325 * To get the job done, the primitives of @segment are sequentially
326 * scanned for intersections with any primitive in @segment2. This
327 * means @segment has a higher precedence over @segment2.
329 * Returns: the number of intersections found
334 cpml_segment_put_intersections(const CpmlSegment
*segment
,
335 const CpmlSegment
*segment2
,
336 size_t n_dest
, CpmlPair
*dest
)
338 CpmlPrimitive portion
;
339 size_t partial
, total
;
341 cpml_primitive_from_segment(&portion
, (CpmlSegment
*) segment
);
344 if (segment
== NULL
|| segment2
== NULL
|| dest
== NULL
)
348 partial
= cpml_primitive_put_intersections_with_segment(&portion
,
353 } while (total
< n_dest
&& cpml_primitive_next(&portion
));
359 * cpml_segment_offset:
360 * @segment: a #CpmlSegment
361 * @offset: the offset distance
363 * Offsets a segment of the specified amount, that is builds a "parallel"
364 * segment at the @offset distance from the original one and returns the
365 * result by replacing the original @segment.
368 * <title>TODO</title>
370 * <listitem>Closed path are not yet managed: an elegant solution is not
371 * so obvious: use <function>cpml_close_offset</function> when
372 * will be available.</listitem>
373 * <listitem>Degenerated primitives, such as lines of length 0, are not
374 * managed properly.</listitem>
381 cpml_segment_offset(CpmlSegment
*segment
, double offset
)
383 CpmlPrimitive primitive
;
384 CpmlPrimitive last_primitive
;
386 cairo_path_data_t org
, *old_org
;
392 cpml_primitive_from_segment(&primitive
, segment
);
397 cpml_pair_to_cairo(&old_end
, &org
);
398 old_org
= primitive
.org
;
399 primitive
.org
= &org
;
402 cpml_primitive_put_point(&primitive
, -1, &old_end
);
403 cpml_primitive_offset(&primitive
, offset
);
406 cpml_primitive_join(&last_primitive
, &primitive
);
407 primitive
.org
= old_org
;
410 cpml_primitive_copy(&last_primitive
, &primitive
);
412 } while (cpml_primitive_next(&primitive
));
416 * cpml_segment_transform:
417 * @segment: a #CpmlSegment
418 * @matrix: the matrix to be applied
420 * Applies @matrix on all the points of @segment.
425 cpml_segment_transform(CpmlSegment
*segment
, const cairo_matrix_t
*matrix
)
427 CpmlPrimitive primitive
;
428 cairo_path_data_t
*data
;
431 if (segment
== NULL
|| matrix
== NULL
)
434 cpml_primitive_from_segment(&primitive
, segment
);
435 cairo_matrix_transform_point(matrix
, &(primitive
.org
)->point
.x
,
436 &(primitive
.org
)->point
.y
);
439 data
= primitive
.data
;
440 if (data
->header
.type
!= CAIRO_PATH_CLOSE_PATH
) {
441 n_points
= cpml_primitive_get_n_points(&primitive
);
443 while (--n_points
> 0) {
445 cairo_matrix_transform_point(matrix
,
446 &data
->point
.x
, &data
->point
.y
);
449 } while (cpml_primitive_next(&primitive
));
453 * cpml_segment_reverse:
454 * @segment: a #CpmlSegment
456 * Reverses @segment in-place. The resulting rendering will be the same,
457 * but with the primitives generated in reverse order.
459 * It is assumed that @segment has already been sanitized, such as when
460 * it is returned by some CPML function or it is a cairo path already
461 * conforming to the * segment rules described by the
462 * cpml_segment_from_cairo() function.
467 cpml_segment_reverse(CpmlSegment
*segment
)
469 cairo_path_data_t
*data
, *dst_data
;
473 size_t n_points
, n_point
;
474 const cairo_path_data_t
*src_data
;
479 data_size
= sizeof(cairo_path_data_t
) * segment
->num_data
;
480 data
= malloc(data_size
);
481 end_x
= segment
->data
[1].point
.x
;
482 end_y
= segment
->data
[1].point
.y
;
484 n
= segment
->data
->header
.length
;
485 data
->header
.type
= CPML_MOVE
;
486 data
->header
.length
= n
;
488 while (n
< segment
->num_data
) {
489 src_data
= segment
->data
+ n
;
490 /* While usually CPML_CLOSE is treated as a CPML_LINE, in this case
491 * it must not, because it does not have a trailing data point */
492 n_points
= src_data
->header
.type
== CAIRO_PATH_CLOSE_PATH
? 1 :
493 cpml_primitive_type_get_n_points(src_data
->header
.type
);
494 length
= src_data
->header
.length
;
496 dst_data
= data
+ segment
->num_data
- n
+ data
->header
.length
;
497 dst_data
->header
.type
= src_data
->header
.type
;
498 dst_data
->header
.length
= length
;
500 for (n_point
= 1; n_point
< n_points
; ++n_point
) {
501 dst_data
[n_points
- n_point
].point
.x
= end_x
;
502 dst_data
[n_points
- n_point
].point
.y
= end_y
;
503 end_x
= src_data
[n_point
].point
.x
;
504 end_y
= src_data
[n_point
].point
.y
;
507 /* Copy also the embedded data, if any */
508 if (n_points
< length
) {
509 size_t size
= (length
- n_points
) * sizeof(cairo_path_data_t
);
510 memcpy(dst_data
+ n_points
, src_data
+ n_points
, size
);
514 data
[1].point
.x
= end_x
;
515 data
[1].point
.y
= end_y
;
516 memcpy(segment
->data
, data
, data_size
);
522 * cpml_segment_to_cairo:
523 * @segment: a #CpmlSegment
524 * @cr: the destination cairo context
526 * Appends the path of @segment to @cr. The segment is "flattened",
527 * that is %CPML_ARC primitives are approximated by one or more
528 * %CPML_CURVE using cpml_arc_to_cairo(). Check its documentation
529 * for further details.
534 cpml_segment_to_cairo(const CpmlSegment
*segment
, cairo_t
*cr
)
536 CpmlPrimitive primitive
;
538 if (segment
== NULL
|| cr
== NULL
)
541 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
544 cpml_primitive_to_cairo(&primitive
, cr
);
545 } while (cpml_primitive_next(&primitive
));
550 * @segment: a #CpmlSegment
552 * Dumps the specified @segment to stdout. Useful for debugging purposes.
557 cpml_segment_dump(const CpmlSegment
*segment
)
559 CpmlPrimitive primitive
;
562 if (segment
== NULL
) {
563 printf("NULL segment\n");
567 cpml_primitive_from_segment(&primitive
, (CpmlSegment
*) segment
);
571 cpml_primitive_dump(&primitive
, first_call
);
573 } while (cpml_primitive_next(&primitive
));
579 * @segment: a #CpmlSegment
581 * Sanitizes @segment by calling ensure_one_leading_move() and reshape().
583 * Returns: 1 on success, 0 on no leading MOVE_TOs or on errors.
586 normalize(CpmlSegment
*segment
)
588 if (!ensure_one_leading_move(segment
))
591 return reshape(segment
);
595 * ensure_one_leading_move:
596 * @segment: a #CpmlSegment
598 * Strips the leading %CPML_MOVE primitives, updating the
599 * <structname>CpmlSegment</structname> structure accordingly.
600 * One, and only one, %CPML_MOVE primitive is left.
602 * Returns: 1 on success, 0 on no leading MOVE_TOs or on empty path
605 ensure_one_leading_move(CpmlSegment
*segment
)
607 cairo_path_data_t
*new_data
;
608 int new_num_data
, move_length
;
610 /* Check for at least one move to */
611 if (segment
->data
->header
.type
!= CAIRO_PATH_MOVE_TO
)
614 new_data
= segment
->data
;
615 new_num_data
= segment
->num_data
;
618 move_length
= new_data
->header
.length
;
620 /* Check for the end of cairo path data, that is when
621 * @segment is composed by only CAIRO_PATH_MOVE_TO */
622 if (new_num_data
<= move_length
)
625 /* Check if this is the last CAIRO_PATH_MOVE_TO */
626 if (new_data
[move_length
].header
.type
!= CAIRO_PATH_MOVE_TO
)
629 new_data
+= move_length
;
630 new_num_data
-= move_length
;
633 segment
->data
= new_data
;
634 segment
->num_data
= new_num_data
;
641 * @segment: a #CpmlSegment
643 * Looks for the segment termination, that is the end of the underlying
644 * cairo path or a %CPML_MOVE operation. <structfield>num_data</structfield>
645 * field is modified to properly point to the end of @segment.
646 * @segment must have only one leading %CPML_MOVE and it is supposed
647 * to be non-empty, conditions yet imposed by the ensure_one_leading_move().
649 * This function also checks that all the components of @segment
650 * are valid primitives.
652 * Returns: 1 on success, 0 on invalid primitive found.
655 reshape(CpmlSegment
*segment
)
657 const cairo_path_data_t
*data
;
658 int trailing_data
, new_num_data
, length
;
660 data
= segment
->data
;
662 trailing_data
= segment
->num_data
;
665 length
= data
->header
.length
;
666 new_num_data
+= length
;
667 trailing_data
-= length
;
670 /* Check for invalid data size */
671 if (trailing_data
< 0)
674 if (trailing_data
== 0 || data
->header
.type
== CAIRO_PATH_MOVE_TO
)
677 /* Ensure that all the components are valid primitives */
678 if (cpml_primitive_type_get_n_points(data
->header
.type
) == 0)
682 segment
->num_data
= new_num_data
;