src/cpml/cpml-primitive.c

   1 /* CPML - Cairo Path Manipulation Library
   2  * Copyright (C) 2007,2008,2009,2010,2011,2012,2013  Nicola Fontana <ntd at entidi.it>
   3  *
   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.
   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  * Lesser General Public License for more details.
  13  *
  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.
  18  */
  19
  20
  21 /**
  22  * SECTION:cpml-primitive
  23  * @Section_Id:CpmlPrimitive
  24  * @title: CpmlPrimitive
  25  * @short_description: Basic component of segments
  26  *
  27  * A primitive is an atomic geometric element found inside #CpmlSegment.
  28  * The available primitives are the same defined by #cairo_path_data_type_t
  29  * with the additional #CPML_ARC type (check #CpmlPrimitiveType
  30  * for further information) and without #CPML_MOVE as it is not
  31  * considered a primitive and it is managed in different way: the move-to
  32  * primitives are only used to define the origin of a segment.
  33  *
  34  * Since: 1.0
  35  **/
  36
  37 /**
  38  * CpmlPrimitiveType:
  39  * @CPML_MOVE:  equivalent to %CAIRO_PATH_MOVE_TO
  40  * @CPML_LINE:  equivalent to %CAIRO_PATH_LINE_TO
  41  * @CPML_CURVE: equivalent to %CAIRO_PATH_CURVE_TO
  42  * @CPML_CLOSE: equivalent to %CAIRO_PATH_CLOSE_PATH
  43  * @CPML_ARC:   an arc representation at CPML level
  44  *
  45  * This is a type compatible with #cairo_path_data_type_t type. It is
  46  * basically the same enum but it embodies an important difference:
  47  * it can be used to specify the special #CPML_ARC primitive. Having
  48  * two different types is a good way to make clear when a function
  49  * expect or not embedded #CPML_ARC primitives.
  50  *
  51  * Arcs are used extensively in technical drawing: some operations are
  52  * trivials with arcs and a nightmare with cubic Bézier curves. Actually,
  53  * at least up to version 1.10.2, the cairo library does not support arc
  54  * primitives natively and there is no plan they will be ever supported.
  55  *
  56  * The CPML library supports arc natively, converting them to curves
  57  * when the #CpmlSegment is returned to the cairo context, for instance
  58  * when using cpml_segment_to_cairo().
  59  *
  60  * Since: 1.0
  61  **/
  62
  63 /**
  64  * CpmlPrimitive:
  65  * @segment: the source #CpmlSegment
  66  * @org: a pointer to the first point of the primitive
  67  * @data: the array of the path data, prepended by the header
  68  *
  69  * As for #CpmlSegment, also the primitive is unobtrusive. This
  70  * means CpmlPrimitive does not include any coordinates but instead
  71  * keeps pointers to the original segment (and, by transition, to
  72  * the underlying #CpmlPath struct).
  73  *
  74  * Since: 1.0
  75  **/
  76
  77
  78 #include "cpml-internal.h"
  79 #include "cpml-extents.h"
  80 #include "cpml-segment.h"
  81 #include "cpml-primitive.h"
  82 #include "cpml-primitive-private.h"
  83 #include "cpml-arc.h"
  84 #include "cpml-curve.h"
  85 #include <string.h>
  86 #include <stdio.h>
  87
  88
  89 static const _CpmlPrimitiveClass *
  90                 _cpml_class_from_type   (CpmlPrimitiveType        type);
  91 static const _CpmlPrimitiveClass *
  92                 _cpml_class_from_obj    (const CpmlPrimitive     *primitive);
  93 static cairo_path_data_t *
  94                 _cpml_get_point         (const CpmlPrimitive     *primitive,
  95                                          int                      n_point);
  96 static void     _cpml_dump_point        (const cairo_path_data_t *path_data);
  97
  98
  99 /**
 100  * cpml_primitive_type_get_n_points:
 101  * @type: a primitive type
 102  *
 103  * Gets the number of points required to identify the @type primitive.
 104  *
 105  * Returns: the number of points or %0 on errors
 106  *
 107  * Since: 1.0
 108  **/
 109 size_t
 110 cpml_primitive_type_get_n_points(CpmlPrimitiveType type)
 111 {
 112     const _CpmlPrimitiveClass *class_data = _cpml_class_from_type(type);
 113
 114     if (class_data == NULL)
 115         return 0;
 116
 117     return class_data->n_points;
 118 }
 119
 120 /**
 121  * cpml_primitive_from_segment:
 122  * @primitive:             the destination #CpmlPrimitive struct
 123  * @segment: (allow-none): the source segment
 124  *
 125  * Initializes @primitive to the first primitive of @segment.
 126  *
 127  * Since: 1.0
 128  **/
 129 void
 130 cpml_primitive_from_segment(CpmlPrimitive *primitive, CpmlSegment *segment)
 131 {
 132     primitive->segment = segment;
 133
 134     if (segment != NULL) {
 135         /* The first element of a CpmlSegment is always a CPML_MOVE,
 136          * as ensured by cpml_segment_from_cairo() and by the browsing APIs,
 137          * so the origin is in the second data item */
 138         primitive->org = segment->data + 1;
 139
 140         /* Also, the segment APIs ensure that @segment is prepended by
 141          * only one CPML_MOVE */
 142         primitive->data = segment->data + segment->data->header.length;
 143     } else {
 144         primitive->org = NULL;
 145         primitive->data = NULL;
 146     }
 147 }
 148
 149 /**
 150  * cpml_primitive_copy:
 151  * @primitive:         the destination #CpmlPrimitive
 152  * @src: (allow-none): the source #CpmlPrimitive
 153  *
 154  * Copies @src in @primitive. This is a shallow copy: the internal fields
 155  * of @primitive refer to the same memory as the original @src primitive.
 156  *
 157  * Since: 1.0
 158  **/
 159 void
 160 cpml_primitive_copy(CpmlPrimitive *primitive, const CpmlPrimitive *src)
 161 {
 162     if (src != NULL) {
 163         memcpy(primitive, src, sizeof(CpmlPrimitive));
 164     }
 165 }
 166
 167 /**
 168  * cpml_primitive_reset:
 169  * @primitive: a #CpmlPrimitive
 170  *
 171  * Resets @primitive so it refers to the first primitive of the
 172  * source segment.
 173  *
 174  * Since: 1.0
 175  **/
 176 void
 177 cpml_primitive_reset(CpmlPrimitive *primitive)
 178 {
 179     cpml_primitive_from_segment(primitive, primitive->segment);
 180 }
 181
 182 /**
 183  * cpml_primitive_next:
 184  * @primitive: a #CpmlPrimitive
 185  *
 186  * Changes @primitive so it refers to the next primitive on the
 187  * source segment. If there are no more primitives, @primitive is
 188  * not changed and 0 is returned.
 189  *
 190  * Returns: (type boolean): %1 on success, %0 if no next primitive found or errors.
 191  *
 192  * Since: 1.0
 193  **/
 194 int
 195 cpml_primitive_next(CpmlPrimitive *primitive)
 196 {
 197     cairo_path_data_t *new_data;
 198     const cairo_path_data_t *end_data;
 199
 200     new_data = primitive->data + primitive->data->header.length;
 201     end_data = primitive->segment->data + primitive->segment->num_data;
 202
 203     if (new_data >= end_data)
 204         return 0;
 205
 206     primitive->org = _cpml_get_point(primitive, -1);
 207     primitive->data = new_data;
 208
 209     return 1;
 210 }
 211
 212 /**
 213  * cpml_primitive_get_n_points:
 214  * @primitive: a #CpmlPrimitive
 215  *
 216  * Gets the number of points required to identify @primitive.
 217  * It is similar to cpml_primitive_type_get_n_points() but using
 218  * a @primitive instance instead of a type.
 219  *
 220  * Returns: the number of points or %0 on errors.
 221  *
 222  * <!-- Virtual: n_points -->
 223  *
 224  * Since: 1.0
 225  **/
 226 size_t
 227 cpml_primitive_get_n_points(const CpmlPrimitive *primitive)
 228 {
 229     return cpml_primitive_type_get_n_points(primitive->data->header.type);
 230 }
 231
 232 /**
 233  * cpml_primitive_get_length:
 234  * @primitive: a #CpmlPrimitive
 235  *
 236  * Abstracts the length() family functions by providing a common
 237  * way to access the underlying primitive-specific implementation.
 238  * The function returns the length of @primitive.
 239  *
 240  * Returns: the requested length or 0 on errors
 241  *
 242  * <!-- Virtual: get_length -->
 243  *
 244  * Since: 1.0
 245  **/
 246 double
 247 cpml_primitive_get_length(const CpmlPrimitive *primitive)
 248 {
 249     const _CpmlPrimitiveClass *class_data = _cpml_class_from_obj(primitive);
 250
 251     if (class_data == NULL || class_data->get_length == NULL)
 252         return 0;
 253
 254     return class_data->get_length(primitive);
 255 }
 256
 257 /**
 258  * cpml_primitive_put_extents:
 259  * @primitive:                       a #CpmlPrimitive
 260  * @extents: (out caller-allocates): where to store the extents
 261  *
 262  * Abstracts the extents() family functions by providing a common
 263  * way to access the underlying primitive-specific implementation.
 264  *
 265  * This function stores in @extents the bounding box of @primitive.
 266  *
 267  * On errors, that is if the extents cannot be calculated for some
 268  * reason, this function does nothing.
 269  *
 270  * <!-- Virtual: put_extents -->
 271  *
 272  * Since: 1.0
 273  **/
 274 void
 275 cpml_primitive_put_extents(const CpmlPrimitive *primitive,
 276                            CpmlExtents *extents)
 277 {
 278     const _CpmlPrimitiveClass *class_data = _cpml_class_from_obj(primitive);
 279
 280     if (class_data == NULL || class_data->put_extents == NULL)
 281         return;
 282
 283     class_data->put_extents(primitive, extents);
 284 }
 285
 286 /**
 287  * cpml_primitive_set_point:
 288  * @primitive:          a #CpmlPrimitive
 289  * @n_point:            the index of the point to retrieve
 290  * @pair: (allow-none): the source #CpmlPair
 291  *
 292  * Sets the specified @n_point of @primitive to @pair. The @n_point
 293  * index starts from 0: if @n_point is 0, the start point (the origin)
 294  * is changed, 1 for the second point and so on. If @n_point is
 295  * negative, it is considered as a negative index from the end, so
 296  * that -1 is the end point, -2 the point before the end point and
 297  * so on.
 298  *
 299  * #CPML_CLOSE is managed in a special way: if @n_point
 300  * is -1 or 1 and @primitive is a close-path, this function cycles
 301  * the source #CpmlSegment and returns the first point. This is
 302  * needed because requesting the end point (or the second point)
 303  * of a close path is a valid operation and must returns the origin
 304  * of the segment.
 305  *
 306  * Since: 1.0
 307  **/
 308 void
 309 cpml_primitive_set_point(CpmlPrimitive *primitive,
 310                          int n_point, const CpmlPair *pair)
 311 {
 312     cairo_path_data_t *point = _cpml_get_point(primitive, n_point);
 313
 314     if (point != NULL && pair != NULL)
 315         cpml_pair_to_cairo(pair, point);
 316 }
 317
 318 /**
 319  * cpml_primitive_put_point:
 320  * @primitive:                    a #CpmlPrimitive
 321  * @n_point:                      the index of the point to retrieve
 322  * @pair: (out caller-allocates): the destination #CpmlPair
 323  *
 324  * Gets the specified @n_point from @primitive and stores it into
 325  * @pair. The @n_point index is subject to the same rules explained
 326  * in the cpml_primitive_set_point() function.
 327  *
 328  * Since: 1.0
 329  **/
 330 void
 331 cpml_primitive_put_point(const CpmlPrimitive *primitive,
 332                          int n_point, CpmlPair *pair)
 333 {
 334     const cairo_path_data_t *point = _cpml_get_point(primitive, n_point);
 335
 336     if (point != NULL)
 337         cpml_pair_from_cairo(pair, point);
 338 }
 339
 340 /**
 341  * cpml_primitive_put_pair_at:
 342  * @primitive:                    a #CpmlPrimitive
 343  * @pos:                          the position value
 344  * @pair: (out caller-allocates): the destination #CpmlPair
 345  *
 346  * Abstracts the put_pair_at() family functions by providing a common
 347  * way to access the underlying primitive-specific implementation.
 348  *
 349  * It gets the coordinates of the point lying on @primitive
 350  * at position @pos. @pos is an homogeneous factor where 0 is the
 351  * start point, 1 the end point, 0.5 the mid point and so on.
 352  * @pos can be less than 0 or greater than %1, in which case the
 353  * coordinates of @pair are interpolated.
 354  *
 355  * On errors, that is if the coordinates cannot be calculated for
 356  * some reason, this function does nothing.
 357  *
 358  * <!-- Virtual: put_pair_at -->
 359  *
 360  * Since: 1.0
 361  **/
 362 void
 363 cpml_primitive_put_pair_at(const CpmlPrimitive *primitive,
 364                            double pos, CpmlPair *pair)
 365 {
 366     const _CpmlPrimitiveClass *class_data = _cpml_class_from_obj(primitive);
 367
 368     if (class_data == NULL || class_data->put_pair_at == NULL)
 369         return;
 370
 371     class_data->put_pair_at(primitive, pos, pair);
 372 }
 373
 374 /**
 375  * cpml_primitive_put_vector_at:
 376  * @primitive:                      a #CpmlPrimitive
 377  * @pos:                            the position value
 378  * @vector: (out caller-allocates): the destination #CpmlVector
 379  *
 380  * Abstracts the put_vector_at() family functions by providing a common
 381  * way to access the underlying primitive-specific implementation.
 382  *
 383  * It gets the steepness of the point at position @pos on @primitive.
 384  * @pos is an homogeneous factor where 0 is the start point, 1 the
 385  * end point, 0.5 the mid point and so on.
 386  * @pos can be less than 0 or greater than %1, in which case the
 387  * coordinates of @pair are interpolated.
 388  *
 389  * On errors, that is if the steepness cannot be calculated for
 390  * some reason, this function does nothing.
 391  *
 392  * <!-- Virtual: put_vector_at -->
 393  *
 394  * Since: 1.0
 395  **/
 396 void
 397 cpml_primitive_put_vector_at(const CpmlPrimitive *primitive,
 398                              double pos, CpmlVector *vector)
 399 {
 400     const _CpmlPrimitiveClass *class_data = _cpml_class_from_obj(primitive);
 401
 402     if (class_data == NULL || class_data->put_vector_at == NULL)
 403         return;
 404
 405     class_data->put_vector_at(primitive, pos, vector);
 406 }
 407
 408 /**
 409  * cpml_primitive_get_closest_pos:
 410  * @primitive:          a #CpmlPrimitive
 411  * @pair: (allow-none): the coordinates of the subject point
 412  *
 413  * Returns the pos value of the point on @primitive nearest to @pair.
 414  * The returned value is always clamped between %0 and %1.
 415  *
 416  * Returns: the requested pos value between %0 and %1, or %-1 on errors.
 417  *
 418  * <!-- Virtual: get_closest_pos -->
 419  *
 420  * Since: 1.0
 421  **/
 422 double
 423 cpml_primitive_get_closest_pos(const CpmlPrimitive *primitive,
 424                                const CpmlPair *pair)
 425 {
 426     const _CpmlPrimitiveClass *class_data;
 427
 428     if (pair == NULL)
 429         return -1;
 430
 431     class_data = _cpml_class_from_obj(primitive);
 432     if (class_data == NULL || class_data->get_closest_pos == NULL)
 433         return -1;
 434
 435     return class_data->get_closest_pos(primitive, pair);
 436 }
 437
 438 /**
 439  * cpml_primitive_put_intersections:
 440  * @primitive:                                                       the first #CpmlPrimitive
 441  * @primitive2: (allow-none)                                         the second #CpmlPrimitive
 442  * @n_dest:                                                          maximum number of intersections to return
 443  * @dest: (out caller-allocates) (array length=n_dest) (allow-none): the destination buffer that can contain @n_dest #CpmlPair
 444  *
 445  * Finds the intersection points between the given primitives and
 446  * returns the result in @dest. The size of @dest should be enough
 447  * to store @n_dest #CpmlPair. The maximum number of intersections
 448  * is dependent on the type of the primitive involved in the
 449  * operation. If there are at least one Bézier curve involved, up to
 450  * %4 intersections could be returned. Otherwise, if there is an arc
 451  * the intersections will be %2 at maximum. For line primitives, there
 452  * is only %1 point (or %0 if the lines are parallel).
 453  *
 454  * <note>
 455  * <para>
 456  * The convention used by the CPML library is that a primitive should
 457  * implement only the intersection algorithms with lower degree
 458  * primitives. This is required to avoid code duplication: intersection
 459  * between arc and Bézier curves must be implemented by #CPML_CURVE and
 460  * intersection between lines and arcs must be implemented by #CPML_ARC.
 461  * cpml_primitive_put_intersections() will take care of swapping the
 462  * arguments if they are not properly ordered.
 463  * </para>
 464  * </note>
 465  *
 466  * Returns: the number of intersection points found or 0 if the
 467  *          primitives do not intersect or on errors.
 468  *
 469  * <!-- Virtual: put_intersections -->
 470  *
 471  * Since: 1.0
 472  **/
 473 size_t
 474 cpml_primitive_put_intersections(const CpmlPrimitive *primitive,
 475                                  const CpmlPrimitive *primitive2,
 476                                  size_t n_dest, CpmlPair *dest)
 477 {
 478     const _CpmlPrimitiveClass *class_data;
 479     size_t n_points, n_points2;
 480
 481     if (primitive2 == NULL || dest == NULL)
 482         return 0;
 483
 484     class_data = _cpml_class_from_obj(primitive);
 485     if (class_data == NULL || class_data->put_intersections == NULL)
 486         return 0;
 487
 488     n_points = cpml_primitive_get_n_points(primitive);
 489     n_points2 = cpml_primitive_get_n_points(primitive2);
 490
 491     if (n_points == 0 || n_points2 == 0)
 492         return 0;
 493
 494     /* Primitives reordering: the first must be the more complex one */
 495     if (n_points < n_points2) {
 496         const CpmlPrimitive *old_primitive2 = primitive2;
 497         primitive2 = primitive;
 498         primitive = old_primitive2;
 499     }
 500
 501     return class_data->put_intersections(primitive, primitive2, n_dest, dest);
 502 }
 503
 504 /**
 505  * cpml_primitive_put_intersections_with_segment:
 506  * @primitive:                                                       a #CpmlPrimitive
 507  * @segment: (allow-none):                                           a #CpmlSegment
 508  * @n_dest:                                                          maximum number of intersections to return
 509  * @dest: (out caller-allocates) (array length=n_dest) (allow-none): the destination buffer that can contain @n_dest #CpmlPair
 510  *
 511  * Computes the intersections between @segment and @primitive by
 512  * sequentially scanning the primitives in @segment and looking
 513  * for their intersections with @primitive.
 514  *
 515  * If the intersections are more than @n_dest, only the first
 516  * @n_dest pairs are stored.
 517  *
 518  * Returns: the number of intersection points found or 0 if the
 519  *          items do not intersect or on errors.
 520  *
 521  * Since: 1.0
 522  **/
 523 size_t
 524 cpml_primitive_put_intersections_with_segment(const CpmlPrimitive *primitive,
 525                                               const CpmlSegment *segment,
 526                                               size_t n_dest, CpmlPair *dest)
 527 {
 528     CpmlPrimitive portion;
 529     size_t found;
 530
 531     if (segment == NULL || dest == NULL)
 532         return 0;
 533
 534     cpml_primitive_from_segment(&portion, (CpmlSegment *) segment);
 535     found = 0;
 536
 537     while (found < n_dest) {
 538         found += cpml_primitive_put_intersections(&portion, primitive,
 539                                                   n_dest-found, dest+found);
 540         if (!cpml_primitive_next(&portion))
 541             break;
 542     }
 543
 544     return found;
 545 }
 546
 547 /**
 548  * cpml_primitive_offset:
 549  * @primitive: a #CpmlPrimitive
 550  * @offset:   distance for the computed offset primitive
 551  *
 552  * Given a primitive, computes the same (or approximated) parallel
 553  * primitive distant @offset from the original one and returns
 554  * the result by changing @primitive.
 555  *
 556  * On errors, that is if the offset primitive cannot be calculated
 557  * for some reason, this function does nothing.
 558  *
 559  * <!-- Virtual: offset -->
 560  *
 561  * Since: 1.0
 562  **/
 563 void
 564 cpml_primitive_offset(CpmlPrimitive *primitive, double offset)
 565 {
 566     const _CpmlPrimitiveClass *class_data = _cpml_class_from_obj(primitive);
 567
 568     if (class_data == NULL || class_data->offset == NULL)
 569         return;
 570
 571     class_data->offset(primitive, offset);
 572 }
 573
 574 /**
 575  * cpml_primitive_join:
 576  * @primitive:                           the first #CpmlPrimitive
 577  * @primitive2: (inout) (transfer none): the second #CpmlPrimitive
 578  *
 579  * Joins two primitive modifying the end point of @primitive and the
 580  * start point of @primitive2 so that the resulting points will overlap.
 581  *
 582  * <important>
 583  * <title>TODO</title>
 584  * <itemizedlist>
 585  * <listitem>Actually, the join is done by extending the end vector
 586  *           of @primitive and the start vector of @primitive2 and
 587  *           interpolating the intersection: this means no primitive
 588  *           dependent code is needed. Anyway, it is likely to change
 589  *           in the future because this approach is quite naive when
 590  *           curves are involved.</listitem>
 591  * </itemizedlist>
 592  * </important>
 593  *
 594  * Returns: (type boolean): %1 on success, %0 if the primitives cannot be joint.
 595  *
 596  * <!-- Virtual: join -->
 597  *
 598  * Since: 1.0
 599  **/
 600 int
 601 cpml_primitive_join(CpmlPrimitive *primitive, CpmlPrimitive *primitive2)
 602 {
 603     cairo_path_data_t *end1, *start2;
 604     CpmlPrimitive line1, line2;
 605     cairo_path_data_t data1[2], data2[2];
 606     CpmlPair joint;
 607
 608     end1 = _cpml_get_point(primitive, -1);
 609     start2 = _cpml_get_point(primitive2, 0);
 610
 611     /* Check if the primitives are yet connected */
 612     if (end1->point.x == start2->point.x && end1->point.y == start2->point.y)
 613         return 1;
 614
 615     line1.org = _cpml_get_point(primitive, -2);
 616     line1.data = data1;
 617     data1[0].header.type = CPML_LINE;
 618     data1[1] = *end1;
 619
 620     line2.org = start2;
 621     line2.data = data2;
 622     data2[0].header.type = CPML_LINE;
 623     data2[1] = *_cpml_get_point(primitive2, 1);
 624
 625     if (!cpml_primitive_put_intersections(&line1, &line2, 1, &joint))
 626         return 0;
 627
 628     cpml_pair_to_cairo(&joint, end1);
 629     cpml_pair_to_cairo(&joint, start2);
 630
 631     return 1;
 632 }
 633
 634 /**
 635  * cpml_primitive_to_cairo:
 636  * @primitive:                   a #CpmlPrimitive
 637  * @cr: (inout) (transfer none): the destination cairo context
 638  *
 639  * Renders a single @primitive to the @cr cairo context.
 640  * As a special case, if the primitive is a #CPML_CLOSE, an
 641  * equivalent line is rendered, because a close path left alone
 642  * is not renderable.
 643  *
 644  * Also a #CPML_ARC primitive is treated specially, as it is not
 645  * natively supported by cairo and has its own rendering API.
 646  *
 647  * Since: 1.0
 648  **/
 649 void
 650 cpml_primitive_to_cairo(const CpmlPrimitive *primitive, cairo_t *cr)
 651 {
 652     CpmlPrimitiveType type;
 653     cairo_path_t path;
 654     cairo_path_data_t *path_data;
 655
 656     cairo_move_to(cr, primitive->org->point.x, primitive->org->point.y);
 657
 658     type = primitive->data->header.type;
 659
 660     if (type == CPML_CLOSE) {
 661         path_data = _cpml_get_point(primitive, -1);
 662         cairo_line_to(cr, path_data->point.x, path_data->point.y);
 663     } else if (type == CPML_ARC) {
 664         cpml_arc_to_cairo(primitive, cr);
 665     } else {
 666         path.status = CAIRO_STATUS_SUCCESS;
 667         path.data = primitive->data;
 668         path.num_data = primitive->data->header.length;
 669         cairo_append_path(cr, &path);
 670     }
 671 }
 672
 673 /**
 674  * cpml_primitive_dump:
 675  * @primitive: a #CpmlPrimitive
 676  * @org_also:  whether to output also the origin coordinates
 677  *
 678  * Dumps info on the specified @primitive to stdout: useful for
 679  * debugging purposes. If @org_also is 1, a #CPML_MOVE to the
 680  * origin is prepended to the data otherwise the
 681  * <structfield>org</structfield> field is not used.
 682  *
 683  * Since: 1.0
 684  **/
 685 void
 686 cpml_primitive_dump(const CpmlPrimitive *primitive, int org_also)
 687 {
 688     const cairo_path_data_t *data;
 689     int type;
 690     const _CpmlPrimitiveClass *class_data;
 691     size_t n, n_points;
 692
 693     data = primitive->data;
 694     type = data->header.type;
 695     class_data = _cpml_class_from_type(type);
 696
 697     if (class_data == NULL) {
 698         printf("Unknown primitive type (%d)\n", type);
 699         return;
 700     }
 701
 702     /* Dump the origin, if requested */
 703     if (org_also) {
 704         printf("move to ");
 705         _cpml_dump_point(primitive->org);
 706         printf("\n");
 707     }
 708
 709     printf("%s ", class_data->name);
 710
 711     n_points = cpml_primitive_get_n_points(primitive);
 712     for (n = 1; n < n_points; ++n)
 713         _cpml_dump_point(_cpml_get_point(primitive, n));
 714
 715     printf("\n");
 716 }
 717
 718
 719 static const _CpmlPrimitiveClass *
 720 _cpml_class_from_type(CpmlPrimitiveType type)
 721 {
 722     if (type == CPML_LINE)
 723         return _cpml_line_get_class();
 724     else if (type == CPML_ARC)
 725         return _cpml_arc_get_class();
 726     else if (type == CPML_CURVE)
 727         return _cpml_curve_get_class();
 728     else if (type == CPML_CLOSE)
 729         return _cpml_close_get_class();
 730
 731     return NULL;
 732 }
 733
 734 static const _CpmlPrimitiveClass *
 735 _cpml_class_from_obj(const CpmlPrimitive *primitive)
 736 {
 737     return _cpml_class_from_type(primitive->data->header.type);
 738 }
 739
 740 /*
 741  * _cpml_get_point:
 742  * @primitive: a #CpmlPrimitive
 743  * @n_point:   the index of the point to retrieve
 744  *
 745  * Gets the specified @n_point from @primitive. The index starts
 746  * at 0: if @n_point is 0, the start point (the origin) is
 747  * returned, 1 for the second point and so on. If @n_point is
 748  * negative, it is considered as a negative index from the end,
 749  * so that -1 is the end point, -2 the point before the end point
 750  * and so on.
 751  *
 752  * #CPML_CLOSE is managed in a special way: if @n_point
 753  * is -1 or 1 and @primitive is a close-path, this function cycles
 754  * the source #CpmlSegment and returns the first point. This is
 755  * needed because requesting the end point (or the second point)
 756  * of a close path is a valid operation and must returns the start
 757  * of the segment.
 758  *
 759  * Returns: a pointer to the requested point (in cairo format)
 760  *          or %NULL if the point is outside the valid range
 761  *
 762  * Since: 1.0
 763  **/
 764 static cairo_path_data_t *
 765 _cpml_get_point(const CpmlPrimitive *primitive, int n_point)
 766 {
 767     size_t n_points;
 768
 769     /* For a start point request, simply return the origin
 770      * without further checking */
 771     if (n_point == 0)
 772         return primitive->org;
 773
 774     /* The CPML_CLOSE special case */
 775     if (primitive->data->header.type == CAIRO_PATH_CLOSE_PATH &&
 776         (n_point == 1 || n_point == -1))
 777         return &primitive->segment->data[1];
 778
 779     n_points = cpml_primitive_get_n_points(primitive);
 780     if (n_points == 0)
 781         return NULL;
 782
 783     /* If n_point is negative, consider it as a negative index from the end */
 784     if (n_point < 0)
 785         n_point = n_points + n_point;
 786
 787     /* Out of range condition */
 788     if (n_point < 0 || n_point >= n_points)
 789         return NULL;
 790
 791     return n_point == 0 ? primitive->org : &primitive->data[n_point];
 792 }
 793
 794 static void
 795 _cpml_dump_point(const cairo_path_data_t *path_data)
 796 {
 797     printf("(%g %g) ", path_data->point.x, path_data->point.y);
 798 }