cpml/cpml-primitive.c

   1 /* CPML - Cairo Path Manipulation Library
   2  * Copyright (C) 2008, 2009  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 %CAIRO_PATH_ARC_TO type (check #CpmlPrimitiveType
  30  * for further information) and without %CAIRO_PATH_MOVE_TO 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
  35 /**
  36  * CpmlPrimitiveType:
  37  *
  38  * This is another name for #cairo_path_data_type_t type. Although
  39  * phisically they are the same struct, #CpmlPrimitiveType conceptually
  40  * embodies an important difference: it can be used to specify the
  41  * special %CAIRO_PATH_ARC_TO primitive. This is not a native cairo
  42  * primitive and having two different types is a good way to make clear
  43  * when a function expect or not embedded arc-to primitives.
  44  **/
  45
  46 /**
  47  * CpmlPrimitive:
  48  * @segment: the source #CpmlSegment
  49  * @org: a pointer to the first point of the primitive
  50  * @data: the array of the path data, prepended by the header
  51  *
  52  * As for #CpmlSegment, also the primitive is unobtrusive. This
  53  * means CpmlPrimitive does not include any coordinates but instead
  54  * keeps pointers to the original segment (and, by transition, to
  55  * the underlying #CpmlPath struct).
  56  **/
  57
  58
  59 #include "cpml-internal.h"
  60 #include "cpml-extents.h"
  61 #include "cpml-segment.h"
  62 #include "cpml-primitive.h"
  63 #include "cpml-primitive-private.h"
  64 #include "cpml-line.h"
  65 #include "cpml-arc.h"
  66 #include "cpml-curve.h"
  67 #include "cpml-close.h"
  68 #include <stdlib.h>
  69 #include <string.h>
  70 #include <stdio.h>
  71
  72
  73 static const _CpmlPrimitiveClass *
  74                 get_class_from_type     (CpmlPrimitiveType        type);
  75 static const _CpmlPrimitiveClass *
  76                 get_class               (const CpmlPrimitive     *primitive);
  77 static void     dump_cairo_point        (const cairo_path_data_t *path_data);
  78
  79
  80 /**
  81  * cpml_primitive_copy:
  82  * @primitive: the destination #CpmlPrimitive
  83  * @src: the source #CpmlPrimitive
  84  *
  85  * Copies @src in @primitive. This is a shallow copy: the internal fields
  86  * of @primitive refer to the same memory as the original @src primitive.
  87  *
  88  * Returns: @primitive
  89  **/
  90 CpmlPrimitive *
  91 cpml_primitive_copy(CpmlPrimitive *primitive, const CpmlPrimitive *src)
  92 {
  93     return memcpy(primitive, src, sizeof(CpmlPrimitive));
  94 }
  95
  96 /**
  97  * cpml_primitive_from_segment:
  98  * @primitive: the destination #CpmlPrimitive struct
  99  * @segment: the source segment
 100  *
 101  * Initializes @primitive to the first primitive of @segment.
 102  *
 103  * Returns: @primitive
 104  **/
 105 CpmlPrimitive *
 106 cpml_primitive_from_segment(CpmlPrimitive *primitive, CpmlSegment *segment)
 107 {
 108     primitive->segment = segment;
 109
 110     /* The first element of a CpmlSegment is always a CAIRO_PATH_MOVE_TO,
 111      * as ensured by cpml_segment_from_cairo() and by the browsing APIs,
 112      * so the origin is in the second data item */
 113     primitive->org = &segment->data[1];
 114
 115     /* Also, the segment APIs ensure that @segment is prepended by
 116      * only one CAIRO_PATH_MOVE_TO */
 117     primitive->data = segment->data + segment->data[0].header.length;
 118
 119     return primitive;
 120 }
 121
 122 /**
 123  * cpml_primitive_reset:
 124  * @primitive: a #CpmlPrimitive
 125  *
 126  * Resets @primitive so it refers to the first primitive of the
 127  * source segment.
 128  **/
 129 void
 130 cpml_primitive_reset(CpmlPrimitive *primitive)
 131 {
 132     cpml_primitive_from_segment(primitive, primitive->segment);
 133 }
 134
 135 /**
 136  * cpml_primitive_next:
 137  * @primitive: a #CpmlPrimitive
 138  *
 139  *
 140  * Changes @primitive so it refers to the next primitive on the
 141  * source segment. If there are no more primitives, @primitive is
 142  * not changed and 0 is returned.
 143  *
 144  * Returns: 1 on success, 0 if no next primitive found or errors
 145  **/
 146 cairo_bool_t
 147 cpml_primitive_next(CpmlPrimitive *primitive)
 148 {
 149     cairo_path_data_t *new_data;
 150
 151     new_data = primitive->data + primitive->data->header.length;
 152     if (new_data - primitive->segment->data >= primitive->segment->num_data)
 153         return 0;
 154
 155     /* TODO: this is a temporary workaround to be removed as soon as
 156      * the issue #21 will be resolved */
 157     if (new_data->header.type == CAIRO_PATH_MOVE_TO)
 158         return 0;
 159
 160     primitive->org = cpml_primitive_get_point(primitive, -1);
 161     primitive->data = new_data;
 162
 163     return 1;
 164 }
 165
 166 /**
 167  * cpml_primitive_get_n_points:
 168  * @primitive: a #CpmlPrimitive
 169  *
 170  * Gets the number of points required to identify @primitive.
 171  * It is similar to cpml_primitive_type_get_n_points() but using
 172  * a @primitive instance instead of a type.
 173  *
 174  * Returns: the number of points or -1 on errors
 175  **/
 176 int
 177 cpml_primitive_get_n_points(const CpmlPrimitive *primitive)
 178 {
 179     return cpml_primitive_type_get_n_points(primitive->data->header.type);
 180 }
 181
 182 /**
 183  * cpml_primitive_get_point:
 184  * @primitive: a #CpmlPrimitive
 185  * @n_point: the index of the point to retrieve
 186  *
 187  * Gets the specified @n_point from @primitive. The index starts
 188  * at 0: if @n_point is 0, the start point (the origin) is
 189  * returned, 1 for the second point and so on. If @n_point is
 190  * negative, it is considered as a negative index from the end,
 191  * so that -1 is the end point, -2 the point before the end point
 192  * and so on.
 193  *
 194  * %CAIRO_PATH_CLOSE_PATH is managed in a special way: if @n_point
 195  * is -1 or 1 and @primitive is a close-path, this function cycles
 196  * the source #CpmlSegment and returns the first point. This is
 197  * needed because requesting the end point (or the second point)
 198  * of a close path is a valid operation and must returns the start
 199  * of the segment.
 200  *
 201  * Returns: a pointer to the requested point (in cairo format)
 202  *          or %NULL if the point is outside the valid range
 203  **/
 204 cairo_path_data_t *
 205 cpml_primitive_get_point(const CpmlPrimitive *primitive, int n_point)
 206 {
 207     int n_points;
 208
 209     /* For a start point request, simply return the origin
 210      * without further checking */
 211     if (n_point == 0)
 212         return primitive->org;
 213
 214     /* The CAIRO_PATH_CLOSE_PATH special case */
 215     if (primitive->data->header.type == CAIRO_PATH_CLOSE_PATH &&
 216         (n_point == 1 || n_point == -1))
 217         return &primitive->segment->data[1];
 218
 219     n_points = cpml_primitive_get_n_points(primitive);
 220     if (n_points < 0)
 221         return NULL;
 222
 223     /* If n_point is negative, consider it as a negative index from the end */
 224     if (n_point < 0)
 225         n_point = n_points + n_point;
 226
 227     /* Out of range condition */
 228     if (n_point < 0 || n_point >= n_points)
 229         return NULL;
 230
 231     return n_point == 0 ? primitive->org : &primitive->data[n_point];
 232 }
 233
 234 /**
 235  * cpml_primitive_to_cairo:
 236  * @primitive: a #CpmlPrimitive
 237  * @cr: the destination cairo context
 238  *
 239  * Renders a single @primitive to the @cr cairo context.
 240  * As a special case, if the primitive is a #CAIRO_PATH_CLOSE_PATH,
 241  * an equivalent line is rendered, because a close path left alone
 242  * is not renderable.
 243  *
 244  * Also a #CAIRO_PATH_ARC_TO primitive is treated specially, as it
 245  * is not natively supported by cairo and has its own rendering API.
 246  **/
 247 void
 248 cpml_primitive_to_cairo(const CpmlPrimitive *primitive, cairo_t *cr)
 249 {
 250     cairo_path_t path;
 251     cairo_path_data_t *path_data;
 252
 253     cairo_move_to(cr, primitive->org->point.x, primitive->org->point.y);
 254
 255     switch (primitive->data->header.type) {
 256
 257     case CAIRO_PATH_CLOSE_PATH:
 258         path_data = cpml_primitive_get_point(primitive, -1);
 259         cairo_line_to(cr, path_data->point.x, path_data->point.y);
 260         break;
 261
 262     case CAIRO_PATH_ARC_TO:
 263         cpml_arc_to_cairo(primitive, cr);
 264         break;
 265
 266     default:
 267         path.status = CAIRO_STATUS_SUCCESS;
 268         path.data = primitive->data;
 269         path.num_data = primitive->data->header.length;
 270         cairo_append_path(cr, &path);
 271         break;
 272     }
 273 }
 274
 275 /**
 276  * cpml_primitive_dump:
 277  * @primitive: a #CpmlPrimitive
 278  * @org_also:  whether to output also the origin coordinates
 279  *
 280  * Dumps info on the specified @primitive to stdout: useful for
 281  * debugging purposes. If @org_also is 1, a %CAIRO_PATH_MOVE_TO
 282  * to the origin is prepended to the data otherwise the
 283  * <structfield>org</structfield> field is not used.
 284  **/
 285 void
 286 cpml_primitive_dump(const CpmlPrimitive *primitive, cairo_bool_t org_also)
 287 {
 288     const cairo_path_data_t *data;
 289     int type, n, n_points;
 290
 291     data = primitive->data;
 292     type = data->header.type;
 293     n_points = cpml_primitive_get_n_points(primitive);
 294     if (n_points < 0) {
 295         printf("Unhandled primitive type (%d)\n", type);
 296         return;
 297     }
 298
 299     /* Dump the origin movement, if requested */
 300     if (org_also) {
 301         printf("Move to ");
 302         dump_cairo_point(primitive->org);
 303         printf("\n");
 304     }
 305
 306     switch (type) {
 307
 308     case CAIRO_PATH_LINE_TO:
 309         printf("Line to ");
 310         break;
 311
 312     case CAIRO_PATH_ARC_TO:
 313         printf("Arc to ");
 314         break;
 315
 316     case CAIRO_PATH_CURVE_TO:
 317         printf("Curve to ");
 318         break;
 319
 320     case CAIRO_PATH_CLOSE_PATH:
 321         printf("Path close");
 322         break;
 323
 324     default:
 325         printf("Unknown primitive (type = %d)", type);
 326         break;
 327     }
 328
 329     for (n = 1; n < n_points; ++n)
 330         dump_cairo_point(cpml_primitive_get_point(primitive, n));
 331
 332     printf("\n");
 333 }
 334
 335 /**
 336  * cpml_primitive_put_intersections_with_segment:
 337  * @primitive: a #CpmlPrimitive
 338  * @segment:   a #CpmlSegment
 339  * @dest:      the destination vector of #CpmlPair
 340  * @max:       maximum number of intersections to return
 341  *
 342  * Computes the intersections between @segment and @primitive by
 343  * sequentially scanning the primitives in @segment and looking
 344  * for intersections with @primitive.
 345  * If the intersections are more than @max, only the first @max pairs
 346  * are stored in @dest.
 347  *
 348  * Returns: the number of intersections found
 349  **/
 350 int
 351 cpml_primitive_put_intersections_with_segment(const CpmlPrimitive *primitive,
 352                                               const CpmlSegment *segment,
 353                                               CpmlPair *dest, int max)
 354 {
 355     CpmlPrimitive portion;
 356     int found;
 357
 358     cpml_primitive_from_segment(&portion, (CpmlSegment *) segment);
 359     found = 0;
 360
 361     while (found < max) {
 362         found += cpml_primitive_put_intersections(&portion, primitive,
 363                                                   max-found, dest+found);
 364         if (!cpml_primitive_next(&portion))
 365             break;
 366     }
 367
 368     return found;
 369 }
 370
 371
 372 /**
 373  * cpml_primitive_type_get_n_points:
 374  * @type: a primitive type
 375  *
 376  * Gets the number of points required to identify the @type primitive.
 377  *
 378  * <note><para>
 379  * This function is primitive dependent, that is every primitive has
 380  * its own implementation.
 381  * </para></note>
 382  *
 383  * Returns: the number of points or -1 on errors
 384  **/
 385 int
 386 cpml_primitive_type_get_n_points(CpmlPrimitiveType type)
 387 {
 388     const _CpmlPrimitiveClass *class_data = get_class_from_type(type);
 389
 390     if (class_data == NULL)
 391         return -1;
 392
 393     return class_data->n_points;
 394 }
 395
 396 /**
 397  * cpml_primitive_get_length:
 398  * @primitive: a #CpmlPrimitive
 399  *
 400  * Abstracts the length() family functions by providing a common
 401  * way to access the underlying primitive-specific implementation.
 402  * The function returns the length of @primitive.
 403  *
 404  * Returns: the requested length or 0 on errors
 405  **/
 406 double
 407 cpml_primitive_get_length(const CpmlPrimitive *primitive)
 408 {
 409     const _CpmlPrimitiveClass *class_data = get_class(primitive);
 410
 411     if (class_data == NULL || class_data->get_length == NULL)
 412         return 0;
 413
 414     return class_data->get_length(primitive);
 415 }
 416
 417 /**
 418  * cpml_primitive_put_extents:
 419  * @primitive: a #CpmlPrimitive
 420  * @extents: where to store the extents
 421  *
 422  * Abstracts the extents() family functions by providing a common
 423  * way to access the underlying primitive-specific implementation.
 424  *
 425  * This function stores in @extents the bounding box of @primitive.
 426  *
 427  * On errors, that is if the extents cannot be calculated for some
 428  * reason, this function does nothing.
 429  **/
 430 void
 431 cpml_primitive_put_extents(const CpmlPrimitive *primitive,
 432                            CpmlExtents *extents)
 433 {
 434     const _CpmlPrimitiveClass *class_data = get_class(primitive);
 435
 436     if (class_data == NULL || class_data->put_extents == NULL)
 437         return;
 438
 439     class_data->put_extents(primitive, extents);
 440 }
 441
 442 /**
 443  * cpml_primitive_put_pair_at:
 444  * @primitive: a #CpmlPrimitive
 445  * @pos:       the position value
 446  * @pair:      the destination #CpmlPair
 447  *
 448  * Abstracts the put_pair_at() family functions by providing a common
 449  * way to access the underlying primitive-specific implementation.
 450  *
 451  * It gets the coordinates of the point lying on @primitive
 452  * at position @pos. @pos is an homogeneous factor where 0 is the
 453  * start point, 1 the end point, 0.5 the mid point and so on.
 454  * @pos can be less than 0 or greater than %1, in which case the
 455  * coordinates of @pair are interpolated.
 456  *
 457  * On errors, that is if the coordinates cannot be calculated for
 458  * some reason, this function does nothing.
 459  **/
 460 void
 461 cpml_primitive_put_pair_at(const CpmlPrimitive *primitive, double pos,
 462                            CpmlPair *pair)
 463 {
 464     const _CpmlPrimitiveClass *class_data = get_class(primitive);
 465
 466     if (class_data == NULL || class_data->put_pair_at == NULL)
 467         return;
 468
 469     class_data->put_pair_at(primitive, pos, pair);
 470 }
 471
 472 /**
 473  * cpml_primitive_put_vector_at:
 474  * @primitive: a #CpmlPrimitive
 475  * @pos:       the position value
 476  * @vector:    the destination #CpmlVector
 477  *
 478  * Abstracts the put_vector_at() family functions by providing a common
 479  * way to access the underlying primitive-specific implementation.
 480  *
 481  * It gets the steepness of the point at position @pos on @primitive.
 482  * @pos is an homogeneous factor where 0 is the start point, 1 the
 483  * end point, 0.5 the mid point and so on.
 484  * @pos can be less than 0 or greater than %1, in which case the
 485  * coordinates of @pair are interpolated.
 486  *
 487  * On errors, that is if the steepness cannot be calculated for
 488  * some reason, this function does nothing.
 489  **/
 490 void
 491 cpml_primitive_put_vector_at(const CpmlPrimitive *primitive, double pos,
 492                              CpmlVector *vector)
 493 {
 494     const _CpmlPrimitiveClass *class_data = get_class(primitive);
 495
 496     if (class_data == NULL || class_data->put_vector_at == NULL)
 497         return;
 498
 499     class_data->put_vector_at(primitive, pos, vector);
 500 }
 501
 502 /**
 503  * cpml_primitive_get_closest_pos:
 504  * @primitive: a #CpmlPrimitive
 505  * @pair:      the coordinates of the subject point
 506  *
 507  * Returns the pos value of the point on @primitive nearest to @pair.
 508  * The returned value is always clamped between %0 and %1.
 509  *
 510  * Returns: the requested pos value between %0 and %1, or %-1 on errors
 511  **/
 512 double
 513 cpml_primitive_get_closest_pos(const CpmlPrimitive *primitive,
 514                                const CpmlPair *pair)
 515 {
 516     const _CpmlPrimitiveClass *class_data = get_class(primitive);
 517
 518     if (class_data == NULL || class_data->get_closest_pos == NULL)
 519         return -1;
 520
 521     return class_data->get_closest_pos(primitive, pair);
 522 }
 523
 524 /**
 525  * cpml_primitive_join:
 526  * @primitive: the first #CpmlPrimitive
 527  * @primitive2: the second #CpmlPrimitive
 528  *
 529  * Joins two primitive modifying the end point of @primitive and the
 530  * start point of @primitive2 so that the resulting points will overlap.
 531  *
 532  * <important>
 533  * <title>TODO</title>
 534  * <itemizedlist>
 535  * <listitem>Actually, the join is done by extending the end vector
 536  *           of @primitive and the start vector of @primitive2 and
 537  *           interpolating the intersection: this means no primitive
 538  *           dependent code is needed. Anyway, it is likely to change
 539  *           in the future because this approach is quite naive when
 540  *           curves are involved.</listitem>
 541  * </itemizedlist>
 542  * </important>
 543  *
 544  * Returns: 1 on success, 0 if the end vector of @primitive
 545  *          and the start vector of @primitive2 are parallel
 546  **/
 547 cairo_bool_t
 548 cpml_primitive_join(CpmlPrimitive *primitive, CpmlPrimitive *primitive2)
 549 {
 550     cairo_path_data_t *end1, *start2;
 551     CpmlPrimitive line1, line2;
 552     cairo_path_data_t data1[2], data2[2];
 553     CpmlPair joint;
 554
 555     end1 = cpml_primitive_get_point(primitive, -1);
 556     start2 = cpml_primitive_get_point(primitive2, 0);
 557
 558     /* Check if the primitives are yet connected */
 559     if (end1->point.x == start2->point.x && end1->point.y == start2->point.y)
 560         return 1;
 561
 562     line1.org = cpml_primitive_get_point(primitive, -2);
 563     line1.data = data1;
 564     data1[0].header.type = CAIRO_PATH_LINE_TO;
 565     data1[1] = *end1;
 566
 567     line2.org = start2;
 568     line2.data = data2;
 569     data2[0].header.type = CAIRO_PATH_LINE_TO;
 570     data2[1] = *cpml_primitive_get_point(primitive2, 1);
 571
 572     if (!cpml_line_put_intersections(&line1, &line2, 1, &joint))
 573         return 0;
 574
 575     cpml_pair_to_cairo(&joint, end1);
 576     cpml_pair_to_cairo(&joint, start2);
 577
 578     return 1;
 579 }
 580
 581 /**
 582  * cpml_primitive_put_intersections:
 583  * @primitive:  the first #CpmlPrimitive
 584  * @primitive2: the second #CpmlPrimitive
 585  * @max:        maximum number of intersections to return
 586  * @dest:       the destination buffer that can contain @max #CpmlPair
 587  *
 588  * Finds the intersection points between the given primitives and
 589  * returns the result in @dest. The size of @dest should be enough
 590  * to store @max #CpmlPair. The absoulte max number of intersections
 591  * is dependent from the type of the primitive involved in the
 592  * operation. If there are at least one Bézier curve involved, up to
 593  * 4 intersections could be returned. Otherwise, if there is an arc
 594  * the intersections will be 2 at maximum. For line line primitives,
 595  * there is only 1 point (or obviously 0 if the lines do not intersect).
 596  *
 597  * <note><para>
 598  * This function is primitive dependent: every new primitive must
 599  * expose API to get intersections with any other primitive type
 600  * (excluding %CAIRO_PATH_CLOSE_PATH, as it is converted to a line
 601  * primitive).</para>
 602  * <para>The convention used by CPML is that a primitive should
 603  * expose only intersection APIs dealing with lower complexity
 604  * primitives. This is required to avoid double functions:
 605  * you will have only a cpml_curve_put_intersections_with_line()
 606  * function, not a cpml_line_put_intersections_with_curve(), as
 607  * the latter is easily reproduced by calling the former with
 608  * @primitive2 and @primitive swapped.
 609  * </para></note>
 610  *
 611  * Returns: the number of intersection points found or 0 if the
 612  *          primitives do not intersect
 613  **/
 614 int
 615 cpml_primitive_put_intersections(const CpmlPrimitive *primitive,
 616                                  const CpmlPrimitive *primitive2,
 617                                  int max, CpmlPair *dest)
 618 {
 619     CpmlPrimitiveType type1, type2;
 620
 621     type1 = primitive->data->header.type;
 622     type2 = primitive->data->header.type;
 623
 624     /* Close path primitives are treated as line-to */
 625     if (type1 == CAIRO_PATH_CLOSE_PATH)
 626         type1 = CAIRO_PATH_LINE_TO;
 627     if (type2 == CAIRO_PATH_CLOSE_PATH)
 628         type2 = CAIRO_PATH_LINE_TO;
 629
 630     /* Order the two primitives in ascending complexity, to facilitate
 631      * the dispatcher logic */
 632     if (cpml_primitive_type_get_n_points(type1) > cpml_primitive_type_get_n_points(type2)) {
 633         const CpmlPrimitive *tmp_primitive;
 634         CpmlPrimitiveType tmp_type;
 635
 636         tmp_type = type1;
 637         tmp_primitive = primitive;
 638
 639         type1 = type2;
 640         primitive = primitive2;
 641
 642         type2 = tmp_type;
 643         primitive2 = tmp_primitive;
 644     }
 645
 646     /* Dispatcher: probably there's a smarter way to do this */
 647     switch (type1) {
 648
 649     case CAIRO_PATH_LINE_TO:
 650         if (type2 == CAIRO_PATH_LINE_TO)
 651             return cpml_line_put_intersections(primitive2, primitive,
 652                                                max, dest);
 653         else if (type2 == CAIRO_PATH_ARC_TO)
 654             return cpml_arc_put_intersections_with_line(primitive2, primitive,
 655                                                         max, dest);
 656         else if (type2 == CAIRO_PATH_CURVE_TO)
 657             return cpml_curve_put_intersections_with_line(primitive2, primitive,
 658                                                           max, dest);
 659         break;
 660
 661     case CAIRO_PATH_ARC_TO:
 662         if (type2 == CAIRO_PATH_ARC_TO)
 663             return cpml_arc_put_intersections(primitive2, primitive,
 664                                               max, dest);
 665         else if (type2 == CAIRO_PATH_CURVE_TO)
 666             return cpml_curve_put_intersections_with_arc(primitive2, primitive,
 667                                                          max, dest);
 668         break;
 669
 670     case CAIRO_PATH_CURVE_TO:
 671         if (type2 == CAIRO_PATH_CURVE_TO)
 672             return cpml_curve_put_intersections(primitive2, primitive,
 673                                                 max, dest);
 674         break;
 675
 676     default:
 677         break;
 678     }
 679
 680     /* Primitive combination not found */
 681     return 0;
 682 }
 683
 684 /**
 685  * cpml_primitive_offset:
 686  * @primitive: a #CpmlPrimitive
 687  * @offset: distance for the computed offset primitive
 688  *
 689  * Given a primitive, computes the same (or approximated) parallel
 690  * primitive distant @offset from the original one and returns
 691  * the result by changing @primitive.
 692  *
 693  * <note><para>
 694  * This function is primitive dependent, that is every primitive has
 695  * its own implementation.
 696  * </para></note>
 697  **/
 698 void
 699 cpml_primitive_offset(CpmlPrimitive *primitive, double offset)
 700 {
 701     switch (primitive->data->header.type) {
 702
 703     case CAIRO_PATH_LINE_TO:
 704         cpml_line_offset(primitive, offset);
 705         break;
 706
 707     case CAIRO_PATH_ARC_TO:
 708         cpml_arc_offset(primitive, offset);
 709         break;
 710
 711     case CAIRO_PATH_CURVE_TO:
 712         cpml_curve_offset(primitive, offset);
 713         break;
 714
 715     case CAIRO_PATH_CLOSE_PATH:
 716         cpml_close_offset(primitive, offset);
 717         break;
 718
 719     default:
 720         break;
 721     }
 722 }
 723
 724
 725 static const _CpmlPrimitiveClass *
 726 get_class_from_type(CpmlPrimitiveType type)
 727 {
 728     switch (type) {
 729     case CAIRO_PATH_LINE_TO:
 730         return _cpml_line_get_class();
 731     case CAIRO_PATH_ARC_TO:
 732         return _cpml_arc_get_class();
 733     case CAIRO_PATH_CURVE_TO:
 734         return _cpml_curve_get_class();
 735     case CAIRO_PATH_CLOSE_PATH:
 736         return _cpml_close_get_class();
 737     default:
 738         break;
 739     }
 740
 741     return NULL;
 742 }
 743
 744 static const _CpmlPrimitiveClass *
 745 get_class(const CpmlPrimitive *primitive)
 746 {
 747     return get_class_from_type(primitive->data->header.type);
 748 }
 749
 750 static void
 751 dump_cairo_point(const cairo_path_data_t *path_data)
 752 {
 753     printf("(%g %g) ", path_data->point.x, path_data->point.y);
 754 }