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-primitive.h"
  60 #include "cpml-line.h"
  61 #include "cpml-arc.h"
  62 #include "cpml-curve.h"
  63 #include "cpml-close.h"
  64
  65 #include <stdlib.h>
  66 #include <string.h>
  67 #include <stdio.h>
  68
  69
  70 static void     dump_cairo_point        (const cairo_path_data_t *path_data);
  71
  72
  73 /**
  74  * cpml_primitive_copy:
  75  * @primitive: the destination #CpmlPrimitive
  76  * @src: the source #CpmlPrimitive
  77  *
  78  * Copies @src in @primitive. This is a shallow copy: the internal fields
  79  * of @primitive refer to the same memory as the original @src primitive.
  80  *
  81  * Return value: @primitive
  82  **/
  83 CpmlPrimitive *
  84 cpml_primitive_copy(CpmlPrimitive *primitive, const CpmlPrimitive *src)
  85 {
  86     return memcpy(primitive, src, sizeof(CpmlPrimitive));
  87 }
  88
  89 /**
  90  * cpml_primitive_from_segment:
  91  * @primitive: the destination #CpmlPrimitive struct
  92  * @segment: the source segment
  93  *
  94  * Initializes @primitive to the first primitive of @segment.
  95  *
  96  * Return value: @primitive
  97  **/
  98 CpmlPrimitive *
  99 cpml_primitive_from_segment(CpmlPrimitive *primitive, CpmlSegment *segment)
 100 {
 101     primitive->segment = segment;
 102
 103     /* The first element of a CpmlSegment is always a CAIRO_PATH_MOVE_TO,
 104      * as ensured by cpml_segment_from_cairo() and by the browsing APIs,
 105      * so the origin is in the second data item */
 106     primitive->org = &segment->data[1];
 107
 108     /* Also, the segment APIs ensure that @segment is prepended by
 109      * only one CAIRO_PATH_MOVE_TO */
 110     primitive->data = segment->data + 2;
 111
 112     return primitive;
 113 }
 114
 115 /**
 116  * cpml_primitive_reset:
 117  * @primitive: a #CpmlPrimitive
 118  *
 119  * Resets @primitive so it refers to the first primitive of the
 120  * source segment.
 121  **/
 122 void
 123 cpml_primitive_reset(CpmlPrimitive *primitive)
 124 {
 125     primitive->org = &primitive->segment->data[1];
 126     primitive->data = primitive->segment->data + 2;
 127 }
 128
 129 /**
 130  * cpml_primitive_next:
 131  * @primitive: a #CpmlPrimitive
 132  *
 133  *
 134  * Changes @primitive so it refers to the next primitive on the
 135  * source segment. If there are no more primitives, @primitive is
 136  * not changed and 0 is returned.
 137  *
 138  * Return value: 1 on success, 0 if no next primitive found or errors
 139  **/
 140 cairo_bool_t
 141 cpml_primitive_next(CpmlPrimitive *primitive)
 142 {
 143     cairo_path_data_t *new_data;
 144
 145     new_data = primitive->data + primitive->data->header.length;
 146     if (new_data - primitive->segment->data >= primitive->segment->num_data)
 147         return 0;
 148
 149     primitive->org = cpml_primitive_get_point(primitive, -1);
 150     primitive->data = new_data;
 151
 152     return 1;
 153 }
 154
 155 /**
 156  * cpml_primitive_get_npoints:
 157  * @primitive: a #CpmlPrimitive
 158  *
 159  * Gets the number of points required to identify @primitive.
 160  * It is similar to cpml_primitive_type_get_npoints() but using
 161  * a @primitive instance instead of a type.
 162  *
 163  * Return value: the number of points or -1 on errors
 164  **/
 165 int
 166 cpml_primitive_get_npoints(const CpmlPrimitive *primitive)
 167 {
 168     return cpml_primitive_type_get_npoints(primitive->data->header.type);
 169 }
 170
 171 /**
 172  * cpml_primitive_get_point:
 173  * @primitive: a #CpmlPrimitive
 174  * @npoint: the index of the point to retrieve
 175  *
 176  * Gets the specified @npoint from @primitive. The index starts
 177  * at 0: if @npoint is 0, the start point (the origin) is
 178  * returned, 1 for the second point and so on. If @npoint is
 179  * negative, it is considered as a negative index from the end,
 180  * so that -1 is the end point, -2 the point before the end point
 181  * and so on.
 182  *
 183  * %CAIRO_PATH_CLOSE_PATH is managed in a special way: if @npoint
 184  * is -1 or 1 and @primitive is a close-path, this function cycles
 185  * the source #CpmlSegment and returns the first point. This is
 186  * needed because requesting the end point (or the second point)
 187  * of a close path is a valid operation and must returns the start
 188  * of the segment.
 189  *
 190  * Return value: a pointer to the requested point (in cairo format)
 191  *               or %NULL if the point is outside the valid range
 192  **/
 193 cairo_path_data_t *
 194 cpml_primitive_get_point(const CpmlPrimitive *primitive, int npoint)
 195 {
 196     int npoints;
 197
 198     /* For a start point request, simply return the origin
 199      * without further checking */
 200     if (npoint == 0)
 201         return primitive->org;
 202
 203     /* The CAIRO_PATH_CLOSE_PATH special case */
 204     if (primitive->data->header.type == CAIRO_PATH_CLOSE_PATH &&
 205         (npoint == 1 || npoint == -1))
 206         return &primitive->segment->data[1];
 207
 208     npoints = cpml_primitive_get_npoints(primitive);
 209     if (npoints < 0)
 210         return NULL;
 211
 212     /* If npoint is negative, consider it as a negative index from the end */
 213     if (npoint < 0)
 214         npoint = npoints + npoint;
 215
 216     /* Out of range condition */
 217     if (npoint < 0 || npoint >= npoints)
 218         return NULL;
 219
 220     return npoint == 0 ? primitive->org : &primitive->data[npoint];
 221 }
 222
 223 /**
 224  * cpml_primitive_to_cairo:
 225  * @primitive: a #CpmlPrimitive
 226  * @cr: the destination cairo context
 227  *
 228  * Renders a single @primitive to the @cr cairo context.
 229  * As a special case, if the primitive is a #CAIRO_PATH_CLOSE_PATH,
 230  * an equivalent line is rendered, because a close path left alone
 231  * is not renderable.
 232  *
 233  * Also a #CAIRO_PATH_ARC_TO primitive is treated specially, as it
 234  * is not natively supported by cairo and has its own rendering API.
 235  **/
 236 void
 237 cpml_primitive_to_cairo(const CpmlPrimitive *primitive, cairo_t *cr)
 238 {
 239     cairo_path_t path;
 240     cairo_path_data_t *path_data;
 241
 242     cairo_move_to(cr, primitive->org->point.x, primitive->org->point.y);
 243
 244     switch (primitive->data->header.type) {
 245
 246     case CAIRO_PATH_CLOSE_PATH:
 247         path_data = cpml_primitive_get_point(primitive, -1);
 248         cairo_line_to(cr, path_data->point.x, path_data->point.y);
 249         break;
 250
 251     case CAIRO_PATH_ARC_TO:
 252         cpml_arc_to_cairo(primitive, cr);
 253         break;
 254
 255     default:
 256         path.status = CAIRO_STATUS_SUCCESS;
 257         path.data = primitive->data;
 258         path.num_data = primitive->data->header.length;
 259         cairo_append_path(cr, &path);
 260         break;
 261     }
 262 }
 263
 264 /**
 265  * cpml_primitive_dump:
 266  * @primitive: a #CpmlPrimitive
 267  * @org_also:  whether to output also the origin coordinates
 268  *
 269  * Dumps info on the specified @primitive to stdout: useful for
 270  * debugging purposes. If @org_also is 1, a %CAIRO_PATH_MOVE_TO
 271  * to the origin is prepended to the data otherwise the
 272  * <structfield>org</structfield> field is not used.
 273  **/
 274 void
 275 cpml_primitive_dump(const CpmlPrimitive *primitive, cairo_bool_t org_also)
 276 {
 277     const cairo_path_data_t *data;
 278     int type, n, npoints;
 279
 280     data = primitive->data;
 281     type = data->header.type;
 282     npoints = cpml_primitive_get_npoints(primitive);
 283     if (npoints < 0) {
 284         printf("Unhandled primitive type (%d)\n", type);
 285         return;
 286     }
 287
 288     /* Dump the origin movement, if requested */
 289     if (org_also) {
 290         printf("Move to ");
 291         dump_cairo_point(primitive->org);
 292         printf("\n");
 293     }
 294
 295     switch (type) {
 296
 297     case CAIRO_PATH_LINE_TO:
 298         printf("Line to ");
 299         break;
 300
 301     case CAIRO_PATH_ARC_TO:
 302         printf("Arc to ");
 303         break;
 304
 305     case CAIRO_PATH_CURVE_TO:
 306         printf("Curve to ");
 307         break;
 308
 309     case CAIRO_PATH_CLOSE_PATH:
 310         printf("Path close");
 311         break;
 312
 313     default:
 314         printf("Unknown primitive (type = %d)", type);
 315         break;
 316     }
 317
 318     for (n = 1; n < npoints; ++n)
 319         dump_cairo_point(cpml_primitive_get_point(primitive, n));
 320
 321     printf("\n");
 322 }
 323
 324 /**
 325  * cpml_primitive_intersection_with_segment:
 326  * @primitive: a #CpmlPrimitive
 327  * @segment:   a #CpmlSegment
 328  * @dest:      the destination vector of #CpmlPair
 329  * @max:       maximum number of intersections to return
 330  *
 331  * Computes the intersections between @segment and @primitive by
 332  * sequentially scanning the primitives in @segment and looking
 333  * for intersections with @primitive.
 334  * If the intersections are more than @max, only the first @max pairs
 335  * are stored in @dest.
 336  *
 337  * Return value: the number of intersections found
 338  **/
 339 int
 340 cpml_primitive_intersection_with_segment(const CpmlPrimitive *primitive,
 341                                          const CpmlSegment *segment,
 342                                          CpmlPair *dest, int max)
 343 {
 344     CpmlPrimitive portion;
 345     int found;
 346
 347     cpml_primitive_from_segment(&portion, (CpmlSegment *) segment);
 348     found = 0;
 349
 350     while (found < max) {
 351         found += cpml_primitive_intersection(&portion, primitive,
 352                                              dest+found, max-found);
 353         if (!cpml_primitive_next(&portion))
 354             break;
 355     }
 356
 357     return found;
 358 }
 359
 360
 361 /**
 362  * cpml_primitive_type_get_npoints:
 363  * @type: a primitive type
 364  *
 365  * Gets the number of points required to identify the @type primitive.
 366  *
 367  * <note><para>
 368  * This function is primitive dependent, that is every primitive has
 369  * its own implementation.
 370  * </para></note>
 371  *
 372  * Return value: the number of points or -1 on errors
 373  **/
 374 int
 375 cpml_primitive_type_get_npoints(CpmlPrimitiveType type)
 376 {
 377     switch (type) {
 378
 379     case CAIRO_PATH_LINE_TO:
 380         return cpml_line_type_get_npoints();
 381
 382     case CAIRO_PATH_ARC_TO:
 383         return cpml_arc_type_get_npoints();
 384
 385     case CAIRO_PATH_CURVE_TO:
 386         return cpml_curve_type_get_npoints();
 387
 388     case CAIRO_PATH_CLOSE_PATH:
 389         return cpml_close_type_get_npoints();
 390
 391     default:
 392         break;
 393     }
 394
 395     return -1;
 396 }
 397
 398 /**
 399  * cpml_primitive_length:
 400  * @primitive: a #CpmlPrimitive
 401  *
 402  * Abstracts the length() family functions by providing a common
 403  * way to access the underlying primitive-specific implementation.
 404  * The function returns the length of @primitive.
 405  *
 406  * <note><para>
 407  * This function is primitive dependent, that is every primitive has
 408  * its own implementation.
 409  * </para></note>
 410  *
 411  * Return value: the requested length or 0 on errors
 412  **/
 413 double
 414 cpml_primitive_length(const CpmlPrimitive *primitive)
 415 {
 416     switch (primitive->data->header.type) {
 417
 418     case CAIRO_PATH_LINE_TO:
 419     case CAIRO_PATH_CLOSE_PATH:
 420         return cpml_line_length(primitive);
 421
 422     case CAIRO_PATH_ARC_TO:
 423         return cpml_arc_length(primitive);
 424
 425     case CAIRO_PATH_CURVE_TO:
 426         return cpml_curve_length(primitive);
 427
 428     default:
 429         break;
 430     }
 431
 432     return 0.;
 433 }
 434
 435 /**
 436  * cpml_primitive_extents:
 437  * @primitive: a #CpmlPrimitive
 438  * @extents: where to store the extents
 439  *
 440  * Abstracts the extents() family functions by providing a common
 441  * way to access the underlying primitive-specific implementation.
 442  * The function stores in @extents the bounding box of @primitive.
 443  *
 444  * <note><para>
 445  * This function is primitive dependent, that is every primitive has
 446  * its own implementation.
 447  * </para></note>
 448  **/
 449 void
 450 cpml_primitive_extents(const CpmlPrimitive *primitive, CpmlExtents *extents)
 451 {
 452     switch (primitive->data->header.type) {
 453
 454     case CAIRO_PATH_LINE_TO:
 455     case CAIRO_PATH_CLOSE_PATH:
 456         return cpml_line_extents(primitive, extents);
 457
 458     case CAIRO_PATH_ARC_TO:
 459         return cpml_arc_extents(primitive, extents);
 460
 461     case CAIRO_PATH_CURVE_TO:
 462         return cpml_curve_extents(primitive, extents);
 463
 464     default:
 465         extents->is_defined = 0;
 466         break;
 467     }
 468 }
 469
 470 /**
 471  * cpml_primitive_pair_at:
 472  * @primitive: a #CpmlPrimitive
 473  * @pair:      the destination #CpmlPair
 474  * @pos:       the position value
 475  *
 476  * Abstracts the pair_at() family functions by providing a common
 477  * way to access the underlying primitive-specific implementation.
 478  *
 479  * It gets the coordinates of the point lying on @primitive
 480  * at position @pos. @pos is an homogeneous factor where 0 is the
 481  * start point, 1 the end point, 0.5 the mid point and so on.
 482  * The relation 0 < @pos < 1 should be satisfied, although some
 483  * primitives accept value outside this range.
 484  *
 485  * <note><para>
 486  * This function is primitive dependent, that is every primitive has
 487  * its own implementation.
 488  * </para></note>
 489  **/
 490 void
 491 cpml_primitive_pair_at(const CpmlPrimitive *primitive,
 492                        CpmlPair *pair, double pos)
 493 {
 494     switch (primitive->data->header.type) {
 495
 496     case CAIRO_PATH_LINE_TO:
 497         cpml_line_pair_at(primitive, pair, pos);
 498         break;
 499
 500     case CAIRO_PATH_ARC_TO:
 501         cpml_arc_pair_at(primitive, pair, pos);
 502         break;
 503
 504     case CAIRO_PATH_CURVE_TO:
 505         cpml_curve_pair_at(primitive, pair, pos);
 506         break;
 507
 508     case CAIRO_PATH_CLOSE_PATH:
 509         cpml_close_pair_at(primitive, pair, pos);
 510         break;
 511
 512     default:
 513         break;
 514     }
 515 }
 516
 517 /**
 518  * cpml_primitive_vector_at:
 519  * @primitive: a #CpmlPrimitive
 520  * @vector:    the destination #CpmlVector
 521  * @pos:       the position value
 522  *
 523  * Abstracts the vector_at() family functions by providing a common
 524  * way to access the underlying primitive-specific implementation.
 525  *
 526  * It gets the steepness of the point at position @pos on @primitive.
 527  * @pos is an homogeneous factor where 0 is the start point, 1 the
 528  * end point, 0.5 the mid point and so on.
 529  * The relation 0 < @pos < 1 should be satisfied, although some
 530  * primitives accept value outside this range.
 531  *
 532  * <note><para>
 533  * This function is primitive dependent, that is every primitive has
 534  * its own implementation.
 535  * </para></note>
 536  **/
 537 void
 538 cpml_primitive_vector_at(const CpmlPrimitive *primitive,
 539                          CpmlVector *vector, double pos)
 540 {
 541     switch (primitive->data->header.type) {
 542
 543     case CAIRO_PATH_LINE_TO:
 544         cpml_line_vector_at(primitive, vector, pos);
 545         break;
 546
 547     case CAIRO_PATH_ARC_TO:
 548         cpml_arc_vector_at(primitive, vector, pos);
 549         break;
 550
 551     case CAIRO_PATH_CURVE_TO:
 552         cpml_curve_vector_at(primitive, vector, pos);
 553         break;
 554
 555     case CAIRO_PATH_CLOSE_PATH:
 556         cpml_close_vector_at(primitive, vector, pos);
 557         break;
 558
 559     default:
 560         break;
 561     }
 562 }
 563
 564 /**
 565  * cpml_primitive_near_pos:
 566  * @primitive: a #CpmlPrimitive
 567  * @pair:      the coordinates of the subject point
 568  *
 569  * Returns the pos value of the point on @primitive nearest to @pair.
 570  * The returned value is always between 0 and 1 or -1 in case of errors.
 571  *
 572  * <note><para>
 573  * This function is primitive dependent, that is every primitive has
 574  * its own implementation.
 575  * </para></note>
 576  *
 577  * Return value: the requested pos value between 0 and 1 or -1 on errors
 578  **/
 579 double
 580 cpml_primitive_near_pos(const CpmlPrimitive *primitive, const CpmlPair *pair)
 581 {
 582     switch (primitive->data->header.type) {
 583
 584     case CAIRO_PATH_LINE_TO:
 585         return cpml_line_near_pos(primitive, pair);
 586
 587     case CAIRO_PATH_ARC_TO:
 588         return cpml_arc_near_pos(primitive, pair);
 589
 590     case CAIRO_PATH_CURVE_TO:
 591         return cpml_curve_near_pos(primitive, pair);
 592
 593     case CAIRO_PATH_CLOSE_PATH:
 594         return cpml_close_near_pos(primitive, pair);
 595
 596     default:
 597         break;
 598     }
 599
 600     return -1.;
 601 }
 602
 603 /**
 604  * cpml_primitive_join:
 605  * @primitive: the first #CpmlPrimitive
 606  * @primitive2: the second #CpmlPrimitive
 607  *
 608  * Joins two primitive modifying the end point of @primitive and the
 609  * start point of @primitive2 so that the resulting points will overlap.
 610  *
 611  * <important>
 612  * <title>TODO</title>
 613  * <itemizedlist>
 614  * <listitem>Actually, the join is done by extending the end vector
 615  *           of @primitive and the start vector of @primitive2 and
 616  *           interpolating the intersection: this means no primitive
 617  *           dependent code is needed. Anyway, it is likely to change
 618  *           in the future because this approach is quite naive when
 619  *           curves are involved.</listitem>
 620  * </itemizedlist>
 621  * </important>
 622  *
 623  * Return value: 1 on success, 0 if the end vector of @primitive
 624  *               and the start vector of @primitive2 are parallel
 625  **/
 626 cairo_bool_t
 627 cpml_primitive_join(CpmlPrimitive *primitive, CpmlPrimitive *primitive2)
 628 {
 629     cairo_path_data_t *end1, *start2;
 630     CpmlPrimitive line1, line2;
 631     cairo_path_data_t data1[2], data2[2];
 632     CpmlPair joint;
 633
 634     end1 = cpml_primitive_get_point(primitive, -1);
 635     start2 = cpml_primitive_get_point(primitive2, 0);
 636
 637     /* Check if the primitives are yet connected */
 638     if (end1->point.x == start2->point.x && end1->point.y == start2->point.y)
 639         return 1;
 640
 641     line1.org = cpml_primitive_get_point(primitive, -2);
 642     line1.data = data1;
 643     data1[0].header.type = CAIRO_PATH_LINE_TO;
 644     data1[1] = *end1;
 645
 646     line2.org = start2;
 647     line2.data = data2;
 648     data2[0].header.type = CAIRO_PATH_LINE_TO;
 649     data2[1] = *cpml_primitive_get_point(primitive2, 1);
 650
 651     if (!cpml_line_intersection(&line1, &line2, &joint, 1))
 652         return 0;
 653
 654     cpml_pair_to_cairo(&joint, end1);
 655     cpml_pair_to_cairo(&joint, start2);
 656
 657     return 1;
 658 }
 659
 660 /**
 661  * cpml_primitive_intersection:
 662  * @primitive:  the first #CpmlPrimitive
 663  * @primitive2: the second #CpmlPrimitive
 664  * @dest:       the destination #CpmlPair (or a vector of #CpmlPair)
 665  * @max:        maximum number of intersections to return
 666  *
 667  * Finds the intersection points between the given primitives and
 668  * returns the result in @dest. The size of @dest should be enough
 669  * to store @max #CpmlPair. The absoulte max number of intersections
 670  * is dependent from the type of the primitive involved in the
 671  * operation. If there are at least one Bézier curve involved, up to
 672  * 4 intersections could be returned. Otherwise, if there is an arc
 673  * the intersections will be 2 at maximum. For line line primitives,
 674  * there is only 1 point (or obviously 0 if the lines do not intersect).
 675  *
 676  * <note><para>
 677  * This function is primitive dependent: every new primitive must
 678  * expose API to get intersections with any other primitive type
 679  * (excluding %CAIRO_PATH_CLOSE_PATH, as it is converted to a line
 680  * primitive).</para>
 681  * <para>The convention used by CPML is that a primitive should
 682  * expose only intersection APIs dealing with lower complexity
 683  * primitives. This is required to avoid double functions:
 684  * you will have only a cpml_curve_intersection_with_line() function,
 685  * not a cpml_line_intersection_with_curve(), as the latter is
 686  * easily reproduced by calling the former with @primitive2
 687  * and @primitive swapped.
 688  * </para></note>
 689  *
 690  * Return value: the number of intersection points found or 0 if the
 691  *               primitives do not intersect
 692  **/
 693 int
 694 cpml_primitive_intersection(const CpmlPrimitive *primitive,
 695                             const CpmlPrimitive *primitive2,
 696                             CpmlPair *dest, int max)
 697 {
 698     CpmlPrimitiveType type1, type2;
 699
 700     type1 = primitive->data->header.type;
 701     type2 = primitive->data->header.type;
 702
 703     /* Close path primitives are treated as line-to */
 704     if (type1 == CAIRO_PATH_CLOSE_PATH)
 705         type1 = CAIRO_PATH_LINE_TO;
 706     if (type2 == CAIRO_PATH_CLOSE_PATH)
 707         type2 = CAIRO_PATH_LINE_TO;
 708
 709     /* Order the two primitives in ascending complexity, to facilitate
 710      * the dispatcher logic */
 711     if (cpml_primitive_type_get_npoints(type1) > cpml_primitive_type_get_npoints(type2)) {
 712         const CpmlPrimitive *tmp_primitive;
 713         CpmlPrimitiveType tmp_type;
 714
 715         tmp_type = type1;
 716         tmp_primitive = primitive;
 717
 718         type1 = type2;
 719         primitive = primitive2;
 720
 721         type2 = tmp_type;
 722         primitive2 = tmp_primitive;
 723     }
 724
 725     /* Dispatcher: probably there's a smarter way to do this */
 726     switch (type1) {
 727
 728     case CAIRO_PATH_LINE_TO:
 729         if (type2 == CAIRO_PATH_LINE_TO)
 730             return cpml_line_intersection(primitive2, primitive,
 731                                           dest, max);
 732         else if (type2 == CAIRO_PATH_ARC_TO)
 733             return cpml_arc_intersection_with_line(primitive2, primitive,
 734                                                    dest, max);
 735         else if (type2 == CAIRO_PATH_CURVE_TO)
 736             return cpml_curve_intersection_with_line(primitive2, primitive,
 737                                                      dest, max);
 738         break;
 739
 740     case CAIRO_PATH_ARC_TO:
 741         if (type2 == CAIRO_PATH_ARC_TO)
 742             return cpml_arc_intersection(primitive2, primitive,
 743                                          dest, max);
 744         else if (type2 == CAIRO_PATH_CURVE_TO)
 745             return cpml_curve_intersection_with_arc(primitive2, primitive,
 746                                                     dest, max);
 747         break;
 748
 749     case CAIRO_PATH_CURVE_TO:
 750         if (type2 == CAIRO_PATH_CURVE_TO)
 751             return cpml_curve_intersection(primitive2, primitive,
 752                                            dest, max);
 753         break;
 754
 755     default:
 756         break;
 757     }
 758
 759     /* Primitive combination not found */
 760     return 0;
 761 }
 762
 763 /**
 764  * cpml_primitive_offset:
 765  * @primitive: a #CpmlPrimitive
 766  * @offset: distance for the computed offset primitive
 767  *
 768  * Given a primitive, computes the same (or approximated) parallel
 769  * primitive distant @offset from the original one and returns
 770  * the result by changing @primitive.
 771  *
 772  * <note><para>
 773  * This function is primitive dependent, that is every primitive has
 774  * its own implementation.
 775  * </para></note>
 776  **/
 777 void
 778 cpml_primitive_offset(CpmlPrimitive *primitive, double offset)
 779 {
 780     switch (primitive->data->header.type) {
 781
 782     case CAIRO_PATH_LINE_TO:
 783         cpml_line_offset(primitive, offset);
 784         break;
 785
 786     case CAIRO_PATH_ARC_TO:
 787         cpml_arc_offset(primitive, offset);
 788         break;
 789
 790     case CAIRO_PATH_CURVE_TO:
 791         cpml_curve_offset(primitive, offset);
 792         break;
 793
 794     case CAIRO_PATH_CLOSE_PATH:
 795         cpml_close_offset(primitive, offset);
 796         break;
 797
 798     default:
 799         break;
 800     }
 801 }
 802
 803 static void
 804 dump_cairo_point(const cairo_path_data_t *path_data)
 805 {
 806     printf("(%g %g) ", path_data->point.x, path_data->point.y);
 807 }