adg/adg-edges.c

   1 /* ADG - Automatic Drawing Generation
   2  * Copyright (C) 2007,2008,2009 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:adg-edges
  23  * @short_description: A model with the edges of another model
  24  *
  25  * The #AdgEdges can be used to render the edges of a yet existing
  26  * #AdgTrail source. It is useful for any part made by revolution,
  27  * where the shape is symmetric along a specific axis and thus the
  28  * corners can be easily computed.
  29  *
  30  * <important>
  31  * <title>TODO</title>
  32  * <itemizedlist>
  33  * <listitem>Actually the edges of the source trail are always computed
  34  *           taking the y=0 axis as the origin: anyway, it would be not
  35  *           too hard to apply an arbitrary transformation to aling the
  36  *           trail on the y=0 axis, compute the edges as usual and apply
  37  *           the inverse transformation to the result.</listitem>
  38  * </itemizedlist>
  39  * </important>
  40  **/
  41
  42 /**
  43  * AdgEdges:
  44  *
  45  * All fields are private and should not be used directly.
  46  * Use its public methods instead.
  47  **/
  48
  49
  50 #include "adg-edges.h"
  51 #include "adg-edges-private.h"
  52 #include "adg-pair.h"
  53 #include "adg-intl.h"
  54
  55 #define PARENT_OBJECT_CLASS  ((GObjectClass *) adg_edges_parent_class)
  56 #define PARENT_MODEL_CLASS   ((AdgModelClass *) adg_edges_parent_class)
  57
  58
  59 enum {
  60     PROP_0,
  61     PROP_SOURCE,
  62     PROP_CRITICAL_ANGLE
  63 };
  64
  65
  66 static void             dispose                 (GObject        *object);
  67 static void             finalize                (GObject        *object);
  68 static void             get_property            (GObject        *object,
  69                                                  guint           param_id,
  70                                                  GValue         *value,
  71                                                  GParamSpec     *pspec);
  72 static void             set_property            (GObject        *object,
  73                                                  guint           param_id,
  74                                                  const GValue   *value,
  75                                                  GParamSpec     *pspec);
  76 static void             clear                   (AdgModel       *model);
  77 static CpmlPath *       get_cpml_path           (AdgTrail       *trail);
  78 static gboolean         set_source              (AdgEdges       *edges,
  79                                                  AdgTrail       *source);
  80 static gboolean         set_critical_angle      (AdgEdges       *edges,
  81                                                  gdouble         angle);
  82 static void             unset_source            (AdgEdges       *edges);
  83 static void             clear_cpml_path         (AdgEdges       *edges);
  84 static GSList *         get_vertices            (CpmlSegment    *segment,
  85                                                  gdouble         threshold);
  86 static GSList *         optimize_vertices       (GSList         *vertices);
  87 static GArray *         build_array             (const GSList   *vertices);
  88
  89
  90 G_DEFINE_TYPE(AdgEdges, adg_edges, ADG_TYPE_TRAIL);
  91
  92
  93 static void
  94 adg_edges_class_init(AdgEdgesClass *klass)
  95 {
  96     GObjectClass *gobject_class;
  97     AdgModelClass *model_class;
  98     AdgTrailClass *trail_class;
  99     GParamSpec *param;
 100
 101     gobject_class = (GObjectClass *) klass;
 102     model_class = (AdgModelClass *) klass;
 103     trail_class = (AdgTrailClass *) klass;
 104
 105     g_type_class_add_private(klass, sizeof(AdgEdgesPrivate));
 106
 107     gobject_class->dispose = dispose;
 108     gobject_class->finalize = finalize;
 109     gobject_class->get_property = get_property;
 110     gobject_class->set_property = set_property;
 111
 112     model_class->clear = clear;
 113
 114     trail_class->get_cpml_path = get_cpml_path;
 115
 116     param = g_param_spec_object("source",
 117                                 P_("Source"),
 118                                 P_("The source where the edges should be computed from"),
 119                                 ADG_TYPE_TRAIL,
 120                                 G_PARAM_READWRITE | G_PARAM_CONSTRUCT);
 121     g_object_class_install_property(gobject_class, PROP_SOURCE, param);
 122
 123     param = g_param_spec_double("critical-angle",
 124                                 P_("Critical Angle"),
 125                                 P_("The angle that defines which corner generates an edge (if the corner angle is greater than this critical angle) and which edge is ignored"),
 126                                 0, G_PI, G_PI / 45,
 127                                 G_PARAM_READWRITE);
 128     g_object_class_install_property(gobject_class, PROP_SOURCE, param);
 129 }
 130
 131 static void
 132 adg_edges_init(AdgEdges *edges)
 133 {
 134     AdgEdgesPrivate *data = G_TYPE_INSTANCE_GET_PRIVATE(edges, ADG_TYPE_EDGES,
 135                                                         AdgEdgesPrivate);
 136
 137     data->source = NULL;
 138     data->threshold = sin(G_PI / 45);
 139     data->threshold *= data->threshold * 2;
 140
 141     data->cpml.path.status = CAIRO_STATUS_INVALID_PATH_DATA;
 142     data->cpml.array = NULL;
 143
 144     edges->data = data;
 145 }
 146
 147 static void
 148 dispose(GObject *object)
 149 {
 150     AdgEdges *edges = (AdgEdges *) object;
 151
 152     adg_edges_set_source(edges, NULL);
 153
 154     if (PARENT_OBJECT_CLASS->dispose != NULL)
 155         PARENT_OBJECT_CLASS->dispose(object);
 156 }
 157
 158 static void
 159 finalize(GObject *object)
 160 {
 161     clear_cpml_path((AdgEdges *) object);
 162
 163     if (PARENT_OBJECT_CLASS->finalize != NULL)
 164         PARENT_OBJECT_CLASS->finalize(object);
 165 }
 166
 167 static void
 168 get_property(GObject *object, guint prop_id, GValue *value, GParamSpec *pspec)
 169 {
 170     AdgEdges *edges;
 171     AdgEdgesPrivate *data;
 172
 173     edges = (AdgEdges *) object;
 174     data = edges->data;
 175
 176     switch (prop_id) {
 177     case PROP_SOURCE:
 178         g_value_set_object(value, &data->source);
 179         break;
 180     case PROP_CRITICAL_ANGLE:
 181         g_value_set_double(value, adg_edges_get_critical_angle(edges));
 182         break;
 183     default:
 184         G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 185         break;
 186     }
 187 }
 188
 189 static void
 190 set_property(GObject *object, guint prop_id,
 191              const GValue *value, GParamSpec *pspec)
 192 {
 193     AdgEdges *edges = (AdgEdges *) object;
 194
 195     switch (prop_id) {
 196     case PROP_SOURCE:
 197         set_source(edges, g_value_get_object(value));
 198         break;
 199     case PROP_CRITICAL_ANGLE:
 200         set_critical_angle(edges, g_value_get_double(value));
 201         break;
 202     default:
 203         G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 204         break;
 205     }
 206 }
 207
 208
 209 /**
 210  * adg_edges_new:
 211  *
 212  * Creates a new undefined model to keep track of the edges of
 213  * another model. You should at least set the referred #AdgTrail
 214  * with adg_edges_set_source().
 215  *
 216  * Returns: the newly created edges model
 217  **/
 218 AdgEdges *
 219 adg_edges_new(void)
 220 {
 221     return g_object_new(ADG_TYPE_EDGES, NULL);
 222 }
 223
 224 /**
 225  * adg_edges_new_with_source:
 226  *
 227  * Creates a new edges model explicitely specifying the source trail.
 228  *
 229  * Returns: the newly created edges model
 230  **/
 231 AdgEdges *
 232 adg_edges_new_with_source(AdgTrail *source)
 233 {
 234     return g_object_new(ADG_TYPE_EDGES, "source", source, NULL);
 235 }
 236
 237 /**
 238  * adg_edges_get_source:
 239  * @edges: an #AdgEdges
 240  *
 241  * Gets the source #AdgTrail of this @edges model.
 242  *
 243  * Returns: the requested #AdgTrail or %NULL on errors
 244  **/
 245 AdgTrail *
 246 adg_edges_get_source(AdgEdges *edges)
 247 {
 248     AdgEdgesPrivate *data;
 249
 250     g_return_val_if_fail(ADG_IS_EDGES(edges), NULL);
 251
 252     data = edges->data;
 253
 254     return data->source;
 255 }
 256
 257 /**
 258  * adg_edges_set_source:
 259  * @edges: an #AdgEdges
 260  * @source: the new source #AdgTrail
 261  *
 262  * Sets @source as the source trail for @edges.
 263  **/
 264 void
 265 adg_edges_set_source(AdgEdges *edges, AdgTrail *source)
 266 {
 267     g_return_if_fail(ADG_IS_EDGES(edges));
 268
 269     if (set_source(edges, source))
 270         g_object_notify((GObject *) edges, "source");
 271 }
 272
 273 /**
 274  * adg_edges_get_critical_angle:
 275  * @edges: an #AdgEdges
 276  *
 277  * Gets the current critical angle of @edges. The angle is internally
 278  * converted to a threshold value, so the returned angle could be not
 279  * exactly what set throught adg_edges_set_critical_angle().
 280  *
 281  * Returns: the value (in radians) of the critical angle
 282  **/
 283 gdouble
 284 adg_edges_get_critical_angle(AdgEdges *edges)
 285 {
 286     AdgEdgesPrivate *data;
 287
 288     g_return_val_if_fail(ADG_IS_EDGES(edges), 0);
 289
 290     data = edges->data;
 291
 292     return asin(sqrt(data->threshold / 2));
 293 }
 294
 295 /**
 296  * adg_edges_set_critical_angle:
 297  * @edges: an #AdgEdges
 298  * @angle: the new angle (in radians)
 299  *
 300  * Sets a new critical angle on @edges. The critical angle defines
 301  * what corner should generate an edge and what not. Typical values
 302  * are close to %0, being %0 the lowest angle where all the corners
 303  * generate an edge.
 304  **/
 305 void
 306 adg_edges_set_critical_angle(AdgEdges *edges, gdouble angle)
 307 {
 308     g_return_if_fail(ADG_IS_EDGES(edges));
 309
 310     if (set_critical_angle(edges, angle))
 311         g_object_notify((GObject *) edges, "critical-angle");
 312 }
 313
 314
 315 static void
 316 clear(AdgModel *model)
 317 {
 318     clear_cpml_path((AdgEdges *) model);
 319
 320     if (PARENT_MODEL_CLASS->clear != NULL)
 321         PARENT_MODEL_CLASS->clear(model);
 322 }
 323
 324 static CpmlPath *
 325 get_cpml_path(AdgTrail *trail)
 326 {
 327     AdgEdges *edges;
 328     AdgEdgesPrivate *data;
 329
 330     edges = (AdgEdges *) trail;
 331     data = edges->data;
 332
 333     /* Check for cached path */
 334     if (data->cpml.path.status == CAIRO_STATUS_SUCCESS)
 335         return &data->cpml.path;
 336
 337     clear_cpml_path((AdgEdges *) trail);
 338
 339     if (data->source != NULL) {
 340         CpmlSegment segment;
 341         GSList *vertices;
 342
 343         adg_trail_get_segment(data->source, &segment, 1);
 344         vertices = get_vertices(&segment, 0.01);
 345         vertices = optimize_vertices(vertices);
 346         data->cpml.array = build_array(vertices);
 347
 348         g_slist_foreach(vertices, (GFunc) g_free, NULL);
 349         g_slist_free(vertices);
 350
 351         data->cpml.path.status = CAIRO_STATUS_SUCCESS;
 352         data->cpml.path.data = (cairo_path_data_t *) (data->cpml.array)->data;
 353         data->cpml.path.num_data = (data->cpml.array)->len;
 354     }
 355
 356     return &data->cpml.path;
 357 }
 358
 359 static gboolean
 360 set_source(AdgEdges *edges, AdgTrail *source)
 361 {
 362     AdgEntity *entity;
 363     AdgEdgesPrivate *data;
 364
 365     entity = (AdgEntity *) edges;
 366     data = edges->data;
 367
 368     if (source == data->source)
 369         return FALSE;
 370
 371     if (data->source != NULL)
 372         g_object_weak_unref((GObject *) data->source,
 373                             (GWeakNotify) unset_source, edges);
 374
 375     data->source = source;
 376     clear((AdgModel *) edges);
 377
 378     if (data->source != NULL)
 379         g_object_weak_ref((GObject *) data->source,
 380                           (GWeakNotify) unset_source, edges);
 381
 382     return TRUE;
 383 }
 384
 385 static gboolean
 386 set_critical_angle(AdgEdges *edges, gdouble angle)
 387 {
 388     AdgEdgesPrivate *data;
 389     gdouble threshold;
 390
 391     data = edges->data;
 392     threshold = sin(angle);
 393     threshold *= threshold * 2;
 394
 395     if (threshold == data->threshold)
 396         return FALSE;
 397
 398     data->threshold = threshold;
 399
 400     return TRUE;
 401 }
 402
 403 static void
 404 unset_source(AdgEdges *edges)
 405 {
 406     AdgEdgesPrivate *data = edges->data;
 407
 408     if (data->source != NULL)
 409         set_source(edges, NULL);
 410 }
 411
 412 static void
 413 clear_cpml_path(AdgEdges *edges)
 414 {
 415     AdgEdgesPrivate *data = edges->data;
 416
 417     if (data->cpml.array != NULL) {
 418         g_array_free(data->cpml.array, TRUE);
 419         data->cpml.array = NULL;
 420     }
 421
 422     data->cpml.path.status = CAIRO_STATUS_INVALID_PATH_DATA;
 423     data->cpml.path.data = NULL;
 424     data->cpml.path.num_data = 0;
 425 }
 426
 427 static GSList *
 428 get_vertices(CpmlSegment *segment, gdouble threshold)
 429 {
 430     GSList *vertices;
 431     CpmlPrimitive primitive;
 432     CpmlVector old, new;
 433
 434     vertices = NULL;
 435     cpml_primitive_from_segment(&primitive, segment);
 436     old.x = old.y = 0;
 437
 438     do {
 439         /* The first vector and the undefined ones
 440          * must always be skipped */
 441         if (old.x != 0 || old.y != 0) {
 442             cpml_vector_set_length(&old, 1);
 443             cpml_primitive_vector_at(&primitive, &new, 0);
 444             cpml_vector_set_length(&new, 1);
 445
 446             /* Vertical vectors are always added, as they represent
 447              * a vertical side and could be filleted, thus skipping
 448              * the edge detection */
 449             if (new.x == 0 ||
 450                 cpml_pair_squared_distance(&old, &new) > threshold) {
 451                 AdgPair pair;
 452
 453                 cpml_primitive_pair_at(&primitive, &pair, 0);
 454                 vertices = g_slist_prepend(vertices, adg_pair_dup(&pair));
 455             }
 456         }
 457
 458         cpml_primitive_vector_at(&primitive, &old, 1);
 459     } while (cpml_primitive_next(&primitive));
 460
 461     return g_slist_reverse(vertices);
 462 }
 463
 464 /* Removes adjacent vertices lying on the same edge */
 465 static GSList *
 466 optimize_vertices(GSList *vertices)
 467 {
 468     GSList *vertex, *old_vertex;
 469     AdgPair *pair, *old_pair;
 470
 471     /* Check for empty list */
 472     if (vertices == NULL)
 473         return vertices;
 474
 475     old_vertex = vertices;
 476
 477     while ((vertex = old_vertex->next) != NULL) {
 478         pair = vertex->data;
 479         old_pair = old_vertex->data;
 480
 481         if (pair->x != old_pair->x) {
 482             old_vertex = vertex;
 483             continue;
 484         }
 485
 486         if (old_pair->y < pair->y) {
 487             /* Preserve the old vertex and remove the current one */
 488             g_free(pair);
 489             vertices = g_slist_delete_link(vertices, vertex);
 490         } else {
 491             /* Preserve the current vertex and remove the old one */
 492             g_free(old_pair);
 493             vertices = g_slist_delete_link(vertices, old_vertex);
 494             old_vertex = vertex;
 495         }
 496     }
 497
 498     return vertices;
 499 }
 500
 501 static GArray *
 502 build_array(const GSList *vertices)
 503 {
 504     cairo_path_data_t line[4];
 505     GArray *array;
 506     const GSList *vertex, *vertex2;
 507     const AdgPair *pair, *pair2;
 508
 509     line[0].header.type = CAIRO_PATH_MOVE_TO;
 510     line[0].header.length = 2;
 511     line[2].header.type = CAIRO_PATH_LINE_TO;
 512     line[2].header.length = 2;
 513
 514     array = g_array_new(FALSE, FALSE, sizeof(cairo_path_data_t));
 515     vertex = vertices;
 516
 517     while (vertex != NULL) {
 518         pair = vertex->data;
 519         vertex = vertex->next;
 520         vertex2 = vertex;
 521
 522         while (vertex2 != NULL) {
 523             pair2 = vertex2->data;
 524
 525             if (pair->x == pair2->x) {
 526                 /* Opposite vertex found: append a line in the path
 527                  * and quit from this loop */
 528                 cpml_pair_to_cairo(pair, &line[1]);
 529                 cpml_pair_to_cairo(pair2, &line[3]);
 530                 array = g_array_append_vals(array, line, G_N_ELEMENTS(line));
 531                 break;
 532             }
 533
 534             vertex2 = vertex2->next;
 535         }
 536     }
 537
 538     return array;
 539 }