adg/adg-entity.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-entity
  23  * @short_description: The base class for renderable objects
  24  *
  25  * This abstract class provides the base for all renderable objects.
  26  *
  27  * To provide a proper #AdgEntity derived type, you must at least
  28  * implement the render() virtual method. Also, if you are using
  29  * some sort of caching, you must implement invalidate() to clear
  30  * this cache.
  31  **/
  32
  33 /**
  34  * AdgEntity:
  35  *
  36  * All fields are private and should not be used directly.
  37  * Use its public methods instead.
  38  **/
  39
  40 /**
  41  * AdgEntityClass:
  42  * @parent_set: called after the parent has changed
  43  * @context_set: called after the context has changed
  44  * @invalidate: invalidating callback, used to clear the cache
  45  * @render: rendering callback, it must be implemented
  46  *
  47  * Any entity (if not abstract) must implement at least the @render method.
  48  **/
  49
  50
  51 #include "adg-entity.h"
  52 #include "adg-entity-private.h"
  53 #include "adg-canvas.h"
  54 #include "adg-font-style.h"
  55 #include "adg-dim-style.h"
  56 #include "adg-intl.h"
  57
  58 #define PARENT_OBJECT_CLASS  ((GObjectClass *) adg_entity_parent_class)
  59
  60
  61 enum {
  62     PROP_0,
  63     PROP_PARENT,
  64     PROP_CONTEXT,
  65     PROP_GLOBAL_MAP,
  66     PROP_LOCAL_MAP
  67 };
  68
  69 enum {
  70     PARENT_SET,
  71     CONTEXT_SET,
  72     INVALIDATE,
  73     RENDER,
  74     LAST_SIGNAL
  75 };
  76
  77
  78 static void             dispose                 (GObject         *object);
  79 static void             get_property            (GObject         *object,
  80                                                  guint            prop_id,
  81                                                  GValue          *value,
  82                                                  GParamSpec      *pspec);
  83 static void             set_property            (GObject         *object,
  84                                                  guint            prop_id,
  85                                                  const GValue    *value,
  86                                                  GParamSpec      *pspec);
  87 static gboolean         set_parent              (AdgEntity       *entity,
  88                                                  AdgEntity       *parent);
  89 static gboolean         set_context             (AdgEntity       *entity,
  90                                                  AdgContext      *context);
  91 static void             set_global_map          (AdgEntity       *entity,
  92                                                  const AdgMatrix *map);
  93 static void             set_local_map           (AdgEntity       *entity,
  94                                                  const AdgMatrix *map);
  95 static void             real_invalidate         (AdgEntity       *entity,
  96                                                  gpointer         user_data);
  97 static void             real_render             (AdgEntity       *entity,
  98                                                  cairo_t         *cr,
  99                                                  gpointer         user_data);
 100
 101 static guint signals[LAST_SIGNAL] = { 0 };
 102
 103
 104 G_DEFINE_ABSTRACT_TYPE(AdgEntity, adg_entity, G_TYPE_INITIALLY_UNOWNED);
 105
 106
 107 static void
 108 adg_entity_class_init(AdgEntityClass *klass)
 109 {
 110     GObjectClass *gobject_class;
 111     GParamSpec *param;
 112     GClosure *closure;
 113     GType param_types[1];
 114
 115     gobject_class = (GObjectClass *) klass;
 116
 117     g_type_class_add_private(klass, sizeof(AdgEntityPrivate));
 118
 119     gobject_class->get_property = get_property;
 120     gobject_class->set_property = set_property;
 121     gobject_class->dispose = dispose;
 122
 123     klass->parent_set = NULL;
 124     klass->context_set = NULL;
 125     klass->invalidate = NULL;
 126     klass->render = NULL;
 127
 128     param = g_param_spec_object("parent",
 129                                 P_("Parent Entity"),
 130                                 P_("The parent entity of this entity or NULL if this is a top-level entity"),
 131                                 ADG_TYPE_ENTITY, G_PARAM_READWRITE);
 132     g_object_class_install_property(gobject_class, PROP_PARENT, param);
 133
 134     param = g_param_spec_object("context",
 135                                 P_("Context"),
 136                                 P_("The context associated to this entity or NULL to inherit the parent context"),
 137                                 ADG_TYPE_CONTEXT, G_PARAM_READWRITE);
 138     g_object_class_install_property(gobject_class, PROP_CONTEXT, param);
 139
 140     param = g_param_spec_boxed("global-map",
 141                                P_("Global Map"),
 142                                P_("The transformation to be combined with the parent ones to get the global matrix"),
 143                                ADG_TYPE_MATRIX, G_PARAM_READWRITE);
 144     g_object_class_install_property(gobject_class, PROP_GLOBAL_MAP, param);
 145
 146     param = g_param_spec_boxed("local-map",
 147                                P_("Local Map"),
 148                                P_("The transformation to be combined with the parent ones to get the local matrix"),
 149                                ADG_TYPE_MATRIX, G_PARAM_READWRITE);
 150     g_object_class_install_property(gobject_class, PROP_LOCAL_MAP, param);
 151
 152     /**
 153      * AdgEntity::parent-set:
 154      * @entity: an #AdgEntity
 155      * @old_parent: the old parent
 156      *
 157      * Emitted after the parent entity has changed. The new parent
 158      * can be inspected using adg_entity_get_parent().
 159      *
 160      * It is allowed for both old and new parent to be %NULL.
 161      **/
 162     signals[PARENT_SET] = g_signal_new("parent-set",
 163                                        G_OBJECT_CLASS_TYPE(gobject_class),
 164                                        G_SIGNAL_RUN_FIRST,
 165                                        G_STRUCT_OFFSET(AdgEntityClass, parent_set),
 166                                        NULL, NULL,
 167                                        g_cclosure_marshal_VOID__OBJECT,
 168                                        G_TYPE_NONE, 1, ADG_TYPE_ENTITY);
 169
 170     /**
 171      * AdgEntity::context-set:
 172      * @entity: an #AdgEntity
 173      * @old_context: the old context
 174      *
 175      * Emitted after the context has changed.
 176      * Emitted after the context has changed. The new context can be
 177      * inspected using adg_entity_get_context().
 178      *
 179      * It is allowed for both old and new context to be %NULL.
 180      **/
 181     signals[CONTEXT_SET] = g_signal_new("context-set",
 182                                         G_OBJECT_CLASS_TYPE(gobject_class),
 183                                         G_SIGNAL_RUN_FIRST,
 184                                         G_STRUCT_OFFSET(AdgEntityClass, context_set),
 185                                         NULL, NULL,
 186                                         g_cclosure_marshal_VOID__OBJECT,
 187                                         G_TYPE_NONE, 1, ADG_TYPE_CONTEXT);
 188
 189     /**
 190      * AdgEntity::invalidate:
 191      * @entity: an #AdgEntity
 192      *
 193      * The inverse of the rendering. Usually, invalidation causes the
 194      * cache of @entity to be cleared. After a succesful invalidation
 195      * the rendered flag is reset: you can access its state using
 196      * adg_entity_get_rendered().
 197      **/
 198     closure = g_cclosure_new(G_CALLBACK(real_invalidate),
 199                              (gpointer)0xdeadbeaf, NULL);
 200     signals[INVALIDATE] = g_signal_newv("invalidate", ADG_TYPE_ENTITY,
 201                                         G_SIGNAL_RUN_LAST, closure, NULL, NULL,
 202                                         g_cclosure_marshal_VOID__VOID,
 203                                         G_TYPE_NONE, 0, param_types);
 204
 205     /**
 206      * AdgEntity::render:
 207      * @entity: an #AdgEntity
 208      * @cr: a #cairo_t drawing context
 209      *
 210      * Causes the rendering of @entity on @cr. After a succesful rendering
 211      * the rendered flag is set: you can access its state using
 212      * adg_entity_get_rendered().
 213      **/
 214     closure = g_cclosure_new(G_CALLBACK(real_render),
 215                              (gpointer)0xdeadbeaf, NULL);
 216     param_types[0] = G_TYPE_POINTER;
 217     signals[RENDER] = g_signal_newv("render", ADG_TYPE_ENTITY,
 218                                     G_SIGNAL_RUN_LAST, closure, NULL, NULL,
 219                                     g_cclosure_marshal_VOID__POINTER,
 220                                     G_TYPE_NONE, 1, param_types);
 221 }
 222
 223 static void
 224 adg_entity_init(AdgEntity *entity)
 225 {
 226     AdgEntityPrivate *data = G_TYPE_INSTANCE_GET_PRIVATE(entity,
 227                                                          ADG_TYPE_ENTITY,
 228                                                          AdgEntityPrivate);
 229     data->parent = NULL;
 230     data->flags = 0;
 231     data->context = NULL;
 232     cairo_matrix_init_identity(&data->local_map);
 233     cairo_matrix_init_identity(&data->global_map);
 234
 235     entity->data = data;
 236 }
 237
 238 static void
 239 dispose(GObject *object)
 240 {
 241     AdgEntity *entity;
 242     AdgEntity *parent;
 243
 244     entity = (AdgEntity *) object;
 245     parent = adg_entity_get_parent(entity);
 246
 247     /* These calls will emit a "notify" signal both for parent and
 248      * context if they are not NULL. Consequentially, the references
 249      * to the old parent and context are dropped. */
 250     adg_entity_set_parent(entity, NULL);
 251     adg_entity_set_context(entity, NULL);
 252
 253     if (PARENT_OBJECT_CLASS->dispose != NULL)
 254         PARENT_OBJECT_CLASS->dispose(object);
 255 }
 256
 257
 258 static void
 259 get_property(GObject *object, guint prop_id, GValue *value, GParamSpec *pspec)
 260 {
 261     AdgEntity *entity;
 262     AdgEntityPrivate *data;
 263
 264     entity = (AdgEntity *) object;
 265     data = entity->data;
 266
 267     switch (prop_id) {
 268     case PROP_PARENT:
 269         g_value_set_object(value, data->parent);
 270         break;
 271     case PROP_CONTEXT:
 272         g_value_set_object(value, adg_entity_get_context(entity));
 273         break;
 274     case PROP_GLOBAL_MAP:
 275         g_value_set_boxed(value, &data->global_map);
 276         break;
 277     case PROP_LOCAL_MAP:
 278         g_value_set_boxed(value, &data->local_map);
 279         break;
 280     default:
 281         G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 282         break;
 283     }
 284 }
 285
 286 static void
 287 set_property(GObject *object,
 288              guint prop_id, const GValue *value, GParamSpec *pspec)
 289 {
 290     AdgEntity *entity = (AdgEntity *) object;
 291
 292     switch (prop_id) {
 293     case PROP_PARENT:
 294         set_parent(entity, g_value_get_object(value));
 295         break;
 296     case PROP_CONTEXT:
 297         set_context(entity, g_value_get_object(value));
 298         break;
 299     case PROP_GLOBAL_MAP:
 300         set_global_map(entity, g_value_get_boxed(value));
 301         break;
 302     case PROP_LOCAL_MAP:
 303         set_local_map(entity, g_value_get_boxed(value));
 304         break;
 305     default:
 306         G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 307         break;
 308     }
 309 }
 310
 311
 312 /**
 313  * adg_entity_get_parent:
 314  * @entity: an #AdgEntity
 315  *
 316  * Gets the parent of @entity.
 317  *
 318  * Returns: the parent entity or %NULL on errors or if @entity is a toplevel
 319  **/
 320 AdgEntity *
 321 adg_entity_get_parent(AdgEntity *entity)
 322 {
 323     AdgEntityPrivate *data;
 324
 325     g_return_val_if_fail(ADG_IS_ENTITY(entity), NULL);
 326
 327     data = entity->data;
 328
 329     return data->parent;
 330 }
 331
 332 /**
 333  * adg_entity_set_parent:
 334  * @entity: an #AdgEntity
 335  * @parent: the parent entity
 336  *
 337  * Sets a new parent on @entity.
 338  *
 339  * This function is only useful in entity implementations.
 340  **/
 341 void
 342 adg_entity_set_parent(AdgEntity *entity, AdgEntity *parent)
 343 {
 344     g_return_if_fail(ADG_IS_ENTITY(entity));
 345
 346     if (set_parent(entity, parent))
 347         g_object_notify((GObject *) entity, "parent");
 348 }
 349
 350 /**
 351  * adg_entity_context:
 352  * @entity: an #AdgEntity instance
 353  *
 354  * Gets the context to be used for @entity. If no context was
 355  * explicitely set, it returns the parent context.
 356  *
 357  * Returns: the requested context or %NULL on errors or if @entity
 358  *          does not have any parent with a context defined
 359  **/
 360 AdgContext *
 361 adg_entity_context(AdgEntity *entity)
 362 {
 363     AdgContext *context;
 364
 365     g_return_val_if_fail(ADG_IS_ENTITY(entity), NULL);
 366
 367     context = adg_entity_get_context(entity);
 368
 369     if (context == NULL) {
 370         AdgEntity *parent = adg_entity_get_parent(entity);
 371
 372         if (parent != NULL)
 373             context = adg_entity_get_context(parent);
 374     }
 375
 376     return context;
 377 }
 378
 379 /**
 380  * adg_entity_get_context:
 381  * @entity: an #AdgEntity instance
 382  *
 383  * Gets the context associated to @entity. This is an accessor method:
 384  * if you need to get the context for rendering, use adg_entity_context()
 385  * instead.
 386  *
 387  * Returns: the context binded to @entity
 388  **/
 389 AdgContext *
 390 adg_entity_get_context(AdgEntity *entity)
 391 {
 392     AdgEntityPrivate *data;
 393
 394     g_return_val_if_fail(ADG_IS_ENTITY(entity), NULL);
 395
 396     data = entity->data;
 397
 398     return data->context;
 399 }
 400
 401 /**
 402  * adg_entity_set_context:
 403  * @entity: an #AdgEntity instance
 404  * @context: the new context
 405  *
 406  * Sets a new context. The old context (if any) will be unreferenced
 407  * while a new reference will be added to @context.
 408  **/
 409 void
 410 adg_entity_set_context(AdgEntity *entity, AdgContext *context)
 411 {
 412     g_return_if_fail(ADG_IS_ENTITY(entity));
 413     g_return_if_fail(ADG_IS_CONTEXT(context));
 414
 415     if (set_context(entity, context))
 416         g_object_notify((GObject *) entity, "context");
 417 }
 418
 419 /**
 420  * adg_entity_get_canvas:
 421  * @entity: an #AdgEntity
 422  *
 423  * Walks on the @entity hierarchy and gets the first parent of @entity that is
 424  * of #AdgCanvas derived type.
 425  *
 426  * Returns: the requested canvas or %NULL on errors or if there is
 427  *          no #AdgCanvas in the @entity hierarchy
 428  **/
 429 AdgCanvas *
 430 adg_entity_get_canvas(AdgEntity *entity)
 431 {
 432     g_return_val_if_fail(ADG_IS_ENTITY(entity), NULL);
 433
 434     while (entity) {
 435         if (ADG_IS_CANVAS(entity))
 436             return (AdgCanvas *) entity;
 437
 438         entity = (AdgEntity *) adg_entity_get_parent(entity);
 439     }
 440
 441     return NULL;
 442 }
 443
 444 /**
 445  * adg_entity_get_rendered:
 446  * @entity: an #AdgEntity object
 447  *
 448  * This function is only useful in entity implementations.
 449  * Gets the rendered flag of @entity.
 450  *
 451  * Returns: the current rendered state
 452  **/
 453 gboolean
 454 adg_entity_get_rendered(AdgEntity *entity)
 455 {
 456     AdgEntityPrivate *data;
 457
 458     g_return_val_if_fail(ADG_IS_ENTITY(entity), FALSE);
 459
 460     data = entity->data;
 461
 462     return ADG_ISSET(data->flags, RENDERED);
 463 }
 464
 465 /**
 466  * adg_entity_set_rendered:
 467  * @entity: an #AdgEntity object
 468  * @rendered: new state for the rendered flag
 469  *
 470  * This function is only useful in entity implementations.
 471  * Sets the rendered flag of @entity to @rendered.
 472  **/
 473 void
 474 adg_entity_set_rendered(AdgEntity *entity, gboolean rendered)
 475 {
 476     AdgEntityPrivate *data;
 477
 478     g_return_if_fail(ADG_IS_ENTITY(entity));
 479
 480     data = entity->data;
 481
 482     if (rendered)
 483         ADG_SET(data->flags, RENDERED);
 484     else
 485         ADG_UNSET(data->flags, RENDERED);
 486 }
 487
 488 /**
 489  * adg_entity_get_global_map:
 490  * @entity: an #AdgEntity object
 491  * @map: where to store the global map
 492  *
 493  * Gets the transformation to be used to compute the global matrix
 494  * of @entity and store it in @map.
 495  **/
 496 void
 497 adg_entity_get_global_map(AdgEntity *entity, AdgMatrix *map)
 498 {
 499     AdgEntityPrivate *data;
 500
 501     g_return_if_fail(ADG_IS_ENTITY(entity));
 502     g_return_if_fail(map != NULL);
 503
 504     data = entity->data;
 505     adg_matrix_copy(map, &data->global_map);
 506 }
 507
 508 /**
 509  * adg_entity_set_global_map:
 510  * @entity: an #AdgEntity object
 511  * @map: the new map
 512  *
 513  * Sets the new global transformation of @entity to @map:
 514  * the old map is discarded. If @map is %NULL an identity
 515  * matrix is implied.
 516  **/
 517 void
 518 adg_entity_set_global_map(AdgEntity *entity, const AdgMatrix *map)
 519 {
 520     g_return_if_fail(ADG_IS_ENTITY(entity));
 521
 522     set_global_map(entity, map);
 523     g_object_notify((GObject *) entity, "global-map");
 524 }
 525
 526 /**
 527  * adg_entity_transform_global_map:
 528  * @entity: an #AdgEntity object
 529  * @transformation: the transformation to apply
 530  *
 531  * Applies a transformation to the global map of @entity. This is
 532  * equivalent to the following code:
 533  *
 534  * <informalexample><programlisting>
 535  * AdgMatrix tmp_map;
 536  * adg_entity_get_global_map(entity, &tmp_map);
 537  * cairo_matrix_multiply(&tmp_map, transformation, &tmp_map);
 538  * adg_entity_set_global_map(entity, &tmp_map);
 539  * </programlisting></informalexample>
 540  **/
 541 void
 542 adg_entity_transform_global_map(AdgEntity *entity,
 543                                 const AdgMatrix *transformation)
 544 {
 545     AdgEntityPrivate *data;
 546
 547     g_return_if_fail(ADG_IS_ENTITY(entity));
 548     g_return_if_fail(transformation != NULL);
 549
 550     data = entity->data;
 551
 552     cairo_matrix_multiply(&data->global_map, transformation, &data->global_map);
 553     g_object_notify((GObject *) entity, "global-map");
 554 }
 555
 556 /**
 557  * adg_entity_get_global_matrix:
 558  * @entity: an #AdgEntity object
 559  * @matrix: where to store the global matrix
 560  *
 561  * Computes the global matrix by combining all the global maps of the
 562  * @entity hierarchy and stores the result in @matrix.
 563  **/
 564 void
 565 adg_entity_get_global_matrix(AdgEntity *entity, AdgMatrix *matrix)
 566 {
 567     AdgEntityPrivate *data;
 568
 569     g_return_if_fail(ADG_IS_ENTITY(entity));
 570     g_return_if_fail(matrix != NULL);
 571
 572     data = entity->data;
 573
 574     if (data->parent == NULL) {
 575         adg_matrix_copy(matrix, &data->global_map);
 576     } else {
 577         adg_entity_get_global_matrix((AdgEntity *) data->parent, matrix);
 578         cairo_matrix_multiply(matrix, &data->global_map, matrix);
 579     }
 580 }
 581
 582 /**
 583  * adg_entity_get_local_map:
 584  * @entity: an #AdgEntity object
 585  * @map: where to store the local map
 586  *
 587  * Gets the transformation to be used to compute the local matrix
 588  * of @entity and store it in @map.
 589  **/
 590 void
 591 adg_entity_get_local_map(AdgEntity *entity, AdgMatrix *map)
 592 {
 593     AdgEntityPrivate *data;
 594
 595     g_return_if_fail(ADG_IS_ENTITY(entity));
 596     g_return_if_fail(map != NULL);
 597
 598     data = entity->data;
 599     adg_matrix_copy(map, &data->local_map);
 600 }
 601
 602 /**
 603  * adg_entity_set_local_map:
 604  * @entity: an #AdgEntity object
 605  * @map: the new map
 606  *
 607  * Sets the new global transformation of @entity to @map:
 608  * the old map is discarded. If @map is %NULL an identity
 609  * matrix is implied.
 610  **/
 611 void
 612 adg_entity_set_local_map(AdgEntity *entity, const AdgMatrix *map)
 613 {
 614     g_return_if_fail(ADG_IS_ENTITY(entity));
 615
 616     set_local_map(entity, map);
 617     g_object_notify((GObject *) entity, "local-map");
 618 }
 619
 620 /**
 621  * adg_entity_transform_local_map:
 622  * @entity: an #AdgEntity object
 623  * @transformation: the transformation to apply
 624  *
 625  * Applies a transformation to the local map of @entity. This is
 626  * equivalent to the following code:
 627  *
 628  * <informalexample><programlisting>
 629  * AdgMatrix tmp_map;
 630  * adg_entity_get_local_map(entity, &tmp_map);
 631  * cairo_matrix_multiply(&tmp_map, transformation, &tmp_map);
 632  * adg_entity_set_local_map(entity, &tmp_map);
 633  * </programlisting></informalexample>
 634  **/
 635 void
 636 adg_entity_transform_local_map(AdgEntity *entity,
 637                                const AdgMatrix *transformation)
 638 {
 639     AdgEntityPrivate *data;
 640
 641     g_return_if_fail(ADG_IS_ENTITY(entity));
 642     g_return_if_fail(transformation != NULL);
 643
 644     data = entity->data;
 645
 646     cairo_matrix_multiply(&data->local_map, transformation, &data->local_map);
 647     g_object_notify((GObject *) entity, "local-map");
 648 }
 649
 650 /**
 651  * adg_entity_get_local_matrix:
 652  * @entity: an #AdgEntity object
 653  * @matrix: where to store the local matrix
 654  *
 655  * Computes the local matrix by combining all the local maps of the
 656  * @entity hierarchy and stores the result in @matrix.
 657  **/
 658 void
 659 adg_entity_get_local_matrix(AdgEntity *entity, AdgMatrix *matrix)
 660 {
 661     AdgEntityPrivate *data;
 662
 663     g_return_if_fail(ADG_IS_ENTITY(entity));
 664     g_return_if_fail(matrix != NULL);
 665
 666     data = entity->data;
 667
 668     if (data->parent == NULL) {
 669         adg_matrix_copy(matrix, &data->local_map);
 670     } else {
 671         adg_entity_get_local_matrix((AdgEntity *) data->parent, matrix);
 672         cairo_matrix_multiply(matrix, &data->local_map, matrix);
 673     }
 674 }
 675
 676 /**
 677  * adg_entity_get_style:
 678  * @entity: an #AdgEntity
 679  * @style_slot: the slot of the style to get
 680  *
 681  * Gets a style from this entity. If the entity has no context associated
 682  * or the style is undefined within this context, gets the style from its
 683  * parent entity.
 684  *
 685  * Returns: the requested style or %NULL on errors or if there is no
 686  *          context with this style defined in the @entity hierarchy
 687  **/
 688 AdgStyle *
 689 adg_entity_get_style(AdgEntity *entity, AdgStyleSlot style_slot)
 690 {
 691     AdgEntityPrivate *data;
 692
 693     g_return_val_if_fail(ADG_IS_ENTITY(entity), NULL);
 694
 695     data = entity->data;
 696
 697     if (data->context) {
 698         AdgStyle *style = adg_context_get_style(data->context, style_slot);
 699         if (style)
 700             return style;
 701     }
 702
 703     if (data->parent)
 704         return adg_entity_get_style((AdgEntity *) data->parent, style_slot);
 705
 706     return NULL;
 707 }
 708
 709 /**
 710  * adg_entity_apply:
 711  * @entity: an #AdgEntity
 712  * @style_slot: the slot of the style to apply
 713  * @cr: a #cairo_t drawing context
 714  *
 715  * Applies the specified style to the @cr cairo context.
 716  **/
 717 void
 718 adg_entity_apply(AdgEntity *entity, AdgStyleSlot style_slot, cairo_t *cr)
 719 {
 720     AdgStyle *style = adg_entity_get_style(entity, style_slot);
 721
 722     if (style)
 723         adg_style_apply(style, cr);
 724 }
 725
 726 /**
 727  * adg_entity_apply_font:
 728  * @entity: an #AdgEntity
 729  * @font_id: a font id
 730  * @cr: a #cairo_t drawing context
 731  *
 732  * Applies the specified font to the @cr cairo context. It is similar
 733  * to adg_entity_apply() but instead of looking for a font slot, it
 734  * searches for a specific font style by inspecting composite styles too.
 735  *
 736  * A typical example is when the tolerance font should be applied: this
 737  * is a font style embedded in the dim style, so it is not enough to
 738  * use adg_entity_apply().
 739  **/
 740 void
 741 adg_entity_apply_font(AdgEntity *entity, AdgFontStyleId font_id, cairo_t *cr)
 742 {
 743     AdgStyle *style;
 744
 745     switch (font_id) {
 746
 747     case ADG_FONT_STYLE_TEXT:
 748         style = adg_entity_get_style(entity, ADG_SLOT_FONT_STYLE);
 749         break;
 750
 751     case ADG_FONT_STYLE_VALUE:
 752         style = adg_entity_get_style(entity, ADG_SLOT_DIM_STYLE);
 753         style = adg_dim_style_get_value_style((AdgDimStyle *) style);
 754         break;
 755
 756     case ADG_FONT_STYLE_TOLERANCE:
 757         style = adg_entity_get_style(entity, ADG_SLOT_DIM_STYLE);
 758         style = adg_dim_style_get_tolerance_style((AdgDimStyle *) style);
 759         break;
 760
 761     case ADG_FONT_STYLE_NOTE:
 762         style = adg_entity_get_style(entity, ADG_SLOT_DIM_STYLE);
 763         style = adg_dim_style_get_note_style((AdgDimStyle *) style);
 764         break;
 765
 766     default:
 767         g_warning ("%s: invalid font id (%d)", G_STRLOC, font_id);
 768         return;
 769     }
 770
 771     if (style)
 772         adg_style_apply(style, cr);
 773 }
 774
 775 /**
 776  * adg_entity_invalidate:
 777  * @entity: an #AdgEntity
 778  *
 779  * Emits the "invalidate" signal on @entity and all its children, if any,
 780  * so subsequent rendering will need a global recomputation.
 781  **/
 782 void
 783 adg_entity_invalidate(AdgEntity *entity)
 784 {
 785     g_return_if_fail(ADG_IS_ENTITY(entity));
 786
 787     g_signal_emit(entity, signals[INVALIDATE], 0, NULL);
 788 }
 789
 790 /**
 791  * adg_entity_render:
 792  * @entity: an #AdgEntity
 793  * @cr: a #cairo_t drawing context
 794  *
 795  * Emits the "render" signal on @entity and all its children, if any,
 796  * causing the rendering operation the @cr cairo context.
 797  **/
 798 void
 799 adg_entity_render(AdgEntity *entity, cairo_t *cr)
 800 {
 801     g_return_if_fail(ADG_IS_ENTITY(entity));
 802
 803     g_signal_emit(entity, signals[RENDER], 0, cr);
 804 }
 805
 806
 807 static gboolean
 808 set_parent(AdgEntity *entity, AdgEntity *parent)
 809 {
 810     AdgEntityPrivate *data;
 811     AdgEntity *old_parent;
 812
 813     data = entity->data;
 814     old_parent = data->parent;
 815
 816     /* Check if parent has changed */
 817     if (parent == old_parent)
 818         return FALSE;
 819
 820     if (parent != NULL)
 821         g_object_ref(parent);
 822
 823     data->parent = parent;
 824     g_signal_emit(entity, signals[PARENT_SET], 0, old_parent);
 825
 826     if (old_parent != NULL)
 827         g_object_unref(old_parent);
 828
 829     return TRUE;
 830 }
 831
 832 static gboolean
 833 set_context(AdgEntity *entity, AdgContext *context)
 834 {
 835     AdgEntityPrivate *data;
 836     AdgContext *old_context;
 837
 838     data = entity->data;
 839     old_context = data->context;
 840
 841     /* Check if context has changed */
 842     if (context == old_context)
 843         return FALSE;
 844
 845     if (context != NULL)
 846         g_object_ref(context);
 847
 848     data->context = context;
 849     g_signal_emit(entity, signals[CONTEXT_SET], 0, old_context);
 850
 851     if (old_context != NULL)
 852         g_object_unref(old_context);
 853
 854     return TRUE;
 855 }
 856
 857 static void
 858 set_global_map(AdgEntity *entity, const AdgMatrix *map)
 859 {
 860     AdgEntityPrivate *data = entity->data;
 861
 862     if (map == NULL)
 863         cairo_matrix_init_identity(&data->global_map);
 864     else
 865         adg_matrix_copy(&data->global_map, map);
 866 }
 867
 868 static void
 869 set_local_map(AdgEntity *entity, const AdgMatrix *map)
 870 {
 871     AdgEntityPrivate *data = entity->data;
 872
 873     if (map == NULL)
 874         cairo_matrix_init_identity(&data->local_map);
 875     else
 876         adg_matrix_copy(&data->local_map, map);
 877 }
 878
 879 static void
 880 real_invalidate(AdgEntity *entity, gpointer user_data)
 881 {
 882     AdgEntityClass *entity_class;
 883     AdgEntityPrivate *data;
 884
 885     g_assert(user_data == (gpointer) 0xdeadbeaf);
 886
 887     entity_class = ADG_ENTITY_GET_CLASS(entity);
 888     if (entity_class->invalidate == NULL) {
 889         /* Assume the entity does not have cache to be cleared */
 890     } else if (!entity_class->invalidate(entity)) {
 891         return;
 892     }
 893
 894     data = entity->data;
 895     ADG_UNSET(data->flags, RENDERED);
 896 }
 897
 898 static void
 899 real_render(AdgEntity *entity, cairo_t *cr, gpointer user_data)
 900 {
 901     AdgEntityClass *entity_class;
 902     AdgEntityPrivate *data;
 903
 904     g_assert(user_data == (gpointer) 0xdeadbeaf);
 905
 906     entity_class = ADG_ENTITY_GET_CLASS(entity);
 907     if (entity_class->render == NULL) {
 908         /* The render method must be defined */
 909         g_warning("%s: `render' method not implemented for type `%s'",
 910                   G_STRLOC, g_type_name(G_OBJECT_TYPE(entity)));
 911         return;
 912     }
 913
 914     data = entity->data;
 915
 916     cairo_save(cr);
 917     cairo_transform(cr, &data->global_map);
 918
 919     if (entity_class->render(entity, cr))
 920         ADG_SET(data->flags, RENDERED);
 921
 922     cairo_restore(cr);
 923 }