src/svgtiny_css.c

   1 #include <libcss/libcss.h>
   2
   3 #include "svgtiny.h"
   4 #include "svgtiny_internal.h"
   5
   6 static css_error node_name(void *pw, void *node, css_qname *qname);
   7 static css_error node_classes(void *pw, void *node,
   8                 lwc_string ***classes, uint32_t *n_classes);
   9 static css_error node_id(void *pw, void *node, lwc_string **id);
  10 static css_error named_parent_node(void *pw, void *node,
  11                 const css_qname *qname, void **parent);
  12 static css_error named_sibling_node(void *pw, void *node,
  13                 const css_qname *qname, void **sibling);
  14 static css_error named_generic_sibling_node(void *pw, void *node,
  15                 const css_qname *qname, void **sibling);
  16 static css_error parent_node(void *pw, void *node, void **parent);
  17 static css_error sibling_node(void *pw, void *node, void **sibling);
  18 static css_error node_has_name(void *pw, void *node,
  19                 const css_qname *qname, bool *match);
  20 static css_error node_has_class(void *pw, void *node,
  21                 lwc_string *name, bool *match);
  22 static css_error node_has_id(void *pw, void *node,
  23                 lwc_string *name, bool *match);
  24
  25
  26 /**
  27  * Resolve a relative URL to an absolute one by doing nothing. This is
  28  * the simplest possible implementation of a URL resolver, needed for
  29  * parsing CSS.
  30  */
  31 css_error svgtiny_resolve_url(void *pw,
  32                 const char *base, lwc_string *rel, lwc_string **abs)
  33 {
  34         UNUSED(pw);
  35         UNUSED(base);
  36
  37         /* Copy the relative URL to the absolute one (the return
  38            value) */
  39         *abs = lwc_string_ref(rel);
  40         return CSS_OK;
  41 }
  42
  43 /**
  44  * Create a stylesheet with the default set of params.
  45  *
  46  * \param sheet A stylesheet pointer, passed in by reference, that
  47  * we use to store the newly-created stylesheet.
  48  * \param inline_style True if this stylesheet represents an inline
  49  * style, and false otherwise.
  50  *
  51  * \return The return value from css_stylesheet_create() is returned.
  52  */
  53 css_error svgtiny_create_stylesheet(css_stylesheet **sheet,
  54                 bool inline_style)
  55 {
  56         css_stylesheet_params params;
  57
  58         params.params_version = CSS_STYLESHEET_PARAMS_VERSION_1;
  59         params.level = CSS_LEVEL_DEFAULT;
  60         params.charset = NULL;
  61         params.url = "";
  62         params.title = NULL;
  63         params.allow_quirks = false;
  64         params.inline_style = inline_style;
  65         params.resolve = svgtiny_resolve_url;
  66         params.resolve_pw = NULL;
  67         params.import = NULL;
  68         params.import_pw = NULL;
  69         params.color = NULL;
  70         params.color_pw = NULL;
  71         params.font = NULL;
  72         params.font_pw = NULL;
  73
  74         return css_stylesheet_create(&params, sheet);
  75 }
  76
  77
  78 /**************************/
  79 /* libcss select handlers */
  80 /**************************/
  81 /*
  82  * From here on we implement the "select handler "API defined in
  83  * libcss's include/libcss/select.h and discussed briefly in its
  84  * docs/API document.
  85  */
  86
  87
  88 /**
  89  * Retrieve the given node's name
  90  *
  91  * \param pw     Pointer to the current SVG parser state
  92  * \param node   Libdom SVG node
  93  * \param qname  Address at which to store the node name
  94  *
  95  * \return CSS_OK on success, or CSS_NOMEM if anything goes wrong
  96  */
  97 css_error node_name(void *pw, void *node, css_qname *qname)
  98 {
  99         dom_string *name;
 100         dom_exception err;
 101         struct svgtiny_parse_state *state;
 102
 103         err = dom_node_get_node_name((dom_node *)node, &name);
 104         if (err != DOM_NO_ERR) {
 105                 return CSS_NOMEM;
 106         }
 107
 108         state = (struct svgtiny_parse_state *)pw;
 109         qname->ns = lwc_string_ref(state->interned_svg_xmlns);
 110
 111         err = dom_string_intern(name, &qname->name);
 112         if (err != DOM_NO_ERR) {
 113                 dom_string_unref(name);
 114                 return CSS_NOMEM;
 115         }
 116
 117         dom_string_unref(name);
 118
 119         return CSS_OK;
 120 }
 121
 122
 123 /**
 124  * Retrieve the given node's classes
 125  *
 126  * \param pw         Pointer to the current SVG parser state
 127  * \param node       Libdom SVG node
 128  * \param classes    Address at which to store the class name array
 129  * \param n_classes  Address at which to store the length of the class
 130  *                   name array
 131  *
 132  * \return CSS_OK on success, or CSS_NOMEM if anything goes wrong
 133  *
 134  * \note CSS_NOMEM is not possible in practice as of libdom-0.4.1,
 135  *       because the underlying libdom function never fails
 136  */
 137 css_error node_classes(void *pw, void *node,
 138                 lwc_string ***classes, uint32_t *n_classes)
 139 {
 140         UNUSED(pw);
 141         dom_exception err;
 142
 143         err = dom_element_get_classes((dom_node *)node, classes, n_classes);
 144
 145         /* The implementation does not do it, but the documentation
 146            for dom_element_get_classes() says that a DOM_NO_MEM_ERR is
 147            possible here, so we handle it to be on the safe side. */
 148         if (err != DOM_NO_ERR) {
 149                 return CSS_NOMEM;
 150         }
 151
 152         return CSS_OK;
 153 }
 154
 155
 156 /**
 157  * Retrieve the given node's id
 158  *
 159  * \param pw    Pointer to the current SVG parser state
 160  * \param node  Libdom SVG node
 161  * \param id    Address at which to store the id
 162  *
 163  * \return      CSS_OK on success, or CSS_NOMEM if anything goes wrong
 164  */
 165 css_error node_id(void *pw, void *node, lwc_string **id)
 166 {
 167         dom_string *attr;
 168         dom_exception err;
 169         struct svgtiny_parse_state *state;
 170
 171         /* Begin with the assumption that this node has no id */
 172         *id = NULL;
 173
 174         state = (struct svgtiny_parse_state *)pw;
 175         err = dom_element_get_attribute((dom_node *)node,
 176                                         state->interned_id, &attr);
 177         if (err != DOM_NO_ERR) {
 178                 return CSS_NOMEM;
 179         }
 180         else if (attr == NULL) {
 181                 /* The node has no id attribute and our return value
 182                    is already set to NULL so we're done */
 183                 return CSS_OK;
 184         }
 185
 186         /* If we found an id attribute (a dom_string), intern it into
 187            an lwc_string that we can return, and then cleanup the
 188            dom_string. */
 189         err = dom_string_intern(attr, id);
 190         if (err != DOM_NO_ERR) {
 191                 dom_string_unref(attr);
 192                 return CSS_NOMEM;
 193         }
 194         dom_string_unref(attr);
 195         return CSS_OK;
 196 }
 197
 198
 199
 200 /**
 201  * Find the first parent of the given element having the given name
 202  *
 203  * \param pw      Pointer to the current SVG parser state
 204  * \param node    Libdom SVG node
 205  * \param qname   Name of the parent node to search for
 206  * \param parent  Address at which to store the parent node pointer
 207  *
 208  * \return Always returns CSS_OK
 209  *
 210  * \post If a suitable element is found, a pointer to it will be
 211  *       stored at the address pointed to by \a parent; otherwise,
 212  *       NULL will be stored at the address pointed to by \a parent
 213  */
 214 css_error named_parent_node(void *pw, void *node,
 215                 const css_qname *qname, void **parent)
 216 {
 217         UNUSED(pw);
 218         /* dom_element_named_parent_node() was invented to implement
 219          * this select handler so there isn't much for us to do except
 220          * call it. It's OK if node isn't an element, libdom checks
 221          * for it. */
 222         dom_element_named_parent_node((dom_element *)node,
 223                                 qname->name,
 224                                 (struct dom_element **)parent);
 225
 226         /* Implementation detail: dom_element_named_parent_node()
 227          * increments the reference count of the parent element before
 228          * returning it to us. According to docs/RefCnt in the libdom
 229          * repository, this will prevent the parent element from being
 230          * destroyed if it is pruned from the DOM. That sounds good,
 231          * since we don't want to be using a pointer to an object that
 232          * has been destroyed... but we also have no way of later
 233          * decrementing the reference count ourselves, and don't want
 234          * to make the returned node eternal. Decrementing the
 235          * reference counter now allows it to be destroyed when the
 236          * DOM no longer needs it, and so long as no other parts of
 237          * libsvgtiny are messing with the DOM during parsing, that
 238          * shouldn't (ha ha) cause any problems. */
 239         dom_node_unref(*parent);
 240
 241         return CSS_OK;
 242 }
 243
 244
 245 /**
 246  * Find the "next-sibling" of the given element having the given name
 247  *
 248  * This search corresponds to the "+ foo" combinator in CSS and will
 249  * find only "foo" element nodes that immediately precede the given
 250  * node under the same parent in the DOM. In CSS the tree is viewed
 251  * top-down and in libdom it is viewed from the bottom-up; as a result
 252  * "next" and "previous" are sometimes backwards. This is case-sensitive.
 253  *
 254  * \param pw       Pointer to the current SVG parser state
 255  * \param node     Libdom SVG node
 256  * \param qname    Name of the sibling node to search for
 257  * \param sibling  Address at which to store the sibling node pointer
 258  *
 259  * \return Always returns CSS_OK
 260  *
 261  * \post If a suitable element is found, a pointer to it will be
 262  *       stored at the address pointed to by \a sibling; otherwise,
 263  *       NULL will be stored at the address pointed to by \a sibling
 264  */
 265 css_error named_sibling_node(void *pw, void *node,
 266                 const css_qname *qname, void **sibling)
 267 {
 268         UNUSED(pw);
 269         dom_node *n = node; /* the current node */
 270         dom_node *prev; /* the previous node */
 271         dom_exception err;
 272         dom_node_type type;
 273         dom_string *name;
 274
 275         *sibling = NULL; /* default to nothing found */
 276
 277         /* Begin the search; the first iteration we do outside of the
 278          * loop. Implementation detil: dom_node_get_previous_sibling()
 279          * increments the reference counter on the returned node. A
 280          * comment within named_parent_node() explains why we
 281          * decrement it ASAP. */
 282         err = dom_node_get_previous_sibling(n, &n);
 283         if (err != DOM_NO_ERR) {
 284                 return CSS_OK;
 285         }
 286
 287         while (n != NULL) {
 288                 /* We're looking for the first ELEMENT sibling */
 289                 err = dom_node_get_node_type(n, &type);
 290                 if (err != DOM_NO_ERR) {
 291                         dom_node_unref(n);
 292                         return CSS_OK;
 293                 }
 294
 295                 if (type == DOM_ELEMENT_NODE) {
 296                         /* We found an element node, does it have the
 297                          * right name? */
 298                         err = dom_node_get_node_name(n, &name);
 299                         if (err != DOM_NO_ERR) {
 300                                 dom_node_unref(n);
 301                                 return CSS_OK;
 302                         }
 303
 304                         if (dom_string_lwc_isequal(name,
 305                                         qname->name)) {
 306                                 /* The name is right, return it */
 307                                 *sibling = n;
 308                         }
 309
 310                         /* There's only one next-sibling element node
 311                          * and we've already found it, so if its name
 312                          * wasn't right, we return the default value
 313                          * of NULL below */
 314                         dom_string_unref(name);
 315                         dom_node_unref(n);
 316                         return CSS_OK;
 317                 }
 318
 319                 /* Not an element node, so we move on the the previous
 320                  * previous sibling */
 321                 err = dom_node_get_previous_sibling(n, &prev);
 322                 if (err != DOM_NO_ERR) {
 323                         dom_node_unref(n);
 324                         return CSS_OK;
 325                 }
 326
 327                 dom_node_unref(n);
 328                 n = prev;
 329         }
 330
 331         return CSS_OK;
 332 }
 333
 334
 335 /**
 336  * Find the first "subsequent-sibling" of the given element having the
 337  * given name
 338  *
 339  * This search corresponds to the "~ foo" combinator in CSS and will
 340  * find only "foo" element nodes that precede the given node (under
 341  * the same parent) in the DOM. In CSS the tree is viewed top-down and
 342  * in libdom it is viewed from the bottom-up; as a result "next" and
 343  * "previous" are sometimes backwards. This is case-sensitive.
 344  *
 345  * \param pw       Pointer to the current SVG parser state
 346  * \param node     Libdom SVG node
 347  * \param qname    Name of the sibling node to search for
 348  * \param sibling  Address at which to store the sibling node pointer
 349  *
 350  * \return Always returns CSS_OK
 351  *
 352  * \post If a suitable element is found, a pointer to it will be
 353  *       stored at the address pointed to by \a sibling; otherwise,
 354  *       NULL will be stored at the address pointed to by \a sibling
 355  */
 356 css_error named_generic_sibling_node(void *pw, void *node,
 357                 const css_qname *qname, void **sibling)
 358 {
 359         UNUSED(pw);
 360         dom_node *n = node; /* the current node */
 361         dom_node *prev;     /* the previous node */
 362         dom_exception err;
 363         dom_node_type type;
 364         dom_string *name;
 365
 366
 367         *sibling = NULL; /* default to nothing found */
 368
 369         /* Begin the search; the first iteration we do outside of the
 370          * loop. Implementation detil: dom_node_get_previous_sibling()
 371          * increments the reference counter on the returned node. A
 372          * comment within named_parent_node() explains why we
 373          * decrement it ASAP. */
 374         err = dom_node_get_previous_sibling(n, &n);
 375         if (err != DOM_NO_ERR) {
 376                 return CSS_OK;
 377         }
 378
 379         while (n != NULL) {
 380                 err = dom_node_get_node_type(n, &type);
 381                 if (err != DOM_NO_ERR) {
 382                         dom_node_unref(n);
 383                         return CSS_OK;
 384                 }
 385
 386                 if (type == DOM_ELEMENT_NODE) {
 387                         /* We only want ELEMENT nodes */
 388                         err = dom_node_get_node_name(n, &name);
 389                         if (err != DOM_NO_ERR) {
 390                                 dom_node_unref(n);
 391                                 return CSS_OK;
 392                         }
 393
 394                         if (dom_string_lwc_isequal(name,
 395                                         qname->name)) {
 396                                 /* Found one. Save it and stop the search */
 397                                 dom_string_unref(name);
 398                                 dom_node_unref(n);
 399                                 *sibling = n;
 400                                 return CSS_OK;
 401                         }
 402
 403                         dom_string_unref(name);
 404                 }
 405
 406                 /* This sibling wasn't an element with the desired
 407                    name, so move on to the previous sibling */
 408                 err = dom_node_get_previous_sibling(n, &prev);
 409                 if (err != DOM_NO_ERR) {
 410                         dom_node_unref(n);
 411                         return CSS_OK;
 412                 }
 413
 414                 dom_node_unref(n);
 415                 n = prev;
 416         }
 417
 418         return CSS_OK;
 419 }
 420
 421
 422 /**
 423  * Return a pointer to the given node's parent
 424  *
 425  * \param pw      Pointer to the current SVG parser state
 426  * \param node    Libdom SVG node
 427  * \param parent  Address at which to store the node's parent pointer
 428  *
 429  * \return Always returns CSS_OK
 430  */
 431 css_error parent_node(void *pw, void *node, void **parent)
 432 {
 433         UNUSED(pw);
 434         /* Libdom basically implements this for us */
 435         dom_element_parent_node(node, (struct dom_element **)parent);
 436
 437         /* See the comment in named_parent_node() for why we decrement
 438          * this reference counter here. */
 439         dom_node_unref(*parent);
 440
 441         return CSS_OK;
 442 }
 443
 444
 445 /**
 446  * Find the "next-sibling" of the given element
 447  *
 448  * This search corresponds "+ *" in CSS and will find the first
 449  * element node that immediately precedes the given node under the
 450  * same parent in the DOM. In CSS the tree is viewed top-down and in
 451  * libdom it is viewed from the bottom-up; as a result "next" and
 452  * "previous" are sometimes backwards.
 453  *
 454  * \param pw       Pointer to the current SVG parser state
 455  * \param node     Libdom SVG node
 456  * \param sibling  Address at which to store the sibling node pointer
 457  *
 458  * \return Always returns CSS_OK
 459  *
 460  * \post If a suitable element is found, a pointer to it will be
 461  *       stored at the address pointed to by \a sibling; otherwise,
 462  *       NULL will be stored at the address pointed to by \a sibling
 463  */
 464 css_error sibling_node(void *pw, void *node, void **sibling)
 465 {
 466         UNUSED(pw);
 467         dom_node *n = node; /* the current node */
 468         dom_node *prev;     /* the previous node */
 469         dom_exception err;
 470         dom_node_type type;
 471
 472         *sibling = NULL; /* default to nothing found */
 473
 474         /* Begin the search; the first iteration we do outside of the
 475          * loop. Implementation detil: dom_node_get_previous_sibling()
 476          * increments the reference counter on the returned node. A
 477          * comment within named_parent_node() explains why we
 478          * decrement it ASAP. */
 479         err = dom_node_get_previous_sibling(n, &n);
 480         if (err != DOM_NO_ERR) {
 481                 return CSS_OK;
 482         }
 483
 484         while (n != NULL) {
 485                 err = dom_node_get_node_type(n, &type);
 486                 if (err != DOM_NO_ERR) {
 487                         dom_node_unref(n);
 488                         return CSS_OK;
 489                 }
 490
 491                 if (type == DOM_ELEMENT_NODE) {
 492                         /* We found a sibling node that is also an
 493                            element and that's all we wanted. */
 494                         *sibling = n;
 495                         dom_node_unref(n);
 496                         return CSS_OK;
 497                 }
 498
 499                 /* This sibling node was not an element; move on to
 500                    the previous sibling */
 501                 err = dom_node_get_previous_sibling(n, &prev);
 502                 if (err != DOM_NO_ERR) {
 503                         dom_node_unref(n);
 504                         return CSS_OK;
 505                 }
 506
 507                 dom_node_unref(n);
 508                 n = prev;
 509         }
 510
 511         return CSS_OK;
 512 }
 513
 514
 515 /**
 516  * Test the given node for the given name
 517  *
 518  * This will return true (via the "match" pointer) if the libdom node
 519  * has the given name or if that name is the universal selector;
 520  * otherwise it returns false. The comparison is case-sensitive. It
 521  * corresponds to a rule like "body { ... }" in CSS.
 522  *
 523  * \param pw       Pointer to the current SVG parser state
 524  * \param node     Libdom SVG node to test
 525  * \param qname    Name to check for
 526  * \param match    Pointer to the test result
 527  *
 528  * \return Always returns CSS_OK
 529  */
 530 css_error node_has_name(void *pw, void *node,
 531                 const css_qname *qname, bool *match)
 532 {
 533         struct svgtiny_parse_state *state;
 534         dom_string *name;
 535         dom_exception err;
 536
 537         /* Start by checking to see if qname is the universal selector */
 538         state = (struct svgtiny_parse_state *)pw;
 539         if (lwc_string_isequal(qname->name,
 540                         state->interned_universal, match) == lwc_error_ok) {
 541           if (*match) {
 542                 /* It's the universal selector. In NetSurf, all node
 543                  * names match the universal selector, and nothing in
 544                  * the libcss documentation suggests another approach,
 545                  * so we follow NetSurf here. */
 546                 return CSS_OK;
 547           }
 548         }
 549
 550         err = dom_node_get_node_name((dom_node *)node, &name);
 551         if (err != DOM_NO_ERR) {
 552           return CSS_OK;
 553         }
 554
 555         /* Unlike with HTML, SVG element names are case-sensitive */
 556         *match = dom_string_lwc_isequal(name, qname->name);
 557         dom_string_unref(name);
 558
 559         return CSS_OK;
 560 }
 561
 562
 563 /**
 564  * Test the given node for the given class
 565  *
 566  * This will return true (via the "match" pointer) if the libdom node
 567  * has the given class. The comparison is case-sensitive. It
 568  * corresponds to node.class in CSS.
 569  *
 570  * \param pw       Pointer to the current SVG parser state
 571  * \param node     Libdom SVG node to test
 572  * \param name     Class name to check for
 573  * \param match    Pointer to the test result
 574  *
 575  * \return Always returns CSS_OK
 576  */
 577 css_error node_has_class(void *pw, void *node,
 578                 lwc_string *name, bool *match)
 579 {
 580         UNUSED(pw);
 581         /* libdom implements this for us and apparently it cannot fail */
 582         dom_element_has_class((dom_node *)node, name, match);
 583         return CSS_OK;
 584 }
 585
 586
 587 /**
 588  * Test the given node for the given id
 589  *
 590  * This will return true (via the "match" pointer) if the libdom node
 591  * has the given id. The comparison is case-sensitive. It corresponds
 592  * to node#id in CSS.
 593  *
 594  * \param pw       Pointer to the current SVG parser state
 595  * \param node     Libdom SVG node to test
 596  * \param name     Id to check for
 597  * \param match    Pointer to the test result
 598  *
 599  * \return Always returns CSS_OK
 600  */
 601 css_error node_has_id(void *pw, void *node,
 602                 lwc_string *name, bool *match)
 603 {
 604         dom_string *attr;
 605         dom_exception err;
 606         struct svgtiny_parse_state *state;
 607
 608         attr = NULL;    /* a priori the "id" attribute may not exist */
 609         *match = false; /* default to no match */
 610
 611         state = (struct svgtiny_parse_state *)pw;
 612         err = dom_element_get_attribute((dom_node *)node,
 613                                 state->interned_id, &attr);
 614         if (err != DOM_NO_ERR || attr == NULL) {
 615                 return CSS_OK;
 616         }
 617
 618         *match = dom_string_lwc_isequal(attr, name);
 619         dom_string_unref(attr);
 620
 621         return CSS_OK;
 622 }