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   1  <?php  // $Id: moodleblock.class.php,v 1.92.2.9 2008/08/06 05:08:36 skodak Exp $
   2  
   3  /**
   4   * This file contains the parent class for moodle blocks, block_base.
   5   *
   6   * @author Jon Papaioannou
   7   * @version  $Id: moodleblock.class.php,v 1.92.2.9 2008/08/06 05:08:36 skodak Exp $
   8   * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
   9   * @package blocks
  10   */
  11  
  12  /// Constants
  13  
  14  /**
  15   * Block type of list. Contents of block should be set as an associative array in the content object as items ($this->content->items). Optionally include footer text in $this->content->footer.
  16   */
  17  define('BLOCK_TYPE_LIST',    1);
  18  
  19  /**
  20   * Block type of text. Contents of block should be set to standard html text in the content object as items ($this->content->text). Optionally include footer text in $this->content->footer.
  21   */
  22  define('BLOCK_TYPE_TEXT',    2);
  23  
  24  /**
  25   * Class for describing a moodle block, all Moodle blocks derive from this class
  26   *
  27   * @author Jon Papaioannou
  28   * @package blocks
  29   */
  30  class block_base {
  31  
  32      /**
  33       * Internal var for storing/caching translated strings
  34       * @var string $str
  35       */
  36      var $str;
  37  
  38      /**
  39       * The title of the block to be displayed in the block title area.
  40       * @var string $title
  41       */
  42      var $title         = NULL;
  43  
  44      /**
  45       * The type of content that this block creates. Currently support options - BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT
  46       * @var int $content_type
  47       */
  48      var $content_type  = BLOCK_TYPE_TEXT;
  49  
  50      /**
  51       * An object to contain the information to be displayed in the block.
  52       * @var stdObject $content
  53       */
  54      var $content       = NULL;
  55  
  56      /**
  57       * A string generated by {@link _add_edit_controls()} to display block manipulation links when the user is in editing mode.
  58       * @var string $edit_controls
  59       */
  60      var $edit_controls = NULL;
  61  
  62      /**
  63       * The current version that the block type defines.
  64       * @var string $version
  65       */
  66      var $version       = NULL;
  67  
  68      /**
  69       * The initialized instance of this block object.
  70       * @var block $instance
  71       */
  72      var $instance      = NULL;
  73  
  74      /**
  75       * An object containing the instance configuration information for the current instance of this block.
  76       * @var stdObject $config
  77       */
  78      var $config        = NULL;
  79  
  80      /** 
  81       * How often the cronjob should run, 0 if not at all.
  82       * @var int $cron
  83       */
  84  
  85      var $cron          = NULL;
  86  
  87      /**
  88       * Indicates blocked is pinned - can not be moved, always present, does not have own context
  89       */
  90      var $pinned        = false;
  91  
  92  /// Class Functions
  93  
  94      /**
  95       * The class constructor
  96       *
  97       */
  98      function block_base() {
  99          $this->init();
 100      }
 101  
 102      /**
 103       * Fake constructor to keep PHP5 happy
 104       *
 105       */
 106      function __construct() {
 107          $this->block_base();
 108      }
 109      
 110      /** 
 111       * Function that can be overridden to do extra setup after
 112       * the database install. (Called once per block, not per instance!)
 113       */
 114      function after_install() {
 115      }
 116      
 117      /**
 118       * Function that can be overridden to do extra cleanup before
 119       * the database tables are deleted. (Called once per block, not per instance!)
 120       */
 121      function before_delete() {
 122      }
 123      
 124      /**
 125       * Function that can be overridden to do extra setup after a block instance has been
 126       * restored from backup. For example, it may need to alter any dates that the block
 127       * stores, if the $restore->course_startdateoffset is set.  
 128       */
 129      function after_restore($restore) {
 130      }
 131  
 132      /**
 133       * Enable custom instance data section in backup and restore.
 134       * 
 135       * If return true, then {@link instance_backup()} and
 136       * {@link instance_restore()} will be called during
 137       * backup/restore routines.
 138       *
 139       * @return boolean
 140       **/
 141      function backuprestore_instancedata_used() {
 142          return false;
 143      }
 144  
 145      /**
 146       * Allows the block class to have a backup routine.  Handy 
 147       * when the block has its own tables that have foreign keys to 
 148       * other tables (example: user table).
 149       * 
 150       * Note: at the time of writing this comment, the indent level 
 151       * for the {@link full_tag()} should start at 5.
 152       *
 153       * @param resource $bf Backup File
 154       * @param object $preferences Backup preferences
 155       * @return boolean
 156       **/
 157      function instance_backup($bf, $preferences) {
 158          return true;
 159      }
 160  
 161      /**
 162       * Allows the block class to restore its backup routine.
 163       * 
 164       * Should not return false if data is empty 
 165       * because old backups would not contain block instance backup data.
 166       * 
 167       * @param object $restore Standard restore object
 168       * @param object $data Object from backup_getid for this block instance
 169       * @return boolean
 170       **/
 171      function instance_restore($restore, $data) {
 172          return true;
 173      }
 174  
 175      /**
 176       * Will be called before an instance of this block is backed up, so that any links in
 177       * in config can be encoded. For example config->text, for the HTML block
 178       * @return string
 179       */
 180      function get_backup_encoded_config() {
 181          return base64_encode(serialize($this->config));
 182      }
 183  
 184      /**
 185       * Return the content encoded to support interactivities linking. This function is
 186       * called automatically from the backup procedure by {@link backup_encode_absolute_links()}.
 187       *
 188       * NOTE: There is no block instance when this method is called.
 189       *
 190       * @param string $content Content to be encoded
 191       * @param object $restore Restore preferences object
 192       * @return string The encoded content
 193       **/
 194      function encode_content_links($content, $restore) {
 195          return $content;
 196      }
 197  
 198      /**
 199       * This function makes all the necessary calls to {@link restore_decode_content_links_worker()}
 200       * function in order to decode contents of this block from the backup 
 201       * format to destination site/course in order to mantain inter-activities 
 202       * working in the backup/restore process. 
 203       * 
 204       * This is called from {@link restore_decode_content_links()} function in the restore process.
 205       *
 206       * NOTE: There is no block instance when this method is called.
 207       *
 208       * @param object $restore Standard restore object
 209       * @return boolean
 210       **/
 211      function decode_content_links_caller($restore) {
 212          return true;
 213      }
 214  
 215      /**
 216       * Return content decoded to support interactivities linking.
 217       * This is called automatically from
 218       * {@link restore_decode_content_links_worker()} function
 219       * in the restore process.
 220       *
 221       * NOTE: There is no block instance when this method is called.
 222       *
 223       * @param string $content Content to be dencoded
 224       * @param object $restore Restore preferences object
 225       * @return string The dencoded content
 226       **/
 227      function decode_content_links($content, $restore) {
 228          return $content;
 229      }
 230  
 231      /**
 232       * Returns the block name, as present in the class name,
 233       * the database, the block directory, etc etc.
 234       *
 235       * @return string
 236       */
 237      function name() {
 238          // Returns the block name, as present in the class name,
 239          // the database, the block directory, etc etc.
 240          static $myname;
 241          if ($myname === NULL) {
 242              $myname = strtolower(get_class($this));
 243              $myname = substr($myname, strpos($myname, '_') + 1);
 244          }
 245          return $myname;
 246      }
 247  
 248      /**
 249       * Parent class version of this function simply returns NULL
 250       * This should be implemented by the derived class to return
 251       * the content object.
 252       *
 253       * @return stdObject
 254       */
 255      function get_content() {
 256          // This should be implemented by the derived class.
 257          return NULL;
 258      }
 259  
 260      /**
 261       * Returns the class $title var value.
 262       *
 263       * Intentionally doesn't check if a title is set. 
 264       * This is already done in {@link _self_test()}
 265       *
 266       * @return string $this->title
 267       */
 268      function get_title() {
 269          // Intentionally doesn't check if a title is set. This is already done in _self_test()
 270          return $this->title;
 271      }
 272  
 273      /**
 274       * Returns the class $content_type var value.
 275       *
 276       * Intentionally doesn't check if content_type is set. 
 277       * This is already done in {@link _self_test()}
 278       *
 279       * @return string $this->content_type
 280       */
 281      function get_content_type() {
 282          // Intentionally doesn't check if a content_type is set. This is already done in _self_test()
 283          return $this->content_type;
 284      }
 285  
 286      /**
 287       * Returns the class $version var value.
 288       *
 289       * Intentionally doesn't check if a version is set. 
 290       * This is already done in {@link _self_test()}
 291       *
 292       * @return string $this->version
 293       */
 294      function get_version() {
 295          // Intentionally doesn't check if a version is set. This is already done in _self_test()
 296          return $this->version;
 297      }
 298  
 299      /**
 300       * Returns true or false, depending on whether this block has any content to display
 301       * and whether the user has permission to view the block
 302       *
 303       * @return boolean
 304       */
 305      function is_empty() {
 306  
 307          if (empty($this->instance->pinned)) {
 308              $context = get_context_instance(CONTEXT_BLOCK, $this->instance->id);
 309          } else {
 310              $context = get_context_instance(CONTEXT_SYSTEM); // pinned blocks do not have own context
 311          }
 312          
 313          if ( !has_capability('moodle/block:view', $context) ) {
 314              return true;
 315          }
 316  
 317          $this->get_content();
 318          return(empty($this->content->text) && empty($this->content->footer));
 319      }
 320  
 321      /**
 322       * First sets the current value of $this->content to NULL
 323       * then calls the block's {@link get_content()} function
 324       * to set its value back.
 325       *
 326       * @return stdObject
 327       */
 328      function refresh_content() {
 329          // Nothing special here, depends on content()
 330          $this->content = NULL;
 331          return $this->get_content();
 332      }
 333  
 334      /**
 335       * Display the block!
 336       */
 337      function _print_block() {
 338          global $COURSE;
 339  
 340          // is_empty() includes a call to get_content()
 341          if ($this->is_empty() && empty($COURSE->javascriptportal)) {
 342              if (empty($this->edit_controls)) {
 343                  // No content, no edit controls, so just shut up
 344                  return;
 345              } else {
 346                  // No content but editing, so show something at least
 347                  $this->_print_shadow();
 348              }
 349          } else {
 350              if ($this->hide_header() && empty($this->edit_controls)) {
 351                  // Header wants to hide, no edit controls to show, so no header it is
 352                  print_side_block(NULL, $this->content->text, NULL, NULL, $this->content->footer, $this->html_attributes());
 353              } else {
 354                  // The full treatment, please. Include the title text.
 355                  print_side_block($this->_title_html(), $this->content->text, NULL, NULL, $this->content->footer, $this->html_attributes(), $this->title);
 356              }
 357          }
 358      }
 359  
 360      /**
 361       * Block contents are missing. Simply display an empty block so that
 362       * edit controls are accessbile to the user and they are aware that this
 363       * block is in place, even if empty.
 364       */
 365      function _print_shadow() {
 366          print_side_block($this->_title_html(), '&nbsp;', NULL, NULL, '', array('class' => 'hidden'), $this->title);
 367      }
 368  
 369  
 370      function _title_html() {
 371          global $CFG;
 372  
 373          //Accessibility: validation, can't have <div> inside <h2>, use <span>.
 374          $title = '<div class="title">';
 375  
 376          if (!empty($CFG->allowuserblockhiding)) {
 377              //Accessibility: added 'alt' text for the +- icon.
 378              //Theme the buttons using, Admin - Miscellaneous - smartpix.
 379              $strshow = addslashes_js(get_string('showblocka', 'access', strip_tags($this->title)));
 380              $strhide = addslashes_js(get_string('hideblocka', 'access', strip_tags($this->title)));
 381              $title .= '<input type="image" src="'.$CFG->pixpath.'/t/switch_minus.gif" '. 
 382                  'id="togglehide_inst'.$this->instance->id.'" '.
 383                  'onclick="elementToggleHide(this, true, function(el) {'.
 384                  'return findParentNode(el, \'DIV\', \'sideblock\'); },'.
 385                  ' \''.$strshow.'\', \''.$strhide.'\'); return false;" '.
 386                  'alt="'.$strhide.'" title="'.$strhide.'" class="hide-show-image" />';
 387          }
 388  
 389          //Accesssibility: added H2 (was in, weblib.php: print_side_block)
 390          $title .= '<h2>'.$this->title.'</h2>';
 391  
 392          if ($this->edit_controls !== NULL) {
 393              $title .= $this->edit_controls;
 394          }
 395  
 396          $title .= '</div>';
 397          return $title;
 398      }
 399  
 400      /**
 401       * Sets class $edit_controls var with correct block manipulation links.
 402       *
 403       * @uses $CFG
 404       * @uses $USER
 405       * @param stdObject $options ?
 406       * @todo complete documenting this function. Define $options.
 407       */
 408      function _add_edit_controls($options) {
 409          global $CFG, $USER, $PAGE;
 410          
 411          if (empty($this->instance->pinned)) {
 412              $context = get_context_instance(CONTEXT_BLOCK, $this->instance->id);
 413          } else {
 414              $context = get_context_instance(CONTEXT_SYSTEM); // pinned blocks do not have own context
 415          }
 416          
 417          // context for site or course, i.e. participant list etc
 418          // check to see if user can edit site or course blocks.
 419          // blocks can appear on other pages such as mod and blog pages...
 420  
 421          switch ($this->instance->pagetype) {
 422              case 'course-view':
 423                  if (!has_capability('moodle/site:manageblocks', $context)) {
 424                      return null;
 425                  }
 426              break;
 427              default:
 428              
 429              break;  
 430          }
 431          
 432          
 433          if (!isset($this->str)) {
 434              $this->str->delete    = get_string('delete');
 435              $this->str->moveup    = get_string('moveup');
 436              $this->str->movedown  = get_string('movedown');
 437              $this->str->moveright = get_string('moveright');
 438              $this->str->moveleft  = get_string('moveleft');
 439              $this->str->hide      = get_string('hide');
 440              $this->str->show      = get_string('show');
 441              $this->str->configure = get_string('configuration');
 442              $this->str->assignroles = get_string('assignroles', 'role');
 443          }
 444  
 445          // RTL support - exchange right and left arrows
 446          if (right_to_left()) {
 447              $rightarrow = 'left.gif';
 448              $leftarrow  = 'right.gif';
 449          } else {
 450              $rightarrow = 'right.gif';
 451              $leftarrow  = 'left.gif';
 452          }
 453  
 454          $movebuttons = '<div class="commands">';
 455  
 456          if ($this->instance->visible) {
 457              $icon = '/t/hide.gif';
 458              $title = $this->str->hide;
 459          } else {
 460              $icon = '/t/show.gif';
 461              $title = $this->str->show;
 462          }
 463  
 464          if (empty($this->instance->pageid)) {
 465              $this->instance->pageid = 0;
 466          }
 467          if (!empty($PAGE->type) and ($this->instance->pagetype == $PAGE->type) and $this->instance->pageid == $PAGE->id) {
 468              $page = $PAGE;
 469          } else {
 470              $page = page_create_object($this->instance->pagetype, $this->instance->pageid);
 471          }
 472          $script = $page->url_get_full(array('instanceid' => $this->instance->id, 'sesskey' => $USER->sesskey));
 473  
 474          if (empty($this->instance->pinned)) {
 475              $movebuttons .= '<a class="icon roles" title="'. $this->str->assignroles .'" href="'.$CFG->wwwroot.'/'.$CFG->admin.'/roles/assign.php?contextid='.$context->id.'">' .
 476                              '<img src="'.$CFG->pixpath.'/i/roles.gif" alt="'.$this->str->assignroles.'" /></a>';
 477          }
 478       
 479          if ($this->user_can_edit()) {
 480              $movebuttons .= '<a class="icon hide" title="'. $title .'" href="'.$script.'&amp;blockaction=toggle">' .
 481                              '<img src="'. $CFG->pixpath.$icon .'" alt="'.$title.'" /></a>';
 482          }
 483  
 484          if ($options & BLOCK_CONFIGURE && $this->user_can_edit()) {
 485              $movebuttons .= '<a class="icon edit" title="'. $this->str->configure .'" href="'.$script.'&amp;blockaction=config">' .
 486                              '<img src="'. $CFG->pixpath .'/t/edit.gif" alt="'. $this->str->configure .'" /></a>';
 487          }
 488  
 489          if ($this->user_can_addto($page)) {
 490              $movebuttons .= '<a class="icon delete" title="'. $this->str->delete .'" href="'.$script.'&amp;blockaction=delete">' .
 491                              '<img src="'. $CFG->pixpath .'/t/delete.gif" alt="'. $this->str->delete .'" /></a>';
 492          }
 493  
 494          if ($options & BLOCK_MOVE_LEFT) {
 495              $movebuttons .= '<a class="icon left" title="'. $this->str->moveleft .'" href="'.$script.'&amp;blockaction=moveleft">' .
 496                              '<img src="'. $CFG->pixpath .'/t/'.$leftarrow.'" alt="'. $this->str->moveleft .'" /></a>';
 497          }
 498          if ($options & BLOCK_MOVE_UP) {
 499              $movebuttons .= '<a class="icon up" title="'. $this->str->moveup .'" href="'.$script.'&amp;blockaction=moveup">' .
 500                              '<img src="'. $CFG->pixpath .'/t/up.gif" alt="'. $this->str->moveup .'" /></a>';
 501          }
 502          if ($options & BLOCK_MOVE_DOWN) {
 503              $movebuttons .= '<a class="icon down" title="'. $this->str->movedown .'" href="'.$script.'&amp;blockaction=movedown">' .
 504                              '<img src="'. $CFG->pixpath .'/t/down.gif" alt="'. $this->str->movedown .'" /></a>';
 505          }
 506          if ($options & BLOCK_MOVE_RIGHT) {
 507              $movebuttons .= '<a class="icon right" title="'. $this->str->moveright .'" href="'.$script.'&amp;blockaction=moveright">' .
 508                              '<img src="'. $CFG->pixpath .'/t/'.$rightarrow.'" alt="'. $this->str->moveright .'" /></a>';
 509          }
 510  
 511          $movebuttons .= '</div>';
 512          $this->edit_controls = $movebuttons;
 513      }
 514  
 515      /**
 516       * Tests if this block has been implemented correctly.
 517       * Also, $errors isn't used right now
 518       *
 519       * @return boolean
 520       */
 521       
 522      function _self_test() {
 523          // Tests if this block has been implemented correctly.
 524          // Also, $errors isn't used right now
 525          $errors = array();
 526  
 527          $correct = true;
 528          if ($this->get_title() === NULL) {
 529              $errors[] = 'title_not_set';
 530              $correct = false;
 531          }
 532          if (!in_array($this->get_content_type(), array(BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT))) {
 533              $errors[] = 'invalid_content_type';
 534              $correct = false;
 535          }
 536          //following selftest was not working when roles&capabilities were used from block 
 537  /*        if ($this->get_content() === NULL) {
 538              $errors[] = 'content_not_set';
 539              $correct = false;
 540          }*/
 541          if ($this->get_version() === NULL) {
 542              $errors[] = 'version_not_set';
 543              $correct = false;
 544          }
 545  
 546          $formats = $this->applicable_formats();
 547          if (empty($formats) || array_sum($formats) === 0) {
 548              $errors[] = 'no_formats';
 549              $correct = false;
 550          }
 551  
 552          $width = $this->preferred_width();
 553          if (!is_int($width) || $width <= 0) {
 554              $errors[] = 'invalid_width';
 555              $correct = false;
 556          }
 557          return $correct;
 558      }
 559  
 560      /**
 561       * Subclasses should override this and return true if the
 562       * subclass block has a config_global.html file.
 563       *
 564       * @return boolean
 565       */
 566      function has_config() {
 567          return false;
 568      }
 569  
 570      /**
 571       * Default behavior: print the config_global.html file
 572       * You don't need to override this if you're satisfied with the above
 573       *
 574       * @uses $CFG
 575       * @return boolean
 576       */
 577      function config_print() {
 578          // Default behavior: print the config_global.html file
 579          // You don't need to override this if you're satisfied with the above
 580          if (!$this->has_config()) {
 581              return false;
 582          }
 583          global $CFG;
 584          print_simple_box_start('center', '', '', 5, 'blockconfigglobal');
 585          include($CFG->dirroot.'/blocks/'. $this->name() .'/config_global.html');
 586          print_simple_box_end();
 587          return true;
 588      }
 589      
 590      /**
 591       * Default behavior: save all variables as $CFG properties
 592       * You don't need to override this if you 're satisfied with the above
 593       *
 594       * @param array $data
 595       * @return boolean
 596       */
 597      function config_save($data) {
 598          foreach ($data as $name => $value) {
 599              set_config($name, $value);
 600          }
 601          return true;
 602      }
 603      
 604      /**
 605       * Default case: the block can be used in all course types
 606       * @return array
 607       * @todo finish documenting this function
 608       */
 609      function applicable_formats() {
 610          // Default case: the block can be used in courses and site index, but not in activities
 611          return array('all' => true, 'mod' => false, 'tag' => false);
 612      }
 613      
 614  
 615      /**
 616       * Default case: the block wants to be 180 pixels wide
 617       * @return int
 618       */
 619      function preferred_width() {
 620          return 180;
 621      }
 622      
 623      /**
 624       * Default return is false - header will be shown
 625       * @return boolean
 626       */
 627      function hide_header() {
 628          return false;
 629      }
 630  
 631      /**
 632       * Default case: an id with the instance and a class with our name in it
 633       * @return array
 634       * @todo finish documenting this function
 635       */
 636      function html_attributes() {
 637          return array('id' => 'inst'.$this->instance->id, 'class' => 'block_'. $this->name());
 638      }
 639      
 640      /**
 641       * Given an instance set the class var $instance to it and
 642       * load class var $config
 643       * @param block $instance
 644       * @todo add additional documentation to further explain the format of instance and config
 645       */
 646      function _load_instance($instance) {
 647          if (!empty($instance->configdata)) {
 648              $this->config = unserialize(base64_decode($instance->configdata));
 649          }
 650          // [pj] This line below is supposed to be an optimization (we don't need configdata anymore)
 651          // but what it does is break in PHP5 because the same instance object will be passed to
 652          // this function twice in each page view, and the second time it won't have any configdata
 653          // so it won't work correctly. Thus it's commented out.
 654          // unset($instance->configdata);
 655          $this->instance = $instance;
 656          $this->specialization();
 657      }
 658  
 659      /**
 660       * This function is called on your subclass right after an instance is loaded
 661       * Use this function to act on instance data just after it's loaded and before anything else is done
 662       * For instance: if your block will have different title's depending on location (site, course, blog, etc)
 663       */
 664      function specialization() {
 665          // Just to make sure that this method exists.
 666      }
 667  
 668      /**
 669       * Is each block of this type going to have instance-specific configuration?
 670       * Normally, this setting is controlled by {@link instance_allow_multiple}: if multiple
 671       * instances are allowed, then each will surely need its own configuration. However, in some
 672       * cases it may be necessary to provide instance configuration to blocks that do not want to
 673       * allow multiple instances. In that case, make this function return true.
 674       * I stress again that this makes a difference ONLY if {@link instance_allow_multiple} returns false.
 675       * @return boolean
 676       * @todo finish documenting this function by explaining per-instance configuration further
 677       */
 678      function instance_allow_config() {
 679          return false;
 680      }
 681  
 682      /**
 683       * Are you going to allow multiple instances of each block?
 684       * If yes, then it is assumed that the block WILL USE per-instance configuration
 685       * @return boolean
 686       * @todo finish documenting this function by explaining per-instance configuration further
 687       */
 688      function instance_allow_multiple() {
 689          // Are you going to allow multiple instances of each block?
 690          // If yes, then it is assumed that the block WILL USE per-instance configuration
 691          return false;
 692      }
 693  
 694      /**
 695       * Default behavior: print the config_instance.html file
 696       * You don't need to override this if you're satisfied with the above
 697       *
 698       * @uses $CFG
 699       * @return boolean
 700       * @todo finish documenting this function
 701       */
 702      function instance_config_print() {
 703          // Default behavior: print the config_instance.html file
 704          // You don't need to override this if you're satisfied with the above
 705          if (!$this->instance_allow_multiple() && !$this->instance_allow_config()) {
 706              return false;
 707          }
 708          global $CFG;
 709  
 710          if (is_file($CFG->dirroot .'/blocks/'. $this->name() .'/config_instance.html')) {
 711              print_simple_box_start('center', '', '', 5, 'blockconfiginstance');
 712              include($CFG->dirroot .'/blocks/'. $this->name() .'/config_instance.html');
 713              print_simple_box_end();
 714          } else {
 715              notice(get_string('blockconfigbad'), str_replace('blockaction=', 'dummy=', qualified_me()));
 716          }
 717          
 718          return true;
 719      }
 720  
 721      /**
 722       * Serialize and store config data
 723       * @return boolean
 724       * @todo finish documenting this function
 725       */
 726      function instance_config_save($data,$pinned=false) {
 727          $data = stripslashes_recursive($data);
 728          $this->config = $data;
 729          $table = 'block_instance';
 730          if (!empty($pinned)) {
 731              $table = 'block_pinned';
 732          }
 733          return set_field($table, 'configdata', base64_encode(serialize($data)), 'id', $this->instance->id);
 734      }
 735  
 736      /**
 737       * Replace the instance's configuration data with those currently in $this->config;
 738       * @return boolean
 739       * @todo finish documenting this function
 740       */
 741      function instance_config_commit($pinned=false) {
 742          $table = 'block_instance';
 743          if (!empty($pinned)) {
 744              $table = 'block_pinned';
 745          }
 746          return set_field($table, 'configdata', base64_encode(serialize($this->config)), 'id', $this->instance->id);
 747      }
 748  
 749       /**
 750       * Do any additional initialization you may need at the time a new block instance is created
 751       * @return boolean
 752       * @todo finish documenting this function
 753       */
 754      function instance_create() {
 755          return true;
 756      }
 757  
 758       /**
 759       * Delete everything related to this instance if you have been using persistent storage other than the configdata field.
 760       * @return boolean
 761       * @todo finish documenting this function
 762       */
 763      function instance_delete() {
 764          return true;
 765      }
 766  
 767       /**
 768       * Allows the block class to have a say in the user's ability to edit (i.e., configure) blocks of this type.
 769       * The framework has first say in whether this will be allowed (e.g., no editing allowed unless in edit mode)
 770       * but if the framework does allow it, the block can still decide to refuse.
 771       * @return boolean
 772       * @todo finish documenting this function
 773       */
 774      function user_can_edit() {
 775          return true;
 776      }
 777  
 778       /**
 779       * Allows the block class to have a say in the user's ability to create new instances of this block.
 780       * The framework has first say in whether this will be allowed (e.g., no adding allowed unless in edit mode)
 781       * but if the framework does allow it, the block can still decide to refuse.
 782       * This function has access to the complete page object, the creation related to which is being determined.
 783       * @return boolean
 784       * @todo finish documenting this function
 785       */
 786      function user_can_addto(&$page) {
 787          return true;
 788      }
 789  
 790      function get_extra_capabilities() {
 791          return array('moodle/block:view');
 792      }
 793  }
 794  
 795  /**
 796   * Specialized class for displaying a block with a list of icons/text labels
 797   *
 798   * @author Jon Papaioannou
 799   * @package blocks
 800   */
 801  
 802  class block_list extends block_base {
 803      var $content_type  = BLOCK_TYPE_LIST;
 804  
 805      function is_empty() {
 806  
 807          if (empty($this->instance->pinned)) {
 808              $context = get_context_instance(CONTEXT_BLOCK, $this->instance->id);
 809          } else {
 810              $context = get_context_instance(CONTEXT_SYSTEM); // pinned blocks do not have own context
 811          }
 812          
 813          if ( !has_capability('moodle/block:view', $context) ) {
 814              return true;
 815          }
 816  
 817          $this->get_content();
 818          return (empty($this->content->items) && empty($this->content->footer));
 819      }
 820  
 821      function _print_block() {
 822          global $COURSE;
 823  
 824          // is_empty() includes a call to get_content()
 825          if ($this->is_empty() && empty($COURSE->javascriptportal)) {
 826              if (empty($this->edit_controls)) {
 827                  // No content, no edit controls, so just shut up
 828                  return;
 829              } else {
 830                  // No content but editing, so show something at least
 831                  $this->_print_shadow();
 832              }
 833          } else {
 834              if ($this->hide_header() && empty($this->edit_controls)) {
 835                  // Header wants to hide, no edit controls to show, so no header it is
 836                  print_side_block(NULL, '', $this->content->items, $this->content->icons, 
 837                                   $this->content->footer, $this->html_attributes());
 838              } else {
 839                  // The full treatment, please. Include the title text.
 840                  print_side_block($this->_title_html(), '', $this->content->items, $this->content->icons, 
 841                                   $this->content->footer, $this->html_attributes(), $this->title);
 842              }
 843          }
 844      }
 845  
 846  }
 847  
 848  ?>