blocks/moodleblock.class.php

   1 <?php  // $Id$
   2
   3 /**
   4  * This file contains the parent class for moodle blocks, block_base.
   5  *
   6  * @author Jon Papaioannou
   7  * @version  $Id$
   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 ?>