blocks/moodleblock.class.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * This file contains the parent class for moodle blocks, block_base.
  19  *
  20  * @package    core_block
  21  * @license    http://www.gnu.org/copyleft/gpl.html GNU Public License
  22  */
  23
  24 /// Constants
  25
  26 /**
  27  * 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 $this->content->footer.
  28  */
  29 define('BLOCK_TYPE_LIST',    1);
  30
  31 /**
  32  * Block type of text. Contents of block should be set to standard html text in the content object as items ($this->content->text). Optionally include footer text in $this->content->footer.
  33  */
  34 define('BLOCK_TYPE_TEXT',    2);
  35 /**
  36  * Block type of tree. $this->content->items is a list of tree_item objects and $this->content->footer is a string.
  37  */
  38 define('BLOCK_TYPE_TREE',    3);
  39
  40 /**
  41  * Class for describing a moodle block, all Moodle blocks derive from this class
  42  *
  43  * @author Jon Papaioannou
  44  * @package core_block
  45  */
  46 class block_base {
  47
  48     /**
  49      * Internal var for storing/caching translated strings
  50      * @var string $str
  51      */
  52     var $str;
  53
  54     /**
  55      * The title of the block to be displayed in the block title area.
  56      * @var string $title
  57      */
  58     var $title         = NULL;
  59
  60     /**
  61      * The name of the block to be displayed in the block title area if the title is empty.
  62      * @var string arialabel
  63      */
  64     var $arialabel         = NULL;
  65
  66     /**
  67      * The type of content that this block creates. Currently support options - BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT
  68      * @var int $content_type
  69      */
  70     var $content_type  = BLOCK_TYPE_TEXT;
  71
  72     /**
  73      * An object to contain the information to be displayed in the block.
  74      * @var stdObject $content
  75      */
  76     var $content       = NULL;
  77
  78     /**
  79      * The initialized instance of this block object.
  80      * @var block $instance
  81      */
  82     var $instance      = NULL;
  83
  84     /**
  85      * The page that this block is appearing on.
  86      * @var moodle_page
  87      */
  88     public $page       = NULL;
  89
  90     /**
  91      * This blocks's context.
  92      * @var stdClass
  93      */
  94     public $context    = NULL;
  95
  96     /**
  97      * An object containing the instance configuration information for the current instance of this block.
  98      * @var stdObject $config
  99      */
 100     var $config        = NULL;
 101
 102     /**
 103      * How often the cronjob should run, 0 if not at all.
 104      * @var int $cron
 105      */
 106
 107     var $cron          = NULL;
 108
 109 /// Class Functions
 110
 111     /**
 112      * Fake constructor to keep PHP5 happy
 113      *
 114      */
 115     function __construct() {
 116         $this->init();
 117     }
 118
 119     /**
 120      * Function that can be overridden to do extra cleanup before
 121      * the database tables are deleted. (Called once per block, not per instance!)
 122      */
 123     function before_delete() {
 124     }
 125
 126     /**
 127      * Returns the block name, as present in the class name,
 128      * the database, the block directory, etc etc.
 129      *
 130      * @return string
 131      */
 132     function name() {
 133         // Returns the block name, as present in the class name,
 134         // the database, the block directory, etc etc.
 135         static $myname;
 136         if ($myname === NULL) {
 137             $myname = strtolower(get_class($this));
 138             $myname = substr($myname, strpos($myname, '_') + 1);
 139         }
 140         return $myname;
 141     }
 142
 143     /**
 144      * Parent class version of this function simply returns NULL
 145      * This should be implemented by the derived class to return
 146      * the content object.
 147      *
 148      * @return stdObject
 149      */
 150     function get_content() {
 151         // This should be implemented by the derived class.
 152         return NULL;
 153     }
 154
 155     /**
 156      * Returns the class $title var value.
 157      *
 158      * Intentionally doesn't check if a title is set.
 159      * This is already done in {@link _self_test()}
 160      *
 161      * @return string $this->title
 162      */
 163     function get_title() {
 164         // Intentionally doesn't check if a title is set. This is already done in _self_test()
 165         return $this->title;
 166     }
 167
 168     /**
 169      * Returns the class $content_type var value.
 170      *
 171      * Intentionally doesn't check if content_type is set.
 172      * This is already done in {@link _self_test()}
 173      *
 174      * @return string $this->content_type
 175      */
 176     function get_content_type() {
 177         // Intentionally doesn't check if a content_type is set. This is already done in _self_test()
 178         return $this->content_type;
 179     }
 180
 181     /**
 182      * Returns true or false, depending on whether this block has any content to display
 183      * and whether the user has permission to view the block
 184      *
 185      * @return boolean
 186      */
 187     function is_empty() {
 188         if ( !has_capability('moodle/block:view', $this->context) ) {
 189             return true;
 190         }
 191
 192         $this->get_content();
 193         return(empty($this->content->text) && empty($this->content->footer));
 194     }
 195
 196     /**
 197      * First sets the current value of $this->content to NULL
 198      * then calls the block's {@link get_content()} function
 199      * to set its value back.
 200      *
 201      * @return stdObject
 202      */
 203     function refresh_content() {
 204         // Nothing special here, depends on content()
 205         $this->content = NULL;
 206         return $this->get_content();
 207     }
 208
 209     /**
 210      * Return a block_contents object representing the full contents of this block.
 211      *
 212      * This internally calls ->get_content(), and then adds the editing controls etc.
 213      *
 214      * You probably should not override this method, but instead override
 215      * {@link html_attributes()}, {@link formatted_contents()} or {@link get_content()},
 216      * {@link hide_header()}, {@link (get_edit_controls)}, etc.
 217      *
 218      * @return block_contents a representation of the block, for rendering.
 219      * @since Moodle 2.0.
 220      */
 221     public function get_content_for_output($output) {
 222         global $CFG;
 223
 224         $bc = new block_contents($this->html_attributes());
 225         $bc->attributes['data-block'] = $this->name();
 226         $bc->blockinstanceid = $this->instance->id;
 227         $bc->blockpositionid = $this->instance->blockpositionid;
 228
 229         if ($this->instance->visible) {
 230             $bc->content = $this->formatted_contents($output);
 231             if (!empty($this->content->footer)) {
 232                 $bc->footer = $this->content->footer;
 233             }
 234         } else {
 235             $bc->add_class('invisibleblock');
 236         }
 237
 238         if (!$this->hide_header()) {
 239             $bc->title = $this->title;
 240         }
 241
 242         if (empty($bc->title)) {
 243             $bc->arialabel = new lang_string('pluginname', get_class($this));
 244             $this->arialabel = $bc->arialabel;
 245         }
 246
 247         if ($this->page->user_is_editing()) {
 248             $bc->controls = $this->page->blocks->edit_controls($this);
 249         } else {
 250             // we must not use is_empty on hidden blocks
 251             if ($this->is_empty() && !$bc->controls) {
 252                 return null;
 253             }
 254         }
 255
 256         if (empty($CFG->allowuserblockhiding)
 257                 || (empty($bc->content) && empty($bc->footer))
 258                 || !$this->instance_can_be_collapsed()) {
 259             $bc->collapsible = block_contents::NOT_HIDEABLE;
 260         } else if (get_user_preferences('block' . $bc->blockinstanceid . 'hidden', false)) {
 261             $bc->collapsible = block_contents::HIDDEN;
 262         } else {
 263             $bc->collapsible = block_contents::VISIBLE;
 264         }
 265
 266         if ($this->instance_can_be_docked() && !$this->hide_header()) {
 267             $bc->dockable = true;
 268         }
 269
 270         $bc->annotation = ''; // TODO MDL-19398 need to work out what to say here.
 271
 272         return $bc;
 273     }
 274
 275
 276     /**
 277      * Return an object containing all the block content to be returned by external functions.
 278      *
 279      * If your block is returning formatted content or provide files for download, you should override this method to use the
 280      * external_format_text, external_format_string functions for formatting or external_util::get_area_files for files.
 281      *
 282      * @param  core_renderer $output the rendered used for output
 283      * @return stdClass      object containing the block title, central content, footer and linked files (if any).
 284      * @since  Moodle 3.6
 285      */
 286     public function get_content_for_external($output) {
 287         $bc = new stdClass;
 288         $bc->title = null;
 289         $bc->content = null;
 290         $bc->contentformat = FORMAT_HTML;
 291         $bc->footer = null;
 292         $bc->files = [];
 293
 294         if ($this->instance->visible) {
 295             $bc->content = $this->formatted_contents($output);
 296             if (!empty($this->content->footer)) {
 297                 $bc->footer = $this->content->footer;
 298             }
 299         }
 300
 301         if (!$this->hide_header()) {
 302             $bc->title = $this->title;
 303         }
 304
 305         return $bc;
 306     }
 307
 308     /**
 309      * Return the plugin config settings for external functions.
 310      *
 311      * In some cases the configs will need formatting or be returned only if the current user has some capabilities enabled.
 312      *
 313      * @return stdClass the configs for both the block instance and plugin (as object with name -> value)
 314      * @since Moodle 3.8
 315      */
 316     public function get_config_for_external() {
 317         return (object) [
 318             'instance' => new stdClass(),
 319             'plugin' => new stdClass(),
 320         ];
 321     }
 322
 323     /**
 324      * Convert the contents of the block to HTML.
 325      *
 326      * This is used by block base classes like block_list to convert the structured
 327      * $this->content->list and $this->content->icons arrays to HTML. So, in most
 328      * blocks, you probaby want to override the {@link get_contents()} method,
 329      * which generates that structured representation of the contents.
 330      *
 331      * @param $output The core_renderer to use when generating the output.
 332      * @return string the HTML that should appearn in the body of the block.
 333      * @since Moodle 2.0.
 334      */
 335     protected function formatted_contents($output) {
 336         $this->get_content();
 337         $this->get_required_javascript();
 338         if (!empty($this->content->text)) {
 339             return $this->content->text;
 340         } else {
 341             return '';
 342         }
 343     }
 344
 345     /**
 346      * Tests if this block has been implemented correctly.
 347      * Also, $errors isn't used right now
 348      *
 349      * @return boolean
 350      */
 351
 352     function _self_test() {
 353         // Tests if this block has been implemented correctly.
 354         // Also, $errors isn't used right now
 355         $errors = array();
 356
 357         $correct = true;
 358         if ($this->get_title() === NULL) {
 359             $errors[] = 'title_not_set';
 360             $correct = false;
 361         }
 362         if (!in_array($this->get_content_type(), array(BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT, BLOCK_TYPE_TREE))) {
 363             $errors[] = 'invalid_content_type';
 364             $correct = false;
 365         }
 366         //following selftest was not working when roles&capabilities were used from block
 367 /*        if ($this->get_content() === NULL) {
 368             $errors[] = 'content_not_set';
 369             $correct = false;
 370         }*/
 371         $formats = $this->applicable_formats();
 372         if (empty($formats) || array_sum($formats) === 0) {
 373             $errors[] = 'no_formats';
 374             $correct = false;
 375         }
 376
 377         return $correct;
 378     }
 379
 380     /**
 381      * Subclasses should override this and return true if the
 382      * subclass block has a settings.php file.
 383      *
 384      * @return boolean
 385      */
 386     function has_config() {
 387         return false;
 388     }
 389
 390     /**
 391      * Default behavior: save all variables as $CFG properties
 392      * You don't need to override this if you 're satisfied with the above
 393      *
 394      * @deprecated since Moodle 2.9 MDL-49385 - Please use Admin Settings functionality to save block configuration.
 395      */
 396     function config_save($data) {
 397         throw new coding_exception('config_save() can not be used any more, use Admin Settings functionality to save block configuration.');
 398     }
 399
 400     /**
 401      * Which page types this block may appear on.
 402      *
 403      * The information returned here is processed by the
 404      * {@link blocks_name_allowed_in_format()} function. Look there if you need
 405      * to know exactly how this works.
 406      *
 407      * Default case: everything except mod and tag.
 408      *
 409      * @return array page-type prefix => true/false.
 410      */
 411     function applicable_formats() {
 412         // Default case: the block can be used in courses and site index, but not in activities
 413         return array('all' => true, 'mod' => false, 'tag' => false);
 414     }
 415
 416
 417     /**
 418      * Default return is false - header will be shown
 419      * @return boolean
 420      */
 421     function hide_header() {
 422         return false;
 423     }
 424
 425     /**
 426      * Return any HTML attributes that you want added to the outer <div> that
 427      * of the block when it is output.
 428      *
 429      * Because of the way certain JS events are wired it is a good idea to ensure
 430      * that the default values here still get set.
 431      * I found the easiest way to do this and still set anything you want is to
 432      * override it within your block in the following way
 433      *
 434      * <code php>
 435      * function html_attributes() {
 436      *    $attributes = parent::html_attributes();
 437      *    $attributes['class'] .= ' mynewclass';
 438      *    return $attributes;
 439      * }
 440      * </code>
 441      *
 442      * @return array attribute name => value.
 443      */
 444     function html_attributes() {
 445         $attributes = array(
 446             'id' => 'inst' . $this->instance->id,
 447             'class' => 'block_' . $this->name() . ' block',
 448             'role' => $this->get_aria_role()
 449         );
 450         if ($this->hide_header()) {
 451             $attributes['class'] .= ' no-header';
 452         }
 453         if ($this->instance_can_be_docked() && get_user_preferences('docked_block_instance_' . $this->instance->id, 0)) {
 454             $attributes['class'] .= ' dock_on_load';
 455         }
 456         return $attributes;
 457     }
 458
 459     /**
 460      * Set up a particular instance of this class given data from the block_insances
 461      * table and the current page. (See {@link block_manager::load_blocks()}.)
 462      *
 463      * @param stdClass $instance data from block_insances, block_positions, etc.
 464      * @param moodle_page $the page this block is on.
 465      */
 466     function _load_instance($instance, $page) {
 467         if (!empty($instance->configdata)) {
 468             $this->config = unserialize(base64_decode($instance->configdata));
 469         }
 470         $this->instance = $instance;
 471         $this->context = context_block::instance($instance->id);
 472         $this->page = $page;
 473         $this->specialization();
 474     }
 475
 476     /**
 477      * Allows the block to load any JS it requires into the page.
 478      *
 479      * By default this function simply permits the user to dock the block if it is dockable.
 480      *
 481      * Left null as of MDL-64506.
 482      */
 483     function get_required_javascript() {
 484     }
 485
 486     /**
 487      * This function is called on your subclass right after an instance is loaded
 488      * Use this function to act on instance data just after it's loaded and before anything else is done
 489      * For instance: if your block will have different title's depending on location (site, course, blog, etc)
 490      */
 491     function specialization() {
 492         // Just to make sure that this method exists.
 493     }
 494
 495     /**
 496      * Is each block of this type going to have instance-specific configuration?
 497      * Normally, this setting is controlled by {@link instance_allow_multiple()}: if multiple
 498      * instances are allowed, then each will surely need its own configuration. However, in some
 499      * cases it may be necessary to provide instance configuration to blocks that do not want to
 500      * allow multiple instances. In that case, make this function return true.
 501      * I stress again that this makes a difference ONLY if {@link instance_allow_multiple()} returns false.
 502      * @return boolean
 503      */
 504     function instance_allow_config() {
 505         return false;
 506     }
 507
 508     /**
 509      * Are you going to allow multiple instances of each block?
 510      * If yes, then it is assumed that the block WILL USE per-instance configuration
 511      * @return boolean
 512      */
 513     function instance_allow_multiple() {
 514         // Are you going to allow multiple instances of each block?
 515         // If yes, then it is assumed that the block WILL USE per-instance configuration
 516         return false;
 517     }
 518
 519     /**
 520      * Serialize and store config data
 521      */
 522     function instance_config_save($data, $nolongerused = false) {
 523         global $DB;
 524         $DB->update_record('block_instances', ['id' => $this->instance->id,
 525                 'configdata' => base64_encode(serialize($data)), 'timemodified' => time()]);
 526     }
 527
 528     /**
 529      * Replace the instance's configuration data with those currently in $this->config;
 530      */
 531     function instance_config_commit($nolongerused = false) {
 532         global $DB;
 533         $this->instance_config_save($this->config);
 534     }
 535
 536     /**
 537      * Do any additional initialization you may need at the time a new block instance is created
 538      * @return boolean
 539      */
 540     function instance_create() {
 541         return true;
 542     }
 543
 544     /**
 545      * Copy any block-specific data when copying to a new block instance.
 546      * @param int $fromid the id number of the block instance to copy from
 547      * @return boolean
 548      */
 549     public function instance_copy($fromid) {
 550         return true;
 551     }
 552
 553     /**
 554      * Delete everything related to this instance if you have been using persistent storage other than the configdata field.
 555      * @return boolean
 556      */
 557     function instance_delete() {
 558         return true;
 559     }
 560
 561     /**
 562      * Allows the block class to have a say in the user's ability to edit (i.e., configure) blocks of this type.
 563      * The framework has first say in whether this will be allowed (e.g., no editing allowed unless in edit mode)
 564      * but if the framework does allow it, the block can still decide to refuse.
 565      * @return boolean
 566      */
 567     function user_can_edit() {
 568         global $USER;
 569
 570         if (has_capability('moodle/block:edit', $this->context)) {
 571             return true;
 572         }
 573
 574         // The blocks in My Moodle are a special case.  We want them to inherit from the user context.
 575         if (!empty($USER->id)
 576             && $this->instance->parentcontextid == $this->page->context->id   // Block belongs to this page
 577             && $this->page->context->contextlevel == CONTEXT_USER             // Page belongs to a user
 578             && $this->page->context->instanceid == $USER->id) {               // Page belongs to this user
 579             return has_capability('moodle/my:manageblocks', $this->page->context);
 580         }
 581
 582         return false;
 583     }
 584
 585     /**
 586      * Allows the block class to have a say in the user's ability to create new instances of this block.
 587      * The framework has first say in whether this will be allowed (e.g., no adding allowed unless in edit mode)
 588      * but if the framework does allow it, the block can still decide to refuse.
 589      * This function has access to the complete page object, the creation related to which is being determined.
 590      *
 591      * @param moodle_page $page
 592      * @return boolean
 593      */
 594     function user_can_addto($page) {
 595         // List of formats this block supports.
 596         $formats = $this->applicable_formats();
 597
 598         // The blocks in My Moodle are a special case and use a different capability.
 599         $mypagetypes = my_page_type_list($page->pagetype); // Get list of possible my page types.
 600
 601         if (array_key_exists($page->pagetype, $mypagetypes)) { // Ensure we are on a page with a my page type.
 602             // If the block cannot be displayed on /my it is ok if the myaddinstance capability is not defined.
 603             // Is 'my' explicitly forbidden?
 604             // If 'all' has not been allowed, has 'my' been explicitly allowed?
 605             if ((isset($formats['my']) && $formats['my'] == false)
 606                 || (empty($formats['all']) && empty($formats['my']))) {
 607
 608                 // Block cannot be added to /my regardless of capabilities.
 609                 return false;
 610             } else {
 611                 $capability = 'block/' . $this->name() . ':myaddinstance';
 612                 return $this->has_add_block_capability($page, $capability)
 613                        && has_capability('moodle/my:manageblocks', $page->context);
 614             }
 615         }
 616         // Check if this is a block only used on /my.
 617         unset($formats['my']);
 618         if (empty($formats)) {
 619             // Block can only be added to /my - return false.
 620             return false;
 621         }
 622
 623         $capability = 'block/' . $this->name() . ':addinstance';
 624         if ($this->has_add_block_capability($page, $capability)
 625                 && has_capability('moodle/block:edit', $page->context)) {
 626             return true;
 627         }
 628
 629         return false;
 630     }
 631
 632     /**
 633      * Returns true if the user can add a block to a page.
 634      *
 635      * @param moodle_page $page
 636      * @param string $capability the capability to check
 637      * @return boolean true if user can add a block, false otherwise.
 638      */
 639     private function has_add_block_capability($page, $capability) {
 640         // Check if the capability exists.
 641         if (!get_capability_info($capability)) {
 642             // Debug warning that the capability does not exist, but no more than once per page.
 643             static $warned = array();
 644             if (!isset($warned[$this->name()])) {
 645                 debugging('The block ' .$this->name() . ' does not define the standard capability ' .
 646                         $capability , DEBUG_DEVELOPER);
 647                 $warned[$this->name()] = 1;
 648             }
 649             // If the capability does not exist, the block can always be added.
 650             return true;
 651         } else {
 652             return has_capability($capability, $page->context);
 653         }
 654     }
 655
 656     static function get_extra_capabilities() {
 657         return array('moodle/block:view', 'moodle/block:edit');
 658     }
 659
 660     /**
 661      * Can be overridden by the block to prevent the block from being dockable.
 662      *
 663      * @return bool
 664      *
 665      * Return false as per MDL-64506
 666      */
 667     public function instance_can_be_docked() {
 668         return false;
 669     }
 670
 671     /**
 672      * If overridden and set to false by the block it will not be hidable when
 673      * editing is turned on.
 674      *
 675      * @return bool
 676      */
 677     public function instance_can_be_hidden() {
 678         return true;
 679     }
 680
 681     /**
 682      * If overridden and set to false by the block it will not be collapsible.
 683      *
 684      * @return bool
 685      */
 686     public function instance_can_be_collapsed() {
 687         return true;
 688     }
 689
 690     /** @callback callback functions for comments api */
 691     public static function comment_template($options) {
 692         $ret = <<<EOD
 693 <div class="comment-userpicture">___picture___</div>
 694 <div class="comment-content">
 695     ___name___ - <span>___time___</span>
 696     <div>___content___</div>
 697 </div>
 698 EOD;
 699         return $ret;
 700     }
 701     public static function comment_permissions($options) {
 702         return array('view'=>true, 'post'=>true);
 703     }
 704     public static function comment_url($options) {
 705         return null;
 706     }
 707     public static function comment_display($comments, $options) {
 708         return $comments;
 709     }
 710     public static function comment_add(&$comments, $options) {
 711         return true;
 712     }
 713
 714     /**
 715      * Returns the aria role attribute that best describes this block.
 716      *
 717      * Region is the default, but this should be overridden by a block is there is a region child, or even better
 718      * a landmark child.
 719      *
 720      * Options are as follows:
 721      *    - landmark
 722      *      - application
 723      *      - banner
 724      *      - complementary
 725      *      - contentinfo
 726      *      - form
 727      *      - main
 728      *      - navigation
 729      *      - search
 730      *
 731      * @return string
 732      */
 733     public function get_aria_role() {
 734         return 'complementary';
 735     }
 736 }
 737
 738 /**
 739  * Specialized class for displaying a block with a list of icons/text labels
 740  *
 741  * The get_content method should set $this->content->items and (optionally)
 742  * $this->content->icons, instead of $this->content->text.
 743  *
 744  * @author Jon Papaioannou
 745  * @package core_block
 746  */
 747
 748 class block_list extends block_base {
 749     var $content_type  = BLOCK_TYPE_LIST;
 750
 751     function is_empty() {
 752         if ( !has_capability('moodle/block:view', $this->context) ) {
 753             return true;
 754         }
 755
 756         $this->get_content();
 757         return (empty($this->content->items) && empty($this->content->footer));
 758     }
 759
 760     protected function formatted_contents($output) {
 761         $this->get_content();
 762         $this->get_required_javascript();
 763         if (!empty($this->content->items)) {
 764             return $output->list_block_contents($this->content->icons, $this->content->items);
 765         } else {
 766             return '';
 767         }
 768     }
 769
 770     function html_attributes() {
 771         $attributes = parent::html_attributes();
 772         $attributes['class'] .= ' list_block';
 773         return $attributes;
 774     }
 775
 776 }
 777
 778 /**
 779  * Specialized class for displaying a tree menu.
 780  *
 781  * The {@link get_content()} method involves setting the content of
 782  * <code>$this->content->items</code> with an array of {@link tree_item}
 783  * objects (these are the top-level nodes). The {@link tree_item::children}
 784  * property may contain more tree_item objects, and so on. The tree_item class
 785  * itself is abstract and not intended for use, use one of it's subclasses.
 786  *
 787  * Unlike {@link block_list}, the icons are specified as part of the items,
 788  * not in a separate array.
 789  *
 790  * @author Alan Trick
 791  * @package core_block
 792  * @internal this extends block_list so we get is_empty() for free
 793  */
 794 class block_tree extends block_list {
 795
 796     /**
 797      * @var int specifies the manner in which contents should be added to this
 798      * block type. In this case <code>$this->content->items</code> is used with
 799      * {@link tree_item}s.
 800      */
 801     public $content_type = BLOCK_TYPE_TREE;
 802
 803     /**
 804      * Make the formatted HTML ouput.
 805      *
 806      * Also adds the required javascript call to the page output.
 807      *
 808      * @param core_renderer $output
 809      * @return string HTML
 810      */
 811     protected function formatted_contents($output) {
 812         // based of code in admin_tree
 813         global $PAGE; // TODO change this when there is a proper way for blocks to get stuff into head.
 814         static $eventattached;
 815         if ($eventattached===null) {
 816             $eventattached = true;
 817         }
 818         if (!$this->content) {
 819             $this->content = new stdClass;
 820             $this->content->items = array();
 821         }
 822         $this->get_required_javascript();
 823         $this->get_content();
 824         $content = $output->tree_block_contents($this->content->items,array('class'=>'block_tree list'));
 825         if (isset($this->id) && !is_numeric($this->id)) {
 826             $content = $output->box($content, 'block_tree_box', $this->id);
 827         }
 828         return $content;
 829     }
 830 }