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   1  /**
   2   * Provides drop down menus for list of action links.
   3   *
   4   * @module moodle-core-actionmenu
   5   */
   6  
   7  var BODY = Y.one(Y.config.doc.body),
   8      CSS = {
   9          MENUSHOWN : 'action-menu-shown'
  10      },
  11      SELECTOR = {
  12          CAN_RECEIVE_FOCUS_SELECTOR: 'input:not([type="hidden"]), a[href], button, textarea, select, [tabindex]',
  13          MENU : '.moodle-actionmenu[data-enhance=moodle-core-actionmenu]',
  14          MENUBAR: '[role="menubar"]',
  15          MENUITEM: '[role="menuitem"]',
  16          MENUCONTENT : '.menu[data-rel=menu-content]',
  17          MENUCONTENTCHILD: 'li a',
  18          MENUCHILD: '.menu li a',
  19          TOGGLE : '.toggle-display',
  20          KEEPOPEN: '[data-keepopen="1"]',
  21          MENUBARITEMS: [
  22              '[role="menubar"] > [role="menuitem"]',
  23              '[role="menubar"] > [role="presentation"] > [role="menuitem"]'
  24          ],
  25          MENUITEMS: [
  26              '> [role="menuitem"]',
  27              '> [role="presentation"] > [role="menuitem"]'
  28          ]
  29      },
  30      ACTIONMENU,
  31      ALIGN = {
  32          TL : 'tl',
  33          TR : 'tr',
  34          BL : 'bl',
  35          BR : 'br'
  36      };
  37  
  38  /**
  39   * Action menu support.
  40   * This converts a generic list of links into a drop down menu opened by hovering or clicking
  41   * on a menu icon.
  42   *
  43   * @namespace M.core.actionmenu
  44   * @class ActionMenu
  45   * @constructor
  46   * @extends Base
  47   */
  48  ACTIONMENU = function() {
  49      ACTIONMENU.superclass.constructor.apply(this, arguments);
  50  };
  51  ACTIONMENU.prototype = {
  52  
  53      /**
  54       * The dialogue used for all action menu displays.
  55       * @property type
  56       * @type M.core.dialogue
  57       * @protected
  58       */
  59      dialogue : null,
  60  
  61      /**
  62       * An array of events attached during the display of the dialogue.
  63       * @property events
  64       * @type Object
  65       * @protected
  66       */
  67      events : [],
  68  
  69      /**
  70       * The node that owns the currently displayed menu.
  71       *
  72       * @property owner
  73       * @type Node
  74       * @default null
  75       */
  76      owner : null,
  77  
  78      /**
  79       * The menu button that toggles this open.
  80       *
  81       * @property menulink
  82       * @type Node
  83       * @protected
  84       */
  85      menulink: null,
  86  
  87      /**
  88       * The set of menu nodes.
  89       *
  90       * @property menuChildren
  91       * @type NodeList
  92       * @protected
  93       */
  94      menuChildren: null,
  95  
  96      /**
  97       * The first menu item.
  98       *
  99       * @property firstMenuChild
 100       * @type Node
 101       * @protected
 102       */
 103      firstMenuChild: null,
 104  
 105      /**
 106       * The last menu item.
 107       *
 108       * @property lastMenuChild
 109       * @type Node
 110       * @protected
 111       */
 112      lastMenuChild: null,
 113  
 114      /**
 115       * Called during the initialisation process of the object.
 116       *
 117       * @method initializer
 118       */
 119      initializer : function() {
 120          Y.log('Initialising the action menu manager', 'debug', ACTIONMENU.NAME);
 121          Y.all(SELECTOR.MENU).each(this.enhance, this);
 122          BODY.delegate('key', this.moveMenuItem, 'down:37,39', SELECTOR.MENUBARITEMS.join(','), this);
 123  
 124          BODY.delegate('click', this.toggleMenu, SELECTOR.MENU + ' ' + SELECTOR.TOGGLE, this);
 125          BODY.delegate('key', this.showIfHidden, 'down:enter,38,40', SELECTOR.MENU + ' ' + SELECTOR.TOGGLE, this);
 126  
 127          // Ensure that we toggle on menuitems when the spacebar is pressed.
 128          BODY.delegate('key', function(e) {
 129              e.currentTarget.simulate('click');
 130              e.preventDefault();
 131          }, 'down:32', SELECTOR.MENUBARITEMS.join(','));
 132      },
 133  
 134      /**
 135       * Enhances a menu adding aria attributes and flagging it as functional.
 136       *
 137       * @method enhance
 138       * @param {Node} menu
 139       * @return boolean
 140       */
 141      enhance : function(menu) {
 142          var menucontent = menu.one(SELECTOR.MENUCONTENT),
 143              align;
 144          if (!menucontent) {
 145              return false;
 146          }
 147          align = menucontent.getData('align') || this.get('align').join('-');
 148          menu.one(SELECTOR.TOGGLE).set('aria-haspopup', true);
 149          menucontent.set('aria-hidden', true);
 150          if (!menucontent.hasClass('align-'+align)) {
 151              menucontent.addClass('align-'+align);
 152          }
 153          if (menucontent.hasChildNodes()) {
 154              menu.setAttribute('data-enhanced', '1');
 155          }
 156      },
 157  
 158      /**
 159       * Handle movement between menu items in a menubar.
 160       *
 161       * @method moveMenuItem
 162       * @param {EventFacade} e The event generating the move request
 163       * @chainable
 164       */
 165      moveMenuItem: function(e) {
 166          var nextFocus,
 167              menuitem = e.target.ancestor(SELECTOR.MENUITEM, true);
 168  
 169          if (e.keyCode === 37) {
 170              nextFocus = this.getMenuItem(menuitem, true);
 171          } else if (e.keyCode === 39) {
 172              nextFocus = this.getMenuItem(menuitem);
 173          }
 174  
 175          if (nextFocus) {
 176              nextFocus.focus();
 177          }
 178          return this;
 179      },
 180  
 181      /**
 182       * Get the next menuitem in a menubar.
 183       *
 184       * @method getMenuItem
 185       * @param {Node} currentItem The currently focused item in the menubar
 186       * @param {Boolean} [previous=false] Move backwards in the menubar instead of forwards
 187       * @return {Node|null} The next item, or null if none was found
 188       */
 189      getMenuItem: function(currentItem, previous) {
 190          var menubar = currentItem.ancestor(SELECTOR.MENUBAR),
 191              menuitems;
 192  
 193          if (!menubar) {
 194              return null;
 195          }
 196  
 197          menuitems = menubar.all(SELECTOR.MENUITEMS.join(','));
 198  
 199          if (!menuitems) {
 200              return null;
 201          }
 202  
 203          var childCount = menuitems.size();
 204  
 205          if (childCount === 1) {
 206              // Only one item, exit now because we should already be on it.
 207              return null;
 208          }
 209  
 210          // Determine the next child.
 211          var index = 0,
 212              direction = 1,
 213              checkCount = 0;
 214  
 215          // Work out the index of the currently selected item.
 216          for (index = 0; index < childCount; index++) {
 217              if (menuitems.item(index) === currentItem) {
 218                  break;
 219              }
 220          }
 221  
 222          // Check that the menu item was found - otherwise return null.
 223          if (menuitems.item(index) !== currentItem) {
 224              return null;
 225          }
 226  
 227          // Reverse the direction if we want the previous item.
 228          if (previous) {
 229              direction = -1;
 230          }
 231  
 232          do {
 233              // Update the index in the direction of travel.
 234              index += direction;
 235  
 236              next = menuitems.item(index);
 237  
 238              // Check that we don't loop multiple times.
 239              checkCount++;
 240          } while (next && next.hasAttribute('hidden'));
 241  
 242          return next;
 243      },
 244  
 245      /**
 246       * Hides the menu if it is visible.
 247       * @method hideMenu
 248       */
 249      hideMenu : function() {
 250          if (this.dialogue) {
 251              Y.log('Hiding an action menu', 'debug', ACTIONMENU.NAME);
 252              this.dialogue.removeClass('show');
 253              this.dialogue.one(SELECTOR.MENUCONTENT).set('aria-hidden', true);
 254              this.dialogue = null;
 255          }
 256          for (var i in this.events) {
 257              if (this.events[i].detach) {
 258                  this.events[i].detach();
 259              }
 260          }
 261          this.events = [];
 262          if (this.owner) {
 263              this.owner.removeClass(CSS.MENUSHOWN);
 264              this.owner = null;
 265          }
 266  
 267          if (this.menulink) {
 268              this.menulink.focus();
 269              this.menulink = null;
 270          }
 271      },
 272  
 273      showIfHidden: function(e) {
 274          var menu = e.target.ancestor(SELECTOR.MENU),
 275              menuvisible = (menu.hasClass('show'));
 276  
 277          if (!menuvisible) {
 278              e.preventDefault();
 279              this.showMenu(e, menu);
 280          }
 281          return this;
 282      },
 283  
 284      /**
 285       * Toggles the display of the menu.
 286       * @method toggleMenu
 287       * @param {EventFacade} e
 288       */
 289      toggleMenu : function(e) {
 290          var menu = e.target.ancestor(SELECTOR.MENU),
 291              menuvisible = (menu.hasClass('show'));
 292  
 293          // Prevent event propagation as it will trigger the hideIfOutside event handler in certain situations.
 294          e.halt(true);
 295          this.hideMenu();
 296          if (menuvisible) {
 297              // The menu was visible and the user has clicked to toggle it again.
 298              return;
 299          }
 300          this.showMenu(e, menu);
 301      },
 302  
 303      /**
 304       * Handle keyboard events when the menu is open. We respond to:
 305       * * escape (exit)
 306       * * tab (move to next menu item)
 307       * * up/down (move to previous/next menu item)
 308       *
 309       * @method handleKeyboardEvent
 310       * @param {EventFacade} e The key event
 311       */
 312      handleKeyboardEvent: function(e) {
 313          var next;
 314  
 315          // Handle when the menu is still selected.
 316          if (e.currentTarget.ancestor(SELECTOR.TOGGLE, true)) {
 317              if ((e.keyCode === 40 || (e.keyCode === 9 && !e.shiftKey)) && this.firstMenuChild) {
 318                  this.firstMenuChild.focus();
 319                  e.preventDefault();
 320              } else if (e.keyCode === 38 && this.lastMenuChild) {
 321                  this.lastMenuChild.focus();
 322                  e.preventDefault();
 323              } else if (e.keyCode === 9 && e.shiftKey) {
 324                  this.hideMenu();
 325                  e.preventDefault();
 326              }
 327              return this;
 328          }
 329  
 330          if (e.keyCode === 27) {
 331              // The escape key was pressed so close the menu.
 332              this.hideMenu();
 333              e.preventDefault();
 334  
 335          } else if (e.keyCode === 32) {
 336              // The space bar was pressed. Trigger a click.
 337              e.preventDefault();
 338              e.currentTarget.simulate('click');
 339          } else if (e.keyCode === 9) {
 340              // The tab key was pressed. Tab moves forwards, Shift + Tab moves backwards through the menu options.
 341              // We only override the Shift + Tab on the first option, and Tab on the last option to change where the focus is moved to.
 342              if (e.target === this.firstMenuChild && e.shiftKey) {
 343                  this.hideMenu();
 344                  e.preventDefault();
 345              } else if (e.target === this.lastMenuChild && !e.shiftKey) {
 346                  if (this.hideMenu()) {
 347                      // Determine the next selector and focus on it.
 348                      next = this.menulink.next(SELECTOR.CAN_RECEIVE_FOCUS_SELECTOR);
 349                      if (next) {
 350                          next.focus();
 351                      }
 352                  }
 353              }
 354  
 355          } else if (e.keyCode === 38 || e.keyCode === 40) {
 356              // The up (38) or down (40) key was pushed.
 357              // On cursor moves we loops through the menu rather than exiting it as in the tab behaviour.
 358              var found = false,
 359                  index = 0,
 360                  direction = 1,
 361                  checkCount = 0;
 362  
 363              // Determine which menu item is currently selected.
 364              while (!found && index < this.menuChildren.size()) {
 365                  if (this.menuChildren.item(index) === e.currentTarget) {
 366                      found = true;
 367                  } else {
 368                      index++;
 369                  }
 370              }
 371  
 372              if (!found) {
 373                  Y.log("Unable to find this menu item in the list of menu children", 'debug', 'moodle-core-actionmenu');
 374                  return;
 375              }
 376  
 377              if (e.keyCode === 38) {
 378                  // Moving up so reverse the direction.
 379                  direction = -1;
 380              }
 381  
 382              // Try to find the next
 383              do {
 384                  index += direction;
 385                  if (index < 0) {
 386                      index = this.menuChildren.size() - 1;
 387                  } else if (index >= this.menuChildren.size()) {
 388                      // Handle wrapping.
 389                      index = 0;
 390                  }
 391                  next = this.menuChildren.item(index);
 392  
 393                  // Add a counter to ensure we don't get stuck in a loop if there's only one visible menu item.
 394                  checkCount++;
 395              } while (checkCount < this.menuChildren.size() && next !== e.currentTarget && next.hasClass('hidden'));
 396  
 397              if (next) {
 398                  next.focus();
 399                  e.preventDefault();
 400              }
 401          }
 402      },
 403  
 404      /**
 405       * Hides the menu if the event happened outside the menu.
 406       *
 407       * @protected
 408       * @method hideIfOutside
 409       * @param {EventFacade} e
 410       */
 411      hideIfOutside : function(e) {
 412          if (!e.target.ancestor(SELECTOR.MENUCHILD, true)) {
 413              this.hideMenu();
 414          }
 415      },
 416  
 417      /**
 418       * Displays the menu with the given content and alignment.
 419       *
 420       * @method showMenu
 421       * @param {EventFacade} e
 422       * @param {Node} menu
 423       * @return M.core.dialogue
 424       */
 425      showMenu : function(e, menu) {
 426          Y.log('Displaying an action menu', 'debug', ACTIONMENU.NAME);
 427          var ownerselector = menu.getData('owner'),
 428              menucontent = menu.one(SELECTOR.MENUCONTENT);
 429          this.owner = (ownerselector) ? menu.ancestor(ownerselector) : null;
 430          this.dialogue = menu;
 431          menu.addClass('show');
 432          if (this.owner) {
 433              this.owner.addClass(CSS.MENUSHOWN);
 434              this.menulink = this.owner.one(SELECTOR.TOGGLE);
 435          } else {
 436              this.menulink = e.target.ancestor(SELECTOR.TOGGLE, true);
 437          }
 438          this.constrain(menucontent.set('aria-hidden', false));
 439  
 440          this.menuChildren = this.dialogue.all(SELECTOR.MENUCHILD);
 441          if (this.menuChildren) {
 442              this.firstMenuChild = this.menuChildren.item(0);
 443              this.lastMenuChild  = this.menuChildren.item(this.menuChildren.size() - 1);
 444  
 445              this.firstMenuChild.focus();
 446          }
 447  
 448          // Close the menu if the user presses escape.
 449          this.events.push(BODY.on('key', this.hideMenu, 'esc', this));
 450  
 451          // Close the menu if the user clicks outside the menu.
 452          this.events.push(BODY.on('click', this.hideIfOutside, this));
 453  
 454          // Close the menu if the user focuses outside the menu.
 455          this.events.push(BODY.delegate('focus', this.hideIfOutside, '*', this));
 456  
 457          // Check keyboard changes.
 458          this.events.push(menu.delegate('key', this.handleKeyboardEvent, 'down:9, 27, 38, 40, 32', SELECTOR.MENUCHILD + ', ' + SELECTOR.TOGGLE, this));
 459  
 460          // Close the menu after a button was pushed.
 461          this.events.push(menu.delegate('click', function(e) {
 462              if (e.currentTarget.test(SELECTOR.KEEPOPEN)) {
 463                  return;
 464              }
 465              this.hideMenu();
 466          }, SELECTOR.MENUCHILD, this));
 467  
 468          return true;
 469      },
 470  
 471      /**
 472       * Constrains the node to its the page width.
 473       *
 474       * @method constrain
 475       * @param {Node} node
 476       */
 477      constrain : function(node) {
 478          var selector = node.getData('constraint'),
 479              nx = node.getX(),
 480              ny = node.getY(),
 481              nwidth = node.get('offsetWidth'),
 482              nheight = node.get('offsetHeight'),
 483              cx = 0,
 484              cy = 0,
 485              cwidth,
 486              cheight,
 487              coverflow = 'auto',
 488              newwidth = null,
 489              newheight = null,
 490              newleft = null,
 491              newtop = null,
 492              boxshadow = null;
 493  
 494          if (selector) {
 495              selector = node.ancestor(selector);
 496          }
 497          if (selector) {
 498              cwidth = selector.get('offsetWidth');
 499              cheight = selector.get('offsetHeight');
 500              cx = selector.getX();
 501              cy = selector.getY();
 502              coverflow = selector.getStyle('overflow') || 'auto';
 503          } else {
 504              cwidth = node.get('docWidth');
 505              cheight = node.get('docHeight');
 506          }
 507  
 508          // Constrain X.
 509          // First up if the width is more than the constrain its easily full width + full height.
 510          if (nwidth > cwidth) {
 511              // The width of the constraint.
 512              newwidth = nwidth = cwidth;
 513              // The constraints xpoint.
 514              newleft = nx = cx;
 515          } else {
 516              if (nx < cx) {
 517                  // If nx is less than cx we need to move it right.
 518                  newleft = nx = cx;
 519              } else if (nx + nwidth >= cx + cwidth) {
 520                  // The top right of the node is outside of the constraint, move it in.
 521                  newleft = cx + cwidth - nwidth;
 522              }
 523          }
 524  
 525          // Constrain Y.
 526          if (nheight > cheight && coverflow.toLowerCase() === 'hidden') {
 527              // The node extends over the constrained area and would be clipped.
 528              // Reduce the height of the node and force its overflow to scroll.
 529              newheight = nheight = cheight;
 530              node.setStyle('overflow', 'auto');
 531          }
 532          // If the node is below the top of the constraint AND
 533          //    the node is longer than the constraint allows.
 534          if (ny >= cy && ny + nheight > cy + cheight) {
 535              // Move it up.
 536              newtop = cy + cheight - nheight;
 537              try {
 538                  boxshadow = node.getStyle('boxShadow').replace(/.*? (\d+)px \d+px$/, '$1');
 539                  if (new RegExp(/^\d+$/).test(boxshadow) && newtop - cy > boxshadow) {
 540                      newtop -= boxshadow;
 541                  }
 542              } catch (ex) {
 543                  Y.log('Failed to determine box-shadow margin.', 'warn', ACTIONMENU.NAME);
 544              }
 545          }
 546  
 547          if (newleft !== null) {
 548              node.setX(newleft);
 549          }
 550          if (newtop !== null) {
 551              node.setY(newtop);
 552          }
 553          if (newwidth !== null) {
 554              node.setStyle('width', newwidth.toString() + 'px');
 555          }
 556          if (newheight !== null) {
 557              node.setStyle('height', newheight.toString() + 'px');
 558          }
 559      }
 560  };
 561  
 562  Y.extend(ACTIONMENU, Y.Base, ACTIONMENU.prototype, {
 563      NAME : 'moodle-core-actionmenu',
 564      ATTRS : {
 565          align : {
 566              value : [
 567                  ALIGN.TR, // The dialogue.
 568                  ALIGN.BR  // The button
 569              ]
 570          }
 571      }
 572  });
 573  
 574  M.core = M.core || {};
 575  M.core.actionmenu = M.core.actionmenu || {};
 576  
 577  /**
 578   *
 579   * @static
 580   * @property M.core.actionmenu.instance
 581   * @type {ACTIONMENU}
 582   */
 583  M.core.actionmenu.instance = null;
 584  
 585  /**
 586   * Init function - will only ever create one instance of the actionmenu class.
 587   *
 588   * @method M.core.actionmenu.init
 589   * @static
 590   * @param {Object} params
 591   */
 592  M.core.actionmenu.init = M.core.actionmenu.init || function(params) {
 593      M.core.actionmenu.instance = M.core.actionmenu.instance || new ACTIONMENU(params);
 594  };
 595  
 596  /**
 597   * Registers a new DOM node with the action menu causing it to be enhanced if required.
 598   *
 599   * @method M.core.actionmenu.newDOMNode
 600   * @param node
 601   * @return {boolean}
 602   */
 603  M.core.actionmenu.newDOMNode = function(node) {
 604      if (M.core.actionmenu.instance === null) {
 605          return true;
 606      }
 607      node.all(SELECTOR.MENU).each(M.core.actionmenu.instance.enhance, M.core.actionmenu.instance);
 608  };