_HasDropDown.js

define([
	"dojo/_base/declare", // declare
	"dojo/Deferred",
	"dojo/dom", // dom.isDescendant
	"dojo/dom-attr", // domAttr.set
	"dojo/dom-class", // domClass.add domClass.contains domClass.remove
	"dojo/dom-geometry", // domGeometry.marginBox domGeometry.position
	"dojo/dom-style", // domStyle.set
	"dojo/has", // has("touch")
	"dojo/keys", // keys.DOWN_ARROW keys.ENTER keys.ESCAPE
	"dojo/_base/lang", // lang.hitch lang.isFunction
	"dojo/on",
	"./registry", // registry.byNode()
	"./focus",
	"./popup",
	"./_FocusMixin",
	"./Viewport"
], function(declare, Deferred, dom, domAttr, domClass, domGeometry, domStyle, has, keys, lang, on,
			registry, focus, popup, _FocusMixin, Viewport){


	// module:
	//		dijit/_HasDropDown

	return declare("dijit._HasDropDown", _FocusMixin, {
		// summary:
		//		Mixin for widgets that need drop down ability.

		// _buttonNode: [protected] DomNode
		//		The button/icon/node to click to display the drop down.
		//		Can be set via a data-dojo-attach-point assignment.
		//		If missing, then either focusNode or domNode (if focusNode is also missing) will be used.
		_buttonNode: null,

		// _arrowWrapperNode: [protected] DomNode
		//		Will set CSS class dijitUpArrow, dijitDownArrow, dijitRightArrow etc. on this node depending
		//		on where the drop down is set to be positioned.
		//		Can be set via a data-dojo-attach-point assignment.
		//		If missing, then _buttonNode will be used.
		_arrowWrapperNode: null,

		// _popupStateNode: [protected] DomNode
		//		The node to set the aria-expanded class on.
		//		Also sets popupActive class but that will be removed in 2.0.
		//		Can be set via a data-dojo-attach-point assignment.
		//		If missing, then focusNode or _buttonNode (if focusNode is missing) will be used.
		_popupStateNode: null,

		// _aroundNode: [protected] DomNode
		//		The node to display the popup around.
		//		Can be set via a data-dojo-attach-point assignment.
		//		If missing, then domNode will be used.
		_aroundNode: null,

		// dropDown: [protected] Widget
		//		The widget to display as a popup.  This widget *must* be
		//		defined before the startup function is called.
		dropDown: null,

		// autoWidth: [protected] Boolean
		//		Set to true to make the drop down at least as wide as this
		//		widget.  Set to false if the drop down should just be its
		//		default width
		autoWidth: true,

		// forceWidth: [protected] Boolean
		//		Set to true to make the drop down exactly as wide as this
		//		widget.  Overrides autoWidth.
		forceWidth: false,

		// maxHeight: [protected] Integer
		//		The max height for our dropdown.
		//		Any dropdown taller than this will have scrollbars.
		//		Set to 0 for no max height, or -1 to limit height to available space in viewport
		maxHeight: 0,

		// dropDownPosition: [const] String[]
		//		This variable controls the position of the drop down.
		//		It's an array of strings with the following values:
		//
		//		- before: places drop down to the left of the target node/widget, or to the right in
		//		  the case of RTL scripts like Hebrew and Arabic
		//		- after: places drop down to the right of the target node/widget, or to the left in
		//		  the case of RTL scripts like Hebrew and Arabic
		//		- above: drop down goes above target node
		//		- below: drop down goes below target node
		//
		//		The list is positions is tried, in order, until a position is found where the drop down fits
		//		within the viewport.
		//
		dropDownPosition: ["below", "above"],

		// _stopClickEvents: Boolean
		//		When set to false, the click events will not be stopped, in
		//		case you want to use them in your subclass
		_stopClickEvents: true,

		_onDropDownMouseDown: function(/*Event*/ e){
			// summary:
			//		Callback when the user mousedown's on the arrow icon
			if(this.disabled || this.readOnly){
				return;
			}

			// Prevent default to stop things like text selection, but don't stop propagation, so that:
			//		1. TimeTextBox etc. can focus the <input> on mousedown
			//		2. dropDownButtonActive class applied by _CssStateMixin (on button depress)
			//		3. user defined onMouseDown handler fires
			e.preventDefault();

			this._docHandler = this.own(on(this.ownerDocument, "mouseup", lang.hitch(this, "_onDropDownMouseUp")))[0];

			this.toggleDropDown();
		},

		_onDropDownMouseUp: function(/*Event?*/ e){
			// summary:
			//		Callback when the user lifts their mouse after mouse down on the arrow icon.
			//		If the drop down is a simple menu and the mouse is over the menu, we execute it, otherwise, we focus our
			//		drop down widget.  If the event is missing, then we are not
			//		a mouseup event.
			//
			//		This is useful for the common mouse movement pattern
			//		with native browser `<select>` nodes:
			//
			//		1. mouse down on the select node (probably on the arrow)
			//		2. move mouse to a menu item while holding down the mouse button
			//		3. mouse up.  this selects the menu item as though the user had clicked it.
			if(e && this._docHandler){
				this.disconnect(this._docHandler);
			}
			var dropDown = this.dropDown, overMenu = false;

			if(e && this._opened){
				// This code deals with the corner-case when the drop down covers the original widget,
				// because it's so large.  In that case mouse-up shouldn't select a value from the menu.
				// Find out if our target is somewhere in our dropdown widget,
				// but not over our _buttonNode (the clickable node)
				var c = domGeometry.position(this._buttonNode, true);
				if(!(e.pageX >= c.x && e.pageX <= c.x + c.w) || !(e.pageY >= c.y && e.pageY <= c.y + c.h)){
					var t = e.target;
					while(t && !overMenu){
						if(domClass.contains(t, "dijitPopup")){
							overMenu = true;
						}else{
							t = t.parentNode;
						}
					}
					if(overMenu){
						t = e.target;
						if(dropDown.onItemClick){
							var menuItem;
							while(t && !(menuItem = registry.byNode(t))){
								t = t.parentNode;
							}
							if(menuItem && menuItem.onClick && menuItem.getParent){
								menuItem.getParent().onItemClick(menuItem, e);
							}
						}
						return;
					}
				}
			}
			if(this._opened){
				if(dropDown.focus && dropDown.autoFocus !== false){
					// Focus the dropdown widget - do it on a delay so that we
					// don't steal back focus from the dropdown.
					this._focusDropDownTimer = this.defer(function(){
						dropDown.focus();
						delete this._focusDropDownTimer;
					});
				}
			}else{
				// The drop down arrow icon probably can't receive focus, but widget itself should get focus.
				// defer() needed to make it work on IE (test DateTextBox)
				this.defer("focus");
			}

			if(has("touch")){
				this._justGotMouseUp = true;
				this.defer(function(){
					this._justGotMouseUp = false;
				});
			}
		},

		_onDropDownClick: function(/*Event*/ e){
			if(has("touch") && !this._justGotMouseUp){
				// If there was no preceding mousedown/mouseup (like on android), then simulate them to
				// toggle the drop down.
				//
				// The if(has("touch") is necessary since IE and desktop safari get spurious onclick events
				// when there are nested tables (specifically, clicking on a table that holds a dijit/form/Select,
				// but not on the Select itself, causes an onclick event on the Select)
				this._onDropDownMouseDown(e);
				this._onDropDownMouseUp(e);
			}

			// The drop down was already opened on mousedown/keydown; just need to stop the event
			if(this._stopClickEvents){
				e.stopPropagation();
				e.preventDefault();
			}
		},

		buildRendering: function(){
			this.inherited(arguments);

			this._buttonNode = this._buttonNode || this.focusNode || this.domNode;
			this._popupStateNode = this._popupStateNode || this.focusNode || this._buttonNode;

			// Add a class to the "dijitDownArrowButton" type class to _buttonNode so theme can set direction of arrow
			// based on where drop down will normally appear
			var defaultPos = {
				"after": this.isLeftToRight() ? "Right" : "Left",
				"before": this.isLeftToRight() ? "Left" : "Right",
				"above": "Up",
				"below": "Down",
				"left": "Left",
				"right": "Right"
			}[this.dropDownPosition[0]] || this.dropDownPosition[0] || "Down";
			domClass.add(this._arrowWrapperNode || this._buttonNode, "dijit" + defaultPos + "ArrowButton");
		},

		postCreate: function(){
			// summary:
			//		set up nodes and connect our mouse and keyboard events

			this.inherited(arguments);

			var keyboardEventNode = this.focusNode || this.domNode;
			this.own(
				on(this._buttonNode, "mousedown", lang.hitch(this, "_onDropDownMouseDown")),
				on(this._buttonNode, "click", lang.hitch(this, "_onDropDownClick")),
				on(keyboardEventNode, "keydown", lang.hitch(this, "_onKey")),
				on(keyboardEventNode, "keyup", lang.hitch(this, "_onKeyUp"))
			);
		},

		destroy: function(){
			if(this.dropDown){
				// Destroy the drop down, unless it's already been destroyed.  This can happen because
				// the drop down is a direct child of <body> even though it's logically my child.
				if(!this.dropDown._destroyed){
					this.dropDown.destroyRecursive();
				}
				delete this.dropDown;
			}
			this.inherited(arguments);
		},

		_onKey: function(/*Event*/ e){
			// summary:
			//		Callback when the user presses a key while focused on the button node

			if(this.disabled || this.readOnly){
				return;
			}
			var d = this.dropDown, target = e.target;
			if(d && this._opened && d.handleKey){
				if(d.handleKey(e) === false){
					/* false return code means that the drop down handled the key */
					e.stopPropagation();
					e.preventDefault();
					return;
				}
			}
			if(d && this._opened && e.keyCode == keys.ESCAPE){
				this.closeDropDown();
				e.stopPropagation();
				e.preventDefault();
			}else if(!this._opened &&
				(e.keyCode == keys.DOWN_ARROW ||
					( (e.keyCode == keys.ENTER || e.keyCode == keys.SPACE) &&
						//ignore enter and space if the event is for a text input
						((target.tagName || "").toLowerCase() !== 'input' ||
							(target.type && target.type.toLowerCase() !== 'text'))))){
				// Toggle the drop down, but wait until keyup so that the drop down doesn't
				// get a stray keyup event, or in the case of key-repeat (because user held
				// down key for too long), stray keydown events
				this._toggleOnKeyUp = true;
				e.stopPropagation();
				e.preventDefault();
			}
		},

		_onKeyUp: function(){
			if(this._toggleOnKeyUp){
				delete this._toggleOnKeyUp;
				this.toggleDropDown();
				var d = this.dropDown;	// drop down may not exist until toggleDropDown() call
				if(d && d.focus){
					this.defer(lang.hitch(d, "focus"), 1);
				}
			}
		},

		_onBlur: function(){
			// summary:
			//		Called magically when focus has shifted away from this widget and it's dropdown

			// Don't focus on button if the user has explicitly focused on something else (happens
			// when user clicks another control causing the current popup to close)..
			// But if focus is inside of the drop down then reset focus to me, because IE doesn't like
			// it when you display:none a node with focus.
			var focusMe = focus.curNode && this.dropDown && dom.isDescendant(focus.curNode, this.dropDown.domNode);

			this.closeDropDown(focusMe);

			this.inherited(arguments);
		},

		isLoaded: function(){
			// summary:
			//		Returns true if the dropdown exists and it's data is loaded.  This can
			//		be overridden in order to force a call to loadDropDown().
			// tags:
			//		protected

			return true;
		},

		loadDropDown: function(/*Function*/ loadCallback){
			// summary:
			//		Creates the drop down if it doesn't exist, loads the data
			//		if there's an href and it hasn't been loaded yet, and then calls
			//		the given callback.
			// tags:
			//		protected

			// TODO: for 2.0, change API to return a Deferred, instead of calling loadCallback?
			loadCallback();
		},

		loadAndOpenDropDown: function(){
			// summary:
			//		Creates the drop down if it doesn't exist, loads the data
			//		if there's an href and it hasn't been loaded yet, and
			//		then opens the drop down.  This is basically a callback when the
			//		user presses the down arrow button to open the drop down.
			// returns: Deferred
			//		Deferred for the drop down widget that
			//		fires when drop down is created and loaded
			// tags:
			//		protected
			var d = new Deferred(),
				afterLoad = lang.hitch(this, function(){
					this.openDropDown();
					d.resolve(this.dropDown);
				});
			if(!this.isLoaded()){
				this.loadDropDown(afterLoad);
			}else{
				afterLoad();
			}
			return d;
		},

		toggleDropDown: function(){
			// summary:
			//		Callback when the user presses the down arrow button or presses
			//		the down arrow key to open/close the drop down.
			//		Toggle the drop-down widget; if it is up, close it, if not, open it
			// tags:
			//		protected

			if(this.disabled || this.readOnly){
				return;
			}
			if(!this._opened){
				this.loadAndOpenDropDown();
			}else{
				this.closeDropDown();
			}
		},

		openDropDown: function(){
			// summary:
			//		Opens the dropdown for this widget.   To be called only when this.dropDown
			//		has been created and is ready to display (ie, it's data is loaded).
			// returns:
			//		return value of dijit/popup.open()
			// tags:
			//		protected

			var dropDown = this.dropDown,
				ddNode = dropDown.domNode,
				aroundNode = this._aroundNode || this.domNode,
				self = this;

			// Prepare our popup's height and honor maxHeight if it exists.

			// TODO: isn't maxHeight dependent on the return value from dijit/popup.open(),
			// ie, dependent on how much space is available (BK)

			if(!this._preparedNode){
				this._preparedNode = true;
				// Check if we have explicitly set width and height on the dropdown widget dom node
				if(ddNode.style.width){
					this._explicitDDWidth = true;
				}
				if(ddNode.style.height){
					this._explicitDDHeight = true;
				}
			}

			// Code for resizing dropdown (height limitation, or increasing width to match my width)
			if(this.maxHeight || this.forceWidth || this.autoWidth){
				var myStyle = {
					display: "",
					visibility: "hidden"
				};
				if(!this._explicitDDWidth){
					myStyle.width = "";
				}
				if(!this._explicitDDHeight){
					myStyle.height = "";
				}
				domStyle.set(ddNode, myStyle);

				// Figure out maximum height allowed (if there is a height restriction)
				var maxHeight = this.maxHeight;
				if(maxHeight == -1){
					// limit height to space available in viewport either above or below my domNode
					// (whichever side has more room)
					var viewport = Viewport.getEffectiveBox(this.ownerDocument),
						position = domGeometry.position(aroundNode, false);
					maxHeight = Math.floor(Math.max(position.y, viewport.h - (position.y + position.h)));
				}

				// Attach dropDown to DOM and make make visibility:hidden rather than display:none
				// so we call startup() and also get the size
				popup.moveOffScreen(dropDown);

				if(dropDown.startup && !dropDown._started){
					dropDown.startup(); // this has to be done after being added to the DOM
				}
				// Get size of drop down, and determine if vertical scroll bar needed.  If no scroll bar needed,
				// use overflow:visible rather than overflow:hidden so off-by-one errors don't hide drop down border.
				var mb = domGeometry.getMarginSize(ddNode);
				var overHeight = (maxHeight && mb.h > maxHeight);
				domStyle.set(ddNode, {
					overflow: overHeight ? "auto" : "visible"
				});
				if(overHeight){
					mb.h = maxHeight;
					if("w" in mb){
						mb.w += 16;	// room for vertical scrollbar
					}
				}else{
					delete mb.h;
				}

				// Adjust dropdown width to match or be larger than my width
				if(this.forceWidth){
					mb.w = aroundNode.offsetWidth;
				}else if(this.autoWidth){
					mb.w = Math.max(mb.w, aroundNode.offsetWidth);
				}else{
					delete mb.w;
				}

				// And finally, resize the dropdown to calculated height and width
				if(lang.isFunction(dropDown.resize)){
					dropDown.resize(mb);
				}else{
					domGeometry.setMarginBox(ddNode, mb);
				}
			}

			var retVal = popup.open({
				parent: this,
				popup: dropDown,
				around: aroundNode,
				orient: this.dropDownPosition,
				onExecute: function(){
					self.closeDropDown(true);
				},
				onCancel: function(){
					self.closeDropDown(true);
				},
				onClose: function(){
					domAttr.set(self._popupStateNode, "popupActive", false);
					domClass.remove(self._popupStateNode, "dijitHasDropDownOpen");
					self._set("_opened", false);	// use set() because _CssStateMixin is watching
				}
			});
			domAttr.set(this._popupStateNode, "popupActive", "true");
			domClass.add(this._popupStateNode, "dijitHasDropDownOpen");
			this._set("_opened", true);	// use set() because _CssStateMixin is watching

			this._popupStateNode.setAttribute("aria-expanded", "true");
			this._popupStateNode.setAttribute("aria-owns", dropDown.id);

			// Set aria-labelledby on dropdown if it's not already set to something more meaningful
			if(ddNode.getAttribute("role") !== "presentation" && !ddNode.getAttribute("aria-labelledby")){
				ddNode.setAttribute("aria-labelledby", this.id);
			}

			return retVal;
		},

		closeDropDown: function(/*Boolean*/ focus){
			// summary:
			//		Closes the drop down on this widget
			// focus:
			//		If true, refocuses the button widget
			// tags:
			//		protected

			if(this._focusDropDownTimer){
				this._focusDropDownTimer.remove();
				delete this._focusDropDownTimer;
			}

			if(this._opened){
				this._popupStateNode.setAttribute("aria-expanded", "false");
				if(focus){
					this.focus();
				}
				popup.close(this.dropDown);
				this._opened = false;
			}
		}

	});
});