/static/scripts/jquery.event.drag.js

/*! 
 * jquery.event.drag - v 2.1.0 
 * Copyright (c) 2010 Three Dub Media - http://threedubmedia.com
 * Open Source MIT License - http://threedubmedia.com/code/license
 */
// Created: 2008-06-04 
// Updated: 2010-09-15
// REQUIRES: jquery 1.4.2+

;(function( $ ){

// add the jquery instance method
$.fn.drag = function( str, arg, opts ){
	// figure out the event type
	var type = typeof str == "string" ? str : "",
	// figure out the event handler...
	fn = $.isFunction( str ) ? str : $.isFunction( arg ) ? arg : null;
	// fix the event type
	if ( type.indexOf("drag") !== 0 ) 
		type = "drag"+ type;
	// were options passed
	opts = ( str == fn ? arg : opts ) || {};
	// trigger or bind event handler
	return fn ? this.bind( type, opts, fn ) : this.trigger( type );
};

// local refs (increase compression)
var $event = $.event, 
$special = $event.special,
// configure the drag special event 
drag = $special.drag = {
	
	// these are the default settings
	defaults: {
		which: 1, // mouse button pressed to start drag sequence
		distance: 0, // distance dragged before dragstart
		not: ':input', // selector to suppress dragging on target elements
		handle: null, // selector to match handle target elements
		relative: false, // true to use "position", false to use "offset"
		drop: true, // false to suppress drop events, true or selector to allow
		click: false // false to suppress click events after dragend (no proxy)
	},
	
	// the key name for stored drag data
	datakey: "dragdata",
		
	// count bound related events
	add: function( obj ){ 
		// read the interaction data
		var data = $.data( this, drag.datakey ),
		// read any passed options 
		opts = obj.data || {};
		// count another realted event
		data.related += 1;
		// extend data options bound with this event
		// don't iterate "opts" in case it is a node 
		$.each( drag.defaults, function( key, def ){
			if ( opts[ key ] !== undefined )
				data[ key ] = opts[ key ];
		});
	},
	
	// forget unbound related events
	remove: function(){
		$.data( this, drag.datakey ).related -= 1;
	},
	
	// configure interaction, capture settings
	setup: function(){
		// check for related events
		if ( $.data( this, drag.datakey ) ) 
			return;
		// initialize the drag data with copied defaults
		var data = $.extend({ related:0 }, drag.defaults );
		// store the interaction data
		$.data( this, drag.datakey, data );
		// bind the mousedown event, which starts drag interactions
		$event.add( this, "touchstart mousedown", drag.init, data );
		// prevent image dragging in IE...
		if ( this.attachEvent ) 
			this.attachEvent("ondragstart", drag.dontstart ); 
	},
	
	// destroy configured interaction
	teardown: function(){
		var data = $.data( this, drag.datakey ) || {};
		// check for related events
		if ( data.related ) 
			return;
		// remove the stored data
		$.removeData( this, drag.datakey );
		// remove the mousedown event
		$event.remove( this, "touchstart mousedown", drag.init );
		// enable text selection
		drag.textselect( true ); 
		// un-prevent image dragging in IE...
		if ( this.detachEvent ) 
			this.detachEvent("ondragstart", drag.dontstart ); 
	},
		
	// initialize the interaction
	init: function( event ){ 
		// sorry, only one touch at a time
		if ( drag.touched ) 
			return;
		// the drag/drop interaction data
		var dd = event.data, results;
		// check the which directive
		if ( event.which != 0 && dd.which > 0 && event.which != dd.which ) 
			return; 
		// check for suppressed selector
		if ( $( event.target ).is( dd.not ) ) 
			return;
		// check for handle selector
		if ( dd.handle && !$( event.target ).closest( dd.handle, event.currentTarget ).length ) 
			return;

		// store/reset some initial attributes
		if ( event.type == "touchstart" ){
			drag.touched = this;
			drag.touchFix( event, dd );
		}
		dd.propagates = 1;
		dd.mousedown = this;
		dd.interactions = [ drag.interaction( this, dd ) ];
		dd.target = event.target;
		dd.pageX = event.pageX;
		dd.pageY = event.pageY;
		dd.dragging = null;
		// handle draginit event... 
		results = drag.hijack( event, "draginit", dd );
		// early cancel
		if ( !dd.propagates )
			return;
		// flatten the result set
		results = drag.flatten( results );
		// insert new interaction elements
		if ( results && results.length ){
			dd.interactions = [];
			$.each( results, function(){
				dd.interactions.push( drag.interaction( this, dd ) );
			});
		}
		// remember how many interactions are propagating
		dd.propagates = dd.interactions.length;
		// locate and init the drop targets
		if ( dd.drop !== false && $special.drop ) 
			$special.drop.handler( event, dd );
		// disable text selection
		drag.textselect( false ); 
		// bind additional events...
		if ( drag.touched )
			$event.add( drag.touched, "touchmove touchend", drag.handler, dd );
		else 
			$event.add( document, "mousemove mouseup", drag.handler, dd );
		// helps prevent text selection or scrolling
		if ( !drag.touched || dd.live )
			return false;
	},	
	
	// fix event properties for touch events
	touchFix: function( event, dd ){
		var orig = event.originalEvent, i = 0;
		// iOS webkit: touchstart, touchmove, touchend
		if ( orig && orig.changedTouches ){ 
			event.pageX = orig.changedTouches[0].pageX;
			event.pageY = orig.changedTouches[0].pageY;	
		}
		//console.log( event.type, event );
	},
	
	// returns an interaction object
	interaction: function( elem, dd ){
		var offset = $( elem )[ dd.relative ? "position" : "offset" ]() || { top:0, left:0 };
		return {
			drag: elem, 
			callback: new drag.callback(), 
			droppable: [],
			offset: offset
		};
	},
	
	// handle drag-releatd DOM events
	handler: function( event ){ 
		// read the data before hijacking anything
		var dd = event.data;
		if ( drag.touched )
			drag.touchFix( event, dd );		
		// handle various events
		switch ( event.type ){
			// mousemove, check distance, start dragging
			case !dd.dragging && 'touchmove': 
				event.preventDefault();
			case !dd.dragging && 'mousemove':
				//  drag tolerance, x? + y? = distance?
				if ( Math.pow(  event.pageX-dd.pageX, 2 ) + Math.pow(  event.pageY-dd.pageY, 2 ) < Math.pow( dd.distance, 2 ) ) 
					break; // distance tolerance not reached
				event.target = dd.target; // force target from "mousedown" event (fix distance issue)
				drag.hijack( event, "dragstart", dd ); // trigger "dragstart"
				if ( dd.propagates ) // "dragstart" not rejected
					dd.dragging = true; // activate interaction
			// mousemove, dragging
			case 'touchmove':
				event.preventDefault();
			case 'mousemove':
				if ( dd.dragging ){
					// trigger "drag"		
					drag.hijack( event, "drag", dd );
					if ( dd.propagates ){
						// manage drop events
						if ( dd.drop !== false && $special.drop )
							$special.drop.handler( event, dd ); // "dropstart", "dropend"							
						break; // "drag" not rejected, stop		
					}
					event.type = "mouseup"; // helps "drop" handler behave
				}
			// mouseup, stop dragging
			case 'touchend': 
			case 'mouseup': 
				if ( drag.touched )
					$event.remove( drag.touched, "touchmove touchend", drag.handler ); // remove touch events
				else 
					$event.remove( document, "mousemove mouseup", drag.handler ); // remove page events	
				if ( dd.dragging ){
					if ( dd.drop !== false && $special.drop ) 
						$special.drop.handler( event, dd ); // "drop"
					drag.hijack( event, "dragend", dd ); // trigger "dragend"	
					} else {
					drag.hijack( event, "dragclickonly", dd ); // trigger "dragclickonly"	
                    }
				drag.textselect( true ); // enable text selection
				// if suppressing click events...
				if ( dd.click === false && dd.dragging ){
					$.data( dd.mousedown, "suppress.click", new Date().getTime() + 5 );
				}
				dd.dragging = drag.touched = false; // deactivate element	
				break;
		}
	},
		
	// re-use event object for custom events
	hijack: function( event, type, dd, x, elem ){
		// not configured
		if ( !dd ) 
			return;
		// remember the original event and type
		var orig = { event:event.originalEvent, type: event.type },
		// is the event drag related or drog related?
		mode = type.indexOf("drop") ? "drag" : "drop",
		// iteration vars
		result, i = x || 0, ia, $elems, callback,
		len = !isNaN( x ) ? x : dd.interactions.length;
		// modify the event type
		event.type = type;
		// remove the original event
		event.originalEvent = null;
		// initialize the results
		dd.results = [];
		// handle each interacted element
		do if ( ia = dd.interactions[ i ] ){
			// validate the interaction
			if ( type !== "dragend" && ia.cancelled )
				continue;
			// set the dragdrop properties on the event object
			callback = drag.properties( event, dd, ia );
			// prepare for more results
			ia.results = [];
			// handle each element
			$( elem || ia[ mode ] || dd.droppable ).each(function( p, subject ){
				// identify drag or drop targets individually
				callback.target = subject;
				// handle the event	
				result = subject ? $event.handle.call( subject, event, callback ) : null;
				// stop the drag interaction for this element
				if ( result === false ){
					if ( mode == "drag" ){
						ia.cancelled = true;
						dd.propagates -= 1;
					}
					if ( type == "drop" ){
						ia[ mode ][p] = null;
					}
				}
				// assign any dropinit elements
				else if ( type == "dropinit" )
					ia.droppable.push( drag.element( result ) || subject );
				// accept a returned proxy element 
				if ( type == "dragstart" )
					ia.proxy = $( drag.element( result ) || ia.drag )[0];
				// remember this result	
				ia.results.push( result );
				// forget the event result, for recycling
				delete event.result;
				// break on cancelled handler
				if ( type !== "dropinit" )
					return result;
			});	
			// flatten the results	
			dd.results[ i ] = drag.flatten( ia.results );	
			// accept a set of valid drop targets
			if ( type == "dropinit" )
				ia.droppable = drag.flatten( ia.droppable );
			// locate drop targets
			if ( type == "dragstart" && !ia.cancelled )
				callback.update(); 
		}
		while ( ++i < len )
		// restore the original event & type
		event.type = orig.type;
		event.originalEvent = orig.event;
		// return all handler results
		return drag.flatten( dd.results );
	},
		
	// extend the callback object with drag/drop properties...
	properties: function( event, dd, ia ){		
		var obj = ia.callback;
		// elements
		obj.drag = ia.drag;
		obj.proxy = ia.proxy || ia.drag;
		// starting mouse position
		obj.startX = dd.pageX;
		obj.startY = dd.pageY;
		// current distance dragged
		obj.deltaX = event.pageX - dd.pageX;
		obj.deltaY = event.pageY - dd.pageY;
		// original element position
		obj.originalX = ia.offset.left;
		obj.originalY = ia.offset.top;
		// adjusted element position
		obj.offsetX = obj.originalX + obj.deltaX; 
		obj.offsetY = obj.originalY + obj.deltaY;
		// assign the drop targets information
		obj.drop = drag.flatten( ( ia.drop || [] ).slice() );
		obj.available = drag.flatten( ( ia.droppable || [] ).slice() );
		return obj;	
	},
	
	// determine is the argument is an element or jquery instance
	element: function( arg ){
		if ( arg && ( arg.jquery || arg.nodeType == 1 ) )
			return arg;
	},
	
	// flatten nested jquery objects and arrays into a single dimension array
	flatten: function( arr ){
		return $.map( arr, function( member ){
			return member && member.jquery ? $.makeArray( member ) : 
				member && member.length ? drag.flatten( member ) : member;
		});
	},
	
	// toggles text selection attributes ON (true) or OFF (false)
	textselect: function( bool ){ 
		$( document )[ bool ? "unbind" : "bind" ]("selectstart", drag.dontstart )
			.css("MozUserSelect", bool ? "" : "none" );
		// .attr("unselectable", bool ? "off" : "on" )
		document.unselectable = bool ? "off" : "on"; 
	},
	
	// suppress "selectstart" and "ondragstart" events
	dontstart: function(){ 
		return false; 
	},
	
	// a callback instance contructor
	callback: function(){}
	
};

// callback methods
drag.callback.prototype = {
	update: function(){
		if ( $special.drop && this.available.length )
			$.each( this.available, function( i ){
				$special.drop.locate( this, i );
			});
	}
};

// patch $.event.handle to allow suppressing clicks
var orighandle = $event.handle;
$event.handle = function( event ){
	if ( $.data( this, "suppress."+ event.type ) - new Date().getTime() > 0 ){
		$.removeData( this, "suppress."+ event.type );
		return;
	}
	return orighandle.apply( this, arguments );
};

// share the same special event configuration with related events...
$special.draginit = $special.dragstart = $special.dragend = drag;

})( jQuery );