Class: Drag {#Drag}
===================

Enables the modification of two CSS properties of an Element based on the position of the mouse while the mouse button is down.

### Implements

[Events][], [Chain][], [Options][]


Drag Method: constructor
------------------------

### Syntax

	var myDragInstance = new Drag(el[, options]);

### Arguments

1. el      - (*element*) The Element to apply the transformations to.
2. options - (*object*, optional) The options object.

### Options

* grid            - (*number*: defaults to false) Distance in pixels for snap-to-grid dragging.
* handle          - (*element*: defaults to the element passed in) The Element to act as the handle for the draggable element.
* invert          - (*boolean*: defaults to false) Whether or not to invert the values reported on start and drag.
* limit           - (*object*: defaults to false) An object with an x and a y property, both an array containing the minimum and maximum limit of movement of the Element.
* modifiers       - (*object*: defaults to {'x': 'left', 'y': 'top'}) An object with x and y properties used to indicate the CSS modifiers (i.e. 'left').
* snap            - (*number*: defaults to 6) The distance to drag before the Element starts to respond to the drag.
* style           - (*boolean*: defaults to true) Whether or not to set the modifier as a style property of the element.
* unit            - (*string*: defaults to 'px') A string indicating the CSS unit to append to all number values.
* preventDefault  - (*boolean*: defaults to false) Calls preventDefault on the event while dragging. See [Event:preventDefault][]
* stopPropagation - (*boolean*: defaults to false) Prevents the event from "bubbling" up in the DOM tree. See [Event:stopPropagation][]

### Events

* beforeStart - Executed before the Drag instance attaches the events. Receives the dragged element as an argument.
* start       - Executed when the user starts to drag (on mousedown). Receives the dragged element and the event as arguments.
* snap        - Executed when the user has dragged past the snap option. Receives the dragged element as an argument.
* drag        - Executed on every step of the drag. Receives the dragged element and the event as arguments.
* complete    - Executed when the user completes the drag. Receives the dragged element and the event as arguments.
* cancel      - Executed when the user has cancelled the drag. Receives the dragged element as an argument.

### Examples

	var myDrag = new Drag('myDraggable', {
		snap: 0,
		onSnap: function(el){
			el.addClass('dragging');
		},
		onComplete: function(el){
			el.removeClass('dragging');
		}
	});

	//create an Adobe reader style drag to scroll container
	var myDragScroller = new Drag('myContainer', {
		style: false,
		invert: true,
		modifiers: {x: 'scrollLeft', y: 'scrollTop'}
	});
	// corresponding HTML and CSS
	<div id="myContainer" style="overflow: auto; width: 300px; height: 300px;">
		<!-- lots of text -->
	</div>

### Notes

- Drag requires the page to be in [Standards Mode](http://hsivonen.iki.fi/doctype/).

### See Also

- [MDC: CSS Units][]



Drag Method: attach {#Drag:attach}
----------------------------------

Attaches the mouse listener to the handle, causing the Element to be draggable.

### Syntax

	myDrag.attach();

### Returns

* (*object*) This Drag instance.

### Examples

	var myDrag = new Drag('myElement').detach(); //The Element can't be dragged.
	$('myActivator').addEvent('click', function(){
		alert('Ok, now you can drag.');
		myDrag.attach();
	});

### See Also

- [document.id][], [Element:makeDraggable][], [Drag:detach](#Drag:detach), [Element:addEvent][]



Drag Method: detach {#Drag:detach}
----------------------------------

Detaches the mouse listener from the handle, preventing the Element from being dragged.

### Syntax

	myDrag.detach();

### Returns

* (*object*) This Drag instance.

### Examples

	var myDrag = new Drag('myElement');
	$('myDeactivator').addEvent('click', function(){
		alert('No more dragging for you, Mister.');
		myDrag.detach();
	});

### See Also

- [document.id][], [Element:makeDraggable][], [Element:addEvent][]



Drag Method: stop {#Drag:stop}
------------------------------

Stops (removes) all attached events from the Drag instance. If the event is passed, it executes the 'complete' Event.

### Syntax

	myDrag.stop([event]);

### Arguments

1. event - (*event*) the Event that is fired (typically by mouseup). This is passed along to the 'complete' Event in addition to the element that was dragged. If you pass along any truth-y value (i.e. not *false*, *zero*, etc) the 'complete' event will be fired and that value will be passed to the 'complete' event.

### Examples

	var myDrag = new Drag('myElement', {
		onSnap: function(){
			this.moved = this.moved || 0;
			this.moved++;
			if (this.moved > 100){
				this.stop();
				alert("Stop! You'll make the Element angry.");
			}
		}
	});



Type: Element {#Element}
==========================

Custom Type to allow all of its methods to be used with any DOM element via the document.id function [document.id][].



Element Method: makeResizable {#Element:makeResizable}
------------------------------------------------------

Adds drag-to-resize behavior to an Element using supplied options.

### Syntax

	var myResize = myElement.makeResizable([options]);

### Arguments

1. options - (*object*, optional) See [Drag][#Drag] for acceptable options.

### Returns

* (*object*) The Drag instance that was created.

### Examples

	var myResize = $('myElement').makeResizable({
		onComplete: function(){
			alert('Done resizing.');
		}
	});

### See Also

- [Drag](#Drag)



[document.id]: /core/Element/Element#Window:document-id
[Element:addEvent]: /core/Element/Element.Event/#Element:addEvent
[Element:makeDraggable]: /more/Drag/Drag.Move/#Element:makeDraggable
[Events]: /core/Class/Class.Extras#Events
[Event:preventDefault]: /core/Types/Event#Event:prevenDefault
[Event:stopPropagation]: /core/Types/Event#Event:stopPropagation
[Chain]: /core/Class/Class.Extras#Chain
[Options]: /core/Class/Class.Extras#Options
[MDC: CSS Units]: https://developer.mozilla.org/en/CSS-2_Quick_Reference/Units