Drag.js

/*
---

script: Drag.js

name: Drag

description: The base Drag Class. Can be used to drag and resize Elements using mouse events.

license: MIT-style license

authors:
  - Valerio Proietti
  - Tom Occhinno
  - Jan Kassens

requires:
  - Core/Events
  - Core/Options
  - Core/Element.Event
  - Core/Element.Style
  - Core/Element.Dimensions
  - /MooTools.More

provides: [Drag]
...

*/

var Drag = new Class({

	Implements: [Events, Options],

	options: {/*
		onBeforeStart: function(thisElement){},
		onStart: function(thisElement, event){},
		onSnap: function(thisElement){},
		onDrag: function(thisElement, event){},
		onCancel: function(thisElement){},
		onComplete: function(thisElement, event){},*/
		snap: 6,
		unit: 'px',
		grid: false,
		style: true,
		limit: false,
		ratio: false,
		handle: false,
		invert: false,
		preventDefault: false,
		stopPropagation: false,
		modifiers: {x: 'left', y: 'top'}
	},

	initialize: function(){
		var params = Array.link(arguments, {
			'options': Type.isObject,
			'element': function(obj){
				return obj != null;
			}
		});

		this.element = document.id(params.element);
		this.document = this.element.getDocument();
		this.setOptions(params.options || {});
		var htype = typeOf(this.options.handle);
		this.handles = ((htype == 'array' || htype == 'collection') ? $$(this.options.handle) : document.id(this.options.handle)) || this.element;
		this.mouse = {'now': {}, 'pos': {}};
		this.value = {'start': {}, 'now': {}};

		this.selection = (Browser.ie) ? 'selectstart' : 'mousedown';


		if (Browser.ie && !Drag.ondragstartFixed){
			document.ondragstart = Function.from(false);
			Drag.ondragstartFixed = true;
		}

		this.bound = {
			start: this.start.bind(this),
			check: this.check.bind(this),
			drag: this.drag.bind(this),
			stop: this.stop.bind(this),
			cancel: this.cancel.bind(this),
			eventStop: Function.from(false)
		};
		this.attach();
	},

	attach: function(){
		this.handles.addEvent('mousedown', this.bound.start);
		return this;
	},

	detach: function(){
		this.handles.removeEvent('mousedown', this.bound.start);
		return this;
	},

	start: function(event){
		var options = this.options;

		if (event.rightClick) return;

		if (options.preventDefault) event.preventDefault();
		if (options.stopPropagation) event.stopPropagation();
		this.mouse.start = event.page;

		this.fireEvent('beforeStart', this.element);

		var limit = options.limit;
		this.limit = {x: [], y: []};

		var z, coordinates;
		for (z in options.modifiers){
			if (!options.modifiers[z]) continue;

			var style = this.element.getStyle(options.modifiers[z]);

			// Some browsers (IE and Opera) don't always return pixels.
			if (style && !style.match(/px$/)){
				if (!coordinates) coordinates = this.element.getCoordinates(this.element.getOffsetParent());
				style = coordinates[options.modifiers[z]];
			}

			if (options.style) this.value.now[z] = (style || 0).toInt();
			else this.value.now[z] = this.element[options.modifiers[z]];

			if (options.invert) this.value.now[z] *= -1;

			this.mouse.pos[z] = event.page[z] - this.value.now[z];

			if (limit && limit[z]){
				var i = 2;
				while (i--){
					var limitZI = limit[z][i];
					if (limitZI || limitZI === 0) this.limit[z][i] = (typeof limitZI == 'function') ? limitZI() : limitZI;
				}
			}
		}

		if (typeOf(this.options.grid) == 'number') this.options.grid = {
			x: this.options.grid,
			y: this.options.grid
		};

		var events = {
			mousemove: this.bound.check,
			mouseup: this.bound.cancel
		};
		events[this.selection] = this.bound.eventStop;
		this.document.addEvents(events);
	},

	check: function(event){
		if (this.options.preventDefault) event.preventDefault();
		var distance = Math.round(Math.sqrt(Math.pow(event.page.x - this.mouse.start.x, 2) + Math.pow(event.page.y - this.mouse.start.y, 2)));
		if (distance > this.options.snap){
			this.cancel();
			this.document.addEvents({
				mousemove: this.bound.drag,
				mouseup: this.bound.stop
			});
			this.fireEvent('start', [this.element, event]).fireEvent('snap', this.element);
		}
	},

	drag: function(event){
		var options = this.options;

		if (options.preventDefault) event.preventDefault();
		this.mouse.now = event.page;

		for (var z in options.modifiers){
			if (!options.modifiers[z]) continue;
			this.value.now[z] = this.mouse.now[z] - this.mouse.pos[z];

			if (options.invert) this.value.now[z] *= -1;

			if (options.limit && this.limit[z]){
				if ((this.limit[z][1] || this.limit[z][1] === 0) && (this.value.now[z] > this.limit[z][1])){
					this.value.now[z] = this.limit[z][1];
				} else if ((this.limit[z][0] || this.limit[z][0] === 0) && (this.value.now[z] < this.limit[z][0])){
					this.value.now[z] = this.limit[z][0];
				}
			}
			
			if(options.ratio) {
				if(this.value.now.x / this.value.now.y < options.ratio) {
					this.value.now.y = this.value.now.x / options.ratio;
				} else {
					this.value.now.x = options.ratio * this.value.now.y;
				}
			}
			
			if (options.grid[z]) this.value.now[z] -= ((this.value.now[z] - (this.limit[z][0]||0)) % options.grid[z]);

			if (options.style) this.element.setStyle(options.modifiers[z], this.value.now[z] + options.unit);
			else this.element[options.modifiers[z]] = this.value.now[z];
		}

		this.fireEvent('drag', [this.element, event]);
	},

	cancel: function(event){
		this.document.removeEvents({
			mousemove: this.bound.check,
			mouseup: this.bound.cancel
		});
		if (event){
			this.document.removeEvent(this.selection, this.bound.eventStop);
			this.fireEvent('cancel', this.element);
		}
	},

	stop: function(event){
		var events = {
			mousemove: this.bound.drag,
			mouseup: this.bound.stop
		};
		events[this.selection] = this.bound.eventStop;
		this.document.removeEvents(events);
		if (event) this.fireEvent('complete', [this.element, event]);
	}

});

Element.implement({

	makeResizable: function(options){
		var drag = new Drag(this, Object.merge({
			modifiers: {
				x: 'width',
				y: 'height'
			}
		}, options));

		this.store('resizer', drag);
		return drag.addEvent('drag', function(){
			this.fireEvent('resize', drag);
		}.bind(this));
	}

});