dd/js/constrain.js

	constrain.js revision 9ebf5de1d269e59a62b4ef3f881da4b055c5dbbf
YUI.add('dd-constrain', function(Y) {

    /**
	 * Plugin for the dd-drag module to add the constraining methods to it. It supports constraining to a node or viewport. It supports tick based moves and XY axis constraints.
	 * @class DDConstrained
	 * @module dd
	 * @submodule dd-constrain
	 * @extends Base
	 * @constructor
	 * @namespace Plugin
	 */

	var DRAG_NODE = 'dragNode',
	    OFFSET_HEIGHT = 'offsetHeight',
	    OFFSET_WIDTH = 'offsetWidth',
	    HOST = 'host',
	    TICK_X_ARRAY = 'tickXArray',
	    TICK_Y_ARRAY = 'tickYArray',
	    DDM = Y.DD.DDM,
	    TOP = 'top',
	    RIGHT = 'right',
	    BOTTOM = 'bottom',
	    LEFT = 'left',
	    VIEW = 'view',
	    proto = null,

		/**
	    * @event drag:tickAlignX
	    * @description Fires when this node is aligned with the tickX value.
	    * @param {EventFacade} event An EventFacade object
	    * @type {CustomEvent}
	    */
	    EV_TICK_ALIGN_X = 'drag:tickAlignX',

		/**
	    * @event drag:tickAlignY
	    * @description Fires when this node is aligned with the tickY value.
	    * @param {EventFacade} event An EventFacade object
	    * @type {CustomEvent}
	    */
	    EV_TICK_ALIGN_Y = 'drag:tickAlignY',

	    C = function(config) {
	        this._lazyAddAttrs = false;
	        C.superclass.constructor.apply(this, arguments);
	    };

	C.NAME = 'ddConstrained';
	/**
	* @property NS
	* @default con
	* @readonly
	* @protected
	* @static
	* @description The Constrained instance will be placed on the Drag instance under the con namespace.
	* @type {String}
*/
	C.NS = 'con';

	C.ATTRS = {
	    host: {
	    },
	    /**
	    * @attribute stickX
	    * @description Stick the drag movement to the X-Axis. Default: false
	    * @type Boolean
	    */
	    stickX: {
	        value: false
	    },
	    /**
	    * @attribute stickY
	    * @description Stick the drag movement to the Y-Axis
	    * @type Boolean
	    */
	    stickY: {
	        value: false
	    },
	    /**
	    * @attribute tickX
	    * @description The X tick offset the drag node should snap to on each drag move. False for no ticks. Default: false
	    * @type Number/false
	    */
	    tickX: {
	        value: false
	    },
	    /**
	    * @attribute tickY
	    * @description The Y tick offset the drag node should snap to on each drag move. False for no ticks. Default: false
	    * @type Number/false
	    */
	    tickY: {
	        value: false
	    },
	    /**
	    * @attribute tickXArray
	    * @description An array of page coordinates to use as X ticks for drag movement.
	    * @type Array
	    */
	    tickXArray: {
	        value: false
	    },
	    /**
	    * @attribute tickYArray
	    * @description An array of page coordinates to use as Y ticks for drag movement.
	    * @type Array
	    */
	    tickYArray: {
	        value: false
	    },
	    /**
	    * @attribute gutter
	    * @description CSS style string for the gutter of a region (supports negative values): '5 0' (sets top and bottom to 5px, left and right to 0px), '1 2 3 4' (top 1px, right 2px, bottom 3px, left 4px)
	    * @type String
	    */
	    gutter: {
	        value: '0',
	        setter: function(gutter) {
	            return Y.DD.DDM.cssSizestoObject(gutter);
	        }
	    },
	    /**
	    * @attribute constrain
	    * @description Will attempt to constrain the drag node to the boundaries. Arguments:<br>
	    * 'view': Contrain to Viewport<br>
	    * '#selector_string': Constrain to this node<br>
	    * '{Region Object}': An Object Literal containing a valid region (top, right, bottom, left) of page positions
	    * @type {String/Object/Node}
	    */
	    constrain: {
	        value: VIEW,
	        setter: function(con) {
	            var node = Y.one(con);
	            if (node) {
	                con = node;
	            }
	            return con;
	        }
	    },
	    /**
	    * @deprecated
	    * @attribute constrain2region
	    * @description An Object Literal containing a valid region (top, right, bottom, left) of page positions to constrain the drag node to.
	    * @type Object
	    */
	    constrain2region: {
	        setter: function(r) {
	            return this.set('constrain', r);
	        }
	    },
	    /**
	    * @deprecated
	    * @attribute constrain2node
	    * @description Will attempt to constrain the drag node to the boundaries of this node.
	    * @type Object
	    */
	    constrain2node: {
	        setter: function(n) {
	            return this.set('constrain', Y.one(n));
	        }
	    },
	    /**
	    * @deprecated
	    * @attribute constrain2view
	    * @description Will attempt to constrain the drag node to the boundaries of the viewport region.
	    * @type Object
	    */
	    constrain2view: {
	        setter: function(n) {
	            return this.set('constrain', VIEW);
	        }
	    },
	    /**
	    * @attribute cacheRegion
	    * @description Should the region be cached for performace. Default: true
	    * @type Boolean
	    */
	    cacheRegion: {
	        value: true
	    }
	};

	proto = {
		_lastTickXFired: null,
		_lastTickYFired: null,

	    initializer: function() {
			this._createEvents();

	        this.get(HOST).on('drag:end', Y.bind(this._handleEnd, this));
	        this.get(HOST).on('drag:start', Y.bind(this._handleStart, this));
	        this.get(HOST).after('drag:align', Y.bind(this.align, this));
	        this.get(HOST).after('drag:drag', Y.bind(this.drag, this));
	    },
	    /**
	    * @private
	    * @method _createEvents
	    * @description This method creates all the events for this Event Target and publishes them so we get Event Bubbling.
	    */
		_createEvents: function() {
			var instance = this;

			var ev = [
				EV_TICK_ALIGN_X,
				EV_TICK_ALIGN_Y
			];

			Y.each(ev, function(v, k) {
	            this.publish(v, {
	                type: v,
	                emitFacade: true,
	                bubbles: true,
	                queuable: false,
	                prefix: 'drag'
	            });
	        }, this);
		},
		/**
	    * @private
	    * @method _handleEnd
	    * @description Fires on drag:end
	    */
	    _handleEnd: function() {
			this._lastTickYFired = null;
			this._lastTickXFired = null;
	    },
	    /**
	    * @private
	    * @method _handleStart
	    * @description Fires on drag:start and clears the _regionCache
	    */
	    _handleStart: function() {
	        this.resetCache();
	    },
	    /**
	    * @private
	    * @property _regionCache
	    * @description Store a cache of the region that we are constraining to
	    * @type Object
	    */
	    _regionCache: null,
	    /**
	    * @private
	    * @method _cacheRegion
	    * @description Get's the region and caches it, called from window.resize and when the cache is null
	    */
	    _cacheRegion: function() {
	        this._regionCache = this.get('constrain').get('region');
	    },
	    /**
	    * @method resetCache
	    * @description Reset the internal region cache.
	    */
	    resetCache: function() {
	        this._regionCache = null;
	    },
	    /**
	    * @private
	    * @method _getConstraint
	    * @description Standardizes the 'constraint' attribute
	    */
	    _getConstraint: function() {
	        var con = this.get('constrain'),
	            g = this.get('gutter'),
	            region;

	        if (con) {
	            if (con instanceof Y.Node) {
	                if (!this._regionCache) {
	                    Y.on('resize', Y.bind(this._cacheRegion, this), Y.config.win);
	                    this._cacheRegion();
	                }
	                region = Y.clone(this._regionCache);
	                if (!this.get('cacheRegion')) {
	                    this.resetCache();
	                }
	            } else if (Y.Lang.isObject(con)) {
	                region = Y.clone(con);
	            }
	        }
	        if (!con || !region) {
	            con = VIEW;
	        }
	        if (con === VIEW) {
	            region = this.get(HOST).get(DRAG_NODE).get('viewportRegion');
	        }

	        Y.each(g, function(i, n) {
	            if ((n == RIGHT) || (n == BOTTOM)) {
	                region[n] -= i;
	            } else {
	                region[n] += i;
	            }
	        });
	        return region;
	    },

	    /**
	    * @method getRegion
	    * @description Get the active region: viewport, node, custom region
	    * @param {Boolean} inc Include the node's height and width
	    * @return {Object}
	    */
	    getRegion: function(inc) {
	        var r = {}, oh = null, ow = null,
	            host = this.get(HOST);

	        r = this._getConstraint();

	        if (inc) {
	            oh = host.get(DRAG_NODE).get(OFFSET_HEIGHT);
	            ow = host.get(DRAG_NODE).get(OFFSET_WIDTH);
	            r[RIGHT] = r[RIGHT] - ow;
	            r[BOTTOM] = r[BOTTOM] - oh;
	        }
	        return r;
	    },
	    /**
	    * @private
	    * @method _checkRegion
	    * @description Check if xy is inside a given region, if not change to it be inside.
	    * @param {Array} _xy The XY to check if it's in the current region, if it isn't inside the region, it will reset the xy array to be inside the region.
	    * @return {Array} The new XY that is inside the region
	    */
	    _checkRegion: function(_xy) {
	        var oxy = _xy,
	            r = this.getRegion(),
	            host = this.get(HOST),
	            oh = host.get(DRAG_NODE).get(OFFSET_HEIGHT),
	            ow = host.get(DRAG_NODE).get(OFFSET_WIDTH);

	            if (oxy[1] > (r[BOTTOM] - oh)) {
	                _xy[1] = (r[BOTTOM] - oh);
	            }
	            if (r[TOP] > oxy[1]) {
	                _xy[1] = r[TOP];

	            }
	            if (oxy[0] > (r[RIGHT] - ow)) {
	                _xy[0] = (r[RIGHT] - ow);
	            }
	            if (r[LEFT] > oxy[0]) {
	                _xy[0] = r[LEFT];
	            }

	        return _xy;
	    },
	    /**
	    * @method inRegion
	    * @description Checks if the XY passed or the dragNode is inside the active region.
	    * @param {Array} xy Optional XY to check, if not supplied this.get('dragNode').getXY() is used.
	    * @return {Boolean} True if the XY is inside the region, false otherwise.
	    */
	    inRegion: function(xy) {
	        xy = xy || this.get(HOST).get(DRAG_NODE).getXY();

	        var _xy = this._checkRegion([xy[0], xy[1]]),
	            inside = false;
	            if ((xy[0] === _xy[0]) && (xy[1] === _xy[1])) {
	                inside = true;
	            }
	        return inside;
	    },
	    /**
	    * @method align
	    * @description Modifies the Drag.actXY method from the after drag:align event. This is where the constraining happens.
	    */
	    align: function() {
	        var host = this.get(HOST),
	            _xy = [host.actXY[0], host.actXY[1]],
	            r = this.getRegion(true);

	        if (this.get('stickX')) {
	            _xy[1] = (host.startXY[1] - host.deltaXY[1]);
	        }
	        if (this.get('stickY')) {
	            _xy[0] = (host.startXY[0] - host.deltaXY[0]);
	        }

	        if (r) {
	            _xy = this._checkRegion(_xy);
	        }

	        _xy = this._checkTicks(_xy, r);

	        host.actXY = _xy;
	    },
	    /**
	    * @method drag
	    * @description Fires after drag:drag. Handle the tickX and tickX align events.
	    */
		drag: function(event) {
			var host = this.get(HOST),
				xt = this.get('tickX'),
				yt = this.get('tickY'),
				_xy = [host.actXY[0], host.actXY[1]];

			if ((Y.Lang.isNumber(xt) || this.get(TICK_X_ARRAY)) && (this._lastTickXFired !== _xy[0])) {
				this._tickAlignX();
				this._lastTickXFired = _xy[0];
			}

			if ((Y.Lang.isNumber(yt) || this.get(TICK_Y_ARRAY)) && (this._lastTickYFired !== _xy[1])) {
				this._tickAlignY();
				this._lastTickYFired = _xy[1];
			}
		},
	    /**
	    * @private
	    * @method _checkTicks
	    * @description This method delegates the proper helper method for tick calculations
	    * @param {Array} xy The XY coords for the Drag
	    * @param {Object} r The optional region that we are bound to.
	    * @return {Array} The calced XY coords
	    */
	    _checkTicks: function(xy, r) {
	        var host = this.get(HOST),
	            lx = (host.startXY[0] - host.deltaXY[0]),
	            ly = (host.startXY[1] - host.deltaXY[1]),
	            xt = this.get('tickX'),
	            yt = this.get('tickY');
	            if (xt && !this.get(TICK_X_ARRAY)) {
	                xy[0] = DDM._calcTicks(xy[0], lx, xt, r[LEFT], r[RIGHT]);
	            }
	            if (yt && !this.get(TICK_Y_ARRAY)) {
	                xy[1] = DDM._calcTicks(xy[1], ly, yt, r[TOP], r[BOTTOM]);
	            }
	            if (this.get(TICK_X_ARRAY)) {
	                xy[0] = DDM._calcTickArray(xy[0], this.get(TICK_X_ARRAY), r[LEFT], r[RIGHT]);
	            }
	            if (this.get(TICK_Y_ARRAY)) {
	                xy[1] = DDM._calcTickArray(xy[1], this.get(TICK_Y_ARRAY), r[TOP], r[BOTTOM]);
	            }

	        return xy;
	    },
	    /**
	    * @private
	    * @method _tickAlignX
	    * @description Fires when the actXY[0] reach a new value respecting the tickX gap.
	    */
	    _tickAlignX: function() {
	        this.fire(EV_TICK_ALIGN_X);
	    },
	    /**
	    * @private
	    * @method _tickAlignY
	    * @description Fires when the actXY[1] reach a new value respecting the tickY gap.
	    */
	    _tickAlignY: function() {
	        this.fire(EV_TICK_ALIGN_Y);
	    }
	};

	Y.namespace('Plugin');
	Y.extend(C, Y.Base, proto);
	Y.Plugin.DDConstrained = C;

	Y.mix(DDM, {
	    /**
	    * @for DDM
	    * @namespace DD
	    * @private
	    * @method _calcTicks
	    * @description Helper method to calculate the tick offsets for a given position
	    * @param {Number} pos The current X or Y position
	    * @param {Number} start The start X or Y position
	    * @param {Number} tick The X or Y tick increment
	    * @param {Number} off1 The min offset that we can't pass (region)
	    * @param {Number} off2 The max offset that we can't pass (region)
	    * @return {Number} The new position based on the tick calculation
	    */
	    _calcTicks: function(pos, start, tick, off1, off2) {
	        var ix = ((pos - start) / tick),
	            min = Math.floor(ix),
	            max = Math.ceil(ix);
	            if ((min !== 0) || (max !== 0)) {
	                if ((ix >= min) && (ix <= max)) {
	                    pos = (start + (tick * min));
	                    if (off1 && off2) {
	                        if (pos < off1) {
	                            pos = (start + (tick * (min + 1)));
	                        }
	                        if (pos > off2) {
	                            pos = (start + (tick * (min - 1)));
	                        }
	                    }
	                }
	            }
	            return pos;
	    },
	    /**
	    * @for DDM
	    * @namespace DD
	    * @private
	    * @method _calcTickArray
	    * @description This method is used with the tickXArray and tickYArray config options
	    * @param {Number} pos The current X or Y position
	    * @param {Number} ticks The array containing our custom tick positions.
	    * @param {Number} off1 The min offset that we can't pass (region)
	    * @param {Number} off2 The max offset that we can't pass (region)
	    * @return The tick position
	    */
	    _calcTickArray: function(pos, ticks, off1, off2) {
	        var i = 0, len = ticks.length, next = 0,
	            diff1, diff2, ret;

	        if (!ticks || (ticks.length === 0)) {
	            return pos;
	        } else if (ticks[0] >= pos) {
	            return ticks[0];
	        } else {
	            for (i = 0; i < len; i++) {
	                next = (i + 1);
	                if (ticks[next] && ticks[next] >= pos) {
	                    diff1 = pos - ticks[i];
	                    diff2 = ticks[next] - pos;
	                    ret = (diff2 > diff1) ? ticks[i] : ticks[next];
	                    if (off1 && off2) {
	                        if (ret > off2) {
	                            if (ticks[i]) {
	                                ret = ticks[i];
	                            } else {
	                                ret = ticks[len - 1];
	                            }
	                        }
	                    }
	                    return ret;
	                }

	            }
	            return ticks[ticks.length - 1];
	        }
	    }
	});

});