jquery-ui/ui/ui.position.js

/*
 * jQuery UI Position @VERSION
 *
 * Copyright (c) 2009 AUTHORS.txt (http://jqueryui.com/about)
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * TODO: create document page for position and add link here
 */
(function($) {

$.ui = $.ui || {};

var horizontalPositions = /left|center|right/,
	horizontalDefault = 'center',
	verticalPositions = /top|center|bottom/,
	verticalDefault = 'center',
	_position = $.fn.position;

$.fn.position = function(options) {
	if (!options || !options.of) {
		return _position.apply(this, arguments);
	}

	options = $.extend({}, $.ui.position.defaults, options);

	var target = $(options.of),
		collision = (options.collision || 'flip').split(' '),
		offset = options.offset ? options.offset.split(' ') : [0, 0],
		targetWidth,
		targetHeight,
		basePosition;

	if (options.of == document) {
		targetWidth = target.width();
		targetHeight = target.height();
		basePosition = { top: 0, left: 0 };
	} else if (options.of == window) {
		targetWidth = target.width();
		targetHeight = target.height();
		basePosition = { top: target.scrollTop(), left: target.scrollLeft() };
	} else if (options.of.preventDefault) {
		targetWidth = targetHeight = 0;
		basePosition = { top: options.of.pageY, left: options.of.pageX };
	} else {
		targetWidth = target.outerWidth();
		targetHeight = target.outerHeight();
		basePosition = target.offset();
	}

	// force my and at to have valid horizontal and veritcal positions
	// if a value is missing or invalid, it will be converted to center 
	$.each(['my', 'at'], function() {
		var pos = options[this].split(' ');
		pos = pos.length == 1
			? horizontalPositions.test(pos[0])
				? pos.concat([verticalDefault])
				: verticalPositions.test(pos[0])
					? [horizontalDefault].concat(pos)
					: [horizontalDefault, verticalDefault]
			: pos;
		pos[0] = horizontalPositions.test(pos[0]) ? pos[0] : horizontalDefault;
		pos[1] = verticalPositions.test(pos[1]) ? pos[1] : verticalDefault;
		options[this] = pos;
	});

	// normalize collision option
	if (collision.length == 1) {
		collision[1] = collision[0];
	}

	// normalize offset option
	offset[0] = parseInt(offset[0], 10) || 0;
	if (offset.length == 1) {
		offset[1] = offset[0];
	}
	offset[1] = parseInt(offset[1], 10) || 0;

	switch (options.at[0]) {
		case 'right':
			basePosition.left += targetWidth;
			break;
		case horizontalDefault:
			basePosition.left += targetWidth / 2;
			break;
	}

	switch (options.at[1]) {
		case 'bottom':
			basePosition.top += targetHeight;
			break;
		case verticalDefault:
			basePosition.top += targetHeight / 2;
			break;
	}

	basePosition.left += offset[0];
	basePosition.top += offset[1];

	return this.each(function() {
		var elem = $(this),
			elemWidth = elem.outerWidth(),
			elemHeight = elem.outerHeight(),
			position = $.extend({}, basePosition),
			over,
			myOffset,
			atOffset;

		switch (options.my[0]) {
			case 'right':
				position.left -= elemWidth;
				break;
			case horizontalDefault:
				position.left -= elemWidth / 2;
				break;
		}

		switch (options.my[1]) {
			case 'bottom':
				position.top -= elemHeight;
				break;
			case verticalDefault:
				position.top -= elemHeight / 2;
				break;
		}

		$.each(['left', 'top'], function(i, dir) {
			($.ui.position[collision[i]] &&
				$.ui.position[collision[i]][dir](position, {
					targetWidth: targetWidth,
					targetHeight: targetHeight,
					elemWidth: elemWidth,
					elemHeight: elemHeight,
					offset: offset,
					my: options.my,
					at: options.at
				}));
		});

		(options.stackfix && $.fn.stackfix && elem.stackfix());
		// the by function is passed the offset values, not the position values
		// we'll need the logic from the .offset() setter to be accessible for
		// us to calculate the position values to make the by option more useful
		($.isFunction(options.by) ? options.by.call(this, position) : elem.offset(position));
	});
};

$.ui.position = {
	defaults:{
		stackFix: true
	},
	fit: {
		left: function(position, data) {
			var over = position.left + data.elemWidth - $(window).width() - $(window).scrollLeft();
			position.left = over > 0 ? position.left - over : Math.max(0, position.left);
		},
		top: function(position, data) {
			var over = position.top + data.elemHeight - $(window).height() - $(window).scrollTop();
			position.top = over > 0 ? position.top - over : Math.max(0, position.top);
		}
	},

	flip: {
		left: function(position, data) {
			if (data.at[0] == 'center')
				return;
			var over = position.left + data.elemWidth - $(window).width() - $(window).scrollLeft(),
				myOffset = data.my[0] == 'left' ? -data.elemWidth : data.my[0] == 'right' ? data.elemWidth : 0,
				offset = -2 * data.offset[0];
			position.left += position.left < 0 ? myOffset + data.targetWidth + offset : over > 0 ? myOffset - data.targetWidth + offset : 0;
		},
		top: function(position, data) {
			if (data.at[1] == 'center')
				return;
			var over = position.top + data.elemHeight - $(window).height() - $(window).scrollTop(),
				myOffset = data.my[1] == 'top' ? -data.elemHeight : data.my[1] == 'bottom' ? data.elemHeight : 0,
				atOffset = data.at[1] == 'top' ? data.targetHeight : -data.targetHeight,
				offset = -2 * data.offset[1];
			position.top += position.top < 0 ? myOffset + data.targetHeight + offset : over > 0 ? myOffset + atOffset + offset : 0;
		}
	}
};


// the following functionality is planned for jQuery 1.4
// based on http://plugins.jquery.com/files/offset.js.txt
$.fn.extend({
	_offset: $.fn.offset,
	offset: function(newOffset) {
	    return !newOffset ? this._offset() : this.each(function() {
			var elem = $(this),
				// we need to convert static positioning to relative positioning
				isRelative = /relative|static/.test(elem.css('position')),
				hide = elem.css('display') == 'none';

			(isRelative && elem.css('position', 'relative'));
			(hide && elem.show());

			var offset = elem.offset(),
				delta = {
					left : parseInt(elem.css('left'), 10),
					top: parseInt(elem.css('top'), 10)
				};

			// in case of 'auto'
			delta.left = !isNaN(delta.left)
				? delta.left
				: isRelative
					? 0
					: this.offsetLeft;
			delta.top = !isNaN(delta.top)
				? delta.top
				: isRelative
					? 0
					: this.offsetTop;

			// allow setting only left or only top
			if (newOffset.left || newOffset.left === 0) {
				elem.css('left', newOffset.left - offset.left + delta.left);
			}
			if (newOffset.top || newOffset.top === 0) {
				elem.css('top', newOffset.top - offset.top + delta.top);
			}

			(hide && elem.hide());
		});
	}
});

})(jQuery);