// jquery.backgrounds.js
// Search container for images and treat that 100% full image backgrounds
// version 1.0
// by Joshua Gildart
;(function($, window, undefined) {
    $.backgrounds = function(element, options) {
        // default plugins options
        var defaults = {
        };
        
        $container = $(element);
        
        var bg = this,
            images;
        
        bg.init = function() {
            // setup the container
            if($container.css('position') == 'static') {
                $container.css('position', 'relative');
            }
            $container.css('overflow', 'hidden');
            
            images = $container.find('img');
            images.css({
                position: 'absolute'
            });
            
            // let the window load before we go crazy
            $(window).load(function() {
                $(window).resize(function() {
                    adjustImages();
                });
                
                $(window).trigger('resize');
                
                $container.mousedown(function(e){ 
                    e.preventDefault();
                });
            
                adjustImages();
            });
        }
        
        var adjustImages = function() {
            images.css({
                top: 0,
                left: 0
            });
            
            images.each(function() {
                var image = $(this),
                    imgW = image.width(),
                    imgH = image.height(),           
                    viewportW = $container.width(),
                    viewportH = $container.height(),
                    diffW = viewportW / imgW,
                    diffH = viewportH / imgH,
                    centerWidth;
                
                if(diffW > 1 || diffW > diffH) { // the width needs adjusting
                    image.width(viewportW);
                    image.height('auto');
                    centerWidth = false;
                } else if(diffH > 1 || diffH > diffW) { // the height needs adjusting
                    image.height(viewportH);
                    image.width('auto');
                    centerWidth = true;
                }
                
                if(centerWidth) { // center by width - 0.9999 is to fix IE9's inability to be 1
                    image.css('left', -1 * Math.round((image.width() - viewportW) / 2));
                } else { // center by height
                    image.css('top', -1 * Math.round((image.height() - viewportH) / 2));
                }
            });
        }
        
        bg.init();
    }

    $.fn.backgrounds = function(options) {
        return $(this).each(function() {
            if (undefined == $(this).data('backgrounds')) {
                var backgrounds = new $.backgrounds(this, options);
                $(this).data('backgrounds', backgrounds);
            }
        });
    }
})(jQuery, window);