/**
 * jQuery crop - takes (IMG) elements and crops them to the dimensions
 * given.  The result is the same image with a background image with the
 * height and width and an offset.  The new DIV should also carry across 
 * the existing style attributes of the image.
 *
 * @author Remy Sharp (leftlogic.com)
 * @date 2006-12-28
 * @example $("img").crop(x, y, height, width)
 * @example $("img").crop({ x: x, y: y, height: height, width: width })
 * @example $("img").crop(height, width)
 * @example $("img").crop(width)
 * @desc Crops image to dimensions given.  If only width (and height), 
 * x and y are selected randomly based on the image's height and width.
 *
 * @name crop
 * @type jQuery
 * @param Number x co-ordinate to start crop
 * @param Number y co-ordinate to start crop
 * @param Number height of final cropped image
 * @param Number width of final cropped image
 * @cat Plugin
 */
jQuery.fn.crop = function(x, y, height, width, transparentURL) {
    var o = {}
    
    if (x && typeof x == 'object') { // property object
        o['x'] = x['x'] || -1;
        o['y'] = x['y'] || -1;
        o['height'] = ((x['height'] || x['width']) || -1);
        o['width'] = x['width'] || x['height'] || -1;
        
        // note: this *will not* work in IE.
        o['transparentURL'] = x['transparentURL'] || "data:image/gif;base64,R0lGODlhAQABAIAAAMJ0IgAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";
    } else if (arguments.length == 1) {
        o['x'] = -1;
        o['y'] = -1;
        o['height'] = x;
        o['width'] = x;
    } else if (arguments.length == 2) {
        o['x'] = -1;
        o['y'] = -1;
        o['height'] = x;
        o['width'] = y;
    } else {
        o['x'] = x;
        o['y'] = y;
        o['height'] = height;
        o['width'] = width || height;
        o['transparentURL'] = transparentURL;
    }
                
    return this.each(function() {
        var x = o.x;
        var y = o.y;
        var t = jQuery(this);
        
        if (o.x == -1) {
            x = Math.round((this.width - o.width + 1) * Math.random())
            if (this.width - x < o.width) x = 0;
        }
        if (o.y == -1) {
            y = Math.round((this.height - o.height + 1) * Math.random())
            if (this.height - y < o.height) y = 0;
        }

        t.height(o.height + 'px');
        t.width(o.width + 'px');
        
        var background = { 
            height: o.height + 'px', 
            width: o.width + 'px', 
            background: 'url(' + this.src + ') no-repeat -' + Math.abs(x) + 'px -' + Math.abs(y) + 'px' 
        };
        
        this.origSrc = this.src;
        this.src = o['transparentURL']; // transparent gif to fill image
        
        t.css(background); // crop!
    })
}