(function ($) {
    var has_VML, create_canvas_for, add_shape_to, clear_canvas, shape_from_area,
canvas_style, fader, hex_to_decimal, css3color, is_image_loaded, options_from_area;

    has_VML = document.namespaces;
    has_canvas = !!document.createElement('canvas').getContext;

    if (!(has_canvas || has_VML)) {
        $.fn.maphilight = function () { return this; };
        return;
    }

    if (has_canvas) {
        fader = function (element, opacity, interval) {
            if (opacity <= 1) {
                element.style.opacity = opacity;
                window.setTimeout(fader, 10, element, opacity + 0.1, 10);
            }
        };

        hex_to_decimal = function (hex) {
            return Math.max(0, Math.min(parseInt(hex, 16), 255));
        };
        css3color = function (color, opacity) {
            return 'rgba(' + hex_to_decimal(color.substr(0, 2)) + ',' + hex_to_decimal(color.substr(2, 2)) + ',' + hex_to_decimal(color.substr(4, 2)) + ',' + opacity + ')';
        };
        create_canvas_for = function (img) {
            var c = $('<canvas style="width:' + img.width + 'px;height:' + img.height + 'px;"></canvas>').get(0);
            c.getContext("2d").clearRect(0, 0, c.width, c.height);
            return c;
        };
        add_shape_to = function (canvas, shape, coords, options, name) {
            var i, context = canvas.getContext('2d');
            context.beginPath();
            if (shape == 'rect') {
                context.rect(coords[0], coords[1], coords[2] - coords[0], coords[3] - coords[1]);
            } else if (shape == 'poly') {
                context.moveTo(coords[0], coords[1]);
                for (i = 2; i < coords.length; i += 2) {
                    context.lineTo(coords[i], coords[i + 1]);
                }
            } else if (shape == 'circ') {
                context.arc(coords[0], coords[1], coords[2], 0, Math.PI * 2, false);
            }
            context.closePath();
            if (options.fill) {
                context.fillStyle = css3color(options.fillColor, options.fillOpacity);
                context.fill();
            }
            if (options.stroke) {
                context.strokeStyle = css3color(options.strokeColor, options.strokeOpacity);
                context.lineWidth = options.strokeWidth;
                context.stroke();
            }
            if (options.fade) {
                fader(canvas, 0);
            }
        };
        clear_canvas = function (canvas) {
            canvas.getContext('2d').clearRect(0, 0, canvas.width, canvas.height);
        };
    } else { // ie executes this code
        create_canvas_for = function (img) {
            return $('<var style="zoom:1;overflow:hidden;display:block;width:' + img.width + 'px;height:' + img.height + 'px;"></var>').get(0);
        };
        add_shape_to = function (canvas, shape, coords, options, name) {
            var fill, stroke, opacity, e;
            fill = '<v:fill color="#' + options.fillColor + '" opacity="' + (options.fill ? options.fillOpacity : 0) + '" />';
            stroke = (options.stroke ? 'strokeweight="' + options.strokeWidth + '" stroked="t" strokecolor="#' + options.strokeColor + '"' : 'stroked="f"');
            opacity = '<v:stroke opacity="' + options.strokeOpacity + '"/>';
            if (shape == 'rect') {
                e = $('<v:rect name="' + name + '" filled="t" ' + stroke + ' style="zoom:1;margin:0;padding:0;display:block;position:absolute;left:' + coords[0] + 'px;top:' + coords[1] + 'px;width:' + (coords[2] - coords[0]) + 'px;height:' + (coords[3] - coords[1]) + 'px;"></v:rect>');
            } else if (shape == 'poly') {
                e = $('<v:shape name="' + name + '" filled="t" ' + stroke + ' coordorigin="0,0" coordsize="' + canvas.width + ',' + canvas.height + '" path="m ' + coords[0] + ',' + coords[1] + ' l ' + coords.join(',') + ' x e" style="zoom:1;margin:0;padding:0;display:block;position:absolute;top:0px;left:0px;width:' + canvas.width + 'px;height:' + canvas.height + 'px;"></v:shape>');
            } else if (shape == 'circ') {
                e = $('<v:oval name="' + name + '" filled="t" ' + stroke + ' style="zoom:1;margin:0;padding:0;display:block;position:absolute;left:' + (coords[0] - coords[2]) + 'px;top:' + (coords[1] - coords[2]) + 'px;width:' + (coords[2] * 2) + 'px;height:' + (coords[2] * 2) + 'px;"></v:oval>');
            }
            e.get(0).innerHTML = fill + opacity;
            $(canvas).append(e);
        };
        clear_canvas = function (canvas) {
            $(canvas).find('[name=highlighted]').remove();
        };
    }

    shape_from_area = function (area) {
        var i, coords = area.getAttribute('coords').split(',');
        for (i = 0; i < coords.length; i++) { coords[i] = parseFloat(coords[i]); }
        return [area.getAttribute('shape').toLowerCase().substr(0, 4), coords];
    };

    options_from_area = function (area, options) {
        var $area = $(area);
        return $.extend({}, options, $.metadata ? $area.metadata() : false, $area.data('maphilight'));
    };

    is_image_loaded = function (img) {
        if (!img.complete) { return false; } // IE
        if (typeof img.naturalWidth != "undefined" && img.naturalWidth == 0) { return false; } // Others
        return true;
    };

    canvas_style = {
        position: 'absolute',
        left: 0,
        top: 0,
        padding: 0,
        border: 0
    };

    var ie_hax_done = false;
    $.fn.maphilight = function (opts) {
        opts = $.extend({}, $.fn.maphilight.defaults, opts);

        if ($.browser.msie && !ie_hax_done) {
            document.namespaces.add("v", "urn:schemas-microsoft-com:vml");
            var style = document.createStyleSheet();
            var shapes = ['shape', 'rect', 'oval', 'circ', 'fill', 'stroke', 'imagedata', 'group', 'textbox'];
            $.each(shapes,
function () {
    style.addRule('v\\:' + this, "behavior: url(#default#VML); antialias:true");
}
);
            ie_hax_done = true;
        }

        return this.each(function () {
            var img, wrap, options, map, canvas, canvas_always, mouseover, highlighted_shape, usemap;
            img = $(this);

            if (!is_image_loaded(this)) {
                // If the image isn't fully loaded, this won't work right. Try again later.
                return window.setTimeout(function () {
                    img.maphilight(opts);
                }, 200);
            }

            options = $.extend({}, opts, $.metadata ? img.metadata() : false, img.data('maphilight'));

            // jQuery bug with Opera, results in full-url#usemap being returned from jQuery's attr.
            // So use raw getAttribute instead.
            usemap = img.get(0).getAttribute('usemap');

            map = $('map[name="' + usemap.substr(1) + '"]');

            if (!(img.is('img') && usemap && map.size() > 0)) { return; }

            if (img.hasClass('maphilighted')) {
                // We're redrawing an old map, probably to pick up changes to the options.
                // Just clear out all the old stuff.
                var wrapper = img.parent();
                img.insertBefore(wrapper);
                wrapper.remove();
                $(map).unbind('.maphilight').find('area[coords]').unbind('.maphilight');
            }

            wrap = $('<div></div>').css({
                display: 'block',
                background: 'url(' + this.src + ')',
                position: 'relative',
                padding: 0,
                width: this.width,
                height: this.height
            });
            if (options.wrapClass) {
                if (options.wrapClass === true) {
                    wrap.addClass($(this).attr('class'));
                } else {
                    wrap.addClass(options.wrapClass);
                }
            }
            img.before(wrap).css('opacity', 0).css(canvas_style).remove();
            if ($.browser.msie) { img.css('filter', 'Alpha(opacity=0)'); }
            wrap.append(img);

            canvas = create_canvas_for(this);
            $(canvas).css(canvas_style);
            canvas.height = this.height;
            canvas.width = this.width;

            mouseover = function (e) {
                var shape, area_options;
                area_options = options_from_area(this, options);
                if (
!area_options.neverOn
&&
!area_options.alwaysOn
) {
                    shape = shape_from_area(this);
                    add_shape_to(canvas, shape[0], shape[1], area_options, "highlighted");
                    if (area_options.groupBy && $(this).attr(area_options.groupBy)) {
                        var first = this;
                        map.find('area[' + area_options.groupBy + '=' + $(this).attr(area_options.groupBy) + ']').each(function () {
                            if (this != first) {
                                var subarea_options = options_from_area(this, options);
                                if (!subarea_options.neverOn && !subarea_options.alwaysOn) {
                                    var shape = shape_from_area(this);
                                    add_shape_to(canvas, shape[0], shape[1], subarea_options, "highlighted");
                                }
                            }
                        });
                    }
                }
            }

            $(map).bind('alwaysOn.maphilight', function () {
                // Check for areas with alwaysOn set. These are added to a *second* canvas,
                // which will get around flickering during fading.
                if (canvas_always) {
                    clear_canvas(canvas_always)
                }
                if (!has_canvas) {
                    $(canvas).empty();
                }
                $(map).find('area[coords]').each(function () {
                    var shape, area_options;
                    area_options = options_from_area(this, options);
                    if (area_options.alwaysOn) {
                        if (!canvas_always && has_canvas) {
                            canvas_always = create_canvas_for(img.get());
                            $(canvas_always).css(canvas_style);
                            canvas_always.width = img.width();
                            canvas_always.height = img.height();
                            img.before(canvas_always);
                        }
                        shape = shape_from_area(this);
                        if (has_canvas) {
                            add_shape_to(canvas_always, shape[0], shape[1], area_options, "");
                        } else {
                            add_shape_to(canvas, shape[0], shape[1], area_options, "");
                        }
                    }
                });
            });

            if (options.alwaysOn) {
                $(map).find('area[coords]').each(mouseover);
            } else {
                $(map).find('area[coords]')
.trigger('alwaysOn.maphilight')
.bind('mouseover.maphilight', mouseover)
.bind('mouseout.maphilight', function (e) { clear_canvas(canvas); });
            }

            img.before(canvas); // if we put this after, the mouseover events wouldn't fire.

            img.addClass('maphilighted');
        });
    };
    $.fn.maphilight.defaults = {
        fill: true,
        fillColor: '000000',
        fillOpacity: 0.2,
        stroke: true,
        strokeColor: 'ff0000',
        strokeOpacity: 1,
        strokeWidth: 1,
        fade: true,
        alwaysOn: true,
        neverOn: false,
        groupBy: false,
        wrapClass: true
    };
})(jQuery);