javascript圆盘抽奖程序实现原理和完整代码例子(3)

var i = 1, sinDeg = 0, cosDeg = 0, timer = null;
        var mRotate = function () {
            var rotate = function (target, msg) {
                target = m$(target);
                var orginW = target.clientWidth, orginH = target.clientHeight;
                clearInterval(timer);
                function run(angle) {
                    if (isIE) {
                        cosDeg = Math.cos(angle * Math.PI / 180);
                        sinDeg = Math.sin(angle * Math.PI / 180);
                        with (target.filters.item(0)) {
                            M11 = M22 = cosDeg; M12 = -(M21 = sinDeg);
                        }
                        target.style.top = (orginH - target.offsetHeight) / 2 + "px";
                        target.style.left = (orginW - target.offsetWidth) / 2 + "px";
                    } else if (target.style.MozTransform !== undefined) {
                        target.style.MozTransform = "rotate(" + angle + "deg)";
                    } else if (target.style.OTransform !== undefined) {
                        target.style.OTransform = "rotate(" + angle + "deg)";
                    } else if (target.style.webkitTransform !== undefined) {
                        target.style.webkitTransform = "rotate(" + angle + "deg)";
                    } else {
                        target.style.transform = "rotate(" + angle + "deg)";
                    }
                }

var tmp = -900;
                var m = -parseInt(Math.random() * 360);
                timer = setInterval(function () {
                    if (i > 3000) {
                        tmp = parseInt(tmp * 0.99);
                        if (tmp > m) {
                            tmp = m;
                            clearInterval(timer);
                            msg(m);
                        }
                        run(tmp);
                    }
                    else if (i > 1000) {
                        i = i + 45;
                        run(i);
                    }
                    else {
                        i = parseInt((i + 1) * 1.01);
                        run(i);
                    }
                }, 50);
            }
            return { rotate: rotate }
        } ();