The source code

    (function(){
        var EXTLIB = Ext.lib,
            noNegatives = /width|height|opacity|padding/i,
            offsetAttribute = /^((width|height)|(top|left))$/,
            defaultUnit = /width|height|top$|bottom$|left$|right$/i,
            offsetUnit =  /\d+(em|%|en|ex|pt|in|cm|mm|pc)$/i,
            isset = function(v){
                return typeof v !== 'undefined';
            },
            now = function(){
                return new Date();
            };

        EXTLIB.Anim = {
            motion : function(el, args, duration, easing, cb, scope) {
                return this.run(el, args, duration, easing, cb, scope, Ext.lib.Motion);
            },

            run : function(el, args, duration, easing, cb, scope, type) {
                type = type || Ext.lib.AnimBase;
                if (typeof easing == "string") {
                    easing = Ext.lib.Easing[easing];
                }
                var anim = new type(el, args, duration, easing);
                anim.animateX(function() {
                    if(Ext.isFunction(cb)){
                        cb.call(scope);
                    }
                });
                return anim;
            }
        };

        EXTLIB.AnimBase = function(el, attributes, duration, method) {
            if (el) {
                this.init(el, attributes, duration, method);
            }
        };

        EXTLIB.AnimBase.prototype = {
            doMethod: function(attr, start, end) {
                var me = this;
                return me.method(me.curFrame, start, end - start, me.totalFrames);
            },

            setAttr: function(attr, val, unit) {
                if (noNegatives.test(attr) && val < 0) {
                    val = 0;
                }
                Ext.fly(this.el, '_anim').setStyle(attr, val + unit);
            },

            getAttr: function(attr) {
                var el = Ext.fly(this.el),
                    val = el.getStyle(attr),
                    a = offsetAttribute.exec(attr) || []

                if (val !== 'auto' && !offsetUnit.test(val)) {
                    return parseFloat(val);
                }

                return (!!(a[2]) || (el.getStyle('position') == 'absolute' && !!(a[3]))) ? el.dom['offset' + a[0].charAt(0).toUpperCase() + a[0].substr(1)] : 0;
            },

            getDefaultUnit: function(attr) {
                return defaultUnit.test(attr) ? 'px' : '';
            },

            animateX : function(callback, scope) {
                var me = this,
                    f = function() {
                    me.onComplete.removeListener(f);
                    if (Ext.isFunction(callback)) {
                        callback.call(scope || me, me);
                    }
                };
                me.onComplete.addListener(f, me);
                me.animate();
            },

            setRunAttr: function(attr) {
                var me = this,
                    a = this.attributes[attr],
                    to = a.to,
                    by = a.by,
                    from = a.from,
                    unit = a.unit,
                    ra = (this.runAttrs[attr] = {}),
                    end;

                if (!isset(to) && !isset(by)){
                    return false;
                }

                var start = isset(from) ? from : me.getAttr(attr);
                if (isset(to)) {
                    end = to;
                }else if(isset(by)) {
                    if (Ext.isArray(start)){
                        end = [];
                        Ext.each(start, function(v, i){
                            end[i] = v + by[i];
                        });
                    }else{
                        end = start + by;
                    }
                }

                Ext.apply(ra, {
                    start: start,
                    end: end,
                    unit: isset(unit) ? unit : me.getDefaultUnit(attr)
                });
            },

            init: function(el, attributes, duration, method) {
                var me = this,
                    actualFrames = 0,
                    mgr = EXTLIB.AnimMgr;

                Ext.apply(me, {
                    isAnimated: false,
                    startTime: null,
                    el: Ext.getDom(el),
                    attributes: attributes || {},
                    duration: duration || 1,
                    method: method || EXTLIB.Easing.easeNone,
                    useSec: true,
                    curFrame: 0,
                    totalFrames: mgr.fps,
                    runAttrs: {},
                    animate: function(){
                        var me = this,
                            d = me.duration;

                        if(me.isAnimated){
                            return false;
                        }

                        me.curFrame = 0;
                        me.totalFrames = me.useSec ? Math.ceil(mgr.fps * d) : d;
                        mgr.registerElement(me);
                    },

                    stop: function(finish){
                        var me = this;

                        if(finish){
                            me.curFrame = me.totalFrames;
                            me._onTween.fire();
                        }
                        mgr.stop(me);
                    }
                });

                var onStart = function(){
                    var me = this,
                        attr;

                    me.onStart.fire();
                    me.runAttrs = {};
                    for(attr in this.attributes){
                        this.setRunAttr(attr);
                    }

                    me.isAnimated = true;
                    me.startTime = now();
                    actualFrames = 0;
                };

                var onTween = function(){
                    var me = this;

                    me.onTween.fire({
                        duration: now() - me.startTime,
                        curFrame: me.curFrame
                    });

                    var ra = me.runAttrs;
                    for (var attr in ra) {
                        this.setAttr(attr, me.doMethod(attr, ra[attr].start, ra[attr].end), ra[attr].unit);
                    }

                    ++actualFrames;
                };

                var onComplete = function() {
                    var me = this,
                        actual = (now() - me.startTime) / 1000,
                        data = {
                            duration: actual,
                            frames: actualFrames,
                            fps: actualFrames / actual
                        };

                    me.isAnimated = false;
                    actualFrames = 0;
                    me.onComplete.fire(data);
                };

                me.onStart = new Ext.util.Event(me);
                me.onTween = new Ext.util.Event(me);
                me.onComplete = new Ext.util.Event(me);
                (me._onStart = new Ext.util.Event(me)).addListener(onStart);
                (me._onTween = new Ext.util.Event(me)).addListener(onTween);
                (me._onComplete = new Ext.util.Event(me)).addListener(onComplete);
            }
        };

        Ext.lib.AnimMgr = new function() {
            var me = this,
                thread = null,
                queue = [],
                tweenCount = 0;

            Ext.apply(me, {
                fps: 1000,
                delay: 1,
                registerElement: function(tween){
                    queue.push(tween);
                    ++tweenCount;
                    tween._onStart.fire();
                    me.start();
                },

                unRegister: function(tween, index){
                    tween._onComplete.fire();
                    index = index || getIndex(tween);
                    if (index != -1) {
                        queue.splice(index, 1);
                    }

                    if (--tweenCount <= 0) {
                        me.stop();
                    }
                },

                start: function(){
                    if(thread === null){
                        thread = setInterval(me.run, me.delay);
                    }
                },

                stop: function(tween){
                    if(!tween){
                        clearInterval(thread);
                        for(var i = 0, len = queue.length; i < len; ++i){
                            if(queue[0].isAnimated){
                                me.unRegister(queue[0], 0);
                            }
                        }

                        queue = [];
                        thread = null;
                        tweenCount = 0;
                    }else{
                        me.unRegister(tween);
                    }
                },

                run: function(){
                    var tf;
                    Ext.each(queue, function(tween){
                        if(tween && tween.isAnimated){
                            tf = tween.totalFrames;
                            if(tween.curFrame < tf || tf === null){
                                ++tween.curFrame;
                                if(tween.useSec){
                                    correctFrame(tween);
                                }
                                tween._onTween.fire();
                            }else{
                                me.stop(tween);
                            }
                        }
                    }, me);
                }
            });

            var getIndex = function(anim) {
                var out = -1;
                Ext.each(queue, function(item, idx){
                    if(item == anim){
                        out = idx;
                        return false;
                    }
                });
                return out;
            };

            var correctFrame = function(tween) {
                var frames = tween.totalFrames,
                    frame = tween.curFrame,
                    duration = tween.duration,
                    expected = (frame * duration * 1000 / frames),
                    elapsed = (now() - tween.startTime),
                    tweak = 0;

                if(elapsed < duration * 1000){
                    tweak = Math.round((elapsed / expected - 1) * frame);
                }else{
                    tweak = frames - (frame + 1);
                }
                if(tweak > 0 && isFinite(tweak)){
                    if(tween.curFrame + tweak >= frames){
                        tweak = frames - (frame + 1);
                    }
                    tween.curFrame += tweak;
                }
            };
        };

        EXTLIB.Bezier = new function() {

            this.getPosition = function(points, t) {
                var n = points.length,
                    tmp = [],
                    c = 1 - t,
                    i,
                    j;

                for (i = 0; i < n; ++i) {
                    tmp[i] = [points[i][0], points[i][1]];
                }

                for (j = 1; j < n; ++j) {
                    for (i = 0; i < n - j; ++i) {
                        tmp[i][0] = c * tmp[i][0] + t * tmp[parseInt(i + 1, 10)][0];
                        tmp[i][1] = c * tmp[i][1] + t * tmp[parseInt(i + 1, 10)][1];
                    }
                }

                return [ tmp[0][0], tmp[0][1] ];

            };
        };

        EXTLIB.Easing = {
            easeNone: function (t, b, c, d) {
                return c * t / d + b;
            },

            easeIn: function (t, b, c, d) {
                return c * (t /= d) * t + b;
            },

            easeOut: function (t, b, c, d) {
                return -c * (t /= d) * (t - 2) + b;
            }
        };

        (function() {
            EXTLIB.Motion = function(el, attributes, duration, method) {
                if (el) {
                    EXTLIB.Motion.superclass.constructor.call(this, el, attributes, duration, method);
                }
            };

            Ext.extend(EXTLIB.Motion, Ext.lib.AnimBase);

            var superclass = EXTLIB.Motion.superclass,
                proto = EXTLIB.Motion.prototype,
                pointsRe = /^points$/i;

            Ext.apply(EXTLIB.Motion.prototype, {
                setAttr: function(attr, val, unit){
                    var me = this,
                        setAttr = superclass.setAttr;

                    if (pointsRe.test(attr)) {
                        unit = unit || 'px';
                        setAttr.call(me, 'left', val[0], unit);
                        setAttr.call(me, 'top', val[1], unit);
                    } else {
                        setAttr.call(me, attr, val, unit);
                    }
                },

                getAttr: function(attr){
                    var me = this,
                        getAttr = superclass.getAttr;

                    return pointsRe.test(attr) ? [getAttr.call(me, 'left'), getAttr.call(me, 'top')] : getAttr.call(me, attr);
                },

                doMethod: function(attr, start, end){
                    var me = this;

                    return pointsRe.test(attr)
                            ? EXTLIB.Bezier.getPosition(me.runAttrs[attr], me.method(me.curFrame, 0, 100, me.totalFrames) / 100)
                            : superclass.doMethod.call(me, attr, start, end);
                },

                setRunAttr: function(attr){
                    if(pointsRe.test(attr)){

                        var me = this,
                            el = this.el,
                            points = this.attributes.points,
                            control = points.control || [],
                            from = points.from,
                            to = points.to,
                            by = points.by,
                            DOM = EXTLIB.Dom,
                            start,
                            i,
                            end,
                            len,
                            ra;

                        if(control.length > 0 && !Ext.isArray(control[0])){
                            control = [control];
                        }else{
                            /*
                            var tmp = [];
                            for (i = 0,len = control.length; i < len; ++i) {
                                tmp[i] = control[i];
                            }
                            control = tmp;
                            */
                        }

                        Ext.fly(el, '_anim').position();
                        DOM.setXY(el, isset(from) ? from : DOM.getXY(el));
                        start = me.getAttr('points');

                        if(isset(to)){
                            end = translateValues.call(me, to, start);
                            for (i = 0,len = control.length; i < len; ++i) {
                                control[i] = translateValues.call(me, control[i], start);
                            }
                        } else if (isset(by)) {
                            end = [start[0] + by[0], start[1] + by[1]];

                            for (i = 0,len = control.length; i < len; ++i) {
                                control[i] = [ start[0] + control[i][0], start[1] + control[i][1] ];
                            }
                        }

                        ra = this.runAttrs[attr] = [start];
                        if (control.length > 0) {
                            ra = ra.concat(control);
                        }

                        ra[ra.length] = end;
                    }else{
                        superclass.setRunAttr.call(this, attr);
                    }
                }
            });

            var translateValues = function(val, start) {
                var pageXY = EXTLIB.Dom.getXY(this.el);
                return [val[0] - pageXY[0] + start[0], val[1] - pageXY[1] + start[1]];
            };
        })();
    })();