前面有一个速度版的运动框架,但是如果不同属性的变化量不同的情况下,使用速度版运动框架会在运动过程中出现‘卡顿’一下的状况。而此时间版运动框架则不会有‘卡顿’情况出现。
此时间版运动框架是基于tween算法的。
tween有4个参数:
-t:current time(当前时间)
-b:beginning value(初始值)
-c: change in value(变化量)
-d:duration(持续时间)
该运动框架共有5个参数:
-obj:运动对象
-json:运动对象的目标属性和属性值
-times:持续时间(默认400ms)
-fx:运动方式(默认匀速)
-fn:回调函数
运动方式包含:
linear:匀速(默认运动形式)
easeIn:加速曲线
easeOut:减速曲线
easeBoth:加速减速曲线
easeInStrong:加加速曲线
easeOutStrong:减减速曲线
easeBothStrong:加加速减减速曲线
elasticIn:正弦衰减曲线(弹动渐入)
elasticOut:正弦增强曲线(弹动渐出)
……
function startMove(obj,json,times,fx,fn){
if( typeof times == 'undefined' ){ //缺times,fx,fn
times = 400;
fx = 'linear';
}
if( typeof times == 'string' ){ //缺times
if(typeof fx == 'function'){
fn = fx;
}
fx = times;
times = 400;
}
else if(typeof times == 'function'){ //缺times,fx
fn = times;
times = 400;
fx = 'linear';
}
else if(typeof times == 'number'){
if(typeof fx == 'function'){ //缺fx
fn = fx;
fx = 'linear';
}
else if(typeof fx == 'undefined'){ //缺fx,fn
fx = 'linear';
}
}
var iCur = {};
for(var attr in json){
iCur[attr] = 0;
if( attr == 'opacity' ){
iCur[attr] = Math.round(getStyle(obj,attr)*100);
}
else{
iCur[attr] = parseInt(getStyle(obj,attr));
}
}
var startTime = now();
clearInterval(obj.timer);
obj.timer = setInterval(function(){
var changeTime = now();
var t = times - Math.max(0,startTime - changeTime + times); //0到2000
for(var attr in json){
var value = Tween[fx](t,iCur[attr],json[attr]-iCur[attr],times);
if(attr == 'opacity'){
obj.style.opacity = value/100;
obj.style.filter = 'alpha(opacity='+value+')';
}
else{
obj.style[attr] = value + 'px';
}
}
if(t == times){
clearInterval(obj.timer);
if(fn){
fn.call(obj);
}
}
},13);
function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}
else{
return getComputedStyle(obj,false)[attr];
}
}
function now(){
return (new Date()).getTime();
}
}
var Tween = {
linear: function (t, b, c, d){ //匀速
return c*t/d + b;
},
easeIn: function(t, b, c, d){ //加速曲线
return c*(t/=d)*t + b;
},
easeOut: function(t, b, c, d){ //减速曲线
return -c *(t/=d)*(t-2) + b;
},
easeBoth: function(t, b, c, d){ //加速减速曲线
if ((t/=d/2) < 1) {
return c/2*t*t + b;
}
return -c/2 * ((--t)*(t-2) - 1) + b;
},
easeInStrong: function(t, b, c, d){ //加加速曲线
return c*(t/=d)*t*t*t + b;
},
easeOutStrong: function(t, b, c, d){ //减减速曲线
return -c * ((t=t/d-1)*t*t*t - 1) + b;
},
easeBothStrong: function(t, b, c, d){ //加加速减减速曲线
if ((t/=d/2) < 1) {
return c/2*t*t*t*t + b;
}
return -c/2 * ((t-=2)*t*t*t - 2) + b;
},
elasticIn: function(t, b, c, d, a, p){ //正弦衰减曲线(弹动渐入)
if (t === 0) {
return b;
}
if ( (t /= d) == 1 ) {
return b+c;
}
if (!p) {
p=d*0.3;
}
if (!a || a < Math.abs(c)) {
a = c;
var s = p/4;
} else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
},
elasticOut: function(t, b, c, d, a, p){ //正弦增强曲线(弹动渐出)
if (t === 0) {
return b;
}
if ( (t /= d) == 1 ) {
return b+c;
}
if (!p) {
p=d*0.3;
}
if (!a || a < Math.abs(c)) {
a = c;
var s = p / 4;
} else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
},
elasticBoth: function(t, b, c, d, a, p){
if (t === 0) {
return b;
}
if ( (t /= d/2) == 2 ) {
return b+c;
}
if (!p) {
p = d*(0.3*1.5);
}
if ( !a || a < Math.abs(c) ) {
a = c;
var s = p/4;
}
else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
if (t < 1) {
return - 0.5*(a*Math.pow(2,10*(t-=1)) *
Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
}
return a*Math.pow(2,-10*(t-=1)) *
Math.sin( (t*d-s)*(2*Math.PI)/p )*0.5 + c + b;
},
backIn: function(t, b, c, d, s){ //回退加速(回退渐入)
if (typeof s == 'undefined') {
s = 1.70158;
}
return c*(t/=d)*t*((s+1)*t - s) + b;
},
backOut: function(t, b, c, d, s){
if (typeof s == 'undefined') {
s = 3.70158; //回缩的距离
}
return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
},
backBoth: function(t, b, c, d, s){
if (typeof s == 'undefined') {
s = 1.70158;
}
if ((t /= d/2 ) < 1) {
return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
}
return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
},
bounceIn: function(t, b, c, d){ //弹球减振(弹球渐出)
return c - Tween['bounceOut'](d-t, 0, c, d) + b;
},
bounceOut: function(t, b, c, d){
if ((t/=d) < (1/2.75)) {
return c*(7.5625*t*t) + b;
} else if (t < (2/2.75)) {
return c*(7.5625*(t-=(1.5/2.75))*t + 0.75) + b;
} else if (t < (2.5/2.75)) {
return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;
}
return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;
},
bounceBoth: function(t, b, c, d){
if (t < d/2) {
return Tween['bounceIn'](t*2, 0, c, d) * 0.5 + b;
}
return Tween['bounceOut'](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;
}
}
实例调用:
oDiv.οnmοuseοver=function(){
startMove(this,{width:200,height:200,left:150,top:150},1000,'easeIn')
}
oDiv.οnmοuseοut=function(){
startMove(this,{width:100,height:100,left:200,top:200})
}