window.requestNextAnimationFrame = (function () {
var originalRequestAnimationFrame = undefined,
wrapper = undefined,
callback = undefined,
geckoVersion = null,
userAgent = navigator.userAgent,
index = 0,
self = this;
wrapper = function (time) {
time = performance.now();
self.callback(time);
};
/*!
bug!
below code:
when invoke b after 1s, will only invoke b, not invoke a!
function a(time){
console.log("a", time);
webkitRequestAnimationFrame(a);
}
function b(time){
console.log("b", time);
webkitRequestAnimationFrame(b);
}
a();
setTimeout(b, 1000);
so use requestAnimationFrame priority!
*/
if(window.requestAnimationFrame) {
return requestAnimationFrame;
}
// Workaround for Chrome 10 bug where Chrome
// does not pass the time to the animation function
if (window.webkitRequestAnimationFrame) {
// Define the wrapper
// Make the switch
originalRequestAnimationFrame = window.webkitRequestAnimationFrame;
window.webkitRequestAnimationFrame = function (callback, element) {
self.callback = callback;
// Browser calls the wrapper and wrapper calls the callback
return originalRequestAnimationFrame(wrapper, element);
}
}
//修改time参数
if (window.msRequestAnimationFrame) {
originalRequestAnimationFrame = window.msRequestAnimationFrame;
window.msRequestAnimationFrame = function (callback) {
self.callback = callback;
return originalRequestAnimationFrame(wrapper);
}
}
// Workaround for Gecko 2.0, which has a bug in
// mozRequestAnimationFrame() that restricts animations
// to 30-40 fps.
if (window.mozRequestAnimationFrame) {
// Check the Gecko version. Gecko is used by browsers
// other than Firefox. Gecko 2.0 corresponds to
// Firefox 4.0.
index = userAgent.indexOf('rv:');
if (userAgent.indexOf('Gecko') != -1) {
geckoVersion = userAgent.substr(index + 3, 3);
if (geckoVersion === '2.0') {
// Forces the return statement to fall through
// to the setTimeout() function.
window.mozRequestAnimationFrame = undefined;
}
}
}
return window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (callback, element) {
var start,
finish;
window.setTimeout(function () {
start = performance.now();
callback(start);
finish = performance.now();
self.timeout = 1000 / 60 - (finish - start);
}, self.timeout);
};
})();
window.cancelNextRequestAnimationFrame = window.cancelRequestAnimationFrame
|| window.webkitCancelAnimationFrame
|| window.webkitCancelRequestAnimationFrame
|| window.mozCancelRequestAnimationFrame
|| window.oCancelRequestAnimationFrame
|| window.msCancelRequestAnimationFrame
|| clearTimeout;