我正试图通过使用onscroll事件修改元素的顶部位置来在firefox中创建视差效果。我抑制了onscroll事件,这样它就不会超载浏览器,我还在css中添加了一个transition top属性,使事情更顺利。这在每个浏览器中都能很好地工作,但由于某种原因,firefox非常不稳定。有什么方法可以让这个过渡更顺利吗?
window.onscroll = throttle(function(){
var scrollDistance = window.pageYOffset || window.document.documentElement.scrollTop || window.document.body.scrollTop;
document.getElementById("back").style.top = -scrollDistance * 0.3 + "px";
document.getElementById("mid").style.top = -scrollDistance * 0.5 + "px";
document.getElementById("fore").style.top = -scrollDistance * 0.9 + "px";
}, 100);
function throttle (callback, limit) {
var wait = false;
return function () {
if (!wait) {
callback.call();
wait = true;
setTimeout(function () {
wait = false;
}, limit);
}
}
}
body{
height: 5000px;
background: url(http://lorempixel.com/output/city-q-c-1920-1920-4.jpg);
}
.parallaxEl {
width: 1920px;
height: 1080px;
position: fixed;
transition: top 0.1s;
}
#back{
background: url(http://wall.rimbuz.com/wp-content/uploads/4K-Wide-Wallpapers.jpg);
}
#mid{
background: url(https://wallpaperscraft.com/image/space_planet_background_83807_3840x2160.jpg);
}
#fore{
background: url(http://wall.rimbuz.com/wp-content/uploads/4K-HD-Background-Wallpapers.jpg);
}
<body>
<div class="parallaxEl" id="back"></div>
<div class="parallaxEl" id="mid"></div>
<div class="parallaxEl" id="fore"></div>
</body>
http://codepen.io/anon/pen/NAzBrX
使用requestAnimationFrame
,您将获得更平滑的节流器。
CCD_ 2具有与屏幕刷新率同步的优点。
这是一个代码演示:
// your callback
var scrollHandler = function() {
var scrollDistance = window.pageYOffset || window.document.documentElement.scrollTop || window.document.body.scrollTop;
document.getElementById("back").style.top = -scrollDistance * 0.3 + "px";
document.getElementById("mid").style.top = -scrollDistance * 0.5 + "px";
document.getElementById("fore").style.top = -scrollDistance * 0.9 + "px";
};
// the throttle function
// returns the function that should be passed has an event listener
var throttle = function(callback) {
// a simple flag
var active = false;
// to keep track of the last event
var evt;
// fired only when screen has refreshed
var handler = function(){
// release our flag
active = false;
// call the callback
callback(evt);
}
// the actual event handler
return function handleEvent(e) {
// save our event at each call
evt = e;
// only if we weren't already doing it
if (!active) {
// raise the flag
active = true;
// wait for next screen refresh
requestAnimationFrame(handler);
};
}
}
// remember to call the function, we need its returned function
window.onscroll = throttle(scrollHandler);
body {
height: 5000px;
background: url(http://lorempixel.com/output/city-q-c-1920-1920-4.jpg);
}
.parallaxEl {
width: 1920px;
height: 1080px;
position: fixed;
transition: top 0.1s;
}
#back {
background: url(http://wall.rimbuz.com/wp-content/uploads/4K-Wide-Wallpapers.jpg);
}
#mid {
background: url(https://wallpaperscraft.com/image/space_planet_background_83807_3840x2160.jpg);
}
#fore {
background: url(http://wall.rimbuz.com/wp-content/uploads/4K-HD-Background-Wallpapers.jpg);
}
<body>
<div class="parallaxEl" id="back"></div>
<div class="parallaxEl" id="mid"></div>
<div class="parallaxEl" id="fore"></div>
</body>
事件"onscroll"是在滚动之后引起的,事件"onmousewheel"("nwheel")是在滚动后引起的。对于使用鼠标滚动的动画会更流畅。
此处的示例:excube.hol.es
在可能的情况下,您应该使用CSS 3D Transforms进行动画处理,因为它可以访问用户GPU并允许更平滑的动画。
硬件加速和CSS动画
https://www.sitepoint.com/introduction-to-hardware-acceleration-css-animations/
此外,这里还有一个使用这种技术的基本视差效果的例子。。。
https://css-tricks.com/tour-performant-responsive-css-site/#article-header-id-2