CSS，向左/向右切换以转换/翻译以获得更好的性能

Question

我发现这个很好的进度条 CSS 动画。

但我想transform: translate而不是left/right。

如何切换到 transform 它？我试过了，但它不起作用:

https://codepen.io/shalimano/pen/wBmNGJ

body{
  background:#ffffff;
  margin:50px 300px;
}

.slider{
  position:absolute;
  width:1000px;
  height:5px;
  overflow-x: hidden;
}

.line{
  position:absolute;
  opacity: 0.4;
  background:#4a8df8;
  width:150%;
  height:5px;
}

.subline{
  position:absolute;
  background:#4a8df8;
  height:5px; 
}
.inc{
animation: increase 2s infinite;
}
.dec{
animation: decrease 2s 0.5s infinite;
}

@keyframes increase {
 from { left: -5%; width: 5%; }
 to { left: 130%; width: 100%;}
}
@keyframes decrease {
 from { left: -80%; width: 80%; }
 to { left: 110%; width: 10%;}
}

<div class="slider">
	  <div class="line"></div>
  <div class="subline inc"></div>
  <div class="subline dec"></div>
</div>

第一次尝试:

@keyframes increase {
 from { transform: translateX(-5%); width: 5%; }
 to { transform: translateX(130%); width: 100%;}
}
@keyframes decrease {
 from { transform: translateX(-100%); width: 80%; }
 to { transform: translateX(1100%); width: 10%;}
}

但这不一样。

Answer 1

您应该考虑 translate 的百分比值这一事实与元素大小相关，而不是父元素大小，如top/left为了获得良好的性能，您还需要更换 width通过 scale这样你就只使用转换，你不会trigger layout changes .

这是仅使用转换的代码的近似值:

body {
  background: #ffffff;
  margin: 50px 10px;
  position:relative;
}

.slider {
  position: absolute;
  left:0;
  right:0;
  height: 5px;
  overflow-x: hidden;
  background: rgba(74, 141, 248, 0.4);
}

.slider:before,
.slider:after {
  content: "";
  position: absolute;
  background: #4a8df8;
  height: 5px;
  width:100%;
  transform:scaleX(0);
  animation: increase 2s infinite linear;
}

.slider:after {
  animation-delay:1s;
}

@keyframes increase {
  from {
    transform:translateX(0%) scaleX(0);
    transform-origin:left;
  }
  50% {
    transform-origin:left;
  }
  60% {
    transform:translateX(0%) scaleX(0.5);
    transform-origin:right;
  }
  80% {
    transform:translateX(20%) scaleX(0.3);
    transform-origin:right;
  }
  100% {
    transform:translateX(0%) scaleX(0);
    transform-origin:right;
  }
}

<div class="slider">
</div>