关键帧动画回到初始状态

Question

我做了一个缓慢的无限 CSS3 动画。它从 top:0; 动画到 top:40px;。错误是当动画结束时，它跳转到起点。我认为它应该用 ease 或 ease-in 跳转，但那没有发生。我尝试了很多来解决这个问题，但我失败了。

我需要 return 过渡才能产生 ease-in 效果。

我的代码：

span {
  margin-left: 200px;
}
/** Down Slow Animation **/

@-webkit-keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
@-moz-keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
@keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
.down-slow {
  position: relative;
  -webkit-animation: downSlow 1.5s infinite;
  -moz-animation: downSlow 1.5s infinite;
  animation: downSlow 1.5s infinite;
  -webkit-animation-fill-mode: forwards;
  -moz-animation-fill-mode: forwards;
  animation-fill-mode: forwards;
}

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

Answer 1

这只是一个替代方案

只需在 animation 的末尾添加 alternate。

span {
  margin-left: 200px;
}
/** Down Slow Animation **/

@-webkit-keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
@-moz-keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
@keyframes downSlow {
  from { top: 0px; }
  to { top: 40px; }
}
.down-slow {
  position: relative;
  -webkit-animation: downSlow 1.5s infinite alternate;
  -moz-animation: downSlow 1.5s infinite alternate;
  animation: downSlow 1.5s infinite alternate;
}

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

同样的代码可以简化为

span {
  margin-left: 200px;
  top: 0px;
}

@-webkit-keyframes downSlow {
  to { top: 40px; }
}
@-moz-keyframes downSlow {
  to { top: 40px; }
}
@keyframes downSlow {
  to { top: 40px; }
}
.down-slow {
  position: relative;
  
  -webkit-animation: downSlow 1.5s infinite alternate;
  -moz-animation: downSlow 1.5s infinite alternate;
  animation: downSlow 1.5s infinite alternate;
}

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

更好的方法是使用 translate 这样您的元素就不会干扰其他 DOM 元素

span {
  margin-left: 200px;
}

@-webkit-keyframes downSlow {
  to { transform: translateY(40px) }
}
@-moz-keyframes downSlow {
  to { transform: translateY(40px) }
}
@keyframes downSlow {
  to { transform: translateY(40px) }
}
.down-slow {
  position: relative;

  -webkit-animation: downSlow 1.5s infinite alternate;
  -moz-animation: downSlow 1.5s infinite alternate;
  animation: downSlow 1.5s infinite alternate;
}

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

但是您可以再次使用 prefixfree frind a cdn here

来减少它

span {
  margin-left: 200px;
}

@keyframes downSlow {
  to { transform: translateY(40px) }
}
.down-slow {
  position: relative;
  animation: downSlow 1.5s infinite alternate;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

最后设置speed/2

span {
  margin-left: 200px;
}

@keyframes downSlow {
  to { transform: translateY(40px) }
}
.down-slow {
  position: relative;
  animation: downSlow .7s infinite alternate forwards;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css" rel="stylesheet" />

<span class="down-slow"><i class="fa fa-angle-down fa-5x"></i></span>

REF: animation-fill-mode

关键帧动画回到初始状态

Keyframe animation back to initial state

html

css

animation

keyframe