标题几乎说明了一切,但这里有一个例子。
假设我有一个CSS"加载微调器",如下所示:
.spinner {
height: 50px;
width: 50px;
position: relative;
animation: rotate .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;;
border-top: 6px solid #ccc;
border-radius: 100%;
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
我想在此添加一个伪元素,例如在.spinner
之前或之后添加content: 'loading...'
。
是否可以确保伪元素不继承.spinner
的动画,或者伪元素必须始终继承父元素的动画?
由于伪元素是父元素的子元素,只要父元素有动画,它就会继续旋转。即使在伪元素上设置animation: none
也没有效果。
让它看起来像孩子没有动画的唯一方法是反转效果,如下面的片段所示。所做的是将完全相同的动画添加到伪元素,但将animation-direction
设置为reverse
。这意味着伪得到了精确的反向变换效果,从而将其保持在相同的位置。
.spinner {
height: 50px;
width: 50px;
position: relative;
animation: rotation .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;
border-top: 6px solid #ccc;
border-radius: 100%;
}
.spinner:after {
position: absolute;
content: 'Loading..';
top: 0px;
left: 0px;
height: 100%;
width: 100%;
animation: rotation .6s infinite linear reverse; /* added this line */
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
<div class='spinner'></div>
上面的代码段使用了transform-origin
的默认设置,即50% 50%
,但如果子伪元素具有padding
和/或margin
,则必须相应地调整transform-origin
设置,以避免伪元素产生类似颤抖的效果。下面的代码段提供了计算逻辑。
.spinner {
height: 50px;
width: 50px;
position: relative;
animation: rotation .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;
border-top: 6px solid #ccc;
border-radius: 100%;
}
.spinner.parent-padded-margin {
padding: 10px;
margin: 10px;
}
.spinner:after {
position: absolute;
content: 'Loading..';
top: 0px;
left: 0px;
height: 100%;
width: 100%;
animation: rotation .6s infinite linear reverse;
/* added this line */
}
.spinner.child-padded-margin:after {
padding: 10px 8px;
margin: 5px 4px;
transform-origin: calc(50% - 12px) calc(50% - 15px); /* calc(50% - ((padding-left + padding-right)/2 + margin-left)) calc(50% - ((padding-top + padding-bottom)/2 + margin-top)) */
}
.spinner.child-padded-margin-2:after {
padding: 10px 6px 16px 14px;
margin: 7px 12px 5px 10px;
transform-origin: calc(50% - 20px) calc(50% - 20px); /* calc(50% - ((padding-left + padding-right)/2 + margin-left)) calc(50% - ((padding-top + padding-bottom)/2 + margin-top)) */
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
<div class='spinner'></div>
<div class='spinner parent-padded-margin'></div>
<div class='spinner child-padded-margin'></div>
<div class='spinner child-padded-margin-2'></div>
定位伪元素(使用top
、left
、bottom
、right
)也会影响动画。它还需要相应地修改transform-origin
,以便动画正常工作。下面的片段中提供了一个示例。
.spinner {
height: 50px;
width: 50px;
position: relative;
animation: rotation .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;
border-top: 6px solid #ccc;
border-radius: 100%;
}
.spinner.parent-padded-margin {
padding: 10px;
margin: 10px;
}
.spinner:after {
position: absolute;
content: 'Loading..';
height: 100%;
width: 100%;
animation: rotation .6s infinite linear reverse; /* added this line */
}
.spinner.child-positioned{
margin-bottom: 40px;
}
.spinner.child-positioned:after {
top: 120%;
left: 2%;
transform-origin: calc(50% - 2%) calc(50% - 120%); /* basically need to subtract the distance from the left and top of the container */
}
.spinner.child-positioned-negative:after {
bottom: -120%;
right: -2%;
transform-origin: calc(50% - 2%) calc(50% - 120%); /* basically need to subtract the distance from the left and top of the container */
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
<div class='spinner child-positioned'></div>
<div class='spinner child-positioned-negative'></div>
注意:以上两种解决方案在最新版本的Chrome、Opera和Safari中都能很好地工作,但会导致文本在IE 11、Edge和Firefox中出现倾斜外观。Firefox似乎需要一个单独的动画,从FF的旋转(-10度)到旋转(-370度),而在IE中它变得更加复杂。
在不对pseudo(child)元素设置反向动画的情况下,唯一的替代方法是使用Chris在评论中提到的方法。这意味着将边界和动画直接设置为伪元素。这意味着父对象的内容将不受影响,因为父对象不会受到子对象变换的影响。
.spinner {
height: 50px;
width: 50px;
position: relative;
}
.spinner:after {
position: absolute;
content: '';
top: 0px;
left: 0px;
height: 100%;
width: 100%;
animation: rotation .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;
border-top: 6px solid #ccc;
border-radius: 100%;
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
<div class='spinner'>Loading...</div>
为了完整起见,在@Harry给出全面答案的同时,我制作了一个文本位于微调器下方的版本。这样做的方法是使用.spinner
作为画布,将实际的旋转圆:before
和loading...
放在:after
中,如下所示:
.spinner:before {
content: ' ';
display: block;
height: 50px;
width: 50px;
margin: 24px auto 6px auto;
animation: rotation .6s infinite linear;
border-left: 6px solid #222;
border-right: 6px solid #222;
border-bottom: 6px solid #222;;
border-top: 6px solid #ccc;
border-radius: 100%;
}
.spinner {
height: 100px;
width: 100px;
position: relative;
}
.spinner:after {
display: block;
text-align: center;
content: 'loading...';
}
@keyframes rotation {
from {
transform: rotate(0deg);
}
to {
transform: rotate(359deg);
}
}
<div class='spinner'></div>