如何用纯 CSS 创作一种按钮被瞄准的交互特效
效果预览
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在线演示https://codepen.io/zhang-ou/pen/ELWMLr
可交互视频教程
此视频是可以交互的,你可以随时暂停视频,编辑视频中的代码。
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源代码下载
本地下载请从 github 下载。
https://github.com/comehope/front-end-daily-challenges/tree/master/009-aimed-button-effects
代码解读
定义 dom,容器中包含 5 个 span,第 1 个是按钮文字,另 4 个用来修饰:
<div class="box">
<span>BUTTON</span>
<span class="top"></span>
<span class="bottom"></span>
<span class="left"></span>
<span class="right"></span>
</div>
居中显示:
html, body {
height: 100%;
display: flex;
align-items: center;
justify-content: center;
background-color: black;
color: silver;
}
设置文字样式:
.box {
width: 9em;
height: 3em;
font-size: 30px;
text-align: center;
line-height: 3em;
letter-spacing: 0.2em;
font-family: sans-serif;
}
画出瞄准镜中间的圆圈:
.box {
position: relative;
}
.box::after {
content: '';
position: absolute;
width: 3em;
height: 3em;
border: 1px solid red;
border-radius: 50%;
left: 3em;
}
画出瞄准镜的十字坐标线:
.box span:not(:first-child) {
position: absolute;
background-color: red;
}
.box span.top,
.box span.bottom {
width: 1px;
height: 3em;
left: 50%;
}
.box span.top {
top: -3em;
}
.box span.bottom {
bottom: -3em;
}
.box span.left,
.box span.right {
width: 3em;
height: 1px;
top: 50%;
}
.box span.left {
left: 0;
}
.box span.right {
right: 0;
}
定义瞄准动画:
@keyframes aim {
from {
filter: opacity(0.2);
}
to {
filter: opacity(0.8);
}
}
应用瞄准动画到瞄准镜上:
.box::after {
filter: opacity(0);
}
.box span:not(:first-child) {
filter: opacity(0);
}
.box:hover::after,
.box:hover span:not(:first-child) {
animation: aim 1s linear infinite alternate;
}
最后,为容器设置从模糊到清晰的缓动效果:
.box {
filter: blur(2px);
transition: 0.5s;
}
.box:hover {
filter: blur(0.2px);
}
大功告成!
知识点
- :not https://developer.mozilla.org/en-US/docs/Web/CSS/:not
- :first-child https://developer.mozilla.org/en-US/docs/Web/CSS/:first-child
- filter functions https://developer.mozilla.org/en-US/docs/Web/CSS/filter#Functions
- animation-direction https://developer.mozilla.org/en-US/docs/Web/CSS/animation-direction