如何在链接悬停时使背景图像模糊？

Question

当你用鼠标光标悬停链接时,我想让我的背景图像模糊,让我们说5px.有没有简单的方法来实现这一目标？我有点纠结于课程和id在这里......

#pic {
  background: url(http://www.metalinjection.net/wp-content/uploads/2014/07/space-metal.jpg);
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-size: cover;
  height: 500px;
  /*blur using this function*/
  filter: blur(0);
  -webkit-filter: blur(0);
  -moz-filter: blur(0);
  -o-filter: blur(0);
  -ms-filter: blur(0);
}

.banner_link {
  font-family: 'Raleway';
  letter-spacing: 0.2em;
  font-size: 13px;
  color: #ffffff;
  text-align: center;
  line-height: 16px;
  padding-top: 45px;
  text-transform: uppercase;
}

.banner_link a:after {
  content: '';
  display: block;
  margin: auto;
  height: 1px;
  width: 90px;
  background: #ffffff;
  transition: width .2s ease, background-color .5s ease;
}

.banner_link a:hover:after {
  width: 0px;
  background: transparent;
}

.banner_link a:hover #pic {
  filter: blur(5px);
  -webkit-filter: blur(5px);
  -moz-filter: blur(5px);
  -o-filter: blur(5px);
  -ms-filter: blur(5px);
}

<div id="pic" class="banner">
  <div class="banner_link"><a>Link</a>
  </div>
</div>

Answer 1

这个问题是,你正试图穿越了文档树与CSS.CSS中没有父选择器,因此当内部<a>元素悬停时,您只能依靠JS来切换模糊效果.

这可以使用原生JS轻松实现,但我选择使用jQuery,因为相对容易使用.

诀窍很简单:绝对定位背景图像的模糊版本,嵌套在伪元素中,比如说::before,其不透明度设置为零.当光标位于内部<a>元素上时,切换一个类,比如.blur将伪元素的不透明度设置为1.

我们不能使用JS来设置伪元素的CSS属性的原因是因为JS无法访问它.

$(function() {
  $('.banner_link a').hover(function() {
    $('#pic').addClass('blur');
  }, function() {
    $('#pic').removeClass('blur');
  });
});

#pic {
  background: url(http://www.metalinjection.net/wp-content/uploads/2014/07/space-metal.jpg);
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-size: cover;
  height: 500px;
  position: relative;
  overflow: hidden;
}
#pic::before {
  position: absolute;
  content: '';
  display: block;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  background: url(http://www.metalinjection.net/wp-content/uploads/2014/07/space-metal.jpg);
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-size: cover;
  -webkit-filter: blur(5px);
  filter: blur(5px);
  opacity: 0;
  transition: opacity .5s ease-in-out;
}
#pic.blur::before {
  opacity: 1;
}
.banner_link {
  font-family: 'Raleway';
  letter-spacing: 0.2em;
  font-size: 13px;
  color: #ffffff;
  text-align: center;
  line-height: 16px;
  padding-top: 45px;
  position: relative;
  text-transform: uppercase;
}

.banner_link a::after {
  content: '';
  display: block;
  margin: auto;
  height: 1px;
  width: 90px;
  background: #ffffff;
  transition: width .2s ease, background-color .5s ease;
}

.banner_link a:hover:after {
  width: 0px;
  background: transparent;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="pic" class="banner">
  <div class="banner_link"><a>Link</a>
  </div>
</div>