是否有一个React包用于显示具有“洞”的半透明覆盖层？

Question

我想通过在整个窗口前面绘制一个半透明的灰色覆盖图（或掩码？），而不是针对该特定元素的来关注页面上的任意HTML元素。即，在特定元素的边界处的叠加层中将会有“空洞”。

我需要动态生成叠加层，因为我无法提前知道元素的位置。

如果形状必须是矩形，那么可以。

通过悬停闪烁的红点，您可以在React包react-joyride的react-joyride demo处看到此行为的示例。

（这是一个艰难的一个谷歌，任何人都有洞察名这个概念？）

Answer 1

不是反应成分（我一直在寻找一个在过去并没有发现任何），但这应该给你如何生成功能的总体思路：

overlay = document.getElementById('overlay'); 
 
overlay.style.height = document.body.scrollHeight + 'px'; 
 
overlay.querySelector('.bottom').style.height = (document.body.scrollHeight - 400) + 'px';

html, body { 
 
    padding: 0; 
 
    margin: 0; 
 
} 
 
h1, h2, h3, p { 
 
    margin: 0; 
 
    padding: 15px 0; 
 
} 
 

 
.overlay { 
 
    position: absolute; 
 
    width: 100%; 
 
    min-height: 100%; 
 
    left: 0; 
 
    top: 0; 
 
    z-index: 1000; 
 
} 
 
.overlay div { 
 
    background: rgba(0, 0, 0, 0.3); 
 
    position: absolute; 
 
    width: 100%; 
 
    height: 100%; 
 
} 
 
.overlay .top { 
 
    height: 200px; 
 
    top: 0; 
 
} 
 
.overlay .middle { 
 
    height: 200px; 
 
    top: 200px; 
 
    background: none; 
 
} 
 
.overlay .middle .left { 
 
    width: 150px; 
 
} 
 
.overlay .middle .center { 
 
    width: 200px; 
 
    height: 200px; 
 
    margin: 0 auto; 
 
    overflow: hidden; 
 
    left: 150px; 
 
    background: none; 
 
} 
 
.overlay .middle .center:after { 
 
    content: ''; 
 
    position: absolute; 
 
    left: 0px; 
 
    top: 0; 
 
    border-radius: 100%; 
 
    width: 200px; 
 
    height: 200px; 
 
    box-shadow: 0px 0px 0px 100px rgba(0, 0 ,0, 0.3); 
 
} 
 
.overlay .middle .right { 
 
    width: calc(100% - 150px - 200px); 
 
    left: calc(150px + 200px); 
 
} 
 
.overlay .bottom { 
 
    top: calc(200px + 200px); 
 
}

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</div> 
 
<div id="overlay" class="overlay"> 
 
    <div class="top"></div> 
 
    <div class="middle"> 
 
    <div class="left"></div> 
 
    <div class="center"></div> 
 
    <div class="right"></div> 
 
    </div> 
 
    <div class="bottom"></div> 
 
</div>