javascript - 是否有用于显示带有 "hole"的半透明叠加层的 React 包？

Question

我想通过在整个窗口前面绘制一个半透明的灰色覆盖层(或掩码？)来引起对页面上任意 HTML 元素的注意，除了该特定元素。也就是说，在特定元素的边界处，叠加层中会有一个“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。

形状必须是矩形也可以。

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

(这很难用谷歌搜索，有人知道这个概念的名称吗？)

Answer 1

不是 React 组件(我过去一直在寻找一个但没有找到)但这应该让您大致了解如何生成该功能:

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>