CSS "inverse border-radius" 在元素的边界框外创建移动 phone 缺口设计

Question

我正在尝试用 HTML 和 CSS 创建看起来像手机 phone 的东西，我希望相机有类似 [=30= 的东西] 与框架顺利连接。

我不能只是把它变大并用白色背景的伪元素掩盖不需要的区域，因为屏幕内容可能并不总是白色的。

此外，我不能在同一个元素上使用 mask-image，因为 "inverted border-radius" 实际上会超出它的边界框，所以我实际上会添加更多区域而不是减去（加上支持真的很低）。

我想尽可能避免使用 SVG。

body {
  position: relative;
  overflow: hidden;
  height: 100vh;
  margin: 0;
}

.phone {
  width: 420px;
  height: 800px;
  padding: 12px 12px 24px;
  position: absolute;
  top: 32px;
  left: 50%;
  transform: translate(-50%, 0);
  background: #000;
  box-shadow: 0 8px 32px 0 rgba(0, 0, 0, .125);
  border-radius: 16px;
}

.screen {
  height: 100%;
  overflow: hidden;
  position: relative;
  background: #FFF;
  border-radius: 8px;
}

.viewport {
  height: 100%;
  position: relative;
  overflow-x: hidden;
  overflow-y: scroll;
}

.notch {
  top: 12px;
  left: 50%;
  width: 24px;
  height: 12px;
  z-index: 10;
  position: absolute;
  transform: translate(-50%, 0);
  background: #000;
  border-bottom-left-radius: 1024px;
  border-bottom-right-radius: 1024px;
}

.camera {
  top: 0;
  left: 50%;
  width: 12px;
  border: 4px solid #33244A;
  height: 12px;
  position: absolute;
  transform: translate(-50%, -50%);
  background:  #304A58;
  border-radius: 1024px;
  box-sizing: border-box;
}

<div class="phone">
  <div class="notch">
    <div class="camera"></div>
  </div>

  <div class="screen">
    <div class="viewport"></div>
  </div>
</div>

Answer 1

有四种方法可以做到这一点，从简单到复杂：

用 radial-gradient 添加 2 个伪元素。

最简单且得到充分支持的解决方案。可能是我会用的那种。
用 mask-image 添加 2 个伪元素（与上面相同，但支持更差）。

在代码方面与预览版非常相似，但带有 really bad support（支持它的浏览器需要前缀）。
添加 2 个带有 border-radius、box-shadow 和 background: transparent 的伪元素。

需要更多的代码，但看起来更流畅一些，至少在 Chrome Version 78.0.3904.108 上是这样，所以也许对您来说值得，尽管差异很小。在任何情况下，您可以做的形状都不能像以前的选择一样复杂，特别是如果您想要使用椭圆而不是圆形，就像在另一个问题中一样：.
使用 SVG。

我认为 SVG 解决方案在这里不值得，但对于更复杂的形状或 animated/transitioning 形状，它是一个很好的替代方案。

在这里您可以查看前 3 个解决方案：

const notch = document.getElementById('notch');
const button = document.getElementById('button');
const xrayCheckbox = document.getElementById('xrayCheckbox');
const xrayLabel = document.getElementById('xrayLabel');
const label = document.getElementById('label');

const solutions = [{
  name: 'pseudoelements + radial-gradient',
  classes: 'notch notch-gradient'
}, {
  name: 'pseudoelements + box-shadow',
  classes: 'notch notch-shadow'
}, {
  name: 'pseudoelements + mask-image',
  classes: 'notch notch-mask'
}];

let currentSolutionIndex = 0;
let currentSolution = solutions[currentSolutionIndex];
let xRayEnabled = false;

button.onclick = () => {
  currentSolutionIndex = (currentSolutionIndex + 1) % solutions.length;
  currentSolution = solutions[currentSolutionIndex];
  
  updateLabels();
};

xrayCheckbox.onchange = () => {  
  xRayEnabled = xrayCheckbox.checked;
  
  updateLabels();
};

function updateLabels() {
  if (xRayEnabled) {
    notch.className = `${ currentSolution.classes }-xray`;
    label.innerText = `${ currentSolution.name } (X-Ray)`;
    xrayLabel.innerText = 'Disable X-Ray';
  } else {
    notch.className = currentSolution.classes;
    label.innerText = currentSolution.name;
    xrayLabel.innerText = 'Enable X-Ray';
  }
}

body {
  position: relative;
  overflow: hidden;
  height: 100vh;
  margin: 0;
}

.phone {
  width: 420px;
  height: 800px;
  padding: 12px 12px 24px;
  position: absolute;
  top: 32px;
  left: 50%;
  transform: translate(-50%, 0);
  background: #000;
  box-shadow: 0 8px 32px 0 rgba(0, 0, 0, .5);
  border-radius: 16px;
}

.screen {
  height: 100%;
  overflow: hidden;
  position: relative;
  background: #FFF;
  border-radius: 8px;
}

.viewport {
  height: 100%;
  position: relative;
  overflow-x: hidden;
  overflow-y: scroll;
}

.notch {
  top: 12px;
  left: 50%;
  width: 24px;
  height: 12px;
  z-index: 10;
  position: absolute;
  transform: translate(-50%, 0);
  background: #000;
  border-bottom-left-radius: 1024px;
  border-bottom-right-radius: 1024px;
}

.notch::before,
.notch::after {
  top: 0;
  width: 8px;
  height: 8px;
  content: "";
  position: absolute;
}

.notch-gradient-xray,
.notch-shadow-xray,
.notch-mask-xray {
  background: red;
}

/* RADIAL GRADIENT SOLUTION */

.notch-gradient::before {
  left: -6px;
  background: radial-gradient(circle at bottom left, transparent 0, transparent 70%, black 70%, black 100%);
}

.notch-gradient::after {
  right: -6px;
  background: radial-gradient(circle at bottom right, transparent 0, transparent 70%, black 70%, black 100%);
}

.notch-gradient-xray::before {
  left: -6px;
  background: green radial-gradient(circle at bottom left, transparent 0, transparent 70%, cyan 70%, cyan 100%);
}

.notch-gradient-xray::after {
  right: -6px;
  background: green radial-gradient(circle at bottom right, transparent 0, transparent 70%, cyan 70%, cyan 100%);
}

/* BOX-SHADOW SOLUTION */

.notch-shadow::before {
  left: -6px;
  background: transparent;
  border-radius: 0 8px 0 0;
  box-shadow: 0 -4px 0 0 #000;
}

.notch-shadow::after {
  right: -6px;
  background: transparent;
  border-radius: 8px 0 0 0;
  box-shadow: 0 -4px 0 0 #000;
}

.notch-shadow-xray::before {
  left: -6px;
  background: green;
  border-radius: 0 8px 0 0;
  box-shadow: 0 -4px 0 0 cyan;
}

.notch-shadow-xray::after {
  right: -6px;
  background: green;
  border-radius: 8px 0 0 0;
  box-shadow: 0 -4px 0 0 cyan;
}

/* MASK SOLUTION */

.notch-mask::before {
  left: -6px;
  background: #000;
  -webkit-mask-image: radial-gradient(circle at bottom left, transparent 0, transparent 70%, black 70%, black 100%);
}

.notch-mask::after {
  right: -6px;
  background: #000;
  -webkit-mask-image: radial-gradient(circle at bottom right, transparent 0, transparent 70%, black 70%, black 100%);
}

.notch-mask-xray::before {
  left: -6px;
  background: cyan;
  -webkit-mask-image: radial-gradient(circle at bottom left, transparent 0, transparent 70%, black 70%, black 100%);
}

.notch-mask-xray::after {
  right: -6px;
  background: cyan;
  -webkit-mask-image: radial-gradient(circle at bottom right, transparent 0, transparent 70%, black 70%, black 100%);
}

.camera {
  top: 0;
  left: 50%;
  width: 12px;
  border: 4px solid #33244A;
  height: 12px;
  position: absolute;
  transform: translate(-50%, -50%);
  background:  #304A58;
  border-radius: 1024px;
  box-sizing: border-box;
}

#button {
  font-family: monospace;
  font-size: 16px;
  padding: 8px 16px;
  margin: 32px auto 16px;
  background: transparent;
  border: 2px solid black;
  display: block;
  border-radius: 2px;
}

#xray {
  font-family: monospace;
  font-size: 16px;
  padding: 0 16px;
  text-align: center;
  display: block;
  margin: 0 0 16px;
  display: flex;
  align-items: center;
  justify-content: center;
}

#xrayCheckbox {
  margin: 0 8px 0 0;
}

#label {
  font-family: monospace;
  font-size: 16px;
  padding: 0 16px;
  text-align: center;
}

<div class="phone">
  <div id="notch" class="notch notch-gradient">
    <div class="camera"></div>
  </div>

  <div class="screen">
    <div class="viewport">
      <button id="button">Change Solution</button>
      
      <label id="xray">
        <input id="xrayCheckbox" type="checkbox" />
        <span id="xrayLabel">Enable X-Ray</span>
      </label>
      
      <div id="label">pseudoelements + radial-gradient</div>
    </div>
  </div>
</div>

CSS "inverse border-radius" 在元素的边界框外创建移动 phone 缺口设计

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