将具有混合（固定和百分比）值的 CSS 剪辑路径转换为 ​​SVG 剪辑路径

Question

我有一张使用clip-path 的带有剪角渐变的卡片图片：

.card {
  width: 200px;
  height: 200px;
  background: linear-gradient(to bottom, blue, green);
  clip-path: polygon(20px 0, 100% 0, 100% 100%, 0 100%, 0 20px);
}

<div class="card"></div>

无论卡片大小如何，剪裁角都必须具有固定大小，因此我使用像素来剪裁角。

但是clip-path 目前还没有最好的浏览器支持，所以我尝试将这个 HTML 和 CSS 转换为 SVG。

.container {
  width: 200px;
  height: 200px;
}

<div class="container">
  <svg viewBox="0 0 100 100" clip-path="url(#myClip)">
    <defs>
      <linearGradient id="grad1" x1="0%" y1="0%" x2="0%" y2="100%">
        <stop offset="0%" style="stop-color:rgb(0,0,255);stop-opacity:1" />
        <stop offset="100%" style="stop-color:rgb(0,255,0);stop-opacity:1" />
      </linearGradient>
    </defs>
  
    <polygon points="20,0 100,0 100,100 0,100 0,20" fill="url(#grad1)" />
 </svg>
</div>

但问题是，无论卡片大小如何，我都无法使这个剪裁角具有固定大小。

Answer 1

为了保持它的固定大小，您不能在 SVG 上使用 viewBox。只需剪下您需要的角落，让其他角落延伸很长一段距离，以便覆盖您可能需要的任何尺寸。在下面的示例中，我已将剪辑路径扩展到 (10000,10000)。

这里我们将渐变应用到 100% x 100% <rect>。这样渐变总是可以缩放以适应屏幕。然后我们将剪贴路径应用于矩形以获得缺口。

html, body {
  height: 100%;
}

.container {
  width: 50%;
  height: 50%;
}

<div class="container">
  <svg width="100%" height="100%">
    <defs>
      <linearGradient id="grad1" x1="0%" y1="0%" x2="0%" y2="100%">
        <stop offset="0%" style="stop-color:rgb(0,0,255);stop-opacity:1" />
        <stop offset="100%" style="stop-color:rgb(0,255,0);stop-opacity:1" />
      </linearGradient>
      <clipPath id="clip1">
        <polygon points="20,0 10000,0 10000,10000 0,10000 0,20"/>
      </clipPath>
    </defs>
  
    <rect width="100%" height="100%" fill="url(#grad1)" clip-path="url(#clip1)"/>
 </svg>
</div>

Answer 2

如果渐变始终具有底部或顶部方向，您可以考虑使用倾斜变换和伪元素的技巧，如下所示：

.card {
  width: 200px;
  height: 200px;
  padding-top: 20px;
  background-image: linear-gradient(to bottom, blue,red,yellow,green); 
  background-clip:content-box;
  background-size:100% 200px; /*same as height*/
  position: relative;
  z-index:0;
  overflow:hidden;
  box-sizing: border-box;
  display:inline-block;
}

.card:before {
  content: "";
  position: absolute;
  z-index:-1;
  top: 0;
  padding: inherit;
  left: 0;
  right: 0;
  background-image: inherit;
  background-size:inherit;
  transform: skewX(-45deg);
  transform-origin: left bottom;
}

body {
  background:pink;
}

<div class="card"></div>
<div class="card" style="background-image:linear-gradient(to top,white,purple,green ,red 90%, blue"></div>

对于任何渐变或任何图像，您都可以添加额外的元素来纠正倾斜：

.card {
  width: 200px;
  height: 200px;
  padding-top: 20px;
  background-image: linear-gradient(to bottom, blue,red,yellow,green); 
  background-clip:content-box;
  background-size:auto 200px; /*same as height*/
  position: relative;
  z-index:0;
  overflow:hidden;
  box-sizing: border-box;
  display:inline-block;
}
.image {
  background-size:cover; /*less restriction when it comes to image*/
}


.card span,
.card span::before {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  background-image: inherit;
  background-size:inherit;
  transform-origin: left bottom;
}

.card span {
  z-index:-1;
  padding: inherit;
  transform: skewX(-45deg);
  overflow:hidden;
}
.card span:before {
   content:"";
   bottom:0;
   transform: skewX(45deg);
}

body {
  background:pink;
}

<div class="card">
<span></span>
</div>
<div class="card" style="background-image:linear-gradient(60deg,white,purple,green ,red 90%, blue)">
<span></span>
</div>

<div class="card image" style="background-image:url(https://picsum.photos/400/400?image=0)">
<span></span>
</div>

<div class="card image" style="background-image:url(https://picsum.photos/600/600?image=15)">
<span></span>
</div>

Answer 3

在 Stack Overflow in Russian 的帮助下使用 SVG mask 我的解决方案是这样的

.container {
  width: 200px;
  height: 200px;
}

svg {
  width: 100%;
  height: 100%;
}

<div class="container">
  <svg>
    <defs>
      <mask id="triangle-clip">
        <rect x="0" y="0" width="100%" height="100%" fill="#fff" />
        <path d="M0,20 v-20 h20 z" fill="#000" />
      </mask>

    <linearGradient id="grad1" x1="0%" y1="0%" x2="0%" y2="100%">
      <stop offset="0%" style="stop-color:rgb(0,0,255);stop-opacity:1" />
      <stop offset="100%" style="stop-color:rgb(0,255,0);stop-opacity:1" />
    </linearGradient>
  </defs>
  <rect width="100%" height="100%" fill="url(#grad1)" mask="url(#triangle-clip)" />
</svg>
</div>