1. Web
  2. CSS
  3. offset

offset

Baseline 已广泛支持

此功能已成熟，并可在多种设备和浏览器版本上运行。自 2022 年 9 月起，所有浏览器都已支持此功能。

offset CSS 简写属性设置了沿定义路径为元素设置动画所需的所有属性。offset 属性共同帮助定义一个 offset 变换，这个变换将元素中的一个点（offset-anchor）与路径（offset-path）上的一个偏移位置（offset-position）对齐，在路径沿线的各个点（offset-distance）上，并可选择旋转元素（offset-rotate）以跟随路径的方向。

注意：规范的早期版本将此属性称为 motion。

试一试

offset: path("M 20 60 L 120 60 L 70 10 L 20 60") 0% auto 90deg;

offset: path(
    "M 20 210 L 74 210 L 118 140 \
 L 62 140 L 20 210"
  )
  20% auto;

<section class="default-example" id="default-example">
  <div class="wrapper">
    <div id="example-element"></div>
  </div>
  <button id="playback" type="button">Play</button>
</section>

#example-element {
  width: 24px;
  height: 24px;
  background: #2bc4a2;
  clip-path: polygon(0% 0%, 70% 0%, 100% 50%, 70% 100%, 0% 100%, 30% 50%);
  animation: distance 3000ms infinite normal ease-in-out;
  animation-play-state: paused;
}

#example-element.running {
  animation-play-state: running;
}

.wrapper {
  height: 220px;
  width: 200px;
  background:
    url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 150 140" width="200" height="140"><path d="M 0 60 L 100 60 L 50 10 L 0 60" fill="none" stroke="lightgrey" stroke-width="2" stroke-dasharray="4.5"/></svg>')
      no-repeat,
    url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 -140 150 230" width="200" height="230"><path d="M 0 70 L 56 70 L 98 0 L 42 0 L 0 70" fill="none" stroke="lightgrey" stroke-width="2" stroke-dasharray="4.5"/></svg>');
}

@keyframes distance {
  to {
    offset-distance: 100%;
  }
}

#playback {
  position: absolute;
  top: 0;
  left: 0;
  font-size: 1em;
}

const example = document.getElementById("example-element");
const button = document.getElementById("playback");

button.addEventListener("click", () => {
  if (example.classList.contains("running")) {
    example.classList.remove("running");
    button.textContent = "Play";
  } else {
    example.classList.add("running");
    button.textContent = "Pause";
  }
});

构成属性

此属性是以下 CSS 属性的简写：

语法

css
/* Offset position */
offset: auto;
offset: 10px 30px;
offset: none;

/* Offset path */
offset: ray(45deg closest-side);
offset: path("M 100 100 L 300 100 L 200 300 z");
offset: url("arc.svg");

/* Offset path with distance and/or rotation */
offset: url("circle.svg") 100px;
offset: url("circle.svg") 40%;
offset: url("circle.svg") 30deg;
offset: url("circle.svg") 50px 20deg;

/* Including offset anchor */
offset: ray(45deg closest-side) / 40px 20px;
offset: url("arc.svg") 2cm / 0.5cm 3cm;
offset: url("arc.svg") 30deg / 50px 100px;

/* Global values */
offset: inherit;
offset: initial;
offset: revert;
offset: revert-layer;
offset: unset;

正式定义

初始值作为简写中的每个属性
应用于可变换元素
继承性否
百分比作为简写中的每个属性
计算值作为简写中的每个属性
动画类型作为简写中的每个属性
创建层叠上下文是

正式语法

offset = 
  [ <'offset-position'>? [ <'offset-path'> [ <'offset-distance'> || <'offset-rotate'> ]? ]? ]! [ / <'offset-anchor'> ]?  

<offset-position> = 
  normal      |
  auto        |
  <position>  

<offset-path> = 
  none                          |
  <offset-path> || <coord-box>  

<offset-distance> = 
  <length-percentage>  

<offset-rotate> = 
  [ auto | reverse ]  ||
  <angle>             

<offset-anchor> = 
  auto        |
  <position>  

<position> = 
  <position-one>   |
  <position-two>   |
  <position-four>  

<offset-path> = 
  <ray()>        |
  <url>          |
  <basic-shape>  

<coord-box> = 
  <paint-box>  |
  view-box     

<length-percentage> = 
  <length>      |
  <percentage>  

<position-one> = 
  left                 |
  center               |
  right                |
  top                  |
  bottom               |
  x-start              |
  x-end                |
  y-start              |
  y-end                |
  block-start          |
  block-end            |
  inline-start         |
  inline-end           |
  <length-percentage>  

<position-two> = 
  [ left | center | right | x-start | x-end ] && [ top | center | bottom | y-start | y-end ]  |
  [ left | center | right | x-start | x-end | <length-percentage> ] [ top | center | bottom | y-start | y-end | <length-percentage> ]  |
  [ block-start | center | block-end ] && [ inline-start | center | inline-end ]  |
  [ start | center | end ]{2}                         

<position-four> = 
  [ [ left | right | x-start | x-end ] <length-percentage> ] && [ [ top | bottom | y-start | y-end ] <length-percentage> ]  |
  [ [ block-start | block-end ] <length-percentage> ] && [ [ inline-start | inline-end ] <length-percentage> ]  |
  [ [ start | end ] <length-percentage> ]{2}          

<ray()> = 
  ray( <angle>          &&
  <ray-size>?           &&
  contain?              &&
  [ at <position> ]? )  

<paint-box> = 
  <visual-box>  |
  fill-box      |
  stroke-box    

<ray-size> = 
  closest-side     |
  closest-corner   |
  farthest-side    |
  farthest-corner  |
  sides            

<visual-box> = 
  content-box  |
  padding-box  |
  border-box

示例

沿路径为元素设置动画

HTML

html
<div id="offsetElement"></div>

CSS

css
@keyframes move {
  from {
    offset-distance: 0%;
  }

  to {
    offset-distance: 100%;
  }
}

#offsetElement {
  width: 50px;
  height: 50px;
  background-color: blue;
  offset: path("M 100 100 L 300 100 L 200 300 z") auto;
  animation: move 3s linear infinite;
}

结果

规范

规范
Motion Path Module Level 1
# offset-简写

浏览器兼容性

另见

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