transform-origin

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015 .

CSS 內的** transform-origin **屬性可以設定元素變化的原點。

嘗試一下 

transform-origin: center;

transform-origin: top left;

transform-origin: 50px 50px;

/* 3D rotation with z-axis origin */
transform-origin: bottom right 60px;

<section id="default-example">
  <div id="example-container">
    <div id="example-element">Rotate me!</div>
      alt=""
      id="crosshair"
      src="/shared-assets/images/examples/crosshair.svg"
      width="24px" />
    <div id="static-element"></div>
</section>

@keyframes rotate {
  from {
    transform: rotate(0);
    transform: rotate(30deg);
@keyframes rotate3d {
  from {
    transform: rotate3d(0);
    transform: rotate3d(1, 2, 0, 60deg);
#example-container {
  width: 160px;
  height: 160px;
  position: relative;
#example-element {
  width: 100%;
  height: 100%;
  display: flex;
  position: absolute;
  align-items: center;
  justify-content: center;
  background: #f7ebee;
  color: #000000;
  font-size: 1.2rem;
  text-transform: uppercase;
#example-element.rotate {
  animation: rotate 1s forwards;
#example-element.rotate3d {
  animation: rotate3d 1s forwards;
#crosshair {
  width: 24px;
  height: 24px;
  opacity: 0;
  position: absolute;
#static-element {
  width: 100%;
  height: 100%;
  position: absolute;
  border: dotted 3px #ff1100;

"use strict";
window.addEventListener("load", () => {
  function update() {
    const selected = document.querySelector(".selected");
    /* Restart the animation
           https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Animations/Tips */
    el.className = "";
    window.requestAnimationFrame(() => {
      window.requestAnimationFrame(() => {
        el.className =
          el.style.transformOrigin.split(" ")[2] === "60px"
            ? "rotate3d"
            : "rotate";
    const transformOrigin = getComputedStyle(el).transformOrigin;
    const pos = transformOrigin.split(/\s+/);
    crosshair.style.left = `calc(${pos[0]} - 12px)`;
    crosshair.style.top = `calc(${pos[1]} - 12px)`;
  const crosshair = document.getElementById("crosshair");
  const el = document.getElementById("example-element");
  const observer = new MutationObserver(() => {
    update();
  observer.observe(el, {
    attributes: true,
    attributeFilter: ["style"],
  update();
  crosshair.style.opacity = "1";

變化原點指的是應用變化的點。舉例來說， rotate()函數的原點為旋轉中心。 (This property is applied by first translating the element by the negated value of the property, then applying the element's transform, then translating by the property value.)

語法

css 
/* One-value syntax */
transform-origin: 2px;
transform-origin: bottom;
/* x-offset | y-offset */
transform-origin: 3cm 2px;
/* x-offset-keyword | y-offset */
transform-origin: left 2px;
/* x-offset-keyword | y-offset-keyword */
transform-origin: right top;
/* y-offset-keyword | x-offset-keyword */
transform-origin: top right;
/* x-offset | y-offset | z-offset */
transform-origin: 2px 30% 10px;
/* x-offset-keyword | y-offset | z-offset */
transform-origin: left 5px -3px;
/* x-offset-keyword | y-offset-keyword | z-offset */
transform-origin: right bottom 2cm;
/* y-offset-keyword | x-offset-keyword | z-offset */
transform-origin: bottom right 2cm;
/* Global values */
transform-origin: inherit;
transform-origin: initial;
transform-origin: unset;

transform-origin 屬性可以使用多次，每一次都代表著一個偏移量。若未設定偏移量，則重置為其對應的初始值。


If two or more values are defined and either no value is a keyword, or the only used keyword is center, then the first value represents the horizontal offset and the second represents the vertical offset.


One-value syntax:


  • The value must be a <length>, a <percentage>, or one of the keywords left, center, right, top or bottom.
    • 

    Two-value syntax:
    

  • One value must be a <length>, a <percentage>, or one of the keywords left, center, and right.
    • 

  • The other value must be a <length>, a <percentage>, or one of the keywords top, center, and bottom.
    • 

    Three-value syntax:
    

  • The first two values are the same as for the two-value syntax.
    • 

  • The third value must be a <length>. It always represents the Z offset.
    •

    Values

    x-offset

    Is a <length> or a <percentage> describing how far from the left edge of the box the origin of the transform is set.

    offset-keyword

    Is one of the left , right , top , bottom , or center keyword describing the corresponding offset.

    y-offset

    Is a <length> or a <percentage> describing how far from the top edge of the box the origin of the transform is set.

    x-offset-keyword

    Is one of the left , right , or center keyword describing how far from the left edge of the box the origin of the transform is set.

    y-offset-keyword

    Is one of the top , bottom , or center keyword describing how far from the top edge of the box the origin of the transform is set.

    z-offset

    Is a <length> (and never a <percentage> which would make the statement invalid) describing how far from the user eye the z=0 origin is set.

    The keywords are convenience shorthands and match the following <percentage> values:

    Keyword Value

    Formal syntax 

    transform-origin = 
      [ left | center | right | top | bottom | <length-percentage> ]  |
      [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ] <length>?  |
      [ [ center | left | right ] && [ center | top | bottom ] ] <length>?  

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

    Examples