ant-design/style/mixins/compatibility.less

// Compatibility for browsers.

// rotate for ie8 and blow
.ie-rotate(@rotation) {
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
}

// rotate for ie8 and blow
// degrees unit
.ie-rotate-via-degrees(@degrees) {
  /* IE6-IE8 */
  @radians: ~`parseInt("@{degrees}") * Math.PI * 2 / 360`;
  @costheta: ~`Math.cos("@{radians}")`;
  @sintheta: ~`Math.sin("@{radians}")`;
  @negsintheta: ~`"@{sintheta}" * -1`;
  filter: ~"progid:DXImageTransform.Microsoft.Matrix(sizingMethod='auto expand', M11=@{costheta}, M12=@{negsintheta}, M21=@{sintheta}, M22=@{costheta})";
  zoom: 1;

  :root & {
    filter: none;
  }
}

// support rotate for all browsers
.cross-rotate(@degrees) {
  .rotate(@degrees);
  .ie-rotate-via-degrees(@degrees);
}

// for iconfont font size
// fix chrome 12px bug, support ie
.iconfont-size-under-12px(@size, @rotate: 0deg) {
  display: inline-block;
  @font-scale: unit(@size/@font-size-base);
  font-size: @font-scale;
  font-size: ~"@{size} \9"; // ie8-9
  transform: scale(@font-scale) rotate(@rotate);
  .ie-rotate-via-degrees(@rotate);
  :root & {
    font-size: @font-size-base; // reset ie9 and above
  }
}