将两个填充样式放在重叠的< rect> 对象，并使用时钟图标作为应用于< rect> 对象的掩码对象。然后，您可以通过动画最上层< rect> 的不透明度来对明显填充样式进行动画处理。请记住对面具对象应用白色填充（白色=不透明，黑色=透明）。

Put the two fill styles on overlapping <rect> objects, and use the clock icon as a mask object applied to both <rect> objects. You can then animate the apparent fill style by animating the opacity of the uppermost <rect>. Remember to apply a white fill to the mask object (white=opaque, black=transparent).

如果以下代码段无效，尝试此jsfiddle链接。

If the following snippet doesn't work, try this jsfiddle link.

#clock-gradient {
  opacity: 0.0;
  display: inline-block;
  -webkit-transition: opacity .4s ease;
  -moz-transition: opacity .4s ease;
  -o-transition: opacity .4s ease;
  transition: opacity .4s ease;
}
#clock-gradient:hover {
  opacity: 1.0;
}

<svg width="96px" height="96px" viewBox="0 0 512 512" xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
    <linearGradient id="gradient" gradientUnits="userSpaceOnUse" fy="90%">
      <stop offset="0" style="stop-color:#1EBEE0" />
      <stop offset="1" style="stop-color:#952491" />
    </linearGradient>
    <mask id="clock-icon-mask" maskUnits="userSpaceOnUse" x="0" y="0" width="512" height="512">
      <path d="M256,50C142.229,50,50,142.229,50,256c0,113.77,92.229,206,206,206c113.77,0,206-92.23,206-206C462,142.229,369.77,50,256,50z M256,417c-88.977,0-161-72.008-161-161c0-88.979,72.008-161,161-161c88.977,0,161,72.007,161,161C417,344.977,344.992,417,256,417z M382.816,265.785c1.711,0.297,2.961,1.781,2.961,3.518v0.093c0,1.72-1.223,3.188-2.914,3.505c-37.093,6.938-124.97,21.35-134.613,21.35c-13.808,0-25-11.192-25-25c0-9.832,14.79-104.675,21.618-143.081c0.274-1.542,1.615-2.669,3.181-2.669h0.008c1.709,0,3.164,1.243,3.431,2.932l18.933,119.904L382.816,265.785z" fill="white" />
    </mask>
  </defs>
  <g mask="url(#clock-icon-mask)">
    <rect x="0" y="0" width="512" height="512" fill="blue" />
    <rect id="clock-gradient" x="0" y="0" width="512" height="512" fill="url(#gradient)" />
  </g>
</svg>