SVGFEDiffuseLightingElement: in1 属性

<svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg">
  <defs>
    <filter id="diffuseLightingFilter">
      <feDiffuseLighting
        in="SourceGraphic"
        result="diffuseLightingResult"
        lighting-color="white"
        surfaceScale="1">
        <feDistantLight azimuth="45" elevation="55" />
      </feDiffuseLighting>
    </filter>
  </defs>
  <rect
    x="20"
    y="20"
    width="100"
    height="100"
    fill="lightblue"
    filter="url(#diffuseLightingFilter)" />
</svg>

const diffuseLighting = document.querySelector("feDiffuseLighting");

console.log(diffuseLighting.in1.baseVal); // Output: "SourceGraphic"