flutter_svg/example/assets/simple/use_opacity_grid.svg

<svg viewBox="0 0 80 20" xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink">
  <!-- Our symbol in its own coordinate system -->
  <!-- note: viewBox not supported yet -->
  <symbol id="myDot" width="10" height="10" viewBox="0 0 2 2">
    <circle cx="1" cy="1" r="1" />
  </symbol>

   <!-- A grid to materialized our symbol positionning -->
  <path d="M0,10 h80 M10,0 v20 M25,0 v20 M40,0 v20 M55,0 v20 M70,0 v20" fill="none" stroke="pink" />

  <!-- All instances of our symbol -->
  <use xlink:href="#myDot" x="5"  y="5" style="opacity:1.0" />
  <use xlink:href="#myDot" x="20" y="5" style="opacity:0.8" />
  <use xlink:href="#myDot" x="35" y="5" style="opacity:0.6" />
  <use xlink:href="#myDot" x="50" y="5" style="opacity:0.4" />
  <use xlink:href="#myDot" x="65" y="5" style="opacity:0.2" />
</svg>