Example


<svg width="8cm" height="4cm" viewBox="0 0 800 400" version="1.1">
     <defs>
          <pattern id="TrianglePattern" patternUnits="userSpaceOnUse" x="0" y="0" width="100" height="100" viewBox="0 0 10 10">
               <path d="M 0 0 L 7 0 L 3.5 7 z" fill="red" stroke="blue"/>
          </pattern>
     </defs>
     <rect fill="none" stroke="blue" x="1" y="1" width="798" height="398"/>
     <ellipse fill="url(#TrianglePattern)" stroke="black" stroke-width="5" cx="400" cy="200" rx="350" ry="150"/>
</svg>
Original SVG source