<svg xmlns="http://www.w3.org/2000/svg">
<pattern width="100%" height="100%" id="pattern" viewBox="0 0 100 100">
<rect width="100" height="100" fill="gray"/>
</pattern>
<mask id="mask">
<circle fill="url(#pattern)" cx="100" cy="100" r="100"/>
</mask>
<rect width="200" height="200" mask="url(#mask)" fill="url(#pattern)"/>
</svg>