====== svg箭头 ======

这个用于svg图形线条，带箭头


<code xml>

<svg width="100%" height="100%" version="1.1" xmlns="http://www.w3.org/2000/svg">

<defs>
<marker id='markerArrow' markerWidth='20' markerHeight='20' refX='0' refY='3' orient='auto'>
<path d='M0,3 L0,6 L9,3 L0,0' style='fill:red' />
</marker>

</defs>


<line x1='10' y1='10' x2='100' y2='50' stroke='red' stroke-width='2' marker-start='url(#markerArrow)' marker-mid='url(#markerArrow)' marker-end='url(#markerArrow)'></line>
<line x1='100' y1='100' x2='200' y2='150' stroke='red' stroke-width='2' marker-end='url(#markerArrow)'></line>


<path d='M50,250 c15,-75 30,30 100,0 s50,-50 150,50'
stroke='brown' stroke-width='5' fill='none' marker-start='url(#markerArrow)' marker-mid='url(#markerArrow)' marker-end='url(#markerArrow)'/>

</svg>

</code>



====== SVG文档 ======
https://www.w3.org/TR/SVG11/