如何使用Javascript添加SVG的标记结束才能正确对齐?

时间:2016-04-05 15:31:29

标签: javascript svg

如果我将SVG写入html文档,我已经获得了正确对齐的SVG代码,然后查看文档:

<html>
<head>
  <script type="text/javascript" src="jquery-1.12.2.min.js"></script>
  <script type="text/javascript" src="script.js"></script>
  <link rel="stylesheet" href="style.css" />
</head>
<body>

  <div id="stage">
  <svg width="100" height="100">
  <defs>
    <marker id="arrow-1" markerWidth="4" markerHeight="3" markerUnits="strokeWidth" refx="1" refy="5" viewBox="0 0 10 10" orient="auto">
      <path d="M 0 0 L 10 5 L 0 10 z" fill="context-stroke"></path>
    </marker>
  </defs>
  <path d="M 0,10 L 90,10" stroke-width="2" stroke="red" marker-end="url(#arrow-1)"></path>
  </svg>
  </div>

</body>
</html>

这很好用,并呈现: Working arrow

请注意,在工作输出中,marker-end与笔划正确对齐

然后我尝试使用JavaScript生成完全相同的SVG结构:

  var arrowID = 0;
  function drawArrow() {
    var ns = 'http://www.w3.org/2000/svg';
    var svg = document.createElementNS(ns, 'svg');
    svg.setAttribute("width",100);
    svg.setAttribute("height",100);

    var defs = document.createElementNS(ns, "defs");
    var marker = document.createElementNS(ns, "marker");
    var id = "arrow-" + arrowID++;
    marker.setAttribute("id", id);
    marker.setAttribute("markerWidth", 4);
    marker.setAttribute("markerHeight", 3);
    marker.setAttribute("markerUnits", "strokeWidth");
    marker.setAttribute("refx", 1);
    marker.setAttribute("refy", 5);
    marker.setAttribute("viewBox", "0 0 10 10");
    marker.setAttribute("orient", "auto");

    var path = document.createElementNS(ns, "path");
    path.setAttribute("d","M 0 0 L 10 5 L 0 10 z");
    path.setAttribute("fill","context-stroke");

    marker.appendChild(path);
    defs.appendChild(marker);
    svg.appendChild(defs);

    var instance = document.createElementNS(ns, "path");
    // todo set actual start and end
    instance.setAttribute("d", "M 0,10 L 90,10");
    instance.setAttribute("stroke-width", "2");
    instance.setAttribute("stroke", "red");
    instance.setAttribute("marker-end", "url(#"+id+")");

    svg.appendChild(instance);

    document.getElementById("stage").appendChild(svg);


  }

即使页面上的SVG是正确的(与上面的相同):

screenshot of chrome dev tools html structure

渲染的SVG错误,看起来像这样: Not aligned arrow

请注意,在失败的输出中,标记端未与笔划正确对齐。

硬编码HTML呈现中存在的JavaScript代码缺少什么?为什么JavaScript会渲染错误对齐的标记结束?

这里的一切都在小提琴中:fiddle

1 个答案:

答案 0 :(得分:3)

SVG区分大小写。正确的属性名称是refX和refY。