How to use an arrow marker on an SVG elemen

问题:

I need to create an arrow in d3.js, but all I find are examples with diagrams of nodes. What I need is to simply make an arrow that goes from point A to point B.

I tried implementing part of the code in the following example: http://bl.ocks.org/1153292

This specific part:

svg.append("svg:defs").selectAll("marker")
    .data(["suit", "licensing", "resolved"])
  .enter().append("svg:marker")
    .attr("id", String)
    .attr("viewBox", "0 -5 10 10")
    .attr("refX", 15)
    .attr("refY", -1.5)
    .attr("markerWidth", 6)
    .attr("markerHeight", 6)
    .attr("orient", "auto")
  .append("svg:path")
    .attr("d", "M0,-5L10,0L0,5");

But as I mentioned earlier, I do not find the way to create the arrow with a svg:line greatly appreciate the help you can give me.

回答1:

If you meant 'how do I use an arrow marker on a <line> element?' then here's how you do that:

<line x1="100" y1="230" x2="300" y2="230" 
 marker-end="url(#yourMarkerId)" stroke="black" stroke-width="10"/>

Here's a full example. And note that marker-end is a css property, so you can also put that part in a stylesheet if you want.

If you meant you want to draw your marker with lines, then just add whatever lines you need as a child of the marker element (and make sure to use the coordinate system defined by the marker's viewBox attribute).