css - Adding an image within a circle object in d3 javascript?

Question

My goal is to add an image into an existing circle with d3. The circle will render and is interactive with mouseover method, but only when I use "fill", "color", and not something more sophisticated like .append("image").

g.append("circle")
    .attr("class", "logo")
    .attr("cx", 700)
    .attr("cy", 300)
    .attr("r", 10)
    .attr("fill", "black")       // this code works OK
    .attr("stroke", "white")     // displays small black dot
    .attr("stroke-width", 0.25)
    .on("mouseover", function(){ // when I use .style("fill", "red") here, it works 
        d3.select(this)        
            .append("svg:image")
            .attr("xlink:href", "/assets/images/logo.jpeg")
            .attr("cx", 700)
            .attr("cy", 300)
            .attr("height", 10)
            .attr("width", 10);
     });

The image doesn't show after I mouse over. Using Ruby on Rails app, where my image "logo.jpeg" is stored in the assets/images/ directory. Any help for getting my logo to show within the circle? Thanks.

Answer 1

As Lars says you need to use pattern, once you do that it becomes pretty straightforward. Here's a link to a conversation in d3 google groups about this. I've set up a fiddle here using the image of a pint from that conversation and your code above.

To set up the pattern:

    <svg id="mySvg" width="80" height="80">
      <defs id="mdef">
        <pattern id="image" x="0" y="0" height="40" width="40">
          <image x="0" y="0" width="40" height="40" xlink:href="http://www.e-pint.com/epint.jpg"></image>
        </pattern>
      </defs>
    </svg>

Then the d3 where we only change the fill:

svg.append("circle")
         .attr("class", "logo")
         .attr("cx", 225)
         .attr("cy", 225)
         .attr("r", 20)
         .style("fill", "transparent")       
         .style("stroke", "black")     
         .style("stroke-width", 0.25)
         .on("mouseover", function(){ 
               d3.select(this)
                   .style("fill", "url(#image)");
         })
          .on("mouseout", function(){ 
               d3.select(this)
                   .style("fill", "transparent");
         });