javascript - Rendering order in d3.js

Question

Here is the code:

//Circle Data Set
var circleData = [
    { "cx": 20, "cy": 20, "radius": 20, "color" : "green" },
    { "cx": 70, "cy": 70, "radius": 20, "color" : "purple" }];

//Create the SVG Viewport
var svgContainer = d3.select("#svgContainer")
    .attr("width",200)
    .attr("height",200);

//Add the SVG Text Element to the svgContainer
var text = svgContainer.selectAll("text")
    .data(circleData)
    .enter()
    .append("text");

var circles = svgContainer.selectAll("circle")
    .data(circleData)
    .enter()
    .append("circle")
    .attr("cx", function(d) {return d.cx})
    .attr("cy", function(d) {return d.cy})
    .attr("r", function(d) {return d.radius})
    .attr("fill", function(d) {return d.color})

//Add SVG Text Element Attributes
var textLabels = text
    .attr("x", function(d) { return d.cx; })
    .attr("y", function(d) { return d.cy; })
    .text( function (d) { return "( " + d.cx + ", " + d.cy +" )"; })
    .attr("font-family", "sans-serif")
    .attr("font-size", "20px")
    .attr("fill", "red");

http://jsfiddle.net/kindlychung/jrsxLfpg/1/

It seems d3 always renders text first, which means the text is partly hidden behind the circles:

<svg id="svgContainer" width="200" height="200">
<text x="20" y="20" font-family="sans-serif" font-size="20px" fill="red">( 20, 20 )</text>
<text x="70" y="70" font-family="sans-serif" font-size="20px" fill="red">( 70, 70 )</text>
<circle cx="20" cy="20" r="20" fill="green"></circle>
<circle cx="70" cy="70" r="20" fill="purple"></circle></svg>

How can I adjust this?

Answer 1

You just need to draw your text nodes after drawing your circles.

//Circle Data Set
var circleData = [
    { "cx": 20, "cy": 20, "radius": 20, "color" : "green" },
    { "cx": 70, "cy": 70, "radius": 20, "color" : "purple" }];

//Create the SVG Viewport
var svgContainer = d3.select("#svgContainer")
    .attr("width",200)
    .attr("height",200);

// draw your circles and any other graphic elements first!
var circles = svgContainer.selectAll("circle")
    .data(circleData)
    .enter()
    .append("circle")
    .attr("cx", function(d) {return d.cx})
    .attr("cy", function(d) {return d.cy})
    .attr("r", function(d) {return d.radius})
    .attr("fill", function(d) {return d.color})

// These will now be appended AFTER the circles
// When you use `append` it will add text nodes to end
// of svgContainer
var text = svgContainer.selectAll("text")
    .data(circleData)
    .enter()
    .append("text");

// Here you are editing the pre-existing `text` nodes that you added above.
// Note that you don't use `append` here.
// Instead, you are modifying the d3 selection stored in `text`
var textLabels = text
    .attr("x", function(d) { return d.cx; })
    .attr("y", function(d) { return d.cy; })
    .text( function (d) { return "( " + d.cx + ", " + d.cy +" )"; })
    .attr("font-family", "sans-serif")
    .attr("font-size", "20px")
    .attr("fill", "red");

Here is an edited version of your code: http://jsfiddle.net/jrsxLfpg/2/