Gauge D3.js display value at the top of the needle
I'm kinda new to D3.js, and I managed to create a gauge with what I found on the Internet. But I couldn't find any gauge showing the current value at the top of the needle. Something like this : what I want
Obviously I'd like the value to follow the needle. I tried to add "text" attribute to the needle itself, but it didn't work.
Here's a codepen link : http://codepen.io/kazu_codepen/pen/wGmGjv?editors=1010
Here's my js code :
// data which need to be fetched
var name = "azerty";
var value = 17;
var gaugeMaxValue = 100;
// data to calculate
var percentValue = value / gaugeMaxValue;
////////////////////////
var needleClient;
(function(){
var barWidth, chart, chartInset, degToRad, repaintGauge,
height, margin, numSections, padRad, percToDeg, percToRad,
percent, radius, sectionIndx, svg, totalPercent, width;
percent = percentValue;
numSections = 1;
sectionPerc = 1 / numSections / 2;
padRad = 0.025;
chartInset = 10;
// Orientation of gauge:
totalPercent = .75;
el = d3.select('.chart-gauge');
margin = {
top: 20,
right: 20,
bottom: 30,
left: 20
};
width = el[0][0].offsetWidth - margin.left - margin.right;
height = width;
radius = Math.min(width, height) / 2;
barWidth = 40 * width / 300;
//Utility methods
percToDeg = function(perc) {
return perc * 360;
};
percToRad = function(perc) {
return degToRad(percToDeg(perc));
};
degToRad = function(deg) {
return deg * Math.PI / 180;
};
// Create SVG element
svg = el.append('svg').attr('width', width + margin.left + margin.right).attr('height', height + margin.top + margin.bottom);
// Add layer for the panel
chart = svg.append('g').attr('transform', "translate(" + ((width + margin.left) / 2) + ", " + ((height + margin.top) / 2) + ")");
chart.append('path').attr('class', "arc chart-first");
chart.append('path').attr('class', "arc chart-second");
chart.append('path').attr('class', "arc chart-third");
arc3 = d3.svg.arc().outerRadius(radius - chartInset).innerRadius(radius - chartInset - barWidth)
arc2 = d3.svg.arc().outerRadius(radius - chartInset).innerRadius(radius - chartInset - barWidth)
arc1 = d3.svg.arc().outerRadius(radius - chartInset).innerRadius(radius - chartInset - barWidth)
repaintGauge = function ()
{
perc = 0.5;
var next_start = totalPercent;
arcStartRad = percToRad(next_start);
arcEndRad = arcStartRad + percToRad(perc / 3);
next_start += perc / 3;
arc1.startAngle(arcStartRad).endAngle(arcEndRad);
arcStartRad = percToRad(next_start);
arcEndRad = arcStartRad + percToRad(perc / 3);
next_start += perc / 3;
arc2.startAngle(arcStartRad + padRad).endAngle(arcEndRad);
arcStartRad = percToRad(next_start);
arcEndRad = arcStartRad + percToRad(perc / 3);
arc3.startAngle(arcStartRad + padRad).endAngle(arcEndRad);
chart.select(".chart-first").attr('d', arc1);
chart.select(".chart-second").attr('d', arc2);
chart.select(".chart-third").attr('d', arc3);
}
/////////
var dataset = [{metric:name, value: value}]
var texts = svg.selectAll("text")
.data(dataset)
.enter();
texts.append("text")
.text(function(){
return dataset[0].metric;
})
.attr('id', "Name")
.attr('transform', "translate(" + ((width + margin.left) / 6) + ", " + ((height + margin.top) / 1.5) + ")")
.attr("font-size",25)
.style("fill", "#000000");
texts.append("text")
.text(function(){
return dataset[0].value;
})
.attr('id', "Value")
.attr('transform', "translate(" + ((width + margin.left) / 1.4) + ", " + ((height + margin.top) / 1.5) + ")")
.attr("font-size",25)
.style("fill", "#000000");
texts.append("text")
.text(function(){
return 0;
})
.attr('id', 'scale0')
.attr('transform', "translate(" + ((width + margin.left) / 100 ) + ", " + ((height + margin.top) / 2) + ")")
.attr("font-size", 15)
.style("fill", "#000000");
texts.append("text")
.text(function(){
return gaugeMaxValue/2;
})
.attr('id', 'scale10')
.attr('transform', "translate(" + ((width + margin.left) / 2.15 ) + ", " + ((height + margin.top) / 30) + ")")
.attr("font-size", 15)
.style("fill", "#000000");
texts.append("text")
.text(function(){
return gaugeMaxValue;
})
.attr('id', 'scale20')
.attr('transform', "translate(" + ((width + margin.left) / 1.03 ) + ", " + ((height + margin.top) / 2) + ")")
.attr("font-size", 15)
.style("fill", "#000000");
var Needle = (function() {
//Helper function that returns the `d` value for moving the needle
var recalcPointerPos = function(perc) {
var centerX, centerY, leftX, leftY, rightX, rightY, thetaRad, topX, topY;
thetaRad = percToRad(perc / 2);
centerX = 0;
centerY = 0;
topX = centerX - this.len * Math.cos(thetaRad);
topY = centerY - this.len * Math.sin(thetaRad);
leftX = centerX - this.radius * Math.cos(thetaRad - Math.PI / 2);
leftY = centerY - this.radius * Math.sin(thetaRad - Math.PI / 2);
rightX = centerX - this.radius * Math.cos(thetaRad + Math.PI / 2);
rightY = centerY - this.radius * Math.sin(thetaRad + Math.PI / 2);
return "M " + leftX + " " + leftY + " L " + topX + " " + topY + " L " + rightX + " " + rightY;
};
function Needle(el) {
this.el = el;
this.len = width / 2.5;
this.radius = this.len / 8;
}
Needle.prototype.render = function() {
this.el.append('circle').attr('class', 'needle-center').attr('cx', 0).attr('cy', 0).attr('r', this.radius);
///////
/**
*
* I tried to add text here
*
*/
///////
return this.el.append('path').attr('class', 'needle').attr('id', 'client-needle').attr('d', recalcPointerPos.call(this, 0));
};
Needle.prototype.moveTo = function(perc) {
var self,
oldValue = this.perc || 0;
this.perc = perc;
self = this;
// Reset pointer position
this.el.transition().delay(100).ease('quad').duration(200).select('.needle').tween('reset-progress', function() {
return function(percentOfPercent) {
var progress = (1 - percentOfPercent) * oldValue;
repaintGauge(progress);
return d3.select(this).attr('d', recalcPointerPos.call(self, progress));
};
});
this.el.transition().delay(300).ease('bounce').duration(1500).select('.needle').tween('progress', function() {
return function(percentOfPercent) {
var progress = percentOfPercent * perc;
repaintGauge(progress);
return d3.select(this).attr('d', recalcPointerPos.call(self, progress));
};
});
};
return Needle;
})();
needle = new Needle(chart);
needle.render();
needle.moveTo(percent);
})();
And here's my html code :
<!DOCTYPE html>
<html>
<head>
<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<style type="text/css" src="gauge.css">
.chart-gauge
{
width: 400px;
margin: 100px auto
}
.chart-first
{
fill: #9FBD35;
}
.chart-second
{
fill: #F2BA3A;
}
.chart-third
{
fill: #FB3033;
}
.needle, .needle-center
{
fill: #000000;
}
.text {
color: "#112864";
font-size: 16px;
}
svg {
font: 10px sans-serif;
}
</style>
</head>
<body>
<div class="chart-gauge"></div>
<script type="text/javascript" src="./gaugeClient.js"></script>
<script type="text/javascript" src="./labels.js"></script>
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
</body>
</html>
If anyone could help, I've spent few days trying unsuccessfully. Thanks.
Answer
Here's an updated codepen
Changes made:
1) As part of initialization, create element valueText
valueText = chart.append("text")
.attr('id', "Value")
.attr("font-size",16)
.attr("text-anchor","middle")
.attr("dy",".5em")
.style("fill", '#000000');
2) Also at initialization, create formatValue, to format percent
formatValue = d3.format('1%');
3) At each frame of the transition, compute the position of the text. It adds an offset of 45 units to self.len (the needle's length) to move the text outwards.
var thetaRad = percToRad(progress / 2);
var textX = - (self.len + 45) * Math.cos(thetaRad);
var textY = - (self.len + 45) * Math.sin(thetaRad);
4) Translate valueText based on the computed position and update its text from current progress
valueText.text(formatValue(progress))
.attr('transform', "translate("+textX+","+textY+")")