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I would like to know if there is an alternative to applying the "stroke-dasharray" to a path. What I'm trying to do is add a dashed line to a certain range in the path. The thing is that the line is not straight. And I want to avoid creating two lines using the same data within different range. Does anyone have an idea?
458
I linked this question which provides a pretty good overview of how stroke-dasharray works, but the interesting part of this question becomes, how can I dash over a specific section of the line? With that in mind, say we have a line from 0 to 10 and we want to dash it from 2.5 to 7:
<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
font: 10px sans-serif;
}
.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}
.x.axis path {
display: none;
}
.line {
fill: none;
stroke: steelblue;
stroke-width: 1.5px;
}
</style>
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
var margin = {
top: 20,
right: 20,
bottom: 30,
left: 50
},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var data = d3.range(11).map(function(d, i) {
return {
x: i,
y: Math.random() * 100
};
});
var x = d3.scaleLinear()
.range([0, width])
.domain([0, 10]);
var y = d3.scaleLinear()
.range([height, 0])
.domain([0, 100]);
var xAxis = d3.axisBottom()
.scale(x);
var yAxis = d3.axisLeft()
.scale(y);
var line = d3.line()
.x(function(d) {
return x(d.x);
})
.y(function(d) {
return y(d.y);
})
.curve(d3.curveBasis);
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
svg.append("g")
.attr("class", "y axis")
.call(yAxis)
var p = svg.append("path")
.datum(data)
.attr("class", "line")
.attr("d", line);
// draw dashed from 2.7 to 7 in the X domain
var dashBetweenX = [2.5, 7]
path = p.node(),
totalLen = path.getTotalLength();
// find the corresponding line lengths
var dashBetweenL = dashBetweenX.map(function(d,i){
var beginning = 0,
end = totalLen,
target = null,
d = x(d);
// find the line lengths the correspond to our X values
// stolen from @duopixel from http://bl.ocks.org/duopixel/3824661
while (true){
target = Math.floor((beginning + end) / 2);
pos = path.getPointAtLength(target);
if ((target === end || target === beginning) && pos.x !== d) {
break;
}
if (pos.x > d) end = target;
else if (pos.x < d) beginning = target;
else break; //position found
}
return target;
})
// draw the dashes
var sd = dashBetweenL[0],
dp = dashBetweenL[0],
count = 0;
while (dp < dashBetweenL[1]){
dp += 2;
sd += ", 2";
count++;
}
// per answer below needs odd number of dash array
if (count % 2 == 0)
sd += ", 2";
sd += ", " + (totalLen - dashBetweenL[1]);
p.attr("stroke-dasharray", sd);
</script>
</body>
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