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@mbostock
Last active February 26, 2019 22:35
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Spline Editor
redirect: https://observablehq.com/@mbostock/d3-spline-editor

Click to add new points. Hit the DELETE key to remove the selected point. Use the dropdown menu to change the interpolation mode.

<!DOCTYPE html>
<meta charset="utf-8">
<title>Spline Editor</title>
<style>
body {
font: 13px sans-serif;
position: relative;
width: 960px;
height: 500px;
}
form {
position: absolute;
bottom: 10px;
left: 10px;
}
rect {
fill: none;
pointer-events: all;
}
circle,
.line {
fill: none;
stroke: steelblue;
stroke-width: 1.5px;
}
circle {
fill: #fff;
fill-opacity: .2;
cursor: move;
}
.selected {
fill: #ff7f0e;
stroke: #ff7f0e;
}
</style>
<form>
<label for="interpolate">Interpolate:</label>
<select id="interpolate"></select><br>
</form>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500;
var points = d3.range(1, 5).map(function(i) {
return [i * width / 5, 50 + Math.random() * (height - 100)];
});
var dragged = null,
selected = points[0];
var line = d3.svg.line();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.attr("tabindex", 1);
svg.append("rect")
.attr("width", width)
.attr("height", height)
.on("mousedown", mousedown);
svg.append("path")
.datum(points)
.attr("class", "line")
.call(redraw);
d3.select(window)
.on("mousemove", mousemove)
.on("mouseup", mouseup)
.on("keydown", keydown);
d3.select("#interpolate")
.on("change", change)
.selectAll("option")
.data([
"linear",
"step-before",
"step-after",
"basis",
"basis-open",
"basis-closed",
"cardinal",
"cardinal-open",
"cardinal-closed",
"monotone"
])
.enter().append("option")
.attr("value", function(d) { return d; })
.text(function(d) { return d; });
svg.node().focus();
function redraw() {
svg.select("path").attr("d", line);
var circle = svg.selectAll("circle")
.data(points, function(d) { return d; });
circle.enter().append("circle")
.attr("r", 1e-6)
.on("mousedown", function(d) { selected = dragged = d; redraw(); })
.transition()
.duration(750)
.ease("elastic")
.attr("r", 6.5);
circle
.classed("selected", function(d) { return d === selected; })
.attr("cx", function(d) { return d[0]; })
.attr("cy", function(d) { return d[1]; });
circle.exit().remove();
if (d3.event) {
d3.event.preventDefault();
d3.event.stopPropagation();
}
}
function change() {
line.interpolate(this.value);
redraw();
}
function mousedown() {
points.push(selected = dragged = d3.mouse(svg.node()));
redraw();
}
function mousemove() {
if (!dragged) return;
var m = d3.mouse(svg.node());
dragged[0] = Math.max(0, Math.min(width, m[0]));
dragged[1] = Math.max(0, Math.min(height, m[1]));
redraw();
}
function mouseup() {
if (!dragged) return;
mousemove();
dragged = null;
}
function keydown() {
if (!selected) return;
switch (d3.event.keyCode) {
case 8: // backspace
case 46: { // delete
var i = points.indexOf(selected);
points.splice(i, 1);
selected = points.length ? points[i > 0 ? i - 1 : 0] : null;
redraw();
break;
}
}
}
</script>
@s2t2
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s2t2 commented Jun 17, 2015

@mbostock I added the "bundle" interpolation method in this fork. I would submit a PR but gist doesn't support them, so instead I'm just commenting in case you wish to update this gist.

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