Skip to content

Instantly share code, notes, and snippets.

@mbostock
Forked from mbostock/.block
Last active April 28, 2022 21:44
Show Gist options
  • Save mbostock/3750558 to your computer and use it in GitHub Desktop.
Save mbostock/3750558 to your computer and use it in GitHub Desktop.
Sticky Force Layout
license: gpl-3.0

This example demonstrates how to prevent D3’s force layout from moving nodes that have been repositioned by the user. When the force layout’s drag behavior dispatches a dragstart event, the fixed property of the dragged node is set to true. This prevents the force layout from subsequently changing the position of the node (due to forces). Double-click to release a node.

Internally, the force layout uses three bits to control whether a node is fixed. The first bit can be set externally, as in this example. The second and third bits are set on mouseover and mousedown, respectively, so that nodes are fixed temporarily during dragging. Although the second and third bits are automatically cleared when dragging ends, the first bit stays true in this example, and thus nodes remain fixed after dragging.

Also note that the force layout resumes automatically on dragmove. This ensures that other nodes in the graph respond naturally to the dragged node’s movement.

{
"nodes": [
{"x": 469, "y": 410},
{"x": 493, "y": 364},
{"x": 442, "y": 365},
{"x": 467, "y": 314},
{"x": 477, "y": 248},
{"x": 425, "y": 207},
{"x": 402, "y": 155},
{"x": 369, "y": 196},
{"x": 350, "y": 148},
{"x": 539, "y": 222},
{"x": 594, "y": 235},
{"x": 582, "y": 185},
{"x": 633, "y": 200}
],
"links": [
{"source": 0, "target": 1},
{"source": 1, "target": 2},
{"source": 2, "target": 0},
{"source": 1, "target": 3},
{"source": 3, "target": 2},
{"source": 3, "target": 4},
{"source": 4, "target": 5},
{"source": 5, "target": 6},
{"source": 5, "target": 7},
{"source": 6, "target": 7},
{"source": 6, "target": 8},
{"source": 7, "target": 8},
{"source": 9, "target": 4},
{"source": 9, "target": 11},
{"source": 9, "target": 10},
{"source": 10, "target": 11},
{"source": 11, "target": 12},
{"source": 12, "target": 10}
]
}
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.link {
stroke: #000;
stroke-width: 1.5px;
}
.node {
cursor: move;
fill: #ccc;
stroke: #000;
stroke-width: 1.5px;
}
.node.fixed {
fill: #f00;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500;
var force = d3.layout.force()
.size([width, height])
.charge(-400)
.linkDistance(40)
.on("tick", tick);
var drag = force.drag()
.on("dragstart", dragstart);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var link = svg.selectAll(".link"),
node = svg.selectAll(".node");
d3.json("graph.json", function(error, graph) {
if (error) throw error;
force
.nodes(graph.nodes)
.links(graph.links)
.start();
link = link.data(graph.links)
.enter().append("line")
.attr("class", "link");
node = node.data(graph.nodes)
.enter().append("circle")
.attr("class", "node")
.attr("r", 12)
.on("dblclick", dblclick)
.call(drag);
});
function tick() {
link.attr("x1", function(d) { return d.source.x; })
.attr("y1", function(d) { return d.source.y; })
.attr("x2", function(d) { return d.target.x; })
.attr("y2", function(d) { return d.target.y; });
node.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
}
function dblclick(d) {
d3.select(this).classed("fixed", d.fixed = false);
}
function dragstart(d) {
d3.select(this).classed("fixed", d.fixed = true);
}
</script>
@DarshanTeerth
Copy link

How to add "marker" property to show the direction from source to target and "text" to give values on it?

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment