{
const d3SvgNode = d3.select(svg`<svg width=${width} height=400></svg>`);
const sourceData = {
x: width / 2 + 0,
y: 150
};
const midData = {
x: width / 2 + 200,
y: 50
};
const targetData = {
x: width / 2 - 200,
y: 250
};
const drag = d3.drag().on("drag", dragged);
const link = d3SvgNode
.append("path")
.attr("d", diagonal(sourceData, targetData, midData))
.attr("fill", "none")
.attr("stroke", "steelblue");
const source = d3SvgNode
.append("circle")
.datum(sourceData)
.attr("r", 10)
.attr("cx", sourceData.x)
.attr("cy", sourceData.y)
.attr("fill", "steelblue")
.attr("cursor", "move")
.call(drag);
const target = d3SvgNode
.append("circle")
.datum(targetData)
.attr("r", 10)
.attr("cx", targetData.x)
.attr("cy", targetData.y)
.attr("fill", "steelblue")
.attr("cursor", "move")
.call(drag);
const mid = d3SvgNode
.append("circle")
.datum(midData)
.attr("r", 10)
.attr("cx", midData.x)
.attr("cy", midData.y)
.attr("fill", "steelblue")
.attr("cursor", "move")
.call(drag);
function dragged(d) {
d.x = d3.event.x;
d.y = d3.event.y;
update();
}
function update() {
source.attr("cx", sourceData.x).attr("cy", sourceData.y);
target.attr("cx", targetData.x).attr("cy", targetData.y);
mid.attr("cx", midData.x).attr("cy", midData.y);
link.attr("d", diagonal(sourceData, targetData, midData));
}
yield d3SvgNode.node();
}
function diagonal(s, t, m) {
// Define source and target x,y coordinates
const x = s.x;
const y = s.y;
const ex = t.x;
const ey = t.y;
let mx = m?.x ?? x;
let my = m?.y ?? y;
// Values in case of top reversed and left reversed diagonals
let xrvs = ex - x < 0 ? -1 : 1;
let yrvs = ey - y < 0 ? -1 : 1;
// Define preferred curve radius
let rdef = 35;
// Reduce curve radius, if source-target x space is smaller
let r = Math.abs(ex - x) / 2 < rdef ? Math.abs(ex - x) / 2 : rdef;
// Further reduce curve radius, is y space is more small
r = Math.abs(ey - y) / 2 < r ? Math.abs(ey - y) / 2 : r;
// Defin width and height of link, excluding radius
let h = Math.abs(ey - y) / 2 - r;
let w = Math.abs(ex - x) / 2 - r;
// Build and return custom arc command
return `
M ${mx} ${my}
L ${mx} ${y}
L ${x} ${y}
L ${x + w * xrvs} ${y}
C ${x + w * xrvs + r * xrvs} ${y}
${x + w * xrvs + r * xrvs} ${y}
${x + w * xrvs + r * xrvs} ${y + r * yrvs}
L ${x + w * xrvs + r * xrvs} ${ey - r * yrvs}
C ${x + w * xrvs + r * xrvs} ${ey}
${x + w * xrvs + r * xrvs} ${ey}
${ex - w * xrvs} ${ey}
L ${ex} ${ey}
`;
}
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