constructor(data, options = {}) {

const {x, y, length, rotate, anchor = "middle", frameAnchor} = options;

const [vl, cl] = maybeNumberChannel(length, 12);

const [vr, cr] = maybeNumberChannel(rotate, 0);

super(

data,

{

x: {value: x, scale: "x", optional: true},

y: {value: y, scale: "y", optional: true},

length: {value: vl, scale: "length", optional: true},

rotate: {value: vr, optional: true}

},

options,

defaults

);

this.length = cl;

this.rotate = cr;

this.anchor = keyword(anchor, "anchor", ["start", "middle", "end"]);

this.frameAnchor = maybeFrameAnchor(frameAnchor);

}

render(index, scales, channels, dimensions, context) {

const {x: X, y: Y, length: L, rotate: R} = channels;

const {length, rotate, anchor} = this;

const [cx, cy] = applyFrameAnchor(this, dimensions);

const fl = L ? (i) => L[i] : () => length;

const fr = R ? (i) => R[i] : () => rotate;

const fx = X ? (i) => X[i] : () => cx;

const fy = Y ? (i) => Y[i] : () => cy;

const k = anchor === "start" ? 0 : anchor === "end" ? 1 : 0.5;

return create("svg:g", context)

.attr("fill", "none")

.call(applyIndirectStyles, this, scales, dimensions)

.call(applyTransform, this, scales)

.call((g) =>

g

.selectAll()

.data(index)

.enter()

.append("path")

.call(applyDirectStyles, this)

.attr("d", (i) => {

const l = fl(i),

a = fr(i) * radians;

const x = Math.sin(a) * l,

y = -Math.cos(a) * l;

const d = (x + y) / 5,

e = (x - y) / 5;

return `M${fx(i) - x * k},${fy(i) - y * k}l${x},${y}m${-e},${-d}l${e},${d}l${-d},${e}`;

})

.call(applyChannelStyles, this, channels)

)

.node();

}