io.data2viz.shape.Pie.kt Maven / Gradle / Ivy
package io.data2viz.shape
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min
// TODO rename PieLayout ?
fun pie(init: PieGenerator.() -> Unit) = PieGenerator().apply(init)
class PieGenerator {
var value: (D) -> Double = const(.0)
var startAngle: (Array) -> Double = const(.0)
var endAngle: (Array) -> Double = const(tau)
var padAngle: (Array) -> Double = const(.0)
/**
* Use the data to generate a line on the path
*/
fun render(data: Array): Array> {
val n = data.size
var sum = .0
val index: Array = Array(n, { 0 })
val arcs: Array> = Array(n, { ArcParams(.0, .0, .0, null, null, null) })
val values: Array = Array(n, { .0})
var a0 = startAngle(data)
val da = min(tau, max(-tau, endAngle(data) - a0))
val p = min(abs(da) / n, padAngle(data)) // min(abs(da) / n, .0)
val pa = if (da < .0) -p else p
for (i in 0 until n) {
index[i] = i
val v = value(data[i])
values[i] = v
if (v > 0) sum += v
}
// TODO : sorting
// Optionally sort the arcs by previously-computed values or by data.
//if (sortValues != null) index.sort(function(i, j) { return sortValues(arcs[i], arcs[j]); });
//else if (sort != null) index.sort(function(i, j) { return sort(data[i], data[j]); });
// Compute the arcs! They are stored in the original data's order.
val k = if (sum > .0) ((da - n * pa) / sum) else .0
for (i in 0 until n) {
val j = index[i]
val v = values[j]
val a1 = a0 + (if (v > .0) (v * k) else .0) + pa
arcs[j] = ArcParams(a0, a1, p, v,i, data[j])
a0 = a1
}
return arcs
}
}