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import {max, range, tickStep} from "d3-array";
import {slice} from "./array";
import {blurX, blurY} from "./blur";
import constant from "./constant";
import contours from "./contours";
function defaultX(d) {
return d[0];
}
function defaultY(d) {
return d[1];
}
function defaultWeight() {
return 1;
}
export default function() {
var x = defaultX,
y = defaultY,
weight = defaultWeight,
dx = 960,
dy = 500,
r = 20, // blur radius
k = 2, // log2(grid cell size)
o = r * 3, // grid offset, to pad for blur
n = (dx + o * 2) >> k, // grid width
m = (dy + o * 2) >> k, // grid height
threshold = constant(20);
function density(data) {
var values0 = new Float32Array(n * m),
values1 = new Float32Array(n * m);
data.forEach(function(d, i, data) {
var xi = (+x(d, i, data) + o) >> k,
yi = (+y(d, i, data) + o) >> k,
wi = +weight(d, i, data);
if (xi >= 0 && xi < n && yi >= 0 && yi < m) {
values0[xi + yi * n] += wi;
}
});
// TODO Optimize.
blurX({width: n, height: m, data: values0}, {width: n, height: m, data: values1}, r >> k);
blurY({width: n, height: m, data: values1}, {width: n, height: m, data: values0}, r >> k);
blurX({width: n, height: m, data: values0}, {width: n, height: m, data: values1}, r >> k);
blurY({width: n, height: m, data: values1}, {width: n, height: m, data: values0}, r >> k);
blurX({width: n, height: m, data: values0}, {width: n, height: m, data: values1}, r >> k);
blurY({width: n, height: m, data: values1}, {width: n, height: m, data: values0}, r >> k);
var tz = threshold(values0);
// Convert number of thresholds into uniform thresholds.
if (!Array.isArray(tz)) {
var stop = max(values0);
tz = tickStep(0, stop, tz);
tz = range(0, Math.floor(stop / tz) * tz, tz);
tz.shift();
}
return contours()
.thresholds(tz)
.size([n, m])
(values0)
.map(transform);
}
function transform(geometry) {
geometry.value *= Math.pow(2, -2 * k); // Density in points per square pixel.
geometry.coordinates.forEach(transformPolygon);
return geometry;
}
function transformPolygon(coordinates) {
coordinates.forEach(transformRing);
}
function transformRing(coordinates) {
coordinates.forEach(transformPoint);
}
// TODO Optimize.
function transformPoint(coordinates) {
coordinates[0] = coordinates[0] * Math.pow(2, k) - o;
coordinates[1] = coordinates[1] * Math.pow(2, k) - o;
}
function resize() {
o = r * 3;
n = (dx + o * 2) >> k;
m = (dy + o * 2) >> k;
return density;
}
density.x = function(_) {
return arguments.length ? (x = typeof _ === "function" ? _ : constant(+_), density) : x;
};
density.y = function(_) {
return arguments.length ? (y = typeof _ === "function" ? _ : constant(+_), density) : y;
};
density.weight = function(_) {
return arguments.length ? (weight = typeof _ === "function" ? _ : constant(+_), density) : weight;
};
density.size = function(_) {
if (!arguments.length) return [dx, dy];
var _0 = Math.ceil(_[0]), _1 = Math.ceil(_[1]);
if (!(_0 >= 0) && !(_0 >= 0)) throw new Error("invalid size");
return dx = _0, dy = _1, resize();
};
density.cellSize = function(_) {
if (!arguments.length) return 1 << k;
if (!((_ = +_) >= 1)) throw new Error("invalid cell size");
return k = Math.floor(Math.log(_) / Math.LN2), resize();
};
density.thresholds = function(_) {
return arguments.length ? (threshold = typeof _ === "function" ? _ : Array.isArray(_) ? constant(slice.call(_)) : constant(_), density) : threshold;
};
density.bandwidth = function(_) {
if (!arguments.length) return Math.sqrt(r * (r + 1));
if (!((_ = +_) >= 0)) throw new Error("invalid bandwidth");
return r = Math.round((Math.sqrt(4 * _ * _ + 1) - 1) / 2), resize();
};
return density;
}
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