d3-geo-zoom/dist/d3-geo-zoom.mjs

Zoom and Pan D3 Geo projections

import { select, pointers } from 'd3-selection';
import { zoom } from 'd3-zoom';
import versor from 'versor/src/index';
import Kapsule from 'kapsule';

var geoZoom = Kapsule({
  props: {
    projection: {
      onChange: function onChange(projection, state) {
        state.unityScale = projection ? projection.scale() : 1;
      }
    },
    scaleExtent: {
      "default": [0.1, 1e3],
      onChange: function onChange(extent, state) {
        state.zoom && state.zoom.scaleExtent(extent);
      }
    },
    northUp: {
      "default": false
    },
    onMove: {
      defaultVal: function defaultVal() {}
    }
  },
  init: function init(nodeEl, state) {
    select(nodeEl).call(state.zoom = zoom().scaleExtent(state.scaleExtent).on('start', zoomStarted).on('zoom', zoomed));
    var v0, r0, q0;
    function zoomStarted(ev) {
      if (!state.projection) return;
      v0 = versor.cartesian(state.projection.invert(getPointerCoords(ev)));
      r0 = state.projection.rotate();
      q0 = versor(r0);
    }
    function zoomed(ev) {
      if (!state.projection) return;
      var scale = ev.transform.k * state.unityScale;
      state.projection.scale(scale);
      var v1 = versor.cartesian(state.projection.rotate(r0).invert(getPointerCoords(ev))),
        q1 = versor.multiply(q0, versor.delta(v0, v1)),
        rotation = versor.rotation(q1);
      if (state.northUp) {
        rotation[2] = 0; // Don't rotate on Z axis
      }
      state.projection.rotate(rotation);
      state.onMove({
        scale: scale,
        rotation: rotation
      });
    }
    function getPointerCoords(zoomEv) {
      var avg = function avg(vals) {
        return vals.reduce(function (agg, v) {
          return agg + v;
        }, 0) / vals.length;
      };
      var pointers$1 = pointers(zoomEv, nodeEl);
      return pointers$1 && pointers$1.length > 1 ? [0, 1].map(function (idx) {
        return avg(pointers$1.map(function (t) {
          return t[idx];
        }));
      }) // calc centroid of all points if multi-touch
      : pointers$1.length ? pointers$1[0] // single point click
      : [undefined, undefined];
    }
  }
});

export { geoZoom as default };