Function d3_geo_clipView

explainshell/web/static/js/d3.v3.js:2646–2785

(x0, y0, x1, y1)

  }
  var d3_geo_clipViewMAX = 1e9;
  function d3_geo_clipView(x0, y0, x1, y1) {
    return function(listener) {
      var listener_ = listener, bufferListener = d3_geo_clipBufferListener(), segments, polygon, ring;
      var clip = {
        point: point,
        lineStart: lineStart,
        lineEnd: lineEnd,
        polygonStart: function() {
          listener = bufferListener;
          segments = [];
          polygon = [];
        },
        polygonEnd: function() {
          listener = listener_;
          if ((segments = d3.merge(segments)).length) {
            listener.polygonStart();
            d3_geo_clipPolygon(segments, compare, inside, interpolate, listener);
            listener.polygonEnd();
          } else if (insidePolygon([ x0, y0 ])) {
            listener.polygonStart(), listener.lineStart();
            interpolate(null, null, 1, listener);
            listener.lineEnd(), listener.polygonEnd();
          }
          segments = polygon = ring = null;
        }
      };
      function inside(point) {
        var a = corner(point, -1), i = insidePolygon([ a === 0 || a === 3 ? x0 : x1, a > 1 ? y1 : y0 ]);
        return i;
      }
      function insidePolygon(p) {
        var wn = 0, n = polygon.length, y = p[1];
        for (var i = 0; i < n; ++i) {
          for (var j = 1, v = polygon[i], m = v.length, a = v[0]; j < m; ++j) {
            b = v[j];
            if (a[1] <= y) {
              if (b[1] > y && isLeft(a, b, p) > 0) ++wn;
            } else {
              if (b[1] <= y && isLeft(a, b, p) < 0) --wn;
            }
            a = b;
          }
        }
        return wn !== 0;
      }
      function isLeft(a, b, c) {
        return (b[0] - a[0]) * (c[1] - a[1]) - (c[0] - a[0]) * (b[1] - a[1]);
      }
      function interpolate(from, to, direction, listener) {
        var a = 0, a1 = 0;
        if (from == null || (a = corner(from, direction)) !== (a1 = corner(to, direction)) || comparePoints(from, to) < 0 ^ direction > 0) {
          do {
            listener.point(a === 0 || a === 3 ? x0 : x1, a > 1 ? y1 : y0);
          } while ((a = (a + direction + 4) % 4) !== a1);
        } else {
          listener.point(to[0], to[1]);
        }
      }