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Added support for GeoJSON MultiPolygon with holes #5

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27 changes: 19 additions & 8 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,8 @@ function getFeatures(url, callback) {
geometry: {},
properties: {}
};
// console.log(record);
// TODO: Crashes here when a Shape file has been appended to and number of
// records do not match in .shp and .dbf.
feature.properties = attrs.values;

switch(record.shapeType) {
Expand All @@ -60,18 +61,28 @@ function getFeatures(url, callback) {
}
break;
case Shp.ShpType.SHAPE_POLYGON:
var coordinates = [],
j, len,
ring, featureRing;
feature.geometry.type = Shp.GeoJsonType[record.shapeType];
feature.geometry.coordinates = [];
var ringsLen = record.shape.rings.length;
for (var j = 0; j < ringsLen; j++) {
var ring = record.shape.rings[j];
for (j = 0, len = record.shape.rings.length; j < len; j++) {
ring = record.shape.rings[j];
if (ring.length < 1) continue;
var featureRing = feature.geometry.coordinates[j] = [];
var ringLen = ring.length;
for (var k = 0; k < ringLen; k++) {
featureRing.push([ring[k].x, ring[k].y]);
featureRing = ring.map(function(point) {
return [point.x, point.y];
});
if (coordinates.length > 0 && ring.isClockwise) {
feature.geometry.type = 'MultiPolygon';
feature.geometry.coordinates.push(coordinates);
coordinates = [];
}
coordinates.push(featureRing);
}
if (feature.geometry.coordinates.length === 0)
feature.geometry.coordinates = coordinates;
else
feature.geometry.coordinates.push(coordinates);
break;
default:
throw(new Error("Error converting SHP to geojson: Unsupported feature type"))
Expand Down
19 changes: 15 additions & 4 deletions lib/shp.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,13 @@
var fs = require('fs');
var BinaryReader = require('./BinaryReader');

function isClockwise(points) {
return points.reduce(function (sum, c, i, points) {
var n = points[(i+1)%points.length];
return sum + (n.x-c.x)*(n.y+c.y);
}, 0) >= 0;
}

var ShpFile = function(path) {
this.header = {};
this._reader = new BinaryReader(path+".shp");
Expand Down Expand Up @@ -266,7 +273,7 @@ function ShpPolyline(reader, size) {

reader.bigEndian = false;

this.box = {
this.box = {
x: reader.readDouble(),
y: reader.readDouble(),
width: reader.readDouble(),
Expand All @@ -289,14 +296,18 @@ function ShpPolyline(reader, size) {

// convert points, and ringOffsets arrays to an array of rings:
var removed = 0;
var split;
var split, ring;
ringOffsets.shift();
while(ringOffsets.length) {
split = ringOffsets.shift();
this.rings.push(points.splice(0,split-removed));
ring = points.splice(0,split-removed);
ring.isClockwise = isClockwise(ring);
this.rings.push(ring);
removed = split;
}
this.rings.push(points);
ring = points;
ring.isClockwise = isClockwise(ring);
this.rings.push(ring);
}
}

Expand Down
9 changes: 5 additions & 4 deletions test/shp.spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,10 +8,11 @@ describe('Shapefile Reader', function() {
it('Can correctly convert multiPolygon shapefile to GeoJSON', function(done){
var good_json = JSON.parse(fs.readFileSync(__dirname + '/data/multipolygon.json', "utf8"));
shpFile.readFile(__dirname + '/data/multipolygon', function(error, data){
expect(data.features[0].geometry.coordinates[0][0][0]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][0], 0.00001);
expect(data.features[0].geometry.coordinates[0][0][1]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][1], 0.00001);
expect(data.features[0].geometry.coordinates[0][1][0]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][1][0], 0.00001);
expect(data.features[0].geometry.coordinates[0][1][1]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][1][1], 0.00001);
expect(data.features[0].geometry.type).to.equal('MultiPolygon');
expect(data.features[0].geometry.coordinates[0][0][0][0]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][0][0], 0.00001);
expect(data.features[0].geometry.coordinates[0][0][0][1]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][0][1], 0.00001);
expect(data.features[0].geometry.coordinates[0][0][1][0]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][1][0], 0.00001);
expect(data.features[0].geometry.coordinates[0][0][1][1]).to.be.closeTo(good_json.features[0].geometry.coordinates[0][0][1][1], 0.00001);
});
done();
});
Expand Down