Add feature id support

src/clip.js

@@ -2,6 +2,8 @@
 
 module.exports = clip;
 
+var createFeature = require('./feature');
+
 /* clip features between two axis-parallel lines:
  *     |        |
  *  ___|___     |     /
@@ -41,13 +43,7 @@ function clip(features, scale, k1, k2, axis, intersect, minAll, maxAll) {
         if (slices.length) {
             // if a feature got clipped, it will likely get clipped on the next zoom level as well,
             // so there's no need to recalculate bboxes
-            clipped.push({
-                geometry: slices,
-                type: type,
-                tags: features[i].tags || null,
-                min: feature.min,
-                max: feature.max
-            });
+            clipped.push(createFeature(feature.tags, type, slices, feature.id));
         }
     }
 

src/convert.js

@@ -3,6 +3,7 @@
 module.exports = convert;
 
 var simplify = require('./simplify');
+var createFeature = require('./feature');
 
 // converts GeoJSON feature into an intermediate projected JSON vector format with simplification data
 
@@ -33,16 +34,17 @@ function convertFeature(features, feature, tolerance) {
         type = geom.type,
         coords = geom.coordinates,
         tags = feature.properties,
+        id = feature.id,
         i, j, rings, projectedRing;
 
     if (type === 'Point') {
-        features.push(create(tags, 1, [projectPoint(coords)]));
+        features.push(createFeature(tags, 1, [projectPoint(coords)], id));
 
     } else if (type === 'MultiPoint') {
-        features.push(create(tags, 1, project(coords)));
+        features.push(createFeature(tags, 1, project(coords), id));
 
     } else if (type === 'LineString') {
-        features.push(create(tags, 2, [project(coords, tolerance)]));
+        features.push(createFeature(tags, 2, [project(coords, tolerance)], id));
 
     } else if (type === 'MultiLineString' || type === 'Polygon') {
         rings = [];
@@ -51,7 +53,7 @@ function convertFeature(features, feature, tolerance) {
             if (type === 'Polygon') projectedRing.outer = (i === 0);
             rings.push(projectedRing);
         }
-        features.push(create(tags, type === 'Polygon' ? 3 : 2, rings));
+        features.push(createFeature(tags, type === 'Polygon' ? 3 : 2, rings, id));
 
     } else if (type === 'MultiPolygon') {
         rings = [];
@@ -62,7 +64,7 @@ function convertFeature(features, feature, tolerance) {
                 rings.push(projectedRing);
             }
         }
-        features.push(create(tags, 3, rings));
+        features.push(createFeature(tags, 3, rings, id));
 
     } else if (type === 'GeometryCollection') {
         for (i = 0; i < geom.geometries.length; i++) {
@@ -77,18 +79,6 @@ function convertFeature(features, feature, tolerance) {
     }
 }
 
-function create(tags, type, geometry) {
-    var feature = {
-        geometry: geometry,
-        type: type,
-        tags: tags || null,
-        min: [2, 1], // initial bbox values;
-        max: [-1, 0]  // note that coords are usually in [0..1] range
-    };
-    calcBBox(feature);
-    return feature;
-}
-
 function project(lonlats, tolerance) {
     var projected = [];
     for (var i = 0; i < lonlats.length; i++) {
@@ -129,25 +119,3 @@ function calcSize(points) {
     points.area = Math.abs(area / 2);
     points.dist = dist;
 }
-
-// calculate the feature bounding box for faster clipping later
-function calcBBox(feature) {
-    var geometry = feature.geometry,
-        min = feature.min,
-        max = feature.max;
-
-    if (feature.type === 1) calcRingBBox(min, max, geometry);
-    else for (var i = 0; i < geometry.length; i++) calcRingBBox(min, max, geometry[i]);
-
-    return feature;
-}
-
-function calcRingBBox(min, max, points) {
-    for (var i = 0, p; i < points.length; i++) {
-        p = points[i];
-        min[0] = Math.min(p[0], min[0]);
-        max[0] = Math.max(p[0], max[0]);
-        min[1] = Math.min(p[1], min[1]);
-        max[1] = Math.max(p[1], max[1]);
-    }
-}

src/feature.js

@@ -0,0 +1,43 @@
+'use strict';
+
+module.exports = createFeature;
+
+function createFeature(tags, type, geom, id) {
+    var feature = {
+        id: id || null,
+        type: type,
+        geometry: geom,
+        tags: tags || null,
+        min: [Infinity, Infinity], // initial bbox values
+        max: [-Infinity, -Infinity]
+    };
+    calcBBox(feature);
+    return feature;
+}
+
+// calculate the feature bounding box for faster clipping later
+function calcBBox(feature) {
+    var geometry = feature.geometry,
+        min = feature.min,
+        max = feature.max;
+
+    if (feature.type === 1) {
+        calcRingBBox(min, max, geometry);
+    } else {
+        for (var i = 0; i < geometry.length; i++) {
+            calcRingBBox(min, max, geometry[i]);
+        }
+    }
+
+    return feature;
+}
+
+function calcRingBBox(min, max, points) {
+    for (var i = 0, p; i < points.length; i++) {
+        p = points[i];
+        min[0] = Math.min(p[0], min[0]);
+        max[0] = Math.max(p[0], max[0]);
+        min[1] = Math.min(p[1], min[1]);
+        max[1] = Math.max(p[1], max[1]);
+    }
+}

src/tile.js

@@ -78,11 +78,15 @@ function addFeature(tile, feature, tolerance, noSimplify) {
     }
 
     if (simplified.length) {
-        tile.features.push({
+        var tileFeature = {
             geometry: simplified,
             type: type,
             tags: feature.tags || null
-        });
+        };
+        if (feature.id !== null) {
+            tileFeature.id = feature.id;
+        }
+        tile.features.push(tileFeature);
     }
 }
 

src/wrap.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var clip = require('./clip');
+var createFeature = require('./feature');
 
 module.exports = wrap;
 
@@ -37,13 +38,7 @@ function shiftFeatureCoords(features, offset) {
             }
         }
 
-        newFeatures.push({
-            geometry: newGeometry,
-            type: type,
-            tags: feature.tags,
-            min: [feature.min[0] + offset, feature.min[1]],
-            max: [feature.max[0] + offset, feature.max[1]]
-        });
+        newFeatures.push(createFeature(feature.tags, type, newGeometry, feature.id));
     }
 
     return newFeatures;

test/fixtures/us-states-z7-37-48.json

@@ -1 +1 @@
-[{"geometry":[[[3415,-64],[3323,-15],[3300,-64],[3415,-64]]],"type":3,"tags":{"name":"Connecticut","density":739.1}},{"geometry":[[[762,2248],[627,2476],[475,2600],[507,2900],[722,3179],[778,3642],[1089,4124],[1233,4144],[1234,4160],[321,4160],[220,2403],[467,2196],[762,2248]]],"type":3,"tags":{"name":"Delaware","density":464.3}},{"geometry":[[[-64,2403],[220,2403],[321,4160],[-64,4160],[-64,2829],[-51,2714],[-64,2717],[-64,2403]]],"type":3,"tags":{"name":"Maryland","density":596.3}},{"geometry":[[[2914,-64],[2964,-36],[2788,523],[2549,649],[2421,943],[2820,1090],[2852,1310],[2677,2331],[2222,3086],[1927,3303],[1664,3775],[1528,3467],[1105,3313],[587,2900],[547,2580],[627,2476],[762,2248],[1153,2092],[1177,1946],[1624,1634],[1696,1467],[1281,1080],[1265,838],[1081,775],[1065,555],[1289,218],[1169,17],[1243,-64],[2914,-64]]],"type":3,"tags":{"name":"New Jersey","density":1189}},{"geometry":[[[3300,-64],[3323,-15],[3945,144],[4072,28],[4160,28],[4160,594],[3929,681],[3458,765],[3147,744],[2916,838],[2788,523],[2964,-36],[2914,-64],[3300,-64]]],"type":3,"tags":{"name":"New York","density":412.3}},{"geometry":[[[1243,-64],[1169,17],[1289,218],[1065,555],[1081,775],[1265,838],[1281,1080],[1696,1467],[1624,1634],[1177,1946],[1153,2092],[762,2248],[467,2196],[220,2403],[-64,2403],[-64,-64],[1243,-64]]],"type":3,"tags":{"name":"Pennsylvania","density":284.3}}]
+[{"geometry":[[[3415,-64],[3323,-15],[3300,-64],[3415,-64]]],"type":3,"tags":{"name":"Connecticut","density":739.1},"id":"09"},{"geometry":[[[762,2248],[627,2476],[475,2600],[507,2900],[722,3179],[778,3642],[1089,4124],[1233,4144],[1234,4160],[321,4160],[220,2403],[467,2196],[762,2248]]],"type":3,"tags":{"name":"Delaware","density":464.3},"id":"10"},{"geometry":[[[-64,2403],[220,2403],[321,4160],[-64,4160],[-64,2829],[-51,2714],[-64,2717],[-64,2403]]],"type":3,"tags":{"name":"Maryland","density":596.3},"id":"24"},{"geometry":[[[2914,-64],[2964,-36],[2788,523],[2549,649],[2421,943],[2820,1090],[2852,1310],[2677,2331],[2222,3086],[1927,3303],[1664,3775],[1528,3467],[1105,3313],[587,2900],[547,2580],[627,2476],[762,2248],[1153,2092],[1177,1946],[1624,1634],[1696,1467],[1281,1080],[1265,838],[1081,775],[1065,555],[1289,218],[1169,17],[1243,-64],[2914,-64]]],"type":3,"tags":{"name":"New Jersey","density":1189},"id":"34"},{"geometry":[[[3300,-64],[3323,-15],[3945,144],[4072,28],[4160,28],[4160,594],[3929,681],[3458,765],[3147,744],[2916,838],[2788,523],[2964,-36],[2914,-64],[3300,-64]]],"type":3,"tags":{"name":"New York","density":412.3},"id":"36"},{"geometry":[[[1243,-64],[1169,17],[1289,218],[1065,555],[1081,775],[1265,838],[1281,1080],[1696,1467],[1624,1634],[1177,1946],[1153,2092],[762,2248],[467,2196],[220,2403],[-64,2403],[-64,-64],[1243,-64]]],"type":3,"tags":{"name":"Pennsylvania","density":284.3},"id":"42"}]

test/test-clip.js

@@ -28,14 +28,15 @@ test('clips polylines', function (t) {
     ], 1, 10, 40, 0, intersectX, -Infinity, Infinity);
 
     var expected = [
-        {geometry: [
+        {id: null, type: 2, geometry: [
             [[10,0],[40,0]],
             [[40,10],[20,10],[20,20],[30,20],[30,30],[40,30]],
             [[40,40],[25,40],[25,50],[10,50]],
-            [[10,60],[25,60]]], type: 2, tags: 1, min: min1, max: max1},
-        {geometry: [
+            [[10,60],[25,60]]], tags: 1, min: [10,0], max: [40,60]},
+        {id: null, type: 2, geometry: [
             [[10,0],[40,0]],
-            [[40,10],[10,10]]], type: 2, tags: 2, min: min2, max: max2}];
+            [[40,10],[10,10]]], tags: 2, min: [10,0], max: [40,10]}
+    ];
 
     t.equal(JSON.stringify(clipped), JSON.stringify(expected));
 
@@ -54,9 +55,9 @@ test('clips polygons', function (t) {
     ], 1, 10, 40, 0, intersectX, -Infinity, Infinity);
 
     var expected = [
-        {geometry: [[[10,0],[40,0],[40,10],[20,10],[20,20],[30,20],[30,30],[40,30],
-                   [40,40],[25,40],[25,50],[10,50],[10,60],[25,60],[10,24],[10,0]]], type: 3, tags: 1, min: min1, max: max1},
-        {geometry: [[[10,0],[40,0],[40,10],[10,10],[10,0]]], type: 3, tags: 2, min: min2, max: max2}
+        {id: null, type: 3, geometry: [[[10,0],[40,0],[40,10],[20,10],[20,20],[30,20],[30,30],[40,30],
+                   [40,40],[25,40],[25,50],[10,50],[10,60],[25,60],[10,24],[10,0]]], tags: 1, min: [10,0], max: [40,60]},
+        {id: null, type: 3, geometry: [[[10,0],[40,0],[40,10],[10,10],[10,0]]], tags: 2, min: [10,0], max: [40,10]}
     ];
 
     t.equal(JSON.stringify(clipped), JSON.stringify(expected));
@@ -71,7 +72,8 @@ test('clips points', function (t) {
         {geometry: geom2[0], type: 1, tags: 2, min: min2, max: max2}
     ], 1, 10, 40, 0, intersectX, -Infinity, Infinity);
 
-    t.same(clipped, [{geometry: [[20,10],[20,20],[30,20],[30,30],[25,40],[25,50],[25,60]], type: 1, tags: 1, min: min1, max: max1}]);
+    t.same(clipped, [{id: null, type: 1,
+        geometry: [[20,10],[20,20],[30,20],[30,30],[25,40],[25,50],[25,60]], tags: 1, min: [20,10], max: [30,60]}]);
 
     t.end();
 });

test/test-get-tile.js

@@ -8,7 +8,8 @@ var geojsonvt = require('../src/index');
 var square = [{
     geometry: [[[-64, 4160], [-64, -64], [4160, -64], [4160, 4160], [-64, 4160]]],
     type: 3,
-    tags: {name: 'Pennsylvania', density: 284.3}
+    tags: {name: 'Pennsylvania', density: 284.3},
+    id: '42'
 }];
 
 test('getTile: us-states.json', function (t) {