fix: adding a mechanism to check for presence of m-values during parsing

shpts/geometry/base.ts

@@ -1,20 +1,24 @@
 import { Coord, CoordType } from '@shpts/types/coordinate';
 import { GeoJsonGeom } from '@shpts/types/geojson';
-import { BoundingBox } from '@shpts/types/data';
+import { BoundingBox, GeomHeader } from '@shpts/types/data';
 import { MemoryStream } from '@shpts/utils/stream';
 
 export abstract class BaseRecord {
-    constructor(readonly coordType: CoordType) {}
+    constructor(readonly coordType: CoordType, private hasMValuesPresent: boolean) {}
     abstract toGeoJson(): GeoJsonGeom;
 
     get hasZ(): boolean {
         return this.coordType === CoordType.XYZM;
     }
 
-    get hasM(): boolean {
+    get hasOptionalM(): boolean {
         return this.coordType === CoordType.XYM || this.coordType === CoordType.XYZM;
     }
 
+    get hasM(): boolean {
+        return this.hasMValuesPresent;
+    }
+
     get coordLength(): number {
         if (this.coordType === CoordType.XY) return 2;
         if (this.coordType === CoordType.XYM) return 3;
@@ -35,6 +39,12 @@ export abstract class BaseRecord {
             yMax: yMax,
         };
     }
+
+    static recordReadingFinalized(shpStream: MemoryStream, header: GeomHeader) {
+        //per spec, each record is (4 + header.length) * 2 bytes long
+        //if the stream is at the end of the record, then we are good
+        return shpStream.tell === header.offset + (4 + header.length) * 2;
+    }
 }
 
 export abstract class BaseRingedRecord extends BaseRecord {

shpts/geometry/multipatch.ts

@@ -12,8 +12,8 @@ import { assemblePolygonsWithHoles } from '@shpts/utils/orientation';
 import { GeomUtil } from '@shpts/utils/geometry';
 
 export class MultiPatchRecord extends BaseRingedRecord {
-    constructor(public coords: MultiPatchCoord, coordType: CoordType) {
-        super(coordType);
+    constructor(public coords: MultiPatchCoord, coordType: CoordType, hasMValuesPresent: boolean) {
+        super(coordType, hasMValuesPresent);
     }
 
     get type() {
@@ -23,7 +23,7 @@ export class MultiPatchRecord extends BaseRingedRecord {
 
     static fromPresetReader(reader: ShapeReader, header: GeomHeader) {
         const hasZ = reader.hasZ;
-        const hasM = reader.hasM;
+        const hasOptionalM = reader.hasOptionalM;
         const shpStream = reader.shpStream;
         let z, m;
 
@@ -34,12 +34,16 @@ export class MultiPatchRecord extends BaseRingedRecord {
         const partTypes = shpStream.readInt32Array(numParts, true);
         const xy = shpStream.readDoubleArray(numPoints * 2, true);
         if (hasZ) z = MultiPatchRecord.getZValues(shpStream, numPoints);
+
+        const hasM = !this.recordReadingFinalized(shpStream, header) && hasOptionalM;
         if (hasM) m = MultiPatchRecord.getMValues(shpStream, numPoints);
+
         const coords = MultiPatchRecord.getCoords(parts, xy, z, m);
         const assembledCoords = MultiPatchRecord.assemblePolygonsWithHoles(coords, partTypes);
         return new MultiPatchRecord(
             assembledCoords as MultiPatchCoord,
-            GeomUtil.coordType(header.type)
+            GeomUtil.coordType(header.type),
+            hasM
         );
     }
 

shpts/geometry/multipoint.ts

@@ -7,8 +7,8 @@ import { GeomHeader } from '@shpts/types/data';
 import { MemoryStream } from '@shpts/utils/stream';
 
 export class MultiPointRecord extends BaseRecord {
-    constructor(public coords: MultiPointCoord, coordType: CoordType) {
-        super(coordType);
+    constructor(public coords: MultiPointCoord, coordType: CoordType, hasMValuesPresent: boolean) {
+        super(coordType, hasMValuesPresent);
     }
 
     get type() {
@@ -17,17 +17,24 @@ export class MultiPointRecord extends BaseRecord {
 
     static fromPresetReader(reader: ShapeReader, header: GeomHeader) {
         const hasZ = reader.hasZ;
-        const hasM = reader.hasM;
+        const hasOptionalM = reader.hasOptionalM;
         const shpStream = reader.shpStream;
         let z, m;
 
         MultiPointRecord.readBbox(shpStream); //throw away the bbox
         const numPoints = shpStream.readInt32(true);
         const xy = shpStream.readDoubleArray(numPoints * 2, true);
         if (hasZ) z = MultiPointRecord.getZValues(shpStream, numPoints);
+
+        const hasM = !this.recordReadingFinalized(shpStream, header) && hasOptionalM;
         if (hasM) m = MultiPointRecord.getMValues(shpStream, numPoints);
+
         const coords = MultiPointRecord.getCoords(numPoints, xy, z, m);
-        return new MultiPointRecord(coords as MultiPointCoord, GeomUtil.coordType(header.type));
+        return new MultiPointRecord(
+            coords as MultiPointCoord,
+            GeomUtil.coordType(header.type),
+            hasM
+        );
     }
 
     private static getZValues(shpStream: MemoryStream, numPoints: number) {

shpts/geometry/null.ts

@@ -4,7 +4,7 @@ import { CoordType } from '@shpts/types/coordinate';
 
 export class ShpNullGeom extends BaseRecord {
     constructor() {
-        super(CoordType.NULL);
+        super(CoordType.NULL, false);
     }
 
     get type() {

shpts/geometry/point.ts

@@ -6,8 +6,8 @@ import { GeomHeader } from '@shpts/types/data';
 import { GeomUtil } from '@shpts/utils/geometry';
 
 export class PointRecord extends BaseRecord {
-    constructor(public coords: PointCoord, coordType: CoordType) {
-        super(coordType);
+    constructor(public coords: PointCoord, coordType: CoordType, hasMValuesPresent: boolean) {
+        super(coordType, hasMValuesPresent);
     }
 
     get type() {
@@ -16,22 +16,19 @@ export class PointRecord extends BaseRecord {
 
     static fromPresetReader(reader: ShapeReader, header: GeomHeader) {
         const hasZ = reader.hasZ;
-        const hasM = reader.hasM;
+        const hasOptionalM = reader.hasOptionalM;
 
         const shpStream = reader.shpStream;
 
         const coord = [];
         coord.push(shpStream.readDouble(true)); //x
         coord.push(shpStream.readDouble(true)); //y
+        if (hasZ) coord.push(shpStream.readDouble(true)); //z
 
-        if (hasM) {
-            if (hasZ) {
-                coord.push(shpStream.readDouble(true)); //z
-            }
-            coord.push(shpStream.readDouble(true)); //m
-        }
+        const hasM = !this.recordReadingFinalized(shpStream, header) && hasOptionalM;
+        if (hasM) coord.push(shpStream.readDouble(true)); //m
 
-        return new PointRecord(coord as PointCoord, GeomUtil.coordType(header.type));
+        return new PointRecord(coord as PointCoord, GeomUtil.coordType(header.type), hasM);
     }
 
     toGeoJson() {

shpts/geometry/polygon.ts

@@ -12,8 +12,8 @@ import { GeomHeader } from '@shpts/types/data';
 import { assemblePolygonsWithHoles } from '@shpts/utils/orientation';
 
 export class PolygonRecord extends BaseRingedRecord {
-    constructor(public coords: PolygonCoord, coordType: CoordType) {
-        super(coordType);
+    constructor(public coords: PolygonCoord, coordType: CoordType, hasMValuesPresent: boolean) {
+        super(coordType, hasMValuesPresent);
     }
 
     get type() {
@@ -23,7 +23,7 @@ export class PolygonRecord extends BaseRingedRecord {
 
     static fromPresetReader(reader: ShapeReader, header: GeomHeader) {
         const hasZ = reader.hasZ;
-        const hasM = reader.hasM;
+        const hasOptionalM = reader.hasOptionalM;
         const shpStream = reader.shpStream;
         let z, m;
 
@@ -33,10 +33,13 @@ export class PolygonRecord extends BaseRingedRecord {
         const parts = shpStream.readInt32Array(numParts, true);
         const xy = shpStream.readDoubleArray(numPoints * 2, true);
         if (hasZ) z = PolygonRecord.getZValues(shpStream, numPoints);
+
+        const hasM = !this.recordReadingFinalized(shpStream, header) && hasOptionalM;
         if (hasM) m = PolygonRecord.getMValues(shpStream, numPoints);
+
         const coords = PolygonRecord.getCoords(parts, xy, z, m);
         const polygons = assemblePolygonsWithHoles(coords);
-        return new PolygonRecord(polygons as PolygonCoord, GeomUtil.coordType(header.type));
+        return new PolygonRecord(polygons as PolygonCoord, GeomUtil.coordType(header.type), hasM);
     }
 
     toGeoJson(): GeoJsonGeom {

shpts/geometry/polyline.ts

@@ -6,8 +6,8 @@ import { GeomUtil } from '@shpts/utils/geometry';
 import { GeomHeader } from '@shpts/types/data';
 
 export class PolyLineRecord extends BaseRingedRecord {
-    constructor(public coords: PolyLineCoord, coordType: CoordType) {
-        super(coordType);
+    constructor(public coords: PolyLineCoord, coordType: CoordType, hasMValuesPresent: boolean) {
+        super(coordType, hasMValuesPresent);
     }
 
     get type() {
@@ -17,7 +17,7 @@ export class PolyLineRecord extends BaseRingedRecord {
 
     static fromPresetReader(reader: ShapeReader, header: GeomHeader) {
         const hasZ = reader.hasZ;
-        const hasM = reader.hasM;
+        const hasOptionalM = reader.hasOptionalM;
         const shpStream = reader.shpStream;
         let z, m;
 
@@ -27,9 +27,12 @@ export class PolyLineRecord extends BaseRingedRecord {
         const parts = shpStream.readInt32Array(numParts, true);
         const xy = shpStream.readDoubleArray(numPoints * 2, true);
         if (hasZ) z = PolyLineRecord.getZValues(shpStream, numPoints);
+
+        const hasM = !this.recordReadingFinalized(shpStream, header) && hasOptionalM;
         if (hasM) m = PolyLineRecord.getMValues(shpStream, numPoints);
+
         const coords = PolyLineRecord.getCoords(parts, xy, z, m);
-        return new PolyLineRecord(coords as PolyLineCoord, GeomUtil.coordType(header.type));
+        return new PolyLineRecord(coords as PolyLineCoord, GeomUtil.coordType(header.type), hasM);
     }
 
     toGeoJson() {

shpts/reader/shpReader.ts

@@ -16,7 +16,7 @@ export class ShapeReader {
 
     readonly recordCount: number = 0;
     readonly hasZ: boolean;
-    readonly hasM: boolean;
+    readonly hasOptionalM: boolean;
 
     private constructor(shp: ArrayBuffer, shx: ArrayBuffer) {
         this.shpStream = new MemoryStream(shp);
@@ -27,9 +27,12 @@ export class ShapeReader {
         if (this.shpHeader.type !== this.shxHeader.type)
             throw new Error('SHP / SHX shapetype mismatch');
 
+        //const zRangeDefined = !isMNaN(this.shpHeader.zRange.min) && !isMNaN(this.shpHeader.zRange.max);
+        //const mRangeDefined = !isMNaN(this.shpHeader.mRange.min) && !isMNaN(this.shpHeader.mRange.max);
+
         this.recordCount = (this.shxHeader.fileLength - 100) / 8;
         this.hasZ = GeomUtil.hasZ(this.shpHeader.type);
-        this.hasM = GeomUtil.hasM(this.shpHeader.type);
+        this.hasOptionalM = GeomUtil.hasOptionalM(this.shpHeader.type);
     }
 
     static async fromFile(shp: File, shx: File) {
@@ -62,10 +65,12 @@ export class ShapeReader {
     }
 
     private readGeomHeader(): GeomHeader {
+        const offset = this.shpStream.tell;
         const recNum = this.shpStream.readInt32(false);
         const len = this.shpStream.readInt32(false);
         const type: ShapeType = this.shpStream.readInt32(true) as ShapeType;
         return {
+            offset,
             length: len,
             recordNum: recNum,
             type: type,

shpts/shpts.ts

@@ -13,6 +13,7 @@ import { DbfFieldDescr, DbfFieldType } from './types/dbfTypes';
 import { Coord, CoordType } from './types/coordinate';
 import { triangulate } from './utils/triangulation';
 import { BaseRecord } from './geometry/base';
+import { ShapeType } from './utils/geometry';
 
 export {
     DbfReader,
@@ -31,4 +32,4 @@ export {
     triangulate,
 };
 
-export type { DbfFieldType, DbfFieldDescr, Coord };
+export type { DbfFieldType, DbfFieldDescr, Coord, ShapeType };

shpts/types/data.ts

@@ -19,6 +19,7 @@ export interface ShxRecord {
 }
 
 export interface GeomHeader {
+    offset: number;
     recordNum: number;
     length: number;
     type: ShapeType;

shpts/utils/geometry.ts

@@ -41,7 +41,7 @@ export class GeomUtil {
         return type === CoordType.XYZM;
     }
 
-    static hasM(shapeType: ShapeType): boolean {
+    static hasOptionalM(shapeType: ShapeType): boolean {
         const type = GeomUtil.coordType(shapeType);
         return type === CoordType.XYZM || type === CoordType.XYM;
     }

test/polygon.test.ts

@@ -1,6 +1,6 @@
 import { expect, test } from 'vitest';
 import { expectGeometry, expectRing, openFileAsArray } from './utils';
-import { ShapeReader, PolygonRecord, CoordType } from '@shpts/shpts';
+import { ShapeReader, PolygonRecord, CoordType, FeatureReader } from '@shpts/shpts';
 
 test('Reading PolygonRecord', async () => {
     const shpBuffer = openFileAsArray('testdata/polygon.shp');
@@ -39,6 +39,7 @@ test('Reading PolygonRecord', async () => {
     ]);
 
     geom = expectGeometry(reader, 1, CoordType.XY, PolygonRecord);
+    expect(geom.hasM).toBeFalsy();
     expect(geom.type).toEqual('Polygon');
     expect(geom.coords.length).toBe(1);
     polygon = geom.coords[0];
@@ -114,6 +115,7 @@ test('Reading PolygonRecord with M', async () => {
     expect(reader.recordCount).toBe(2);
 
     let geom = expectGeometry(reader, 0, CoordType.XYM, PolygonRecord);
+    expect(geom.hasM).toBeTruthy();
     expect(geom.type).toEqual('Polygon');
     expect(geom.coords.length).toBe(1);
     let polygon = geom.coords[0];
@@ -256,3 +258,19 @@ test('Reading PolygonZ Terrain Example', async () => {
     const reader = await ShapeReader.fromArrayBuffer(shpBuffer, shxBuffer);
     expect(reader.recordCount).toBe(42798);
 });
+
+test('Reading PolygonZ without M values', async () => {
+    const shpBuffer = openFileAsArray('testdata/polygonZ.shp');
+    const shxBuffer = openFileAsArray('testdata/polygonZ.shx');
+    const dbfBuffer = openFileAsArray('testdata/polygonZ.dbf');
+
+    const reader = await FeatureReader.fromArrayBuffers(shpBuffer, shxBuffer, dbfBuffer);
+    const col = reader.readFeatureCollection();
+    const features = col.features;
+    expect(features.length).toBe(1);
+
+    const geom = features[0].geom;
+    expect(geom.type).toEqual('Polygon');
+    expect(geom.hasM).toBeFalsy();
+    expect(geom.hasZ).toBeTruthy();
+});

testdata/polygonZ.cpg

@@ -0,0 +1 @@
+UTF-8

testdata/polygonZ.prj

@@ -0,0 +1 @@
+PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator_Auxiliary_Sphere"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],PARAMETER["Auxiliary_Sphere_Type",0.0],UNIT["Meter",1.0]]