Allow replacing fetch tile and decode image for local Dem manager

src/dem-source.ts

@@ -1,8 +1,12 @@
-import type { DemManager } from "./dem-manager";
-import { LocalDemManager } from "./dem-manager";
+import { LocalDemManager } from "./local-dem-manager";
 import { decodeOptions, encodeOptions, getOptionsForZoom } from "./utils";
 import RemoteDemManager from "./remote-dem-manager";
-import type { DemTile, GlobalContourTileOptions, Timing } from "./types";
+import type {
+  DemManager,
+  DemTile,
+  GlobalContourTileOptions,
+  Timing,
+} from "./types";
 import type WorkerDispatch from "./worker-dispatch";
 import Actor from "./actor";
 import { Timer } from "./performance";
@@ -129,14 +133,14 @@ export class DemSource {
     this.sharedDemProtocolUrl = `${this.sharedDemProtocolId}://{z}/{x}/{y}`;
     this.contourProtocolUrlBase = `${this.contourProtocolId}://{z}/{x}/{y}`;
     const ManagerClass = worker ? RemoteDemManager : LocalDemManager;
-    this.manager = new ManagerClass(
-      url,
+    this.manager = new ManagerClass({
+      demUrlPattern: url,
       cacheSize,
       encoding,
       maxzoom,
       timeoutMs,
       actor,
-    );
+    });
   }
 
   /** Registers a callback to be invoked with a performance report after each tile is requested. */

src/e2e.test.ts

@@ -6,6 +6,7 @@ import { MainThreadDispatch } from "./remote-dem-manager";
 import type { DemTile, Timing } from "./types";
 import { VectorTile } from "@mapbox/vector-tile";
 import Pbf from "pbf";
+import { LocalDemManager } from "./local-dem-manager";
 
 beforeEach(() => {
   jest.useFakeTimers({ now: 0, doNotFake: ["performance"] });
@@ -282,3 +283,28 @@ test("decode image from worker", async () => {
     data: expectedElevations,
   });
 });
+
+test("fake decode image and fetch tile", async () => {
+  const getTileSpy = jest.fn().mockReturnValue(Promise.resolve({}));
+  const demManager = new LocalDemManager({
+    demUrlPattern: "https://example/{z}/{x}/{y}.png",
+    cacheSize: 100,
+    encoding: "terrarium",
+    maxzoom: 11,
+    timeoutMs: 10000,
+    decodeImage: async () => ({
+      width: 4,
+      height: 4,
+      data: expectedElevations,
+    }),
+    getTile: getTileSpy,
+  });
+  const demTile = await demManager.fetchAndParseTile(
+    1,
+    2,
+    3,
+    new AbortController(),
+  );
+  expect(demTile.data).toEqual(expectedElevations);
+  expect(getTileSpy.mock.calls[0][0]).toBe("https://example/1/2/3.png");
+});

src/index.ts

@@ -1,7 +1,7 @@
 import generateIsolines from "./isolines";
 import { DemSource } from "./dem-source";
 import { decodeParsedImage } from "./decode-image";
-import { LocalDemManager } from "./dem-manager";
+import { LocalDemManager } from "./local-dem-manager";
 import CONFIG from "./config";
 import { HeightTile } from "./height-tile";
 

src/dem-manager.ts → src/local-dem-manager.ts

@@ -1,47 +1,39 @@
 import AsyncCache from "./cache";
-import decodeImage from "./decode-image";
+import defaultDecodeImage from "./decode-image";
 import { HeightTile } from "./height-tile";
 import generateIsolines from "./isolines";
 import { encodeIndividualOptions, isAborted, withTimeout } from "./utils";
 import type {
   ContourTile,
+  DecodeImageFunction,
+  DemManager,
+  DemManagerInitizlizationParameters,
   DemTile,
   Encoding,
   FetchResponse,
+  GetTileFunction,
   IndividualContourTileOptions,
 } from "./types";
 import encodeVectorTile, { GeomType } from "./vtpbf";
 import { Timer } from "./performance";
 
-/**
- * Holds cached tile state, and exposes `fetchContourTile` which fetches the necessary
- * tiles and returns an encoded contour vector tiles.
- */
-export interface DemManager {
-  loaded: Promise<any>;
-  fetchTile(
-    z: number,
-    x: number,
-    y: number,
-    abortController: AbortController,
-    timer?: Timer,
-  ): Promise<FetchResponse>;
-  fetchAndParseTile(
-    z: number,
-    x: number,
-    y: number,
-    abortController: AbortController,
-    timer?: Timer,
-  ): Promise<DemTile>;
-  fetchContourTile(
-    z: number,
-    x: number,
-    y: number,
-    options: IndividualContourTileOptions,
-    abortController: AbortController,
-    timer?: Timer,
-  ): Promise<ContourTile>;
-}
+const defaultGetTile: GetTileFunction = async (
+  url: string,
+  abortController: AbortController,
+) => {
+  const options: RequestInit = {
+    signal: abortController.signal,
+  };
+  const response = await fetch(url, options);
+  if (!response.ok) {
+    throw new Error(`Bad response: ${response.status} for ${url}`);
+  }
+  return {
+    data: await response.blob(),
+    expires: response.headers.get("expires") || undefined,
+    cacheControl: response.headers.get("cache-control") || undefined,
+  };
+};
 
 /**
  * Caches, decodes, and processes raster tiles in the current thread.
@@ -55,26 +47,19 @@ export class LocalDemManager implements DemManager {
   maxzoom: number;
   timeoutMs: number;
   loaded = Promise.resolve();
-  decodeImage: (
-    blob: Blob,
-    encoding: Encoding,
-    abortController: AbortController,
-  ) => Promise<DemTile> = decodeImage;
+  decodeImage: DecodeImageFunction;
+  getTile: GetTileFunction;
 
-  constructor(
-    demUrlPattern: string,
-    cacheSize: number,
-    encoding: Encoding,
-    maxzoom: number,
-    timeoutMs: number,
-  ) {
-    this.tileCache = new AsyncCache(cacheSize);
-    this.parsedCache = new AsyncCache(cacheSize);
-    this.contourCache = new AsyncCache(cacheSize);
-    this.timeoutMs = timeoutMs;
-    this.demUrlPattern = demUrlPattern;
-    this.encoding = encoding;
-    this.maxzoom = maxzoom;
+  constructor(options: DemManagerInitizlizationParameters) {
+    this.tileCache = new AsyncCache(options.cacheSize);
+    this.parsedCache = new AsyncCache(options.cacheSize);
+    this.contourCache = new AsyncCache(options.cacheSize);
+    this.timeoutMs = options.timeoutMs;
+    this.demUrlPattern = options.demUrlPattern;
+    this.encoding = options.encoding;
+    this.maxzoom = options.maxzoom;
+    this.decodeImage = options.decodeImage || defaultDecodeImage;
+    this.getTile = options.getTile || defaultGetTile;
   }
 
   fetchTile(
@@ -92,24 +77,11 @@ export class LocalDemManager implements DemManager {
     return this.tileCache.get(
       url,
       (_, childAbortController) => {
-        const options: RequestInit = {
-          signal: childAbortController.signal,
-        };
         timer?.fetchTile(url);
         const mark = timer?.marker("fetch");
         return withTimeout(
           this.timeoutMs,
-          fetch(url, options).then(async (response) => {
-            mark?.();
-            if (!response.ok) {
-              throw new Error(`Bad response: ${response.status} for ${url}`);
-            }
-            return {
-              data: await response.blob(),
-              expires: response.headers.get("expires") || undefined,
-              cacheControl: response.headers.get("cache-control") || undefined,
-            };
-          }),
+          this.getTile(url, childAbortController).finally(() => mark?.()),
           childAbortController,
         );
       },

src/remote-dem-manager.ts

@@ -2,10 +2,11 @@ import Actor from "./actor";
 import CONFIG from "./config";
 import type WorkerDispatch from "./worker-dispatch";
 import decodeImage from "./decode-image";
-import type { DemManager } from "./dem-manager";
 import { Timer } from "./performance";
 import type {
   ContourTile,
+  DemManager,
+  DemManagerInitizlizationParameters,
   DemTile,
   Encoding,
   FetchResponse,
@@ -41,28 +42,17 @@ export default class RemoteDemManager implements DemManager {
   actor: Actor<WorkerDispatch>;
   loaded: Promise<any>;
 
-  constructor(
-    demUrlPattern: string,
-    cacheSize: number,
-    encoding: Encoding,
-    maxzoom: number,
-    timeoutMs: number,
-    actor?: Actor<WorkerDispatch>,
-  ) {
+  constructor(options: DemManagerInitizlizationParameters) {
     const managerId = (this.managerId = ++id);
-    this.actor = actor || defaultActor();
+    this.actor = options.actor || defaultActor();
     this.loaded = this.actor.send(
       "init",
       [],
       new AbortController(),
       undefined,
       {
-        cacheSize,
-        demUrlPattern,
-        encoding,
-        maxzoom,
+        ...options,
         managerId,
-        timeoutMs,
       },
     );
   }

src/types.ts

@@ -1,3 +1,7 @@
+import type Actor from "./actor";
+import type { Timer } from "./performance";
+import type WorkerDispatch from "./worker-dispatch";
+
 /** Scheme used to map pixel rgb values elevations. */
 export type Encoding = "terrarium" | "mapbox";
 export interface IsTransferrable {
@@ -77,15 +81,6 @@ export interface Image {
   data: Uint8Array;
 }
 
-export interface InitMessage {
-  managerId: number;
-  demUrlPattern: string;
-  cacheSize: number;
-  encoding: Encoding;
-  maxzoom: number;
-  timeoutMs: number;
-}
-
 export type TimingCategory = "main" | "worker" | "fetch" | "decode" | "isoline";
 
 /** Performance profile for a tile request */
@@ -114,3 +109,63 @@ export interface Timing {
   /** If the tile failed with an error */
   error?: boolean;
 }
+
+/**
+ * Holds cached tile state, and exposes `fetchContourTile` which fetches the necessary
+ * tiles and returns an encoded contour vector tiles.
+ */
+export interface DemManager {
+  loaded: Promise<any>;
+  fetchTile(
+    z: number,
+    x: number,
+    y: number,
+    abortController: AbortController,
+    timer?: Timer,
+  ): Promise<FetchResponse>;
+  fetchAndParseTile(
+    z: number,
+    x: number,
+    y: number,
+    abortController: AbortController,
+    timer?: Timer,
+  ): Promise<DemTile>;
+  fetchContourTile(
+    z: number,
+    x: number,
+    y: number,
+    options: IndividualContourTileOptions,
+    abortController: AbortController,
+    timer?: Timer,
+  ): Promise<ContourTile>;
+}
+
+export type GetTileFunction = (
+  url: string,
+  abortController: AbortController,
+) => Promise<FetchResponse>;
+
+export type DecodeImageFunction = (
+  blob: Blob,
+  encoding: Encoding,
+  abortController: AbortController,
+) => Promise<DemTile>;
+
+export type DemManagerRequiredInitizlizationParameters = {
+  demUrlPattern: string;
+  cacheSize: number;
+  encoding: Encoding;
+  maxzoom: number;
+  timeoutMs: number;
+};
+
+export type DemManagerInitizlizationParameters =
+  DemManagerRequiredInitizlizationParameters & {
+    decodeImage?: DecodeImageFunction;
+    getTile?: GetTileFunction;
+    actor?: Actor<WorkerDispatch>;
+  };
+
+export type InitMessage = DemManagerRequiredInitizlizationParameters & {
+  managerId: number;
+};

src/worker-dispatch.ts

@@ -1,4 +1,4 @@
-import { LocalDemManager } from "./dem-manager";
+import { LocalDemManager } from "./local-dem-manager";
 import { Timer } from "./performance";
 import type {
   ContourTile,
@@ -20,13 +20,7 @@ export default class WorkerDispatch {
   managers: { [id: number]: LocalDemManager } = {};
 
   init = (message: InitMessage, _: AbortController): Promise<void> => {
-    this.managers[message.managerId] = new LocalDemManager(
-      message.demUrlPattern,
-      message.cacheSize,
-      message.encoding,
-      message.maxzoom,
-      message.timeoutMs,
-    );
+    this.managers[message.managerId] = new LocalDemManager(message);
     return Promise.resolve();
   };