Implemented LERC_ZSTD decoding with zstddec; Added DOM types to tsconfig for WebAssembly

package-lock.json

@@ -15,7 +15,8 @@
         "parse-headers": "^2.0.2",
         "quick-lru": "^6.1.1",
         "web-worker": "^1.2.0",
-        "xml-utils": "^1.0.2"
+        "xml-utils": "^1.0.2",
+        "zstddec": "^0.1.0"
       },
       "devDependencies": {
         "@babel/core": "^7.8.7",
@@ -7776,6 +7777,11 @@
       "engines": {
         "node": ">=6"
       }
+    },
+    "node_modules/zstddec": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/zstddec/-/zstddec-0.1.0.tgz",
+      "integrity": "sha512-w2NTI8+3l3eeltKAdK8QpiLo/flRAr2p8AGeakfMZOXBxOg9HIu4LVDxBi81sYgVhFhdJjv1OrB5ssI8uFPoLg=="
     }
   },
   "dependencies": {
@@ -13637,6 +13643,11 @@
         "lodash": "^4.17.15",
         "yargs": "^13.3.0"
       }
+    },
+    "zstddec": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/zstddec/-/zstddec-0.1.0.tgz",
+      "integrity": "sha512-w2NTI8+3l3eeltKAdK8QpiLo/flRAr2p8AGeakfMZOXBxOg9HIu4LVDxBi81sYgVhFhdJjv1OrB5ssI8uFPoLg=="
     }
   }
 }

package.json

@@ -88,7 +88,8 @@
     "parse-headers": "^2.0.2",
     "quick-lru": "^6.1.1",
     "web-worker": "^1.2.0",
-    "xml-utils": "^1.0.2"
+    "xml-utils": "^1.0.2",
+    "zstddec": "^0.1.0"
   },
   "devDependencies": {
     "@babel/core": "^7.8.7",

src/compression/index.js

@@ -25,5 +25,11 @@ addDecoder(6, () => {
 addDecoder(7, () => import('./jpeg.js').then((m) => m.default));
 addDecoder([8, 32946], () => import('./deflate.js').then((m) => m.default));
 addDecoder(32773, () => import('./packbits.js').then((m) => m.default));
-addDecoder(34887, () => import('./lerc.js').then((m) => m.default));
+addDecoder(34887, () => import('./lerc.js')
+  .then(async (m) => {
+    await m.zstd.init();
+    return m;
+  })
+  .then((m) => m.default),
+);
 addDecoder(50001, () => import('./webimage.js').then((m) => m.default));

src/compression/lerc.js

@@ -1,8 +1,11 @@
 import { inflate } from 'pako';
 import Lerc from 'lerc';
+import { ZSTDDecoder } from 'zstddec';
 import BaseDecoder from './basedecoder.js';
 import { LercParameters, LercAddCompression } from '../globals.js';
 
+export const zstd = new ZSTDDecoder();
+
 export default class LercDecoder extends BaseDecoder {
   constructor(fileDirectory) {
     super();
@@ -20,6 +23,9 @@ export default class LercDecoder extends BaseDecoder {
       case LercAddCompression.Deflate:
         buffer = inflate(new Uint8Array(buffer)).buffer; // eslint-disable-line no-param-reassign, prefer-destructuring
         break;
+      case LercAddCompression.Zstandard:
+        buffer = zstd.decode(new Uint8Array(buffer)).buffer; // eslint-disable-line no-param-reassign, prefer-destructuring
+        break;
       default:
         throw new Error(`Unsupported LERC additional compression method identifier: ${this.addCompression}`);
     }

src/globals.js

@@ -235,6 +235,7 @@ export const LercParameters = {
 export const LercAddCompression = {
   None: 0,
   Deflate: 1,
+  Zstandard: 2,
 };
 
 export const geoKeyNames = {

tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "target": "ES5",
-    "lib": ["ES2020"],
+    "lib": ["ES2020", "DOM"],
     "allowJs": true,
     "declaration": true,
     "declarationMap": true,