test 4

package-lock.json

@@ -32,6 +32,7 @@
         "morgan": "1.10.0",
         "pbf": "4.0.1",
         "pmtiles": "3.0.7",
+        "pngjs": "^7.0.0",
         "proj4": "2.12.1",
         "sanitize-filename": "1.6.3",
         "sharp": "0.33.5",
@@ -6622,6 +6623,14 @@
         "fflate": "^0.8.0"
       }
     },
+    "node_modules/pngjs": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/pngjs/-/pngjs-7.0.0.tgz",
+      "integrity": "sha512-LKWqWJRhstyYo9pGvgor/ivk2w94eSjE3RGVuzLGlr3NmD8bf7RcYGze1mNdEHRP6TRP6rMuDHk5t44hnTRyow==",
+      "engines": {
+        "node": ">=14.19.0"
+      }
+    },
     "node_modules/prelude-ls": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",

package.json

@@ -41,6 +41,7 @@
     "morgan": "1.10.0",
     "pbf": "4.0.1",
     "pmtiles": "3.0.7",
+    "pngjs": "^7.0.0",
     "proj4": "2.12.1",
     "sanitize-filename": "1.6.3",
     "sharp": "0.33.5",

src/contour.js

@@ -1,6 +1,7 @@
 import sharp from 'sharp';
 import mlcontour from '../node_modules/maplibre-contour/dist/index.mjs';
 import { getPMtilesTile } from './pmtiles_adapter.js';
+import { PNG } from 'pngjs';
 
 /**
  * Manages local DEM (Digital Elevation Model) data using maplibre-contour.
@@ -60,27 +61,15 @@ export class LocalDemManager {
    */
   async getImageData(blob, abortController) {
     try {
-      if (Boolean(abortController?.signal?.aborted)) return null;
-
       const buffer = await blob.arrayBuffer();
-      const image = sharp(Buffer.from(buffer));
-      await image.metadata();
-
-      if (Boolean(abortController?.signal?.aborted)) return null;
-
-      const { data, info } = await image
-        .raw()
-        .toBuffer({ resolveWithObject: true });
-      if (Boolean(abortController?.signal?.aborted)) return null;
-
+      const png = PNG.sync.read(Buffer.from(buffer));
       const parsed = mlcontour.decodeParsedImage(
-        info.width,
-        info.height,
+        png.width,
+        png.height,
         this.encoding,
-        data,
+        png.data,
       );
       if (Boolean(abortController?.signal?.aborted)) return null;
-
       return parsed;
     } catch (error) {
       console.error('Error processing image:', error);