planning

node_modules/geotiff/dist-module/source/file.js

@@ -0,0 +1,68 @@
+import fs from 'fs';
+import { BaseSource } from './basesource.js';
+
+function closeAsync(fd) {
+  return new Promise((resolve, reject) => {
+    fs.close(fd, (err) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve();
+      }
+    });
+  });
+}
+
+function openAsync(path, flags, mode = undefined) {
+  return new Promise((resolve, reject) => {
+    fs.open(path, flags, mode, (err, fd) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(fd);
+      }
+    });
+  });
+}
+
+function readAsync(...args) {
+  return new Promise((resolve, reject) => {
+    fs.read(...args, (err, bytesRead, buffer) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve({ bytesRead, buffer });
+      }
+    });
+  });
+}
+
+class FileSource extends BaseSource {
+  constructor(path) {
+    super();
+    this.path = path;
+    this.openRequest = openAsync(path, 'r');
+  }
+
+  async fetchSlice(slice) {
+    // TODO: use `signal`
+    const fd = await this.openRequest;
+    const { buffer } = await readAsync(
+      fd,
+      Buffer.alloc(slice.length),
+      0,
+      slice.length,
+      slice.offset,
+    );
+    return buffer.buffer;
+  }
+
+  async close() {
+    const fd = await this.openRequest;
+    await closeAsync(fd);
+  }
+}
+
+export function makeFileSource(path) {
+  return new FileSource(path);
+}