First version of JPEG and EXIF parser with starter unit tests and updated docs.

tests/image-parsers-jpeg.spec.js

@@ -0,0 +1,43 @@
+import * as fs from 'node:fs';
+import 'mocha';
+import { expect } from 'chai';
+import { JpegParser } from '../image/parsers/jpeg.js';
+import { ExifDataFormat, ExifTagNumber } from '../image/parsers/exif.js';
+
+/**
+ * @typedef {import('../image/parsers/jpeg.js').JpegStartOfFrame} JpegStartOfFrame
+ */
+/**
+ * @typedef {import('../image/parsers/exif.js').ExifValue} ExifValue
+ */
+
+const FILE_LONG_DESC = 'tests/image-testfiles/long_description.jpg'
+
+describe('bitjs.image.parsers.JpegParser', () => {
+  it('extracts Exif and SOF', async () => {
+    const nodeBuf = fs.readFileSync(FILE_LONG_DESC);
+    const ab = nodeBuf.buffer.slice(nodeBuf.byteOffset, nodeBuf.byteOffset + nodeBuf.length);
+
+    /** @type {Map<number, ExifValue} */
+    let exif;
+    /** @type {JpegStartOfFrame} */
+    let sof;
+
+    const parser = new JpegParser(ab)
+        .onApp1Exif(evt => { exif = evt.exifValueMap })
+        .onStartOfFrame(evt => { sof = evt.startOfFrame });
+    await parser.start();
+
+    const descVal = exif.get(ExifTagNumber.IMAGE_DESCRIPTION);
+    expect(descVal.dataFormat).equals(ExifDataFormat.ASCII_STRING);
+
+    const LONG_DESC = 'Operation Mountain Viper put the soldiers of A Company, 2nd Battalion 22nd '
+      + 'Infantry Division, 10th Mountain in the Afghanistan province of Daychopan to search for '
+      + 'Taliban and or weapon caches that could be used against U.S. and allied forces. Soldiers '
+      + 'quickly walk to the ramp of the CH-47 Chinook cargo helicopter that will return them to '
+      + 'Kandahar Army Air Field.  (U.S. Army photo by Staff Sgt. Kyle Davis) (Released)';
+    expect(descVal.stringValue).equals(LONG_DESC);
+    expect(exif.get(ExifTagNumber.EXIF_IMAGE_HEIGHT).numericalValue).equals(sof.imageHeight);
+    expect(exif.get(ExifTagNumber.EXIF_IMAGE_WIDTH).numericalValue).equals(sof.imageWidth);
+  });
+});