chore: import upstream snapshot with attribution

tools/ui/tests/unit/jpeg-orientation.test.ts

@@ -0,0 +1,100 @@
+import { describe, expect, it } from 'vitest';
+import { getJpegOrientationFromDataURL, isJpegMimeType } from '$lib/utils/jpeg-orientation';
+
+// Builds the TIFF payload of an APP1 segment holding a single IFD0 entry
+function buildTiff(littleEndian: boolean, tag: number, value: number): number[] {
+	const u16 = (v: number) => (littleEndian ? [v & 0xff, v >> 8] : [v >> 8, v & 0xff]);
+	const u32 = (v: number) =>
+		littleEndian
+			? [v & 0xff, (v >> 8) & 0xff, (v >> 16) & 0xff, (v >> 24) & 0xff]
+			: [(v >> 24) & 0xff, (v >> 16) & 0xff, (v >> 8) & 0xff, v & 0xff];
+
+	return [
+		...(littleEndian ? [0x49, 0x49] : [0x4d, 0x4d]),
+		...u16(42),
+		...u32(8),
+		...u16(1),
+		...u16(tag),
+		...u16(3),
+		...u32(1),
+		// SHORT value sits left justified in the 4 byte value field
+		...u16(value),
+		...u16(0),
+		...u32(0)
+	];
+}
+
+// Wraps a TIFF payload into a complete minimal JPEG data URL
+function buildJpegDataURL(tiff: number[] | null, prependApp0 = false): string {
+	const bytes: number[] = [0xff, 0xd8];
+
+	if (prependApp0) {
+		// JFIF APP0 segment, irrelevant content the parser walks over
+		bytes.push(0xff, 0xe0, 0x00, 0x07, 0x4a, 0x46, 0x49, 0x46, 0x00);
+	}
+
+	if (tiff) {
+		const payload = [0x45, 0x78, 0x69, 0x66, 0x00, 0x00, ...tiff];
+		const length = payload.length + 2;
+		bytes.push(0xff, 0xe1, length >> 8, length & 0xff, ...payload);
+	}
+
+	// SOS marker terminates the metadata scan
+	bytes.push(0xff, 0xda, 0x00, 0x02);
+
+	return `data:image/jpeg;base64,${btoa(String.fromCharCode(...bytes))}`;
+}
+
+describe('getJpegOrientationFromDataURL', () => {
+	it('returns the orientation from a little endian EXIF block', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(buildTiff(true, 0x0112, 6)))).toBe(6);
+	});
+
+	it('returns the orientation from a big endian EXIF block', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(buildTiff(false, 0x0112, 8)))).toBe(8);
+	});
+
+	it('walks over a leading APP0 segment', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(buildTiff(true, 0x0112, 3), true))).toBe(
+			3
+		);
+	});
+
+	it('returns 1 when the EXIF block holds no orientation tag', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(buildTiff(true, 0x0100, 6)))).toBe(1);
+	});
+
+	it('returns 1 when the orientation value is out of range', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(buildTiff(true, 0x0112, 9)))).toBe(1);
+	});
+
+	it('returns 1 when the JPEG has no APP1 segment', () => {
+		expect(getJpegOrientationFromDataURL(buildJpegDataURL(null, true))).toBe(1);
+	});
+
+	it('returns 1 for a payload that is not a JPEG', () => {
+		const png = btoa(String.fromCharCode(0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a));
+		expect(getJpegOrientationFromDataURL(`data:image/png;base64,${png}`)).toBe(1);
+	});
+
+	it('returns 1 for a truncated payload', () => {
+		const truncated = btoa(String.fromCharCode(0xff, 0xd8, 0xff));
+		expect(getJpegOrientationFromDataURL(`data:image/jpeg;base64,${truncated}`)).toBe(1);
+	});
+
+	it('returns 1 for a malformed data URL', () => {
+		expect(getJpegOrientationFromDataURL('not a data url')).toBe(1);
+	});
+});
+
+describe('isJpegMimeType', () => {
+	it('matches both JPEG MIME variants', () => {
+		expect(isJpegMimeType('image/jpeg')).toBe(true);
+		expect(isJpegMimeType('image/jpg')).toBe(true);
+	});
+
+	it('rejects other image MIME types', () => {
+		expect(isJpegMimeType('image/png')).toBe(false);
+		expect(isJpegMimeType('image/webp')).toBe(false);
+	});
+});