Refactor: Group mp4 and heic with other offset-based types (#28)

* Refactor: Group mp4 and heic with other offset-based types

Moves the `mp4` and `heic` cases in the `get` method to group them with other file types that use an `offset` match type. This change improves code readability and organization without altering functionality.

* feat: Use byRange matching for mp4 and heic

Moves `FileMagicNumberType.mp4` and `FileMagicNumberType.heic` to use the `byRange` matching strategy instead of `exact`.

This change groups them with other formats like `webp`, `wav`, and `avi` that already use range-based magic number matching.

* feat: Add test case for combined file types

Adds a new test to verify that `detectFileTypeFromBytes` correctly identifies a file type based on its initial magic number, even when it contains another file type embedded within it.

Specifically, the test uses a byte slice representing a PDF that contains a JP2 file signature and confirms that it is correctly detected as a PDF.

* feat: Add test case for combined file types

Adds a new test to verify that `detectFileTypeFromBytes` correctly identifies a file type based on its initial magic number, even when it contains another file type embedded within it.

Specifically, the test uses a byte slice representing a PDF that contains a JP2 file signature and confirms that it is correctly detected as a PDF.

* fix: Correctly identify PDFs containing JP2 images

Bumps the version to 1.4.1.

This patch addresses an issue where a PDF file containing a JPEG 2000 (JP2) image was incorrectly identified as a JP2 file.

Changes include:
- Corrected the file type detection logic to properly distinguish between a standalone JP2 file and a PDF embedding a JP2.
- Added a new test case to verify the fix and prevent future regressions for PDFs that contain other file types.

* Fix: Update CHANGELOG for 1.4.1

Adds the issue number to the changelog entry for version 1.4.1, referencing the fix for an issue where a PDF containing a JP2 image was incorrectly identified as a JP2 file.

Author: daniJimen

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.4.1
+* Fixed an error that confused a PDF with a JP2 image inside, with a JP2 file [#27](https://github.com/vicajilau/file_magic_number/issues/27).
+* Added new test about pdfs with another files inside (ej: pdfs with jp2)
+
 ## 1.4.0
 * Fixed an issue where JPEG files were detected as TIFF files [#17](https://github.com/vicajilau/file_magic_number/issues/17).
 * Added webp support.

lib/src/file_magic_number_match_type.dart

@@ -19,14 +19,14 @@ enum FileMagicNumberMatchType {
   /// This method is used internally by the library during file type detection.
   static FileMagicNumberMatchType get(FileMagicNumberType type) {
     switch (type) {
-      case FileMagicNumberType.mp4:
-      case FileMagicNumberType.heic:
       case FileMagicNumberType.pdf:
         return offset;
       case FileMagicNumberType.webp:
       case FileMagicNumberType.wav:
       case FileMagicNumberType.avi:
         return byRange;
+      case FileMagicNumberType.mp4:
+      case FileMagicNumberType.heic:
       default:
         return exact;
     }

pubspec.yaml

@@ -1,6 +1,6 @@
 name: file_magic_number
 description: "A Flutter package to detect file types based on their magic number instead of MIME types. Supports Flutter on mobile, desktop, and web without native code."
-version: 1.4.0
+version: 1.4.1
 homepage: https://github.com/vicajilau/file_magic_number
 
 environment:

test/file_magic_number_bytes_test.dart

@@ -90,6 +90,51 @@ void main() {
       expect(result, FileMagicNumberType.wav);
     });
 
+    test('Detects combined files (e.g., PDF containing a JP2)', () {
+      // A PDF file can contain other file types. The detection should identify
+      // it as PDF based on the initial bytes, not the embedded content.
+      // PDF magic number: %PDF (0x25 0x50 0x44 0x46)
+      // JP2 magic number: ....jP J.. (0x00 0x00 0x00 0x0C 0x6A 0x50 0x20 0x20 0x0D 0x0A)
+      final bytes = Uint8List.fromList([
+        0x25, 0x50, 0x44, 0x46, // PDF header
+        0x2D, 0x31, 0x2E, 0x37, // PDF version
+        0x0A, 0x25, 0xC4, 0xE5, 0xF2, 0xE5, 0xEB, 0xA7, // Some more PDF data
+        0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20, 0x20, 0x0D, 0x0A // Embedded JP2 signature
+      ]);
+      final result = FileMagicNumber.detectFileTypeFromBytes(bytes);
+      expect(result, FileMagicNumberType.pdf);
+    });
+
+    test('Detects combined files (e.g., PDF containing an image)', () {
+      // A PDF file can contain other file types. The detection should identify
+      // it as PDF based on the initial bytes, not the embedded content.
+      // PDF magic number: %PDF (0x25 0x50 0x44 0x46)
+      // PNG magic number: 0x89 0x50 0x4E 0x47
+      final bytes = Uint8List.fromList([
+        0x25, 0x50, 0x44, 0x46, // PDF header
+        0x2D, 0x31, 0x2E, 0x37, // PDF version
+        0x0A, 0x31, 0x20, 0x30, 0x20, 0x6F, 0x62, 0x6A, // Some PDF objects
+        0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A // Embedded PNG signature
+      ]);
+      final result = FileMagicNumber.detectFileTypeFromBytes(bytes);
+      expect(result, FileMagicNumberType.pdf);
+    });
+
+    test('Detects combined files (e.g., PDF containing an MP4)', () {
+      // A PDF file can contain other file types. The detection should identify
+      // it as PDF based on the initial bytes, not the embedded content.
+      // PDF magic number: %PDF (0x25 0x50 0x44 0x46)
+      // MP4 magic number (ftypisom): 0x66 0x74 0x79 0x70 0x69 0x73 0x6F 0x6D
+      final bytes = Uint8List.fromList([
+        0x25, 0x50, 0x44, 0x46, // PDF header
+        0x2D, 0x31, 0x2E, 0x37, // PDF version
+        0x0A, 0x31, 0x20, 0x30, 0x20, 0x6F, 0x62, 0x6A, // Some PDF objects
+        0x66, 0x74, 0x79, 0x70, 0x69, 0x73, 0x6F, 0x6D // Embedded MP4 signature
+      ]);
+      final result = FileMagicNumber.detectFileTypeFromBytes(bytes);
+      expect(result, FileMagicNumberType.pdf);
+    });
+
     test('Detects WebP file', () {
       // RIFF....WEBP (offset 0: "RIFF", offset 8: "WEBP")
       final bytes = Uint8List.fromList([