Add needRotate for Size

library/lib/src/decoder/impl/jpeg_decoder.dart

@@ -1,3 +1,4 @@
+import 'package:collection/collection.dart';
 import 'package:image_size_getter/image_size_getter.dart';
 import 'package:image_size_getter/src/entity/block_entity.dart';
 
@@ -17,6 +18,7 @@ class JpegDecoder extends BaseDecoder with SimpleTypeValidator {
   Size getSize(ImageInput input) {
     int start = 2;
     BlockEntity? block;
+    var orientation = 1;
 
     while (true) {
       block = _getBlockSync(input, start);
@@ -25,26 +27,41 @@ class JpegDecoder extends BaseDecoder with SimpleTypeValidator {
         throw Exception('Invalid jpeg file');
       }
 
+      // Check for App1 block
+      if (block.type == 0xE1) {
+        final app1BlockData = input.getRange(
+          start,
+          block.start + block.length,
+        );
+        final exifOrientation = _getOrientation(app1BlockData);
+        if (exifOrientation != null) {
+          orientation = exifOrientation;
+          print('Orientation: $orientation');
+        }
+      }
+
       if (block.type == 0xC0 || block.type == 0xC2) {
         final widthList = input.getRange(start + 7, start + 9);
         final heightList = input.getRange(start + 5, start + 7);
-        return _getSize(widthList, heightList);
+        return _getSize(widthList, heightList, orientation);
       } else {
         start += block.length;
       }
     }
   }
 
-  Size _getSize(List<int> widthList, List<int> heightList) {
+  Size _getSize(List<int> widthList, List<int> heightList, int orientation) {
     final width = convertRadix16ToInt(widthList);
     final height = convertRadix16ToInt(heightList);
-    return Size(width, height);
+    final needRotate = [5, 6, 7, 8].contains(orientation);
+    return Size(width, height, needRotate: needRotate);
   }
 
   @override
   Future<Size> getSizeAsync(AsyncImageInput input) async {
     int start = 2;
     BlockEntity? block;
+    var orientation = 1;
 
     while (true) {
       block = await _getBlockAsync(input, start);
@@ -53,59 +70,139 @@ class JpegDecoder extends BaseDecoder with SimpleTypeValidator {
         throw Exception('Invalid jpeg file');
       }
 
+      if (block.type == 0xE1) {
+        final app1BlockData = await input.getRange(
+          start,
+          block.start + block.length,
+        );
+        final exifOrientation = _getOrientation(app1BlockData);
+        if (exifOrientation != null) {
+          orientation = exifOrientation;
+          print('Orientation: $orientation');
+        }
+      }
+
       if (block.type == 0xC0 || block.type == 0xC2) {
         final widthList = await input.getRange(start + 7, start + 9);
         final heightList = await input.getRange(start + 5, start + 7);
-        return _getSize(widthList, heightList);
+        final orientation = (await input.getRange(start + 9, start + 10))[0];
+        return _getSize(widthList, heightList, orientation);
       } else {
         start += block.length;
       }
     }
   }
 
-  BlockEntity? _getBlockSync(ImageInput input, int blackStart) {
+  BlockEntity? _getBlockSync(ImageInput input, int blockStart) {
     try {
-      final blockInfoList = input.getRange(blackStart, blackStart + 4);
+      final blockInfoList = input.getRange(blockStart, blockStart + 4);
 
       if (blockInfoList[0] != 0xFF) {
         return null;
       }
 
-      final radix16List = input.getRange(blackStart + 2, blackStart + 4);
+      final blockSizeList = input.getRange(blockStart + 2, blockStart + 4);
 
-      return _createBlock(radix16List, blackStart, blockInfoList);
+      return _createBlock(blockSizeList, blockStart, blockInfoList);
     } catch (e) {
       return null;
     }
   }
 
   Future<BlockEntity?> _getBlockAsync(
-      AsyncImageInput input, int blackStart) async {
+      AsyncImageInput input, int blockStart) async {
     try {
-      final blockInfoList = await input.getRange(blackStart, blackStart + 4);
+      final blockInfoList = await input.getRange(blockStart, blockStart + 4);
 
       if (blockInfoList[0] != 0xFF) {
         return null;
       }
 
-      final sizeList = await input.getRange(blackStart + 2, blackStart + 4);
+      final blockSizeList =
+          await input.getRange(blockStart + 2, blockStart + 4);
 
-      return _createBlock(sizeList, blackStart, blockInfoList);
+      return _createBlock(blockSizeList, blockStart, blockInfoList);
     } catch (e) {
       return null;
     }
   }
 
   BlockEntity _createBlock(
-      List<int> sizeList, int blackStart, List<int> blockInfoList) {
-    final blockLength = convertRadix16ToInt(sizeList) + 2;
+    List<int> sizeList,
+    int blockStart,
+    List<int> blockInfoList,
+  ) {
+    final blockLength =
+        convertRadix16ToInt(sizeList) + 2; // +2 for 0xFF and TYPE
     final typeInt = blockInfoList[1];
 
-    return BlockEntity(typeInt, blockLength);
+    return BlockEntity(typeInt, blockLength, blockStart);
   }
 
   @override
   SimpleFileHeaderAndFooter get simpleFileHeaderAndFooter => _JpegInfo();
+
+  int? _getOrientation(List<int> app1blockData) {
+    // About EXIF, See: https://www.media.mit.edu/pia/Research/deepview/exif.html#orientation
+
+    // app1 block buffer:
+    // header (2 bytes)
+    // length (2 bytes)
+    // exif header (6 bytes)
+    // exif for little endian (2 bytes), 0x4d4d is for big endian, 0x4949 is for little endian
+    // tag mark (2 bytes)
+    // offset first IFD (4 bytes)
+    // IFD data :
+    // number of entries (2 bytes)
+    // for each entry:
+    //   exif tag (2 bytes)
+    //   data format (2 bytes), 1 = unsigned byte, 2 = ascii, 3 = unsigned short, 4 = unsigned long, 5 = unsigned rational, 6 = signed byte, 7 = undefined, 8 = signed short, 9 = signed long, 10 = signed rational
+    //   number of components (4 bytes)
+    //   value (4 bytes)
+    //   padding (0 ~ 3 bytes, depends on data format)
+    // So, the IFD data starts at offset 14.
+
+    // Check app1 block exif info is valid
+    if (app1blockData.length < 14) {
+      return null;
+    }
+
+    // Check app1 block exif info is valid
+    final exifIdentifier = app1blockData.sublist(4, 10);
+
+    final listEquality = ListEquality();
+
+    if (!listEquality
+        .equals(exifIdentifier, [0x45, 0x78, 0x69, 0x66, 0x00, 0x00])) {
+      return null;
+    }
+
+    final littleEndian = app1blockData[10] == 0x49;
+
+    int getNumber(int start, int end) {
+      final numberList = app1blockData.sublist(start, end);
+      return convertRadix16ToInt(numberList, reverse: littleEndian);
+    }
+
+    // Get idf byte
+    var idf0Start = 18;
+    final tagEntryCount = getNumber(idf0Start, idf0Start + 2);
+
+    var currentIndex = idf0Start + 2;
+
+    for (var i = 0; i < tagEntryCount; i++) {
+      final tagType = getNumber(currentIndex, currentIndex + 2);
+
+      if (tagType == 0x0112) {
+        return getNumber(currentIndex + 8, currentIndex + 10);
+      }
+
+      // every tag length is 0xC bytes
+      currentIndex += 0xC;
+    }
+
+    return null;
+  }
 }
 
 class _JpegInfo with SimpleFileHeaderAndFooter {

library/lib/src/entity/block_entity.dart

@@ -1,16 +1,19 @@
 /// The block of jpeg format.
 class BlockEntity {
   /// The block of jpeg format.
-  BlockEntity(this.type, this.length);
+  BlockEntity(this.type, this.length, this.start);
 
   /// The type of the block.
   int type;
 
   /// The length of the block.
   int length;
 
+  /// Start of offset
+  int start;
+
   /// Error block.
-  static BlockEntity error = BlockEntity(-1, -1);
+  static BlockEntity error = BlockEntity(-1, -1, -1);
 
   @override
   String toString() {

library/lib/src/entity/size.dart

@@ -7,21 +7,44 @@ import 'package:hashcodes/hashcodes.dart';
 /// The size contains [width] and [height].
 ///
 /// {@endtemplate}
+///
+/// ---
+///
+/// {@macro image_size_getter.Size.needToRotate}
 class Size {
-  const Size(this.width, this.height);
+  /// {@macro image_size_getter.Size}
+  ///
+  /// ---
+  ///
+  /// {@macro image_size_getter.Size.needToRotate}
+  const Size(
+    this.width,
+    this.height, {
+    this.needRotate = false,
+  });
 
   /// The width of the media.
   final int width;
 
   /// The height of the media.
   final int height;
 
+  /// {@template image_size_getter.Size.needToRotate}
+  ///
+  /// If the [needRotate] is true,
+  /// the [width] and [height] need to be swapped when using.
+  ///
+  /// Such as, orientation value of the jpeg format is [5, 6, 7, 8].
+  ///
+  /// {@endtemplate}
+  final bool needRotate;
+
   /// The [width] is zero and [height] is zero.
   static Size zero = Size(0, 0);
 
   @override
   String toString() {
-    return "Size( $width, $height )";
+    return "Size( $width, $height, needRotate: $needRotate )";
   }
 
   @override
@@ -35,8 +58,11 @@ class Size {
     }
 
     if (obj is Size) {
-      return width == obj.width && height == obj.height;
+      return width == obj.width &&
+          height == obj.height &&
+          needRotate == obj.needRotate;
     }
+
     return false;
   }
 

library/test/image_size_getter_test.dart

@@ -55,6 +55,23 @@ void main() {
       assert(decoder.isValid(input));
       expect(decoder.getSize(input), Size(256, 256));
     });
+
+    test('Test have orientation jpeg', () {
+      final orientation3 = File('../example/asset/have_orientation_exif_3.jpg');
+
+      const JpegDecoder decoder = JpegDecoder();
+      final input = FileInput(orientation3);
+
+      assert(decoder.isValid(input));
+      expect(decoder.getSize(input), Size(533, 799));
+
+      final orientation6 = File('../example/asset/have_orientation_exif_6.jpg');
+      final input2 = FileInput(orientation6);
+
+      assert(decoder.isValid(input2));
+      final size = decoder.getSize(input2);
+      expect(size, Size(3264, 2448, needRotate: true));
+    });
   });
 
   group('Test get size.', () {