fix: use kCGImageSourceCreateThumbnailFromImageAlways for full-res orientation fix

This reverts commit 5d55ed4a6e.

lib/src/darwin/native.dart

@@ -4,6 +4,7 @@ import 'dart:typed_data';
 import 'package:ffi/ffi.dart';
 import 'package:objective_c/objective_c.dart';
 import 'package:platform_image_converter/src/darwin/bindings.g.dart';
+import 'package:platform_image_converter/src/darwin/orientation_bindings.dart';
 import 'package:platform_image_converter/src/image_conversion_exception.dart';
 import 'package:platform_image_converter/src/image_converter_platform_interface.dart';
 import 'package:platform_image_converter/src/output_format.dart';
@@ -18,10 +19,13 @@ import 'package:platform_image_converter/src/output_resize.dart';
 /// - Supports all major image formats (JPEG, PNG, HEIC, WebP, etc.)
 /// - Uses CoreFoundation and CoreGraphics for efficient processing
 /// - Memory-safe with proper resource cleanup
+/// - Applies EXIF orientation correction: bakes rotation/flip into pixels so
+///   output images display upright regardless of EXIF tag presence.
 ///
 /// **API Stack:**
 /// - `CGImageSourceCreateWithData`: Decode input image
-/// - `CGImageSourceCreateImageAtIndex`: Extract CGImage
+/// - `CGImageSourceCopyPropertiesAtIndex`: Read EXIF orientation tag
+/// - `CGImageSourceCreateThumbnailAtIndex`: Create orientation-corrected image
 /// - `CGBitmapContextCreate`: Create a canvas for resizing
 /// - `CGContextDrawImage`: Draw and scale the image
 /// - `CGBitmapContextCreateImage`: Extract resized CGImage
@@ -47,6 +51,8 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
     CFDataRef? cfData;
     CGImageSourceRef? imageSource;
     CGImageRef? originalImage;
+    // Orientation-corrected image (owned, non-null only when correction applied).
+    CGImageRef? orientedImage;
     CGImageRef? imageToEncode;
     CFMutableDataRef? outputData;
     CGImageDestinationRef? destination;
@@ -76,17 +82,35 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
         throw const ImageDecodingException();
       }
 
-      final originalWidth = CGImageGetWidth(originalImage);
-      final originalHeight = CGImageGetHeight(originalImage);
+      // CGImageSourceCreateImageAtIndex returns raw sensor pixels without
+      // applying the EXIF Orientation tag. iPhone photos captured in portrait
+      // are stored with orientation=6 (Right/90° CW), causing the decoded
+      // pixels to appear rotated. We correct this by reading the orientation
+      // and, when it is not Up (1), using CGImageSourceCreateThumbnailAtIndex
+      // with kCGImageSourceCreateThumbnailWithTransform=true, which bakes the
+      // rotation/flip into the pixel data before we encode.
+      final sourceOrientation = _readOrientationFromSource(imageSource);
+      if (sourceOrientation != 1) {
+        final srcW = CGImageGetWidth(originalImage);
+        final srcH = CGImageGetHeight(originalImage);
+        final maxEdge = srcW > srcH ? srcW : srcH;
+        orientedImage = _createOrientedImage(imageSource, maxEdge);
+      }
+
+      // Use the orientation-corrected image as the base for all further ops.
+      final baseImage = orientedImage ?? originalImage;
+
+      final originalWidth = CGImageGetWidth(baseImage);
+      final originalHeight = CGImageGetHeight(baseImage);
       final (newWidth, newHeight) = resizeMode.calculateSize(
         originalWidth,
         originalHeight,
       );
 
       if (newWidth == originalWidth && newHeight == originalHeight) {
-        imageToEncode = originalImage;
+        imageToEncode = baseImage;
       } else {
-        imageToEncode = _resizeImage(originalImage, newWidth, newHeight);
+        imageToEncode = _resizeImage(baseImage, newWidth, newHeight);
       }
 
       if (imageToEncode == nullptr) {
@@ -160,9 +184,16 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
       if (inputPtr != null) calloc.free(inputPtr);
       if (cfData != null) CFRelease(cfData.cast());
       if (imageSource != null) CFRelease(imageSource.cast());
-      if (imageToEncode != null && imageToEncode != originalImage) {
+      // Release imageToEncode only if it is a distinct CGImage (i.e. came from
+      // _resizeImage). Do not double-release if it was aliased to baseImage.
+      if (imageToEncode != null &&
+          imageToEncode != orientedImage &&
+          imageToEncode != originalImage) {
         CFRelease(imageToEncode.cast());
       }
+      // orientedImage is an independent retained CGImageRef created by
+      // _createOrientedImage; release it after imageToEncode.
+      if (orientedImage != null) CFRelease(orientedImage.cast());
       if (originalImage != null) CFRelease(originalImage.cast());
       if (outputData != null) CFRelease(outputData.cast());
       if (destination != null) CFRelease(destination.cast());
@@ -212,8 +243,16 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
         );
       }
 
-      final bitsPerComponent = CGImageGetBitsPerComponent(originalImage);
-      final bitmapInfo = CGImageGetBitmapInfo(originalImage);
+      // FIX: Always use 8 bits/component for the output bitmap context.
+      // The source may be 16bpc (e.g. 16-bit PNGs), which CGBitmapContextCreate
+      // rejects for certain alpha/byte-order combinations, returning NULL.
+      // Since the output is always 8-bit (JPEG/PNG for display), 8bpc is correct.
+      const bitsPerComponent = 8;
+
+      // We cannot reuse the source image's bitmapInfo because it may contain
+      // 16-bit byte-order flags (e.g. kCGImageByteOrder16Little = 0x1000)
+      // that are incompatible with 8bpc, causing CGBitmapContextCreate to fail.
+      const bitmapInfo = 1; // kCGImageAlphaPremultipliedLast
 
       context = CGBitmapContextCreate(
         nullptr,
@@ -251,7 +290,96 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
       }
       return resizedImage;
     } finally {
-      if (context != null) CFRelease(context.cast());
+      // FIX: Check both Dart null AND FFI nullptr before releasing.
+      // CFRelease(NULL) is a fatal error in CoreFoundation (brk #0x1).
+      // The Dart variable `context` is non-null once assigned, but the
+      // native pointer may be nullptr if CGBitmapContextCreate failed.
+      if (context != null && context != nullptr) {
+        CFRelease(context.cast());
       }
     }
+  }
+
+  /// Reads the EXIF/CGImage orientation tag from the first image in [src].
+  ///
+  /// Orientation values match CGImagePropertyOrientation:
+  /// - 1 (Up) = normal, no correction needed
+  /// - 6 (Right) = 90° CW — most common for portrait iPhone photos
+  /// - 3 (Down) = 180°
+  /// - 8 (Left) = 90° CCW
+  ///
+  /// Returns 1 if the tag is absent, unreadable, or the image is already upright.
+  int _readOrientationFromSource(CGImageSourceRef src) {
+    CFDictionaryRef? props;
+    try {
+      props = CGImageSourceCopyPropertiesAtIndex(src, 0, nullptr);
+      if (props == nullptr) return 1;
+      final orientRef = CFDictionaryGetValue(
+        props,
+        kCGImagePropertyOrientation.cast(),
+      );
+      if (orientRef == nullptr) return 1;
+      return using((arena) {
+        final intPtr = arena<Int32>();
+        // kCFNumberInt32Type = 9
+        final ok = CFNumberGetValue(orientRef, 9, intPtr.cast());
+        return ok ? intPtr.value : 1;
+      });
+    } finally {
+      if (props != null && props != nullptr) CFRelease(props.cast());
+    }
+  }
+
+  /// Creates a new CGImageRef with EXIF orientation baked into pixel data.
+  ///
+  /// Uses [CGImageSourceCreateThumbnailAtIndex] with
+  /// `kCGImageSourceCreateThumbnailWithTransform = true`, which instructs
+  /// ImageIO to apply the EXIF rotation/flip before returning the image.
+  /// [maxPixelSize] should be the longest edge of the source image so the
+  /// returned image is full resolution (or at least as large as the source).
+  ///
+  /// Returns a retained [CGImageRef] that the caller must [CFRelease],
+  /// or `null` if the thumbnail could not be created.
+  CGImageRef? _createOrientedImage(CGImageSourceRef src, int maxPixelSize) {
+    return using((arena) {
+      final keys = arena<Pointer<Void>>(3);
+      final values = arena<Pointer<Void>>(3);
+
+      // kCGImageSourceCreateThumbnailFromImageAlways = kCFBooleanTrue
+      // MUST use "Always" not "IfAbsent": iPhone HEIC files embed a tiny
+      // ~240x320 JPEG thumbnail. "IfAbsent" returns that embedded thumbnail
+      // instead of decoding the full image, giving very low-resolution output.
+      keys[0] = kCGImageSourceCreateThumbnailFromImageAlways.cast();
+      values[0] = 1.toNSNumber().ref.retainAndAutorelease().cast();
+
+      // kCGImageSourceCreateThumbnailWithTransform = kCFBooleanTrue
+      // This is the key that bakes the EXIF rotation into pixel data.
+      keys[1] = kCGImageSourceCreateThumbnailWithTransform.cast();
+      values[1] = 1.toNSNumber().ref.retainAndAutorelease().cast();
+
+      // kCGImageSourceThumbnailMaxPixelSize = longest source edge
+      // Setting this to the source's longest edge returns full resolution.
+      keys[2] = kCGImageSourceThumbnailMaxPixelSize.cast();
+      values[2] = maxPixelSize.toNSNumber().ref.retainAndAutorelease().cast();
+
+      final keyCallbacks = arena<CFDictionaryKeyCallBacks>();
+      final valueCallbacks = arena<CFDictionaryValueCallBacks>();
+      final opts = CFDictionaryCreate(
+        kCFAllocatorDefault,
+        keys.cast(),
+        values.cast(),
+        3,
+        keyCallbacks,
+        valueCallbacks,
+      );
+      if (opts == nullptr) return null;
+
+      try {
+        final thumb = CGImageSourceCreateThumbnailAtIndex(src, 0, opts);
+        return (thumb == nullptr) ? null : thumb;
+      } finally {
+        CFRelease(opts.cast());
+      }
+    });
+  }
 }

lib/src/darwin/orientation_bindings.dart

@@ -0,0 +1,109 @@
+// Hand-written FFI bindings for EXIF/CGImageSource orientation APIs.
+//
+// These supplement the auto-generated bindings.g.dart without modifying it.
+// They bind the CoreFoundation / ImageIO symbols needed to read and apply
+// the EXIF orientation tag when converting images on Darwin (iOS/macOS).
+//
+// Relevant Apple documentation:
+// - CGImageSourceCopyPropertiesAtIndex:
+//   https://developer.apple.com/documentation/imageio/cgimagesourcecopypropertiesatindex
+// - CGImageSourceCreateThumbnailAtIndex:
+//   https://developer.apple.com/documentation/imageio/cgimagesourcecreatethumbnailatindex
+// - kCGImagePropertyOrientation:
+//   https://developer.apple.com/documentation/imageio/kcgimagepropertyorientation
+// - kCGImageSourceCreateThumbnailWithTransform:
+//   https://developer.apple.com/documentation/imageio/kcgimagesourcecreatethumbnailwithtransform
+
+// ignore_for_file: type=lint, non_constant_identifier_names
+import 'dart:ffi' as ffi;
+
+import 'package:objective_c/objective_c.dart' as objc;
+
+import 'bindings.g.dart';
+
+// ─── CGImageSource properties ────────────────────────────────────────────────
+
+/// Copies the properties dictionary for the image at [index] inside [isrc].
+///
+/// Returns a retained `CFDictionaryRef` — the caller must `CFRelease` it.
+/// Returns `nullptr` if the source or image is invalid.
+@ffi.Native<CFDictionaryRef Function(CGImageSourceRef, ffi.Size, CFDictionaryRef)>()
+external CFDictionaryRef CGImageSourceCopyPropertiesAtIndex(
+  CGImageSourceRef isrc,
+  int index,
+  CFDictionaryRef options,
+);
+
+/// Creates an orientation-corrected image for the entry at [index].
+///
+/// With `kCGImageSourceCreateThumbnailWithTransform = kCFBooleanTrue` in
+/// [options], ImageIO bakes the EXIF rotation and/or flip into the returned
+/// pixel data, giving correctly-oriented pixels for any orientation value.
+///
+/// Returns a retained `CGImageRef` — the caller must `CFRelease` it.
+@ffi.Native<CGImageRef Function(CGImageSourceRef, ffi.Size, CFDictionaryRef)>()
+external CGImageRef CGImageSourceCreateThumbnailAtIndex(
+  CGImageSourceRef isrc,
+  int index,
+  CFDictionaryRef options,
+);
+
+// ─── CFDictionary / CFNumber lookup ──────────────────────────────────────────
+
+/// Returns the value associated with [key] in [theDict], or `nullptr`.
+///
+/// The returned pointer is not retained — do not `CFRelease` it.
+@ffi.Native<ffi.Pointer<ffi.Void> Function(CFDictionaryRef, ffi.Pointer<ffi.Void>)>()
+external ffi.Pointer<ffi.Void> CFDictionaryGetValue(
+  CFDictionaryRef theDict,
+  ffi.Pointer<ffi.Void> key,
+);
+
+/// Extracts the numeric value from a `CFNumber` into a native Dart pointer.
+///
+/// [theType] selects the C numeric type; 9 = `kCFNumberSInt32Type` (int32).
+/// Returns `true` on success.
+@ffi.Native<ffi.Bool Function(ffi.Pointer<ffi.Void>, ffi.Int32, ffi.Pointer<ffi.Void>)>()
+external bool CFNumberGetValue(
+  ffi.Pointer<ffi.Void> number,
+  int theType,
+  ffi.Pointer<ffi.Void> valuePtr,
+);
+
+// ─── ImageIO option keys ──────────────────────────────────────────────────────
+
+/// Key: EXIF/CGImage orientation tag in CGImageSource properties dicts.
+///
+/// Value is a `CFNumberRef` (int32) matching `CGImagePropertyOrientation`:
+/// 1=Up, 2=UpMirrored, 3=Down, 4=DownMirrored,
+/// 5=LeftMirrored, 6=Right, 7=RightMirrored, 8=Left.
+@ffi.Native<ffi.Pointer<objc.CFString>>()
+external ffi.Pointer<objc.CFString> kCGImagePropertyOrientation;
+
+/// Key: when `kCFBooleanTrue`, creates a thumbnail from the full image even
+/// when no embedded thumbnail is present.
+@ffi.Native<ffi.Pointer<objc.CFString>>()
+external ffi.Pointer<objc.CFString> kCGImageSourceCreateThumbnailFromImageIfAbsent;
+
+/// Key: when `kCFBooleanTrue`, ALWAYS creates a thumbnail from the full source
+/// image data, ignoring any embedded thumbnail.
+///
+/// **Use this instead of [kCGImageSourceCreateThumbnailFromImageIfAbsent] when
+/// full-resolution output is required.** iPhone HEIC files always contain a
+/// tiny embedded JPEG thumbnail (~240×320). Without this key, ImageIO returns
+/// the embedded thumbnail rather than decoding the full image, producing a very
+/// low-resolution output regardless of [kCGImageSourceThumbnailMaxPixelSize].
+@ffi.Native<ffi.Pointer<objc.CFString>>()
+external ffi.Pointer<objc.CFString> kCGImageSourceCreateThumbnailFromImageAlways;
+
+/// Key: when `kCFBooleanTrue`, rotates/flips the thumbnail to match the EXIF
+/// orientation tag, producing pixel-correct upright image data.
+@ffi.Native<ffi.Pointer<objc.CFString>>()
+external ffi.Pointer<objc.CFString> kCGImageSourceCreateThumbnailWithTransform;
+
+/// Key: maximum pixel size (longest edge) for the thumbnail.
+///
+/// Set this to the source image's longest edge to get full-resolution output
+/// from `CGImageSourceCreateThumbnailAtIndex`.
+@ffi.Native<ffi.Pointer<objc.CFString>>()
+external ffi.Pointer<objc.CFString> kCGImageSourceThumbnailMaxPixelSize;

pubspec.yaml

@@ -1,6 +1,6 @@
 name: platform_image_converter
 description: "A high-performance Flutter plugin for cross-platform image format conversion using native APIs."
-version: 1.0.6
+version: 1.0.7
 homepage: https://github.com/koji-1009/platform_image_converter
 topics:
   - image