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fix: use kCGImageSourceCreateThumbnailFromImageAlways for full-res orientation fix

This commit is contained in:
JohnE 2026-02-20 00:14:25 -08:00
parent 32e37d2b5f
commit 92b967bfc5
2 changed files with 16 additions and 3 deletions
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8
lib/src/darwin/native.dart
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@ -345,9 +345,11 @@ final class ImageConverterDarwin implements ImageConverterPlatform {
final keys = arena<Pointer<Void>>(3);
final values = arena<Pointer<Void>>(3);
// kCGImageSourceCreateThumbnailFromImageIfAbsent = kCFBooleanTrue
// Use 1.toNSNumber() — bool has no toNSNumber() extension; NSNumber(1) = YES.
keys[0] = kCGImageSourceCreateThumbnailFromImageIfAbsent.cast();
// 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

11
lib/src/darwin/orientation_bindings.dart
View File

@ -85,6 +85,17 @@ external ffi.Pointer<objc.CFString> kCGImagePropertyOrientation;
@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>>()