chooseFromGallery returns the original library asset (HEIC on iOS) where pickImages re-encoded to JPEG

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issue の種類
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静か
技術スタック
swift, typescript
領域
mobile-dev

調査の方向性

IONCAMRPhotoLibraryService.fetchImage(from:) とその fetchImageURL(for: asset) パスから始め、次に didFinishPicking と thumbnailAsData の分岐を調べます。iOS の動作を Android の onChooseFromGalleryResult および createImageMediaResult と比較します。選択したギャラリーフォーマットの動作が選択した解像度と一貫しており、chooseFromGallery のドキュメントで結果として得られるエンコーディングが説明されていれば完了です。

索引モデルが issue の本文から書いたものです。

説明

Summary

chooseFromGallery returns the original photo-library asset without re-encoding it, so on iOS a normally-shot iPhone photo comes back as HEIC. The deprecated pickImages/getPhoto it replaces always re-encoded to JPEG, so migrating off them is a behaviour change for any app that assumed a browser-renderable format.

This isn't obvious from the docs: ChooseFromGalleryOptions carries a quality field documented as "Only applicable for MediaType.Photo and JPEG format", which reads as though photos come back as JPEG.

Where it happens

iOS — IONCameraLib's IONCAMRPhotoLibraryService.fetchImage(from:) builds its result from fetchImageURL(for: asset), which is asset.requestContentEditingInput { … editingInput?.fullSizeImageURL }. That URL is the original asset in the library; nothing decodes or re-encodes it.

Worth noting this applies to both selection modes, not just allowMultipleSelection: true. didFinishPicking branches on thumbnailAsData rather than on the selection mode:

if self.thumbnailAsData {
    let results = await self.fetchMultipleResult(assetArray)   // original asset URL
    …
} else {
    let item = await self.fetchSingleResult(assetArray.first)  // UIImage → toData()
    …
}

IONCAMRGalleryOptions decodes thumbnailAsData with a default of true, and ChooseFromGalleryOptions in the plugin's TypeScript has no field that maps to it — so a chooseFromGallery call can only ever take the first branch.

Android — ioncamera-android's onChooseFromGalleryResult resolves the picked URI to a file path and passes it to createImageMediaResult, whose bitmap decode/compress feeds only the base64 thumbnail; the result's uri still names the original file. Less visible in practice because Android cameras usually write JPEG, but the same pass-through.

takePhoto is unaffected — UIImage.toData(with:) honours encodingType, which defaults to JPEG.

Why it matters

HEIC uploads fine and then fails to render for most viewers: Chrome and Firefox decode none of it, and server-side sharp's prebuilt libvips ships no HEVC decoder, so thumbnailing fails too. An app that offers "choose from library" and accepts what it gets will store images that a majority of its users see as broken — and the failure lands after upload, where the only remedy is rejecting a photo the user already chose.

Versions: @capacitor/camera 8.2.2, IONCameraLib 1.0.5, ioncamera-android 1.0.2.

Steps to reproduce
  1. On an iPhone with Settings → Camera → Formats → High Efficiency, take a photo.
  2. Call chooseFromGallery({ mediaType: MediaTypeSelection.Photo, includeMetadata: true }) and pick it.
  3. results[0].metadata.format is heic, and uri points at a .HEIC file.

Expected (and what pickImages did): a JPEG.

Possible resolutions

Any one of these would be enough, in rough order of preference:

  1. Give ChooseFromGalleryOptions an encodingType like TakePhotoOptions has, and re-encode to it.
  2. Re-encode gallery picks to JPEG by default, matching the deprecated methods' behaviour.
  3. If pass-through is the intended design, say so in the chooseFromGallery docs and in the deprecation notes on getPhoto/pickImages — the format change is the migration's sharpest edge and currently isn't mentioned.
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TypeScript
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マージ済み PR（30日）
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