Lower minimum Flutter SDK floor to 3.24.0 (real API boundary)

[alexey-pelykh]

Context

The plugin currently requires flutter: ">=3.29.2" and sdk: ^3.7.0. This was set to avoid Impeller rendering bugs (black screens on MediaTek/PowerVR GPUs) present in Flutter 3.27.x. However, a code audit shows the actual API floor is Flutter 3.24.0 (Dart 3.5).

Related:

• Support for Flutter version 3.27 #60 — community request to support Flutter 3.27
• (chore) flutter: downgrade to 3.27.0 #61 — PR to downgrade to Flutter 3.27.0
• Black screen #39 — black screen reports
• Black screen on Android 14/15 despite camera detection and initialization (Flutter 3.38.x) #75 — black screen on Android 14/15

Analysis

The plugin's hard API dependency is TextureRegistry.SurfaceProducer and TextureRegistry.SurfaceProducer.Callback, which became stable in Flutter 3.24. No Dart 3.7-only language features or Flutter 3.29-only APIs are used anywhere in the codebase.

The 3.29.2 constraint was purely about Impeller runtime behavior, not API compatibility. But Impeller's impact is version-dependent — and for most versions below 3.27, Impeller wasn't even the default on Android:

Flutter Version	Impeller on Android	Black Screen Risk	Workaround Needed
3.24.0 – 3.26.x	Not default	None	None
3.27.0 – 3.28.x	Default (Vulkan)	High on MediaTek/PowerVR	Disable Impeller via manifest
3.29.0 – 3.29.1	Default with GLES fallback	Low	None (but crash on API < 29)
3.29.2+	Default with GLES fallback + crash fix	None	None

Enforcing 3.29.2 excludes users on 3.24–3.26 who would have zero issues, and users on 3.27–3.28 who have a simple workaround.

Proposed Change

environment:
  sdk: ">=3.5.0 <4.0.0"
  flutter: ">=3.24.0"

Add a README section:

Flutter 3.29.2+ is strongly recommended. Flutter 3.27–3.28 enabled Impeller by default on Android, which causes black screens on some devices (MediaTek/PowerVR GPUs). This was fixed in Flutter 3.29.0 with automatic GLES fallback (and a crash fix in 3.29.2). If you use Flutter 3.27.x–3.28.x and experience a black screen, disable Impeller:

<meta-data android:name="io.flutter.embedding.android.EnableImpeller" android:value="false" />

Flutter 3.24–3.26 users are unaffected (Impeller was not default on Android).

Rationale

• The official camera plugin enforces 3.29, but that's Google's choice with Google's support resources. A community plugin benefits more from wider adoption.
• The Impeller issue is a Flutter engine concern, not a plugin bug. Documenting it is appropriate; enforcing it at the SDK floor is not.
• Directly unblocks Support for Flutter version 3.27 #60 and supersedes PR (chore) flutter: downgrade to 3.27.0 #61 (which targeted 3.27.0).