[Android][Impeller OpenGL ES] Gradients rendered incorrectly after Vulkan → OpenGL ES fallback

[Pancreax]

Steps to reproduce

1. Add the code provided in the Code sample section to any widget.
2. Run the app in the Android device.

I was able to reproduce the bug in the device Positivo Q20 with Android 10 and PowerVR IMG8322 GPU.
The bug seems to happen when the fallback from Vulkan to OpenGLES occurs.
It happened running with impeller enabled in Flutter 3.38.3 channel stable and in 3.39.0-1.0.pre-340 channel master.
It did not happen running with Impeller disabled in Flutter 3.38.3 and did not happen in Flutter 3.27.4 independently of Impeller.

This issue might be related to #177873

Expected results

The radial gradient should render correctly.

Actual results

The gradient is rendered incorrectly.

Code sample

Code sample

Just add this in any Widget. In my test, i added as children of the Column in the sample genereted by flutter create:

ShaderMask(
  shaderCallback: (bounds) => RadialGradient(
    stops: const [0, 0.5, 1],
    colors: [Colors.grey[800]!, Colors.grey[800]!.withAlpha(204), Colors.grey[800]!.withAlpha(0)],
  ).createShader(bounds),
  blendMode: BlendMode.srcOver,
  child: Container(height: 200, width: 200, color: Colors.red),
),
CircularProgressIndicator(),

Screenshots or Video

Screenshots / Video demonstration

Expected result.
With Flutter 3.38.3 and Impeller disabled, or with Flutter 3.27.4 (Impeller enabled or disabled has the same result).

impellerDisabled_3_38_3.mov

Actual result with Flutter 3.38.3 and Impeller enabled:

impellerEnabled_3_38_3.mov

Logs

Logs

I believe the relevant detail is that rendering breaks only when Vulkan → OpenGL ES fallback occurs.
If Vulkan is used alone or OpenGL ES is used alone, the issue does not happen.

• Flutter 3.38.3 with Impeller enabled (bad rendering):

Launching lib/main.dart on Positivo Q20 in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk
D/FlutterJNI(10516): Beginning load of flutter...
D/FlutterJNI(10516): flutter (null) was loaded normally!
I/flutter (10516): [IMPORTANT:flutter/shell/platform/android/android_context_vk_impeller.cc(62)] Using the Impeller rendering backend (Vulkan).
I/flutter (10516): [IMPORTANT:flutter/shell/platform/android/android_context_gl_impeller.cc(104)] Using the Impeller rendering backend (OpenGLES).
Connecting to VM Service at ws://127.0.0.1:59868/bbztvVO6O9A=/ws
Connected to the VM Service.
D/        (10516): Gralloc Free  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:157887 line = 2376
D/        (10516): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:157894, sSize:4239360, line = 2270
D/SurfaceCallbackHelper(10516): dispatchSurfaceRedrawNeededAsync, callbacks=[Landroid.view.SurfaceHolder$Callback;@12fd0fa, callbacks.length=1
I/Choreographer(10516): Skipped 237 frames!  The application may be doing too much work on its main thread.
I/Choreographer(10516): Skipped 278 frames!  The application may be doing too much work on its main thread.
D/SurfaceCallbackHelper(10516): mFinishDrawingRunnable, mFinishDrawingCollected=1, mFinishDrawingExpected=1
D/ProfileInstaller(10516): Installing profile for com.example.impeller
D/        (10516): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:157939, sSize:4239360, line = 2270
D/        (10516): Gralloc Register  w:720, h:1560, f:0x1, usage:0xb00, ui64Stamp:157944, sSize:4517888, line = 2270
D/        (10516): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:157954, sSize:4239360, line = 2270

• Flutter 3.38.3 with Impeller disabled (rendering OK):

Launching lib/main.dart on Positivo Q20 in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk
D/FlutterJNI( 9983): Beginning load of flutter...
D/FlutterJNI( 9983): flutter (null) was loaded normally!
I/flutter ( 9983): [IMPORTANT:flutter/shell/common/shell.cc(527)] [Action Required]: Impeller opt-out deprecated.
I/flutter ( 9983):     The application opted out of Impeller by either using the
I/flutter ( 9983):     `--no-enable-impeller` flag or the
I/flutter ( 9983):     `io.flutter.embedding.android.EnableImpeller` `AndroidManifest.xml` entry.
I/flutter ( 9983):     These options are going to go away in an upcoming Flutter release. Remove
I/flutter ( 9983):     the explicit opt-out. If you need to opt-out, please report a bug describing
I/flutter ( 9983):     the issue.
I/flutter ( 9983):
I/flutter ( 9983):     https://github.com/flutter/flutter/issues/new?template=02_bug.yml
I/flutter ( 9983):
Connecting to VM Service at ws://127.0.0.1:59279/hfDmsPCdWsY=/ws
Connected to the VM Service.
I/Choreographer( 9983): Skipped 268 frames!  The application may be doing too much work on its main thread.
D/ProfileInstaller( 9983): Installing profile for com.example.impeller
D/SurfaceCallbackHelper( 9983): mFinishDrawingRunnable, mFinishDrawingCollected=1, mFinishDrawingExpected=1
D/        ( 9983): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:150514, sSize:4239360, line = 2270
D/        ( 9983): Gralloc Register  w:720, h:1560, f:0x1, usage:0xb00, ui64Stamp:150518, sSize:4517888, line = 2270
D/        ( 9983): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:150527, sSize:4239360, line = 2270

• Flutter 3.27.4 with Impeller enabled (rendering OK):

Launching lib/main.dart on Positivo Q20 in debug mode...
Warning: SDK processing. This version only understands SDK XML versions up to 3 but an SDK XML file of version 4 was encountered. This can happen if you use versions of Android Studio and the command-line tools that were released at different times.
✓ Built build/app/outputs/flutter-apk/app-debug.apk
I/flutter (11445): [IMPORTANT:flutter/shell/platform/android/android_context_vk_impeller.cc(60)] Using the Impeller rendering backend (Vulkan).
Connecting to VM Service at ws://127.0.0.1:62100/Aqojj1yiIwI=/ws
Connected to the VM Service.
D/ProfileInstaller(11445): Installing profile for com.example.impeller
I/xample.impelle(11445): Compiler allocated 4181KB to compile void android.view.ViewRootImpl.performTraversals()
D/        (11445): Gralloc Register  w:720, h:1560, f:0x1, usage:0xb00, ui64Stamp:158387, sSize:4517888, line = 2270

Flutter Doctor output

Doctor output

flutter doctor -v                
[✓] Flutter (Channel master, 3.39.0-1.0.pre-340, on macOS 15.3.1 24D70 darwin-arm64, locale en-BR) [1,536ms]
    • Flutter version 3.39.0-1.0.pre-340 on channel master at /Users/guilhermess/.asdf/installs/flutter/3.27.4-stable
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 05d6005dd8 (5 hours ago), 2025-12-01 04:15:13 -0500
    • Engine revision 05d6005dd8
    • Dart version 3.11.0 (build 3.11.0-189.0.dev)
    • DevTools version 2.52.0
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-native-assets,
      omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [1,223ms]
    • Android SDK at /Users/guilhermess/Library/Android/sdk
    • Emulator version 34.2.16.0 (build_id 12038310) (CL:N/A)
    • Platform android-36, build-tools 35.0.0
    • ANDROID_HOME = /Users/guilhermess/Library/Android/sdk
    • ANDROID_SDK_ROOT = ~/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.0) [1,283ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 16A242d
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [5ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Connected device (5 available) [6.9s]
    • Positivo Q20 (mobile)         • 5A1869T99                 • android-arm64  • Android 10 (API 29)
    • sdk gphone64 arm64 (mobile)   • emulator-5556             • android-arm64  • Android 15 (API 35) (emulator)
    • bicicleta (wireless) (mobile) • 00008110-000878312E0B801E • ios            • iOS 18.3.1 22D72
    • macOS (desktop)               • macos                     • darwin-arm64   • macOS 15.3.1 24D70 darwin-arm64
    • Chrome (web)                  • chrome                    • web-javascript • Google Chrome 142.0.7444.176

[✓] Network resources [696ms]
    • All expected network resources are available.

• No issues found!

[darshankawar]

@Pancreax Thanks for the detailed report. Can you set as below and check if it helps to resolve the issue on affected device ?

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

[Pancreax]

@Pancreax Thanks for the detailed report. Can you set as below and check if it helps to resolve the issue on affected device ?

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

Hi, @darshankawar . Thank you for looking into this. I did the requested test and the gradient was rendered incorrectly. This suggests the issue may not be related to the Vulkan → OpenGLES fallback, but rather something specific to Impeller when using OpenGLES.

I also tested this with some versions between Flutter 3.39.0-1.0.pre-340 • channel master down through Flutter 3.29.0 until 3.28.0-0.1.pre • channel beta and the incorrect rendering occurred in all of them.

The problem does not occur in Flutter 3.27.4 under the same conditions.

Let me know if any additional tests or device information would help.

Logs

The logs (taken with Flutter 3.39.0-1.0.pre-340 • channel master) confirm that only OpenGLES was used during this test:

Launching lib/main.dart on Positivo Q20 in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk
D/FlutterJNI( 5133): Beginning load of flutter...
D/FlutterJNI( 5133): flutter (null) was loaded normally!
I/flutter ( 5133): [IMPORTANT:flutter/shell/platform/android/android_context_gl_impeller.cc(104)] Using the Impeller rendering backend (OpenGLES).
Connecting to VM Service at ws://127.0.0.1:49941/fh-7kQjjBR8=/ws
Connected to the VM Service.
D/        ( 5133): Gralloc Free  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:162473 line = 2376
D/        ( 5133): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:162478, sSize:4239360, line = 2270
D/SurfaceCallbackHelper( 5133): dispatchSurfaceRedrawNeededAsync, callbacks=[Landroid.view.SurfaceHolder$Callback;@12fd0fa, callbacks.length=1
I/Choreographer( 5133): Skipped 236 frames!  The application may be doing too much work on its main thread.
I/Choreographer( 5133): Skipped 294 frames!  The application may be doing too much work on its main thread.
D/SurfaceCallbackHelper( 5133): mFinishDrawingRunnable, mFinishDrawingCollected=1, mFinishDrawingExpected=1
D/ProfileInstaller( 5133): Installing profile for com.example.impeller
D/        ( 5133): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:162523, sSize:4239360, line = 2270
D/        ( 5133): Gralloc Register  w:720, h:1560, f:0x1, usage:0xb00, ui64Stamp:162528, sSize:4517888, line = 2270
D/        ( 5133): Gralloc Register  w:720, h:1464, f:0x1, usage:0xb00, ui64Stamp:162538, sSize:4239360, line = 2270

[darshankawar]

@Pancreax Please try with vulkan as below to check if you still get same rendering issue or not. That will indicate if this is specific to vulkan or opengles.

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

[Pancreax]

@Pancreax Please try with vulkan as below to check if you still get same rendering issue or not. That will indicate if this is specific to vulkan or opengles.

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

@darshankawar i've tested with some Flutter versions:

• With Flutter 3.38.3 and Flutter 3.32.7, the app crashes on start. In both cases, the logs are similar:

Logs

flutter run
Launching lib/main.dart on Positivo Q20 in debug mode...
Running Gradle task 'assembleDebug'...                           1,517ms
✓ Built build/app/outputs/flutter-apk/app-debug.apk
Installing build/app/outputs/flutter-apk/app-debug.apk...           4.5s
D/FlutterJNI(29505): Beginning load of flutter...
D/FlutterJNI(29505): flutter (null) was loaded normally!
I/flutter (29505): [IMPORTANT:flutter/shell/platform/android/android_context_vk_impeller.cc(62)] Using the Impeller rendering backend (Vulkan).
F/flutter (29505): [FATAL:flutter/shell/platform/android/platform_view_android.cc(163)] Check failed: android_context_->IsValid(). Could not create surface from invalid Android context.
An error occurred when setting up filtering for adb logs. Unable to communicate with the VM service.
Error initializing DevFS: DevFSException(Service disconnected, _createDevFS: (-32000) Service connection disposed, null)
Lost connection to device.

• With Flutter 3.28.0-0.1.pre • channel beta, the app ran and the gradient was rendered correctly with vulkan:

flutter run
Launching lib/main.dart on Positivo Q20 in debug mode...
Running Gradle task 'assembleDebug'...                             10.0s
✓ Built build/app/outputs/flutter-apk/app-debug.apk
Installing build/app/outputs/flutter-apk/app-debug.apk...          18.4s
I/flutter (31647): [IMPORTANT:flutter/shell/platform/android/android_context_vk_impeller.cc(60)] Using the Impeller rendering backend (Vulkan).
Syncing files to device Positivo Q20...                             36ms

Flutter run key commands.
r Hot reload. 🔥🔥🔥
R Hot restart.
h List all available interactive commands.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).

A Dart VM Service on Positivo Q20 is available at: http://127.0.0.1:63332/sFkxbmSyZS0=/
I/Choreographer(31647): Skipped 408 frames!  The application may be doing too much work on its main thread.
The Flutter DevTools debugger and profiler on Positivo Q20 is available at: http://127.0.0.1:9102?uri=http://127.0.0.1:63332/sFkxbmSyZS0=/
W/Gralloc3(31647): mapper 3.x is not supported
D/        (31647): Gralloc Register  w:720, h:1464, f:0x1, usage:0x8900, ui64Stamp:188106, sSize:4239360, line = 2270
D/        (31647): Gralloc Register  w:720, h:1464, f:0x1, usage:0x8900, ui64Stamp:188110, sSize:4239360, line = 2270
D/        (31647): Gralloc Register  w:720, h:1464, f:0x1, usage:0x8900, ui64Stamp:188113, sSize:4239360, line = 2270
D/SurfaceCallbackHelper(31647): dispatchSurfaceRedrawNeededAsync, callbacks=[Landroid.view.SurfaceHolder$Callback;@55c80a1, callbacks.length=1
D/SurfaceCallbackHelper(31647): mFinishDrawingRunnable, mFinishDrawingCollected=1, mFinishDrawingExpected=1
I/Choreographer(31647): Skipped 33 frames!  The application may be doing too much work on its main thread.
D/        (31647): Gralloc Register  w:720, h:1560, f:0x1, usage:0xb00, ui64Stamp:188151, sSize:4517888, line = 2270
D/ProfileInstaller(31647): Installing profile for com.example.impeller

[darshankawar]

device Positivo Q20 with Android 10 and PowerVR IMG8322 GPU.

Device details: https://benchmarks.ul.com/hardware/phone/Positivo+Q20+review

I'll keep the issue open as this seems to be specific to said device, as on S10+, I was unable to replicate the reported behavior.