Contents

Impeller rendering engine

Contents

What is Impeller?

Impeller provides a new rendering runtime for Flutter. The Flutter team’s believes this solves Flutter’s early-onset jank issue. Impeller precompiles a smaller, simpler set of shaders at Engine build time so they don’t compile at runtime.

For a video introduction to Impeller, check out the following talk from the Flutter Foward 2023 conference.

What is Impeller?

Impeller has the following objectives:

  • Predictable performance: Impeller compiles all shaders and reflection offline at build time. It builds all pipeline state objects upfront. The engine controls caching and caches explicitly.
  • Instrumentable: Impeller tags and labels all graphics resources like textures, and buffers. It can capture and persist animations to disk without affecting per-frame rendering performance.
  • Portable: Flutter doesn’t tie Impeller to a specific client rendering API. You can author shaders once and convert them to backend-specific formats as necessary.
  • Leverages modern graphics APIs: Impeller uses, but doesn’t depend on, features available in modern APIs like Metal and Vulkan.
  • Leverages concurrency: Impeller can distribute single-frame workloads across multiple threads if necessary.

Availability

Where can you use Impeller?

iOS

Flutter enables Impeller by default on iOS.

  • To disable Impeller on iOS when debugging, pass --no-enable-impeller to the flutter run command.

    $ flutter run --no-enable-impeller

  • To disable Impeller on iOS when deploying your app, add the following tags under the top-level <dict> tag in your app’s Info.plist file.

      <key>FLTEnableImpeller</key>
  <false />

The team continues to improve iOS support. If you encounter performance or fidelity issues with Impeller on iOS, file an issue in the GitHub tracker. Prefix the issue title with [Impeller] and include a small reproducible test case.

Android

Android development continues but it’s not ready for preview. Impeller on Android might not work on the master channel. To see what direction Android support will take, experiment with Impeller in the 3.7 or later stable release.

To enable Impeller on Android, take one of the following actions:

  • Pass --enable-impeller to the flutter run command.

    $ flutter run --enable-impeller

  • Add the following tag to your AndroidManifest.xml file under the <application> tag.

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

Architecture

To learn more details about Impeller’s design and architecture, check out the README.md file in the source tree.

Additional Information