The platform embedder is the native OS application that hosts all Flutter
content, and acts as the glue between the host operating system and Flutter.
When you start a Flutter app, the embedder provides the entrypoint, initializes
the Flutter engine, obtains threads for UI and rastering, and creates a texture
that Flutter can write to. The embedder is also responsible for the app
lifecycle, including input gestures (such as mouse, keyboard, touch), window
sizing, thread management, and platform messages. Flutter includes platform
embedders for Android, iOS, Windows, macOS, and Linux; you can also create a
custom platform embedder, as in this worked
example that supports remoting
Flutter sessions through a VNC-style framebuffer or this worked example for
Raspberry Pi.

Each platform has its own set of APIs and constraints. Some brief
platform-specific notes: