Todo Skia

The examples/todo UI on the slint_skia backend: its own ui/todo.slint imports the same shared list (examples/todo_shared/ui/todo_view.slint) — minus the AOT tree-shaking canary — compiled at runtime by SkiaSlintEngine, rendered by Skia on the GPU and shown as a Flutter external texture.

The page creates a SkiaTextureRenderTarget at the laid-out size (physical pixels), shows it with Texture(textureId:), renders from a Ticker and forwards pointer events. What the backend has not grown yet — callbacks — the page reports on screen in the words of the backend's own UnimplementedError, as it does any error from the GPU path. See the slint_skia package, "Shortcuts & Ceilings", for what is still a shortcut.

Building

slint_skia's build hook compiles slint-skia-ffi, which pulls in all of Skia (10+ GB of artifacts), and each platform build compiles the slint_skia plugin. The default check does not build either; the skia-* jobs in .github/workflows/ci.yml build the app for macOS, the iOS simulator, Android (arm64), Linux and Windows. The example ships no Linux or Windows runner: those jobs generate one with flutter create --platforms=... first. Locally, the everyday checks are:

cd examples/todo_skia && dart run build_runner build   # ui/todo.slint → lib/todo.g.dart
        dart analyze .
        

Both run without the native build.

Codegen

lib/todo.g.dart comes from slint_generator's builder, opted into ui/ by build.yaml. slint_skia has no SlintComponentFactory, so the wrapper has no load/register/defaultFactory; the rest of the typed API is there. main.dart writes the embedded tree to disk, so the import of the shared list resolves, compiles its entry with SkiaSlintEngine, and hands the component to the generated constructor:

final defs = engine.compile(
          TodoApp.slintSource,
          path: writeSlintTree(TodoApp.slintSource, TodoApp.slintFiles,
              name: 'todo.slint'),
        );
        final component = defs.single.instantiate() as SkiaSlintComponent;
        final app = TodoApp(component);
        app.todoModel = [
          for (final e in store.items) TodoItem(title: e.title, checked: e.checked),
        ];
        

The list itself lives in the shared TodoStore (examples/todo_shared, same seed and rules as examples/todo) and reaches Slint only through app.todoModel. main.dart registers onAddTodo/onToggleTodo/ onRemoveDone too; the backend throws UnimplementedError for callbacks today, which the page reports as a ceiling. The wrapper's renderTarget throws StateError for a Skia component — it renders to a texture, not a software target — so the frame goes through SkiaTextureRenderTarget.

As in examples/todo, nothing under flutter: assets: — the source ships only as the string the builder embedded.

What differs from examples/todo