BackgroundUseCase<T, Params> class abstract

A UseCase that executes expensive operations on a separate isolate.

Use BackgroundUseCase for CPU-intensive operations that would block the main UI thread, such as:

• Image processing
• Large data parsing
• Complex calculations
• Encryption/decryption

Key Features

• Runs on a separate isolate to avoid UI jank
• Streams results back via Result<Type, AppFailure>
• Proper resource cleanup
• Built-in cancellation support

Important Constraints

• The buildTask must return a static or top-level function
• Parameters must be serializable (primitives, Lists, Maps)
• Not supported on web (will throw assertion error)

Example

class MatrixMultiplyUseCase extends BackgroundUseCase<Matrix, MatrixParams> {
  @override
  BackgroundTask<MatrixParams> buildTask() => _multiply;

  // MUST be static or top-level
  static void _multiply(BackgroundTaskContext<MatrixParams> context) {
    final params = context.params;
    final result = params.matrixA * params.matrixB;
    context.sendData(result);
    context.sendDone();
  }
}

// Usage
matrixMultiplyUseCase(params).listen((result) {
  result.fold(
    (matrix) => print('Result: $matrix'),
    (failure) => print('Error: ${failure.message}'),
  );
});

Mixed-in types

• Loggable

Constructors

BackgroundUseCase()

Create a new BackgroundUseCase.

Properties

hashCode → int

The hash code for this object.

no setter, inherited

isRunning → bool

Whether the use case is currently running

no setter

logger → Logger

Logger instance for this class.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

state → BackgroundUseCaseState

Current execution state

no setter

Methods

buildTask() → BackgroundTask<Params>

Override this method to provide the background task.

call(Params params, {CancelToken? cancelToken}) → Stream<Result<T, AppFailure>>

Execute the use case with the given params.

dispose() → void

Dispose of all resources.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited