transformSync method

ImageResult transformSync(Uint8List input, { List<ImageOperation> operations = const [], required ImageEncoding encoding, })

Decodes input, applies operations in order, and encodes the result.

Input is read during the call, never mutated or retained. The result owns read-only Dart bytes. Even an empty operation list decodes and re-encodes. Supports static PNG/JPEG/WebP decoded as RGB8/RGBA8, without EXIF orientation or metadata preservation. Run costly calls in a worker isolate.

Throws ArgumentError for empty input, input over 256 MiB, or more than 64 operations. Known execution failures throw SlimPixelsException.

Implementation

ImageResult transformSync(
  Uint8List input, {
  List<ImageOperation> operations = const [],
  required ImageEncoding encoding,
}) {
  _validateRequest(input, operations);
  final plan = utf8.encode(
    jsonEncode({
      'operations': operations.map((op) => op._json).toList(),
      'format': encoding._format.name,
      'quality': encoding._quality,
    }),
  );
  // Typed requests have bounded size; a protocol overflow indicates a bug.
  if (plan.length > 65536) {
    throw SlimPixelsException._(SlimPixelsErrorCode.internalFailure);
  }
  return using((arena) {
    final source = arena<Uint8>(input.length)
      ..asTypedList(input.length).setAll(0, input);
    final config = arena<Uint8>(plan.length)
      ..asTypedList(plan.length).setAll(0, plan);
    final out = arena<Pointer<Uint8>>();
    final length = arena<UintPtr>();
    final width = arena<Uint32>();
    final height = arena<Uint32>();
    final format = arena<Uint32>();
    final operation = arena<Int32>();
    out.value = nullptr;
    length.value = 0;
    try {
      final status = native.run(
        source,
        input.length,
        config,
        plan.length,
        out,
        length,
        width,
        height,
        format,
        operation,
      );
      if (status != 0) {
        final index = operation.value;
        if (index < -1 || index >= operations.length) {
          throw SlimPixelsException._(SlimPixelsErrorCode.internalFailure);
        }
        throw SlimPixelsException._(
          _statusCode(status),
          operationIndex: index < 0 ? null : index,
        );
      }
      if (out.value == nullptr ||
          length.value == 0 ||
          length.value > 256 * 1024 * 1024 ||
          width.value == 0 ||
          height.value == 0 ||
          width.value * height.value > 32000000 ||
          format.value != encoding._format._id) {
        throw SlimPixelsException._(SlimPixelsErrorCode.internalFailure);
      }
      return ImageResult._(
        Uint8List.fromList(out.value.asTypedList(length.value)),
        width.value,
        height.value,
        encoding._format,
      );
    } finally {
      native.free(out.value, length.value);
    }
  });
}