46 lines
1.2 KiB
Dart
46 lines
1.2 KiB
Dart
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import 'dart:typed_data';
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import 'native_ocr_backend.dart';
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import 'ocr_backend.dart';
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import 'onnx_recognition_backend.dart';
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/// Selects and caches the active local OCR backend.
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///
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/// Preference order: the embedded ONNX recognition backend if its model is
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/// bundled and loads, otherwise the native platform backend, otherwise none.
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class OcrBackends {
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OcrBackends._();
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static OcrBackend? _active;
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static bool _resolved = false;
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/// Resolve (once) and return the preferred available backend, or null when
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/// no backend is available on this device/build.
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static Future<OcrBackend?> active() async {
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if (_resolved) return _active;
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final candidates = <OcrBackend>[
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OnnxRecognitionBackend(),
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NativeOcrBackend(),
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];
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for (final backend in candidates) {
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if (await backend.isAvailable()) {
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_active = backend;
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break;
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}
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}
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_resolved = true;
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return _active;
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}
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/// Recognize text using the active backend. Returns null when no backend is
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/// available or nothing was recognized.
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static Future<String?> recognize(Uint8List png) async {
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final backend = await active();
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if (backend == null) return null;
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return backend.recognize(png);
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}
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}
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