Live, on-device text recognition for Flutter. Apple Vision on iOS, ML Kit on Android. Like mobile_scanner, but for text instead of barcodes.

Android · ML Kit

iOS · Apple Vision

_{iOS gives every line the same confidence, so the tier colours are off there. See API at a glance.}

• Why text_sight?
• A quick taste
  • Live camera
  • A single image
  • Tweak it mid-session
  • Know what the camera is doing
  • The example app
• API at a glance
• Platform support
  • Gotchas
• Install
  • iOS
  • Android
• The recognition model
• Performance
• Upgrading to 1.0
• Going deeper

Why text_sight?

Most cross-platform OCR plugins run Google ML Kit on both platforms, which quietly drags GoogleMLKit into your iOS build. text_sight doesn't.

No ML framework in your iOS app	iOS recognition is Apple Vision, which is already part of the OS. No GoogleMLKit, nothing third-party to ship, so your iOS build stays smaller. CI fails the moment one sneaks in.
Android fetches its model on demand	The ML Kit model stays unbundled by default, so your APK carries a ~260 KB stub instead of the whole thing. Want it baked in? One line of Gradle.
fast or accurate, per call	Switch mid-session. On one live page accurate read 15 lines where fast got 9, for roughly 4x the time. iOS only, since ML Kit's Latin recognizer has no such knob.
No permission package	requestCameraPermission() goes straight to AVFoundation and the Android permission flow. Already using permission_handler? That still works.
The same boxes everywhere	Every box is normalized [0, 1] from the top-left on both platforms, so your overlay never branches on Platform.
Camera optional	One-shot recognition reads bytes or a file path. No camera, no permission, runs anywhere.

Nothing recognition-related ever reaches your pubspec.yaml, so the two platforms can't bleed into each other.

A quick taste

Live camera

Point the camera at some text:

final controller = TextSightController();

TextSightView(
  controller: controller,
  onResult: (capture) => capture.lines.forEach((line) => print(line.text)),
  overlayBuilder: (context, capture, constraints) => /* paint line.boundingBox */,
);

await controller.requestCameraPermission(); // prompts via the OS
await controller.start();

A single image

No camera, no permission, works on a simulator:

final capture = await TextSight.recognizeImage(bytes); // or .recognizePath('/photo.jpg')

Tweak it mid-session

Hand the controller a region of interest to scan just a scan-box. Everything Apple Vision alone can do sits under darwin, so a setting Android ignores can't be reached without naming the platform.

final controller = TextSightController(
  options: TextSightOptions(
    roi: Rect.fromLTWH(0.1, 0.4, 0.8, 0.2),
    darwin: DarwinOptions(
      recognitionLevel: RecognitionLevel.accurate,
      usesLanguageCorrection: false,
    ),
  ),
);

usesLanguageCorrection is on by default. It helps prose, mangles serials and part numbers, and roughly doubles the time on iOS, so scanning codes wants it off on both counts.

updateOptions swaps the whole set at once, so read options first when you only mean to change one thing. The torch is its own call, since a still image has no such concept.

await controller.updateOptions(
  TextSightOptions(darwin: controller.options.darwin), // roi back to the whole frame
);
await controller.updateTorchEnabled(enabled: true);

Scanning small print? Turn the camera up. Set once, unlike the knobs above.

TextSightController(resolution: CaptureResolution.high);

minimumTextHeight is the iOS half, and it is already 0, so nothing is being skipped for you to turn back on. That leaves pixels as the only lever, and text small enough still comes back empty.

Know what the camera is doing

The plugin pauses the session when the app backgrounds and resumes it on return, and the OS can take the camera away or fail it. None of that shows in the frame stream, so sessionState does:

ListenableBuilder(
  listenable: controller,
  builder: (context, _) => switch (controller.sessionState) {
    SessionIdle() => const Text('Not started'),
    SessionActive() => const Text('Scanning'),
    SessionPaused(:final reason) => Text('Paused: ${reason.name}'),
    SessionFailed(:final details) => Text('Camera failed: $details'),
  },
);

• Your own calls throw at the call site. Whatever happens to the session afterwards arrives as a state, and SessionFailed stays parked until you call start() again.
• Active means the camera runs. Frames are recognized only while isRecognizing is on and something listens to captures. Camera up but no work? pauseRecognition().
• One live controller at a time.
• A backgrounded app may only see SessionPaused once it's back, and after a hot restart the controller says SessionIdle until you start(). Render from the value and neither shows.

One Android thing worth knowing up front: the model downloads on first use, so give it a head start when the user opens your scanner, or that first scan comes back empty.

The example app

The example/ app is the place to look next. Live overlay, torch, region-of-interest, permissions, and the one-shot screen, all wired up and ready to crib from.

Android · ML Kit

iOS · Apple Vision

API at a glance

One import gets you everything: package:text_sight/text_sight.dart.

Type	What it's for
TextSightView + TextSightController	the live camera path
TextSight	the static one-shot, on bytes or a file path
TextSightOptions	region of interest, plus a darwin group of Vision-only knobs
TextSightCapture and RecognizedLine	results: text, normalized box, confidence
TextSightSessionState	what the camera session is doing: idle, active, paused, failed
TextSightEngine	what this device's engine is like, e.g. confidenceScale
ConfidenceScale	what a confidence number means here, and whether it ranks
TextSightModel	Android model readiness, ensureReady() plus a stream
DarwinOptions	recognitionLevel, usesLanguageCorrection, preferredLanguages, minimumTextHeight. iOS and macOS only
RecognitionLevel	fast or accurate, inside DarwinOptions
CaptureResolution	how many pixels the camera feeds the recognizer
CameraPermissionStatus	granted, denied, permanently denied
RecognizedElement	reserved. Always null in v1, word-level results come later

Platform support

Platform	Minimum	Engine
iOS	15.0	Apple Vision. RecognizeTextRequest on 18+, VNRecognizeTextRequest on 15 to 17
Android	API 24	ML Kit Text Recognition v2 (Latin)

The right Vision API is picked for you. Android reads Latin script only for now. Live scanning needs a real device, since the iOS Simulator has no camera, but the one-shot runs anywhere.

Those minimums are what your users need. Building the iOS side needs Xcode 26 or newer, because the plugin names an AVCaptureSession interruption reason that Apple added in the iOS 26 SDK. Your own deployment target still goes as low as 15.0.

Gotchas

⚠️ iOS 15 and 16: the preview and recognition don't follow device rotation. Those versions predate AVCaptureDevice.RotationCoordinator, so live capture isn't rotated to match how the phone is held. iOS 17+ is fine, and one-shot recognition is fine everywhere (it reads the image's own orientation). It's a deliberate trade-off for a device population we don't expect to see. If it affects you, open an issue and a proper fallback will follow.

Hosting Flutter inside a native iOS app?

Call controller.dispose() a step ahead of releasing the FlutterEngine or dismissing its FlutterViewController, not in the same breath. dispose() hands the native side a teardown request and returns before it finishes, so it isn't a barrier. The plugin also releases the camera on engine detach, which covers the usual routes, but a host that keeps the engine alive forever gets neither, and a live session that outlives its FlutterViewController can crash the app.

Plain Flutter apps need none of this.

Install

flutter pub add text_sight

iOS

Add a camera-usage string to ios/Runner/Info.plist. This is required, because iOS kills the app the moment the camera is requested without it.

<key>NSCameraUsageDescription</key>
<string>Used to recognize text from the camera.</string>

Then call controller.requestCameraPermission() before controller.start(), or checkCameraPermission() if you want a priming screen first.

Android

Nothing to do. The manifest already has what it needs.

The recognition model

iOS is free here, Vision ships with the OS. Android pulls its ML Kit model from Play Services on first use, so your APK carries a ~260 KB stub instead of the whole thing. Warm it up with TextSightModel.ensureReady() when your scanner opens, or bundle it: doc/android-model.md.

Performance

Both engines keep up with a live preview, and on iOS fast runs several times quicker than accurate. Getting results from native to Dart costs microseconds a frame, so the recognizer is what sets the pace. Numbers, charts and method: doc/performance.md.

Upgrading to 1.0

Coming from 0.2? stop() is now pauseRecognition(), the three update* setters are one updateOptions(), and the Vision-only settings moved under darwin. Full table, plus the two behaviour changes the compiler won't catch: doc/upgrading.md.

Going deeper

Coordinate handling, the per-line confidence contract, the session state model, how region-of-interest differs across platforms, and what's next: all in APPENDIX.md. The longer guides live in doc/.