doclens 0.0.3

Document scanner for Flutter with native edge detection and a 100% Flutter UI you fully control, plus a one-line escape hatch to the OS-native scanner.

0.0.3

Android preview no longer stretches

• The live preview now reports its size in the rotated (displayed) orientation instead of the sensor-natural landscape buffer size, so a portrait preview fills a portrait screen without BoxFit.cover stretching it. Driven off CameraX's setTransformationInfoListener, with identical sizes deduped and 0x0 events dropped so a stale or repeat emission can't corrupt the layout.

Overlay shows from the first frame

• DoclensView now paints the quad overlay during the brief window between the first camera frame and the first previewSize event. Previously the overlay was missing for that window; the corners are normalized [0,1] so they align to the texture rect immediately.

Primary button

• The default primary button in DoclensScreen is now icon-only (forward arrow), dropping the inline label + icon row for a cleaner control.

0.0.2

EditCornersScreen

• AppBar styled with white foreground, no elevation, and weighted title text.
• Bottom buttons are now full-width (Expanded) with 12 px gap between them.
• onSave return value (warped image path) is passed back via Navigator.pop.
• New parameters: resetLabel, saveLabel, savingLabel — customise button text without supplying a full buttonBuilder.
• New parameters: buttonStyle (ButtonStyle?) and buttonTextStyle (TextStyle?) — style the default buttons without a custom builder.

0.0.1

Initial release.

Drop-in scanner

• DoclensScreen.scan(context) — one-line, full-screen scanner route with live preview, auto-capture, and a built-in review screen (retake / edit corners / accept). Returns Future<ScanResult?>.
• Every visible string and behaviour knob (auto-capture timing, JPEG quality, flash mode, lens, accent colours, labels, edit-corners toggle) exposed as a top-level parameter with rich dartdoc.

Custom UI

• DoclensView Flutter widget rendering a Texture-backed live camera preview plus your overlay / shutter / flash button builders. Every slot accepts null to render nothing, a static default for quick start, or a custom widget.
• DoclensController extends ChangeNotifier owning the session. Streams: quadStream, statusStream, autoCaptureStream, lowLightStream, previewSizeStream. Methods: initialize, capture, warpImage, focusAt, setFlashMode, cycleFlashMode, switchCamera, pause, resume, dispose.
• QuadOverlay family of pre-built overlay widgets with named constructors: outline, filled, corners, cornersFilled, dots, dotsLine, glow. Status-driven colour follows accent / warning. The drop-in DoclensScreen exposes an overlayStyle: QuadOverlayStyle parameter so consumers can switch the look without writing a builder.

Native detection pipeline

• iOS — VNDetectDocumentSegmentationRequest (the Core ML detector used by VisionKit) on iOS 15+, with a docs-tuned VNDetectRectanglesRequest fallback on iOS 13/14.
• Android — pure-Kotlin Sobel + connected-components + convex-hull approximation on CameraX (no OpenCV, no on-device ML model bundling on the live-preview path).
• Streams normalised Quad to Dart at a configurable throttle rate (default 15 Hz).
• Two-stage auto-capture with DetectionStatus.confirming phase, configurable thresholds and durations.

Focus

• Continuous autofocus enabled by default on both platforms (iOS .continuousAutoFocus + near-distance hint; Android CameraX CONTROL_AF_MODE_CONTINUOUS_PICTURE).
• Tap-to-focus on the preview triggers a one-shot focus + auto-exposure at the tap point, with a focus-reticle animation. Reverts to continuous AF after ~3 seconds. Programmatic access via controller.focusAt(Offset).

Capture + warp

• Full-resolution still capture with native perspective warp (CIPerspectiveCorrection on iOS, Matrix.setPolyToPoly on Android), EXIF orientation baked into pixel layout.
• Graceful fallback when warp fails — ScanResult.warpError is surfaced, raw image and quad still returned.
• EditCornersScreen with draggable handles, customisable builders, and re-warp callback.

Quality of life

• Median-of-N corner smoothing (QuadSmoother) to kill single-frame jitter.
• Flash / torch toggle, camera switching, pause/resume on app lifecycle.
• Low-light detection emitted on the status stream.
• Preview-size event so the overlay coordinate space always matches the rendered preview pixels.
• ScannerConfig with feature flags for auto-capture timing, smoothing, detection throttle, JPEG quality, flash mode, lens, lifecycle, telemetry, tap-to-focus, pinch-to-zoom — all with sensible defaults.
• Typed exceptions: ScannerPermissionException, ScannerUnavailableException, ScannerInitializationException, ScannerCaptureException.

OS-native scanner (one-line opt-in)

• scanWithNativeUI() launches the OS-native scanner UI: VNDocumentCameraViewController on iOS, GmsDocumentScanner (Google Play services) on Android.
• Returns the cropped page image paths or null on user cancel, consistently on both platforms.
• Pre-launch Google Play services check on Android with ScannerUnavailableException on devices without GMS.

Tests + docs

• Pure-Dart unit tests for Quad, StabilityTracker, StatusClassifier, and QuadSmoother.
• doc/architecture.md with the Dart ↔ native pipeline diagram.
• doc/decisions.md — every non-obvious design choice cited against Apple / Google docs.