ContourDetector class

Contour detection and polygon simplification engine implemented in pure Dart.

Inspired by OpenCV's findContours() + approxPolyDP() and Scanbot SDK's document quad detection pipeline:

1. Connected component labeling (Union-Find)
2. Contour boundary tracing (Moore-Neighbor / Suzuki-Abe inspired)
3. Douglas-Peucker polygon simplification
4. Convex hull computation (Graham scan)
5. Best quadrilateral selection

Constructors

ContourDetector()

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

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

Static Methods

convexHull(List<Offset> points) → List<Offset>

Computes the convex hull of a set of points using the Graham scan algorithm.

detectDocumentQuad(Uint8List gray, int width, int height, {int candidateCount = 5, double minAreaRatio = 0.15}) → DocumentCorners

Detects the best document quadrilateral from a grayscale image.

findBestQuadrilateral(List<Offset> contour, int imageWidth, int imageHeight, {double minAreaRatio = 0.1, double maxAreaRatio = 0.95}) → DocumentCorners?

Finds the best quadrilateral approximation from a contour.

findContours(Uint8List edgeMap, int width, int height, {int minContourLength = 20}) → List<List<Offset>>

Detects all contours in a binary edge map.

simplifyPolygon(List<Offset> contour, double epsilon) → List<Offset>

Simplifies a contour using the Douglas-Peucker algorithm.