ImageProcess/native_vision/lib/edge_detection.dart

import 'dart:async';
import 'dart:ffi';
import 'dart:ui';
import 'package:ffi/ffi.dart';
import 'package:flutter/material.dart';
import 'package:native_vision/native/doc_scanner.dart';

class Coordinate extends Struct {
  @Float()
  external double x;
  @Float()
  external double y;
}

class CoordinateArray extends Struct {
  external Pointer<Coordinate> coordsPtr;
  @Uint32()
  external int length;
}

class EdgeDetectionResult {
  EdgeDetectionResult({
    required this.topLeft,
    required this.topRight,
    required this.bottomLeft,
    required this.bottomRight,
  });

  Offset topLeft;
  Offset topRight;
  Offset bottomLeft;
  Offset bottomRight;

  Pointer<CoordinateArray> toNativeCoords() {
    final coordsPtr = CoordinateArrayExtention.createCoordsPtr();

    coordsPtr.ref.coordsPtr[0].x = topLeft.dx;
    coordsPtr.ref.coordsPtr[0].y = topLeft.dy;

    coordsPtr.ref.coordsPtr[1].x = topRight.dx;
    coordsPtr.ref.coordsPtr[1].y = topRight.dy;

    coordsPtr.ref.coordsPtr[3].x = bottomRight.dx;
    coordsPtr.ref.coordsPtr[3].y = bottomRight.dy;

    coordsPtr.ref.coordsPtr[2].x = bottomLeft.dx;
    coordsPtr.ref.coordsPtr[2].y = bottomLeft.dy;

    return coordsPtr;
  }
}

extension CoordinateArrayExtention on Pointer<CoordinateArray> {
  static Pointer<CoordinateArray> createCoordsPtr() {
    var bytes = sizeOf<CoordinateArray>();
    final coordArrPtr = malloc.allocate<CoordinateArray>(bytes);
    bytes = sizeOf<Coordinate>();
    coordArrPtr.ref.coordsPtr = malloc.allocate(bytes * 4);
    coordArrPtr.ref.length = 4;
    return coordArrPtr;
  }

  EdgeDetectionResult toEdgeDetectionResult() {
    return EdgeDetectionResult(
        topLeft: Offset(ref.coordsPtr[0].x, ref.coordsPtr[0].y),
        topRight: Offset(ref.coordsPtr[1].x, ref.coordsPtr[1].y),
        bottomLeft: Offset(ref.coordsPtr[3].x, ref.coordsPtr[3].y),
        bottomRight: Offset(ref.coordsPtr[2].x, ref.coordsPtr[2].y));
  }

  void release() {
    malloc.free(ref.coordsPtr);
    malloc.free(this);
  }
}

class ROI {
  // Below is pixel unit
  int left;
  int top;
  int width;
  int height;

  //Below is logical unit
  double maxWidth;
  double maxHeight;

  ROI.create(this.left, this.top, this.width, this.height, this.maxWidth,
      this.maxHeight);

  Pointer<NativeROI> toNativeROI() {
    final roiPtr = malloc.allocate<NativeROI>(sizeOf<NativeROI>());
    roiPtr.ref.left = left;
    roiPtr.ref.top = top;
    roiPtr.ref.width = width;
    roiPtr.ref.height = height;
    return roiPtr;
  }
}