fis_lib_measure/test/ellipse.dart

import 'dart:math' as math;
import 'package:fis_measure/interfaces/date_types/matrix.dart';
import 'package:fis_measure/interfaces/date_types/point.dart';
import 'package:fis_measure/interfaces/date_types/vector.dart';

class EllipseTest {
  static void calculateYAxisPoints(
    DPoint yAxisStart,
    DPoint yAxisEnd,
    DPoint xAxisStart,
    DPoint xAxisEnd,
    DPoint adjustYAxisPoint,
    bool keepYAxisLength,
  ) {
    var reverseMatrix = DMatrix();

    var vertical = DVector(1, 0);
    var angleAngleBetweenVertical =
        calculateAngel(xAxisEnd, xAxisStart, vertical);

    var centroidX = (xAxisStart.x + xAxisEnd.x) * 0.5;
    var centroidY = (xAxisStart.y + xAxisEnd.y) * 0.5;
    var centroid = DPoint(centroidX, centroidY);

    reverseMatrix.rotateAt(angleAngleBetweenVertical, centroid.x, centroid.y);

    var convertMatrix = reverseMatrix;
    convertMatrix.invert();

    double length;
    if (adjustYAxisPoint == xAxisEnd) {
      if (keepYAxisLength) {
        length = (yAxisStart - yAxisEnd).length / 2;
      } else {
        length = (xAxisEnd - xAxisStart).length / 2;
      }
    } else {
      length = distance(xAxisStart, xAxisEnd, adjustYAxisPoint);
    }

    var pt3 = DPoint(centroid.x, centroid.y + length);
    var pt4 = DPoint(centroid.x, centroid.y - length);

    var yAxisStartTrans = convertMatrix.transformWidthPoint(pt3);
    var yAxisEndTrans = convertMatrix.transformWidthPoint(pt4);
    yAxisStart.update(yAxisStartTrans);
    yAxisStart.update(yAxisEndTrans);
  }

  static double calculateAngel(DPoint pt1, DPoint pt2, DVector axis) {
    DVector xAxis = pt2 - pt1;
    var angle = DVector.angleBetween(xAxis, axis);
    return angle;
  }

  static double distance(DPoint pt1, DPoint pt2, DPoint pt) {
    double dis = 0;
    if (pt1.x == pt2.x) {
      dis = (pt.x - pt1.x).abs();
      return dis;
    }
    var lineK = (pt2.y - pt1.y) / (pt2.x - pt1.x);
    var lineC = (pt2.x * pt1.y - pt1.x * pt2.y) / (pt2.x - pt1.x);
    dis = (lineK * pt.x - pt.y + lineC).abs() / (math.sqrt(lineK * lineK + 1));
    return dis;
  }
}