/// <summary>
/// 給定 3 點，找圓心座標
/// </summary>
/// <param name="pA"></param>
/// <param name="pB"></param>
/// <param name="pC"></param>
/// <param name="centerRow"></param>
/// <param name="centerCol"></param>
public static void CalculateCircleCenter(GeoPoint pA, GeoPoint pB, GeoPoint pC
, out double centerRow, out double centerCol)
{
centerRow = centerCol = -1;
if (pA != null && pB != null && pC != null)
{
var a1 = pA.Col;
var b1 = pA.Row;
var a2 = pB.Col;
var b2 = pB.Row;
var a3 = pC.Col;
var b3 = pC.Row;
var a1s = Math.Pow(a1, 2);
var a2s = Math.Pow(a2, 2);
var a3s = Math.Pow(a3, 2);
var b1s = Math.Pow(b1, 2);
var b2s = Math.Pow(b2, 2);
var b3s = Math.Pow(b3, 2);
centerCol = (a1s * b2
- a1s * b3
+ b1 * b3s
- b1 * a2s
+ b3 * a2s
- b3s * b2
+ b3 * b2s
- b1 * b2s
+ b1 * a3s
- b1s * b3
- a3s * b2
+ b1s * b2) /
(2 * (a1 * b2 + a3 * b1 - a3 * b2 - a1 * b3 - a2 * b1 + a2 * b3));
centerRow = -0.5 * (-1 * a1 * a2s
+ a2 * b1s
- a1 * b2s
- a3 * a1s
- a2 * b3s
- a3 * b1s
+ a3 * a2s
+ a1 * b3s
+ a3 * b2s
+ a1 * a3s
- a2 * a3s
+ a2 * a1s) /
(a1 * b2 + a3 * b1 - a3 * b2 - a1 * b3 - a2 * b1 + a2 * b3);
}
}
/// <summary>
/// 給定 3 點，找圓心座標及半徑
/// </summary>
/// <param name="pA"></param>
/// <param name="pB"></param>
/// <param name="pC"></param>
/// <param name="centerRow"></param>
/// <param name="centerCol"></param>
/// <param name="radius"></param>
public static void CalculateCircleCenter(GeoPoint pA, GeoPoint pB, GeoPoint pC
, out double centerRow, out double centerCol, out double radius)
{
radius = -1;
CalculateCircleCenter(pA, pB, pC, out centerRow, out centerCol);
if (pA != null && pA.Row > 0 && pA.Col > 0 && centerRow > 0 && centerCol > 0)
{
radius = CalculateDistance(centerRow, centerCol, pA.Row, pA.Col);
}
}
public bool WaitForClickPoints(double x, double y)
{
if (_clickedPointsPositionList.Count < _clickPoints)
{
_clickedPointsPositionList.Add(new PositionModel() { ColBegin = x, RowBegin = y });
}
_initPointsDone = _clickedPointsPositionList.Count == _clickPoints;
if (_initPointsDone)
{
//3 點求圓
var rows = _clickedPointsPositionList.Select(p => p.RowBegin).ToArray();
var cols = _clickedPointsPositionList.Select(p => p.ColBegin).ToArray();
GeoOperatorSet.CalculateCircleCenter(rows, cols, out midR, out midC, out radius);
//檢查 and notify
_success = (midR > 0 && midC > 0 && radius > 0);
if (_success)
{
_FirstPoint = new GeoPoint() { Row = rows[0], Col = cols[0] };
_SecondPoint = new GeoPoint() { Row = rows[1], Col = cols[1] };
_EndPoint = new GeoPoint() { Row = rows[2], Col = cols[2] };
//
sizeR = midR;
sizeC = midC - radius;
//toDo, 計算startPhi, extentPhi
// 角度為正，表示在圓心的上方，反之在下方
// 角度越大，表示越接近左上角，視為起始點
// 角度越小，視為終點
var agOne = HMisc.AngleLx(midR, midC, _FirstPoint.Row, _FirstPoint.Col);
var agTwo = HMisc.AngleLx(midR, midC, _SecondPoint.Row, _SecondPoint.Col);
var agThree = HMisc.AngleLx(midR, midC, _EndPoint.Row, _EndPoint.Col);
Dictionary<string, double> agDict = new Dictionary<string, double>() { };
agDict.Add("1", agOne);
agDict.Add("2", agTwo);
agDict.Add("3", agThree);
//逆排序，再取奇數, 即為 StartPhi, EndPhi
var angles = agDict.OrderByDescending(p => p.Value)
.Where((p, idx) => idx % 2 == 0)
.Select(p => p.Value).ToArray();
_startPhi = angles[0];
var endPhi = angles[1];
//計算延伸長度
/*
* 起始點在第一，二象限，則
*/
_extentPhi = (_startPhi < 0) ? Math.Abs(_startPhi) - Math.Abs(endPhi)
: endPhi - _startPhi;
_pointOrder = "negative";//clockwise 畫弧
determineArcHandles();
updateArrowHandle();
}
}
return _initPointsDone;
}
