Rotate curve (serie of DataPoints) X degrees defined their new Baseline

Question

I am using MSchart to plot serie into it, i need to rotate Curve (serie of datapoint) X degrees, P1 is fisrt click (mouseDown) and P2 second click (mouseUp), the angle between P1 and P2 represent the angle to rotate (i have this calculated), the problem is the curve deform when i apply different methods to do this

for (int x = 1; x < curve.nPoints; x++)
{   
     double X0 = curve.get_array_X[x];
     double Y0 = curve.get_array_Y[x];

     System.Windows.Media.Matrix m = new System.Windows.Media.Matrix();
     m.Rotate(45 * (Math.PI / 180.0));
     System.Windows.Vector v = new System.Windows.Vector(X0, Y0);
     v = System.Windows.Vector.Multiply(v, m);
     sAus.Points.AddXY(v.X, v.Y);
}

and this other code

public Series nueva(float X, float Y)
    {
        Series sAus = new Series(curvaActual.Tag);
        int nearest1 = curvaActual.FindNearestXCV(new DataPoint(chartWorking1.ChartAreas[0].AxisX.PixelPositionToValue(X),
                                 chartWorking1.ChartAreas[0].AxisY.PixelPositionToValue(Y)).XValue,
                                 new DataPoint(chartWorking1.ChartAreas[0].AxisX.PixelPositionToValue(X), chartWorking1.ChartAreas[0].AxisY.PixelPositionToValue(Y)).YValues[0], 0, curvaActual.nPoints);
        int nearest2 = curvaActual.FindNearestXCV(new DataPoint(chartWorking1.ChartAreas[0].AxisX.PixelPositionToValue(X),
                                      chartWorking1.ChartAreas[0].AxisY.PixelPositionToValue(Y)).XValue,
                                      new DataPoint(chartWorking1.ChartAreas[0].AxisX.PixelPositionToValue(X), chartWorking1.ChartAreas[0].AxisY.PixelPositionToValue(Y)).YValues[0], 0, curvaActual.nPoints);

        double x1 = (double)curvaActual.get_array_X[nearest1];
        double y1 = (double)curvaActual.get_array_Y[nearest1];


        double x2 = (double)curvaActual.get_array_X[nearest2];
        double y2 = (double)curvaActual.get_array_Y[nearest2];
        double pendiente = Math.Atan2(y2 - y1, x2 - x1);
        double anguloF = pendiente;
        double deg = Math.PI * 45 / 180.0;
        double coseno = Math.Cos(deg);
        double seno = Math.Sin(deg);

        double[] arrayX = new double[curvaActual.nPoints];
        double[] arrayY = new double[curvaActual.nPoints];

        for (int x = 1; x < curvaActual.nPoints; x++)
        {

            PointF rotatedPoint = RotatePoint(new PointF((float)curvaActual.get_array_X[x], (float)curvaActual.get_array_Y[x]), new PointF((float)curvaActual.get_array_X[x - 1], (float)curvaActual.get_array_Y[x - 1]), 45);
            double angleRotatedPoint = angleFromPoint(rotatedPoint, new PointF((float)curvaActual.get_array_X[x - 1], (float)curvaActual.get_array_Y[x - 1]));


            PointF pointROtado = RotatePoint(new PointF((float)curvaActual.get_array_X[x], (float)curvaActual.get_array_Y[x]), new PointF((float)0, (float)0), 45);
            sAus.Points.AddXY((double)pointROtado.X, (double)pointROtado.Y);

        }

        return sAus;
    }

[proof]

original serie

rotate 33

using your code (modify point to pointF)

void rotateSeries(Series src, Series tgt, DataPoint center, float angle)
    {

        PointF c = new PointF((float)center.XValue, (float)center.YValues[0]);

        tgt.Points.Clear();
        foreach (DataPoint dp in src.Points)
        {
            PointF p0 = new PointF((float)dp.XValue, (float)dp.YValues[0]);
            PointF p = RotatePoint(p0, c, angle);
            tgt.Points.AddXY(p.X, p.Y);
        }
    }
    static PointF RotatePoint(PointF pointToRotate, PointF centerPoint, double angleInDegrees)
    {
        double angleInRadians = angleInDegrees * (Math.PI / 180);
        double cosTheta = Math.Cos(angleInRadians);
        double sinTheta = Math.Sin(angleInRadians);
        return new PointF
        {
            X = (float)
                (cosTheta * (pointToRotate.X - centerPoint.X) -
                sinTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.X),
            Y = (float)
                (sinTheta * (pointToRotate.X - centerPoint.X) +
                cosTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.Y)
        };
    }

Answer 1

Here is one example of how you can do it. It..

• assumes you have found the DataPoint center around which you want to rotate the graphic
• assumes you have calculated the angle by which it shall be rotated
• uses two Series s1 and s2, the first being the source and the latter the rotated target.
• uses a version of RotatePoint from Fraser's anwser, slightly updated for PointF.

Here is the result for rotating around the 5th point by 33 degrees:

private void button1_Click(object sender, EventArgs e)
{
    rotateSeries(s1, s2, s1.Points[4], 33);
}

void rotateSeries(Series src, Series tgt, DataPoint center, float angle)
{

    PointF c = new PointF((float)center.XValue, (float)center.YValues[0]);

    tgt.Points.Clear();
    foreach (DataPoint dp in src.Points)
    {
        PointF p0 = new Point((float)dp.XValue, (float)dp.YValues[0]);
        PointF p = RotatePoint(p0, c, angle);
        tgt.Points.AddXY(p.X, p.Y);
    }
}

static PointF RotatePoint(PointF pointToRotate, PointF centerPoint, double angleInDegrees)
{
    double angleInRadians = angleInDegrees * (Math.PI / 180);
    double cosTheta = Math.Cos(angleInRadians);
    double sinTheta = Math.Sin(angleInRadians);
    return new PointF
    {
        X = (float)
            (cosTheta * (pointToRotate.X - centerPoint.X) -
            sinTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.X),
        Y = (float)
            (sinTheta * (pointToRotate.X - centerPoint.X) +
            cosTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.Y)
    };
}

If you want to use the MouseClick to determine the angle you can use the Points from the e parameter directly. But to find out the center you will need to convert the pixel coordinates to chart value coordinates.

Here is a call you can use during the MouseClick event:

DataPoint clickedValuePoint(ChartArea ca, Point pt)
{
    return new DataPoint(ca.AxisX.PixelPositionToValue(pt.X), 
                         ca.AxisY.PixelPositionToValue(pt.Y));
}

Now let's see it at work, using a DataPoint:

DataPoint centerPoint = null;

private void chart1_MouseClick(object sender, MouseEventArgs e)
{
    ChartArea ca = chart1.ChartAreas[0];
    centerPoint = clickedValuePoint(ca, e.Location);

    rotateSeries(s1, s2, centerPoint, 33);
}