here you go.

in the Windows Forms ultrachart, polylines don't normally participate in hit testing, so what you need to do is create a transparent polygon to overlay the polyline.

the code goes like this:

private void ultraChart1_FillSceneGraph(object sender, FillSceneGraphEventArgs e)

{

PrimitiveCollection primitivesToAdd = new PrimitiveCollection();

foreach (Primitive currentPrimitive in e.SceneGraph)

{

Polyline currentPolyline = currentPrimitive as Polyline;

if (currentPolyline != null)

{

Polygon overlayPolygon = this.PolylineToPolygon(currentPolyline);

overlayPolygon.Caps |= PCaps.HitTest | PCaps.Tooltip;

overlayPolygon.PE.FillOpacity = overlayPolygon.PE.StrokeOpacity = 0;

overlayPolygon.Value = overlayPolygon.Row = overlayPolygon.Column = 0;

overlayPolygon.Chart = e.ChartCore.ChartType;

overlayPolygon.Layer = e.ChartCore.GetChartLayer();

primitivesToAdd.Add(overlayPolygon);

}

}

e.SceneGraph.AddRange(primitivesToAdd.ToArray());

}

private Polygon PolylineToPolygon(Polyline input)

{

double halfThickness = input.PE.StrokeWidth / 2.0;

double halfPi = Math.PI / 2.0;

//DataPoint[] newPoints = new DataPoint[input.points.Length * 2 + 1];

Point[] newPoints = new Point[input.points.Length * 2 + 1];

double[] slopes = new double[input.points.Length - 1];

for (int i = 0; i < input.points.Length - 1; i++)

{

slopes[i] = Slope(input.points[i].point, input.points[i + 1].point);

}

for (int i = 0; i < input.points.Length - 1; i++)

{

double segmentAngle = Math.Atan(slopes[i]);

double perpendicularAngle1 = segmentAngle + halfPi;

double perpendicularAngle2 = segmentAngle - halfPi;

Point segmentStart1 = Geometry.AngularToCartesian(input.points[i].point, halfThickness, perpendicularAngle1);

Point segmentStart2 = Geometry.AngularToCartesian(input.points[i].point, halfThickness, perpendicularAngle2);

Point segmentEnd1 = Geometry.AngularToCartesian(input.points[i + 1].point, halfThickness, perpendicularAngle1);

Point segmentEnd2 = Geometry.AngularToCartesian(input.points[i + 1].point, halfThickness, perpendicularAngle2);

newPoints[i] = segmentStart1;

newPoints[i + 1] = segmentStart2;

newPoints[newPoints.Length - i - 2] = segmentEnd1;

newPoints[newPoints.Length - i - 3] = segmentEnd2;

}

newPoints[newPoints.Length - 1] = newPoints[0];

return new Polygon(newPoints);

}

public static double Slope(PointF point1, PointF point2)

{

return (point2.Y - point1.Y) / (point2.X - point1.X);

}

Hi David,

  Could you provide a sample of your solution? I can't figure out how you do this. I have a scatter chart where 2 points are connected with a line and I want to display a tooltip when my mouse is over the line as well as the mouse is over the datapoints

Thanks,