/// <summary>
/// Returns the index of a scatter point that is nearest to the location <c>hitpoint</c>
/// </summary>
/// <param name="layer">The layer in which this plot item is drawn into.</param>
/// <param name="hitpoint">The point where the mouse is pressed.</param>
/// <returns>The information about the point that is nearest to the location, or null if it can not be determined.</returns>
public XYScatterPointInformation GetNearestPlotPoint(IPlotArea layer, PointF hitpoint)
{
Processed2DPlotData pdata;
if (null != (pdata = _cachedPlotDataUsedForPainting))
{
PlotRangeList rangeList = pdata.RangeList;
PointF[] ptArray = pdata.PlotPointsInAbsoluteLayerCoordinates;
double mindistance = double.MaxValue;
int minindex = -1;
for (int i = 1; i < ptArray.Length; i++)
{
double distance = Drawing2DRelated.SquareDistanceLineToPoint(ptArray[i - 1], ptArray[i], hitpoint);
if (distance < mindistance)
{
mindistance = distance;
minindex = Drawing2DRelated.Distance(ptArray[i - 1], hitpoint) < Drawing2DRelated.Distance(ptArray[i], hitpoint) ? i - 1 : i;
}
}
// ok, minindex is the point we are looking for
// so we have a look in the rangeList, what row it belongs to
int rowindex = rangeList.GetRowIndexForPlotIndex(minindex);
return(new XYScatterPointInformation(ptArray[minindex], rowindex, minindex));
}
return(null);
}
/// <summary>
/// Test wether the mouse hits a plot item.
/// </summary>
/// <param name="layer">The layer in which this plot item is drawn into.</param>
/// <param name="hitpoint">The point where the mouse is pressed.</param>
/// <returns>Null if no hit, or a <see cref="IHitTestObject" /> if there was a hit.</returns>
public override IHitTestObject HitTest(IPlotArea layer, PointF hitpoint)
{
Processed2DPlotData pdata = _cachedPlotDataUsedForPainting;
if (null == pdata)
{
return(null);
}
PlotRangeList rangeList = pdata.RangeList;
PointF[] ptArray = pdata.PlotPointsInAbsoluteLayerCoordinates;
if (ptArray.Length < 2048)
{
GraphicsPath gp = new GraphicsPath();
gp.AddLines(ptArray);
if (gp.IsOutlineVisible(hitpoint.X, hitpoint.Y, new Pen(Color.Black, 5)))
{
gp.Widen(new Pen(Color.Black, 5));
return(new HitTestObject(gp, this));
}
}
else // we have too much points for the graphics path, so make a hit test first
{
int hitindex = -1;
for (int i = 1; i < ptArray.Length; i++)
{
if (Drawing2DRelated.IsPointIntoDistance(ptArray[i - 1], ptArray[i], hitpoint, 5))
{
hitindex = i;
break;
}
}
if (hitindex < 0)
{
return(null);
}
GraphicsPath gp = new GraphicsPath();
int start = Math.Max(0, hitindex - 1);
gp.AddLine(ptArray[start], ptArray[start + 1]);
gp.AddLine(ptArray[start + 1], ptArray[start + 2]);
gp.Widen(new Pen(Color.Black, 5));
return(new HitTestObject(gp, this));
}
return(null);
}
