/// <summary>
/// Retrieves the data points of the current active plot.
/// </summary>
/// <param name="ctrl">The graph controller which controls the graph from which the points are to retrieve.</param>
/// <param name="xarr">The array of the data point's x values.</param>
/// <param name="yarr">The array of the data point's y values.</param>
/// <param name="nPlotPoints">The number of plot points (may be smaller than the length of x and y arrays.</param>
/// <returns>Null if all is ok, or error message if not.</returns>
public static string GetActivePlotPoints(Altaxo.Graph.GUI.GraphController ctrl, ref double[] xarr, ref double[] yarr, out int nPlotPoints)
{
nPlotPoints = 0;
ctrl.EnsureValidityOfCurrentLayerNumber();
ctrl.EnsureValidityOfCurrentPlotNumber();
IGPlotItem plotItem = ctrl.ActiveLayer.PlotItems.Flattened[ctrl.CurrentPlotNumber];
XYColumnPlotItem xyPlotItem = plotItem as XYColumnPlotItem;
if (xyPlotItem == null)
{
return("No active plot!");
}
XYColumnPlotData data = xyPlotItem.XYColumnPlotData;
if (data == null)
{
return("Active plot item has no data");
}
if (!(data.XColumn is Altaxo.Data.INumericColumn) || !(data.YColumn is Altaxo.Data.INumericColumn))
{
return("X-Y values of plot data are not both numeric");
}
Altaxo.Data.INumericColumn xcol = (Altaxo.Data.INumericColumn)data.XColumn;
Altaxo.Data.INumericColumn ycol = (Altaxo.Data.INumericColumn)data.YColumn;
int n = data.PlottablePoints;
if (null == xarr || xarr.Length < n)
{
xarr = new double[n];
}
if (null == yarr || yarr.Length < n)
{
yarr = new double[n];
}
int end = data.PlotRangeEnd;
int j = 0;
for (int i = data.PlotRangeStart; i < end && j < n; i++)
{
double x = xcol[i];
double y = ycol[i];
if (double.IsNaN(x) || double.IsNaN(y))
{
continue;
}
xarr[j] = x;
yarr[j] = y;
++j;
}
nPlotPoints = j;
return(null);
}
