SignalXY: last point sometimes does not get rendered

[swharden]

Perhaps because a binning issue?

[swharden]

This is reproducible and only affects "high density mode"

using ScottPlot;

namespace Sandbox.WinForms;

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        int count = 1000;
        double[] xs = Generate.Consecutive(count);
        double[] ys = Generate.RandomWalk(count);
        ys[^1] = -100;

        formsPlot1.Plot.Add.SignalXY(xs, ys);
    }
}

[swharden]

Interestingly, it's only the very last point, and only about half the frames. It "flickers" as you zoom horizontally.

using ScottPlot;

namespace Sandbox.WinForms;

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        int count = 1000;
        double[] xs = Generate.Consecutive(count);
        double[] ys = Generate.RandomWalk(count);
        ys[0] = -100;
        ys[499] = -100;
        ys[999] = -100;

        var sig = formsPlot1.Plot.Add.SignalXY(xs, ys);
        sig.MarkerShape = MarkerShape.OpenCircle;
        sig.MarkerColor = Colors.Black;
        sig.MarkerSize = 10;
    }
}

[swharden]

I'm pretty sure the issue is in here

ScottPlot/src/ScottPlot5/ScottPlot5/DataSources/SignalXYSourceDoubleArray.cs

Lines 156 to 187 in 6468dbe

	private IEnumerable<Pixel> GetColumnPixelsX(int pixelColumnIndex, IndexRange rng, RenderPack rp, IAxes axes)
	{
	float xPixel = pixelColumnIndex + rp.DataRect.Left;
	double unitsPerPixelX = axes.XAxis.Width / rp.DataRect.Width;
	double start = axes.XAxis.Min + unitsPerPixelX * pixelColumnIndex;
	double end = start + unitsPerPixelX;
	// add slight overlap to prevent floating point errors from missing points
	// https://github.com/ScottPlot/ScottPlot/issues/3665
	double overlap = unitsPerPixelX * .01;
	end += overlap;
	var (startPosition, startIndex) = SearchIndex(start, rng);
	var (endPosition, endIndex) = SearchIndex(end, rng);
	int pointsInRange = Math.Abs(endPosition - startPosition);
	if (pointsInRange == 0)
	{
	yield break;
	}
	yield return new Pixel(xPixel, axes.GetPixelY(Ys[startIndex] * YScale + YOffset)); // enter
	if (pointsInRange > 1)
	{
	int lastIndex = startIndex < endIndex ? endIndex - 1 : endIndex + 1;
	CoordinateRange yRange = GetRangeY(startIndex, lastIndex); //YOffset is added in GetRangeY
	yield return new Pixel(xPixel, axes.GetPixelY(yRange.Min)); // min
	yield return new Pixel(xPixel, axes.GetPixelY(yRange.Max)); // max
	yield return new Pixel(xPixel, axes.GetPixelY(Ys[lastIndex] * YScale + YOffset)); // exit
	}
	}

[swharden]

I'm thinking the issue is here:

ScottPlot/src/ScottPlot5/ScottPlot5/DataSources/SignalXYSourceDoubleArray.cs

Lines 170 to 175 in 6468dbe

	int pointsInRange = Math.Abs(endPosition - startPosition);
	if (pointsInRange == 0)
	{
	yield break;
	}

For the last point, it's possible where the last pixel column contains a single value, so start and stop index positions will be the same

[BrianAtZetica]

This fix introduced a bug with rotated SignalXY plots that can be demonstrated with the following code (I'm using the WPF Sandbox here):

'''

    InitializeComponent();

    var amplitude = Generate.Sin();
    double[] time = new double[51];
    for (int i = 0; i < time.Length; i++)
        time[i] = i;

    var signal = WpfPlot1.Plot.Add.SignalXY(time, amplitude, color: ScottPlot.Colors.Black);
    signal.Data.Rotated = true;

'''

It looks like the last point (which should be at X = 0, Y = 51, is being plotted without cooridnate rotation (i.e. at X = 51 and Y = 0).