/// <summary>
/// Gets the value at a given point on the X-axis.
/// </summary>
/// <param name="x">Position on x-axis to get value.</param>
/// <param name="result">Reference to variable to store value in.</param>
/// <returns>
/// True if a value was retrieved. False if a value could not be retrieved because no data points are available
/// for the given position on the x-axis.
/// </returns>
public bool GetValueAtPoint(float x, out float result)
{
result = 0.0f;
for (int i = 0; i < Data.Count; i++)
{
GraphDataPoint point = Data[i];
// Point is exactly x.
if (point.X == x)
{
result = point.Y;
return(true);
}
// Point is somewhere between last value and this value.
if (point.X > x)
{
if (i > 0)
{
GraphDataPoint prevPoint = Data[i - 1];
// Linear interpolate to get value at x-value.
float delta = (x - prevPoint.X) / (point.X - prevPoint.X);
result = prevPoint.Y + (point.Y - prevPoint.Y) * delta;
return(true);
}
// No last value = no data for given point.
return(false);
}
}
return(false);
}
/// <summary>
/// Adds a new data point to the graph.
/// </summary>
/// <param name="x">Data points value on the x-axis.</param>
/// <param name="y">Data points value on the y-axis.</param>
public void AddDataPoint(float x, float y)
{
if (MinimumInterval != 0 && Data.Count > 0)
{
float Elapsed = x - Data[Data.Count - 1].X;
if (Elapsed < MinimumInterval)
{
return;
}
}
GraphDataPoint newPoint = new GraphDataPoint {
X = x, Y = y
};
Data.Add(newPoint);
// Adjust Y axis if value added is over current max.
if (YAxis.AutoAdjustMax)
{
float OriginalMax = YAxis.Max;
YAxis.Max = Math.Max(y, YAxis.Max);
YAxis.GridInterval = YAxis.Max / 5.0f;
if (YAxis.Max != OriginalMax)
{
YAxis.MaxLabel = FormatValue(YAxis.Max);
}
}
// If this is a sliding window we need to remove any points outside the window.
if (SlidingWindow)
{
bool bWasRemoved = false;
float startValue = 0.0f;
for (int i = 0; i < Data.Count; i++)
{
GraphDataPoint point = Data[i];
if (x - point.X > XAxis.Max)
{
Data.RemoveAt(i);
i--;
bWasRemoved = true;
startValue = point.Y;
}
}
// If we have removed an entry, add a dummy value back to the start to ensure our graph
// doesn't suddenly clip at the end. Happens if the value being removed is over window and the value being
// added is less than the window.
if (bWasRemoved)
{
AddDataPoint(x - XAxis.Max, startValue);
}
}
// Always sort the resulting data along the X-axis, it makes drawing simpler.
// If this becomes an issue, do sorting at the insertion point rather than sorting
// entire list.
// this.Data.Sort((c1, c2) => Math.Sign(c1.X - c2.X));
}
