[chronojump] forceSensorAnalyze manual: fixed max RFD line, now cross max RFD

[Xavier de Blas <xaviblas src gnome org>]

commit 7ae14ab3b11690fb7d8bcfb76a0a6aaaead90a4f
Author: Xavier de Blas <xaviblas gmail com>
Date:   Wed May 9 17:57:36 2018 +0200

    forceSensorAnalyze manual: fixed max RFD line, now cross max RFD

 src/forceSensor.cs |   35 +++++++++++++++++++----------------
 1 files changed, 19 insertions(+), 16 deletions(-)
---
diff --git a/src/forceSensor.cs b/src/forceSensor.cs
index ce21920..b34136c 100644
--- a/src/forceSensor.cs
+++ b/src/forceSensor.cs
@@ -794,23 +794,26 @@ public class ForceSensorAnalyzeInstant
 
        public void CalculateRFDTangentLine(int countRFDMax, out int lineXStart, out int lineXEnd, out int 
lineYStart, out int lineYEnd)
        {
-               int segXBefore = GetXFromSampleCount(countRFDMax -1, GetLength());
-               int segXAfter = GetXFromSampleCount(countRFDMax +1, GetLength());
-               int segYBefore = GetPxAtForce(GetForceAtCount(countRFDMax -1));
-               int segYAfter = GetPxAtForce(GetForceAtCount(countRFDMax +1));
-
-               double slope = Math.Abs(
-                               Util.DivideSafe( segYAfter - segYBefore,
-                                       (1.0 * (segXAfter- segXBefore)) )
-                               );
-               //LogB.Information(string.Format("segXA: {0}, segXB: {1}, segYA: {2}, segYB: {3}, slope: {4}",
-               //                      segXA, segXB, segYA, segYB, slope));
-
-               lineXStart = segXBefore - Convert.ToInt32(Util.DivideSafe(
-                                       (graphHeight - segYBefore),
+               // 1) calculate X and Y of points before and after RFD
+               int pointXBefore = GetXFromSampleCount(countRFDMax -1, GetLength());
+               int pointXAfter = GetXFromSampleCount(countRFDMax +1, GetLength());
+               int pointYBefore = GetPxAtForce(GetForceAtCount(countRFDMax -1));
+               int pointYAfter = GetPxAtForce(GetForceAtCount(countRFDMax +1));
+
+               // 2) calculate the slope of the line that could pass across this points
+               double slope = Math.Abs( Util.DivideSafe( pointYAfter - pointYBefore,
+                                       (1.0 * (pointXAfter- pointXBefore)) ) );
+
+               // 3) get the RFD point
+               int pointXRFD = GetXFromSampleCount(countRFDMax, GetLength());
+               int pointYRFD = GetPxAtForce(GetForceAtCount(countRFDMax));
+
+               // 4) calculate line that cross RFD point with calculated slope
+               lineXStart = pointXRFD - Convert.ToInt32(Util.DivideSafe(
+                                       (graphHeight - pointYRFD),
                                        slope));
-               lineXEnd = segXAfter + Convert.ToInt32(Util.DivideSafe(
-                                       (segYAfter - 0),
+               lineXEnd = pointXRFD + Convert.ToInt32(Util.DivideSafe(
+                                       (pointYRFD - 0),
                                        slope));
                lineYStart = graphHeight;
                lineYEnd = 0;