[chronojump] force sensor capture thread more threadsafe on redo graph

[Xavier de Blas <xaviblas src gnome org>]

commit a790202acc5895403e01d42938716f0f8635d8fa
Author: Xavier de Blas <xaviblas gmail com>
Date:   Sat Oct 28 01:40:26 2017 +0200

    force sensor capture thread more threadsafe on redo graph

 src/gui/forceSensor.cs |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)
---
diff --git a/src/gui/forceSensor.cs b/src/gui/forceSensor.cs
index 0de48f4..bf5fc95 100644
--- a/src/gui/forceSensor.cs
+++ b/src/gui/forceSensor.cs
@@ -575,7 +575,7 @@ public partial class ChronoJumpWindow
 
                LogB.Information(" fc H ");
                        //------------------- realtime graph -----------------
-                       if(redoingPoints || fscPoints.Points == null || force_capture_drawingarea == null)
+                       if(redoingPoints || fscPoints == null || fscPoints.Points == null || 
force_capture_drawingarea == null)
                                return true;
 
                LogB.Information(" fc I ");
@@ -586,15 +586,16 @@ public partial class ChronoJumpWindow
                        }
 
                LogB.Information(" fc J ");
-                       //use this integer and this List to not have errors by updating data on the other 
thread
+                       //use these integers and this List to not have errors by updating data on the other 
thread
                        int numCaptured = fscPoints.NumCaptured;
+                       int numPainted = fscPoints.NumPainted;
                        List<Gdk.Point> points = fscPoints.Points;
 
                LogB.Information(" fc K ");
-                       int toDraw = numCaptured - fscPoints.NumPainted;
+                       int toDraw = numCaptured - numPainted;
 
-                       LogB.Information("fscPointsCount: " + points.Count +
-                                       "; NumCaptured: " + numCaptured + "; NumPainted: " 
+fscPoints.NumPainted +
+                       LogB.Information("points count: " + points.Count +
+                                       "; NumCaptured: " + numCaptured + "; NumPainted: " + numPainted +
                                        "; toDraw: " + toDraw.ToString() );
 
                LogB.Information(" fc L ");
@@ -604,7 +605,7 @@ public partial class ChronoJumpWindow
 
                LogB.Information(" fc M ");
                        Gdk.Point [] paintPoints;
-                       if(fscPoints.NumPainted > 0)
+                       if(numPainted > 0)
                                paintPoints = new Gdk.Point[toDraw +1]; // if something has been painted, 
connected first point with previous points
                        else
                                paintPoints = new Gdk.Point[toDraw];
@@ -612,19 +613,19 @@ public partial class ChronoJumpWindow
                LogB.Information(" fc N ");
                        int jStart = 0;
                        int iStart = 0;
-                       if(fscPoints.NumPainted > 0)
+                       if(numPainted > 0)
                        {
                                // if something has been painted, connected first point with previous points
-                               paintPoints[0] = points[fscPoints.NumPainted -1];
+                               paintPoints[0] = points[numPainted -1];
                                jStart = 1;
-                               iStart = fscPoints.NumPainted;
+                               iStart = numPainted;
                                //LogB.Information("X: " + paintPoints[0].X.ToString() + "; Y: " + 
paintPoints[0].Y.ToString());
                        }
                LogB.Information(" fc O ");
-
                        for(int j=jStart, i = iStart ; i < numCaptured ; i ++, j++)
                        {
-                               paintPoints[j] = points[i];
+                               if(points.Count > i)    //extra check to avoid going outside of arrays
+                                       paintPoints[j] = points[i];
                                //LogB.Information("X: " + paintPoints[j].X.ToString() + "; Y: " + 
paintPoints[j].Y.ToString());
                        }
                LogB.Information(" fc P ");