From 3dbbbec3b2a3fdeb6a22a9d73689ffd1fba635d5 Mon Sep 17 00:00:00 2001
From: oliexdev <olie.xdev@googlemail.com>
Date: Fri, 11 Dec 2020 07:31:07 +0100
Subject: [PATCH] don't calculate zero measurements into the trendline
 calculations

---
 .../gui/measurement/ChartMeasurementView.java | 26 ++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/android_app/app/src/main/java/com/health/openscale/gui/measurement/ChartMeasurementView.java b/android_app/app/src/main/java/com/health/openscale/gui/measurement/ChartMeasurementView.java
index 1630aba1..85b7db29 100644
--- a/android_app/app/src/main/java/com/health/openscale/gui/measurement/ChartMeasurementView.java
+++ b/android_app/app/src/main/java/com/health/openscale/gui/measurement/ChartMeasurementView.java
@@ -484,22 +484,36 @@ public class ChartMeasurementView extends LineChart {
 
     private void addTrendLine(List<ILineDataSet> lineDataSets) {
 
-        List<ScaleMeasurement> scaleMeasurementsAsTrendlineList = getScaleMeasurementsAsTrendline(scaleMeasurementList);
-
         for (MeasurementView view : measurementViews) {
             if (view instanceof FloatMeasurementView && view.isVisible()) {
                 final FloatMeasurementView measurementView = (FloatMeasurementView) view;
 
                 final List<Entry> lineEntries = new ArrayList<>();
 
+                ArrayList<ScaleMeasurement> nonZeroScaleMeasurementList = new ArrayList<>();
+
+                // filter first all zero measurements out, so that the follow-up trendline calculations are not based on them
+                for (int i=0; i<scaleMeasurementList.size(); i++) {
+                    ScaleMeasurement measurement = scaleMeasurementList.get(i);
+                    float value = measurementView.getMeasurementValue(measurement);
+
+                    if (value != 0.0f) {
+                        nonZeroScaleMeasurementList.add(measurement);
+                    }
+                }
+
+                // check if we have some data left otherwise skip the measurement
+                if (nonZeroScaleMeasurementList.isEmpty()) {
+                    continue;
+                }
+
+                // calculate the trendline from the non-zero scale measurement list
+                List<ScaleMeasurement> scaleMeasurementsAsTrendlineList = getScaleMeasurementsAsTrendline(nonZeroScaleMeasurementList);
+
                 for (int i=0; i<scaleMeasurementsAsTrendlineList.size(); i++) {
                     ScaleMeasurement measurement = scaleMeasurementsAsTrendlineList.get(i);
                     float value = measurementView.getMeasurementValue(measurement);
 
-                    if (value == 0.0f) {
-                        continue;
-                    }
-
                     Entry entry = new Entry();
                     entry.setX(convertDateToInt(measurement.getDateTime()));
                     entry.setY(value);