Fixed sparkline y axis labelling. Reverted it to how it previously worked (negative data values instead of negative scale).

issue #32

racevisionGame/src/main/java/visualiser/model/Sparkline.java

@@ -115,7 +115,7 @@ public class Sparkline {
                 }
 
                 //Update height of y axis.
-                yAxis.setLowerBound(boats.size());
+                setYAxisLowerBound();
             });
 
         });
@@ -143,17 +143,47 @@ public class Sparkline {
         xAxis.setUpperBound(race.getLegCount());
         xAxis.setTickUnit(1);
 
+
+        //The y-axis uses negative values, with the minus sign hidden (e.g., boat in 1st has position -1, which becomes 1, boat in 6th has position -6, which becomes 6).
+        //This is necessary to actually get the y-axis labelled correctly. Negative tick count doesn't work.
         //Set y axis details
-        yAxis.setLowerBound(boats.size());
-        yAxis.setUpperBound(1);
         yAxis.setAutoRanging(false);
+
+        yAxis.setTickUnit(1);
+        yAxis.setMinorTickCount(0);
+
+        yAxis.setUpperBound(0);
+        setYAxisLowerBound();
+
         yAxis.setLabel("Position in Race");
-        yAxis.setTickUnit(-1);//Negative tick reverses the y axis.
 
         yAxis.setTickMarkVisible(true);
         yAxis.setTickLabelsVisible(true);
-        yAxis.setTickMarkVisible(true);
-        yAxis.setMinorTickVisible(true);
+        yAxis.setMinorTickVisible(false);
+
+
+
+        //Hide minus number from displaying on axis.
+        yAxis.setTickLabelFormatter(new NumberAxis.DefaultFormatter(yAxis) {
+            @Override
+            public String toString(Number value) {
+                if ((value.intValue() == 0) || (value.intValue() < -boats.size())) {
+                    return "";
+
+                } else {
+                    return String.format("%d", -value.intValue());
+                }
+            }
+        });
+
+    }
+
+
+    /**
+     * Sets the lower bound of the y-axis.
+     */
+    private void setYAxisLowerBound() {
+        yAxis.setLowerBound( -(boats.size() + 1));
     }
 
 
@@ -179,7 +209,7 @@ public class Sparkline {
 
 
         //All boats start in "last" place.
-        series.getData().add(new XYChart.Data<>(0, boats.size()));
+        series.getData().add(new XYChart.Data<>(0, -(boats.size())));
 
         //Listen for changes in the boat's leg - we only update the graph when it changes leg.
         boat.legProperty().addListener(
@@ -188,7 +218,7 @@ public class Sparkline {
                     //Get the data to plot.
                     List<VisualiserBoat> boatOrder = race.getLegCompletionOrder().get(oldValue);
                     //Find boat position in list.
-                    int boatPosition = boatOrder.indexOf(boat) + 1;
+                    int boatPosition = -(boatOrder.indexOf(boat) + 1);
 
                     //Get leg number.
                     int legNumber = oldValue.getLegNumber() + 1;