Had to reimplement getValue to not use TreeMap/SortedMap apis unavailable in Froyo...

git-svn-id: https://openrocket.svn.sourceforge.net/svnroot/openrocket/trunk@912 180e2498-e6e9-4542-8430-84ac67f01cd8

diff --git a/core/src/net/sf/openrocket/util/LinearInterpolator.java b/core/src/net/sf/openrocket/util/LinearInterpolator.java
index db422d52a6d2f103e08bd77e26773133202e95a3..6a9a308b6f11e3b8cde69e4a223080d8b11ea548 100644 (file)
--- a/core/src/net/sf/openrocket/util/LinearInterpolator.java
+++ b/core/src/net/sf/openrocket/util/LinearInterpolator.java
@@ -1,7 +1,7 @@
 package net.sf.openrocket.util;
 
 import java.util.Iterator;
-import java.util.Map;
+import java.util.SortedMap;
 import java.util.TreeMap;
 
 public class LinearInterpolator implements Cloneable {
@@ -14,7 +14,7 @@ public class LinearInterpolator implements Cloneable {
         */
        public LinearInterpolator() {
        }
-       
+
        /**
         * Construct a <code>LinearInterpolator</code> with the given points.
         * 
@@ -27,8 +27,8 @@ public class LinearInterpolator implements Cloneable {
        public LinearInterpolator(double[] x, double[] y) {
                addPoints(x,y);
        }
-       
-       
+
+
        /**
         * Add the point to the linear interpolation.
         * 
@@ -38,7 +38,7 @@ public class LinearInterpolator implements Cloneable {
        public void addPoint(double x, double y) {
                sortMap.put(x, y);
        }
-       
+
        /**
         * Add the points to the linear interpolation.
         * 
@@ -56,41 +56,66 @@ public class LinearInterpolator implements Cloneable {
                        sortMap.put(x[i],y[i]);
                }
        }
-       
-       
-       
+
+
+
        public double getValue(double x) {
-               Map.Entry<Double,Double> e1, e2;
                double x1, x2;
-               double y1, y2;
+               Double y1, y2;
+               // Froyo does not support floorEntry, firstEntry or higherEntry.  We instead have to
+               // resort to using other more awkward methods.
+
+               y1 = sortMap.get(x);
+
+               if ( y1 != null ) {
+                       // Wow, x was a key in the map.  Such luck.
+                       return y1.doubleValue();
+               }
+
+               // we now know that x is not in the map, so we need to find the lower and higher keys.
                
-               e1 = sortMap.floorEntry(x);
+               // let's just make certain that our map is not empty.
+               if ( sortMap.isEmpty() ) {
+                       throw new IllegalStateException("No points added yet to the interpolator.");
+               }
                
-               if (e1 == null) {
-                       // x smaller than any value in the set
-                       e1 = sortMap.firstEntry();
-                       if (e1 == null) {
-                               throw new IllegalStateException("No points added yet to the interpolator.");
-                       }
-                       return e1.getValue();
+               // firstKey in the map - cannot be null since the map is not empty.
+               Double firstKey = sortMap.firstKey();
+
+               // x is smaller than the first entry in the map.
+               if ( x < firstKey.doubleValue() ) {
+                       y1 = sortMap.get(firstKey);
+                       return y1.doubleValue();
                }
                
-               x1 = e1.getKey();
-               e2 = sortMap.higherEntry(x1);
+               // floor key is the largest key smaller than x - since we have at least one key,
+               // and x>=firstKey, we know that floorKey != null.
+               Double floorKey = sortMap.subMap(firstKey, x).lastKey();
+
+               x1 = floorKey.doubleValue();
+               y1 = sortMap.get(floorKey);
 
-               if (e2 == null) {
-                       // x larger than any value in the set
-                       return e1.getValue();
+               // Now we need to find the key that is greater or equal to x
+               SortedMap<Double,Double> tailMap = sortMap.tailMap(x);
+
+               // Check if x is bigger than all the entries.
+               if ( tailMap.isEmpty() ) {
+                       return y1.doubleValue();
                }
+               Double ceilKey = tailMap.firstKey();
                
-               x2 = e2.getKey();
-               y1 = e1.getValue();
-               y2 = e2.getValue();
+               // Check if x is bigger than all the entries.
+               if ( ceilKey == null ) {
+                       return y1.doubleValue();
+               }
                
+               x2 = ceilKey.doubleValue();
+               y2 = sortMap.get(ceilKey);
+
                return (x - x1)/(x2-x1) * (y2-y1) + y1;
        }
-       
-       
+
+
        public double[] getXPoints() {
                double[] x = new double[sortMap.size()];
                Iterator<Double> iter = sortMap.keySet().iterator();
@@ -99,8 +124,8 @@ public class LinearInterpolator implements Cloneable {
                }
                return x;
        }
-       
-       
+
+
        @SuppressWarnings("unchecked")
        @Override
        public LinearInterpolator clone() {