--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/raster/ExternalIndexConverter.java	Fri Sep 28 12:13:56 2012 +0200
@@ -0,0 +1,65 @@
+package de.intevation.gnv.raster;
+
+import org.apache.log4j.Logger;
+
+/**
+ * Converts the interal color index of a polygon to the external index
+ * defined by the corresponding palette entry.
+ *
+ * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
+ */
+public class ExternalIndexConverter
+implements   JTSMultiPolygonProducer.ValueConverter
+{
+    private static Logger log = Logger.getLogger(
+        ExternalIndexConverter.class);
+
+    /**
+     * The palette where to find the color indices.
+     */
+    protected Palette palette;
+
+    /**
+     * Default constructor.
+     */
+    public ExternalIndexConverter() {
+    }
+
+    /**
+     * Constrcutor to create an ExternalIndexConverter with
+     * a given palette.
+     * @param palette The palette where to find the color indices.
+     */
+    public ExternalIndexConverter(Palette palette) {
+        this.palette = palette;
+    }
+
+    /**
+     * Maps the color index of a polygon to the external index
+     * defined by the corresponing palette entry.
+     * @param value The value to convert
+     * @return The mapped value or the original value if
+     * no corresponing palette entry was found.
+     */
+    public Integer convert(Integer value) {
+        if (value == null) {
+            return value;
+        }
+
+        int v = value.intValue();
+
+        if (v == -1) {
+            return value;
+        }
+
+        Palette.Entry entry = palette.getEntryByIndex(v);
+
+        if (entry == null) {
+            log.warn("cannot find palette entry for index: " + v);
+            return value;
+        }
+
+        return Integer.valueOf(entry.getExternalIndex());
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :