/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.filter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.geotools.factory.CommonFactoryFinder;
import org.opengis.filter.FilterFactory2;
import org.opengis.filter.capability.FunctionName;
import org.opengis.filter.expression.Expression;
import org.opengis.filter.expression.ExpressionVisitor;
import org.opengis.filter.expression.Function;
import org.opengis.filter.expression.Literal;
import org.opengis.filter.Filter;
/**
* Implementation of "Categorize" as a normal function.
* <p>
* This implementation is compatible with the Function
* interface; the parameter list can be used to set the
* threshold values etc...
* <p>
* This function expects:
* <ol>
* <li>PropertyName; use "Rasterdata" to indicate this is a color map
* <li>Literal: lookup value
* <li>Literal: threshold 1
* <li>Literal: value 1
* <li>Literal: threshold 2
* <li>Literal: value 2
* <li>Literal: (Optional) succeeding or preceding
* </ol>
* In reality any expression will do.
* @author Jody Garnett
* @author Johann Sorel (Geomatys)
*
* @source $URL$
*/
public class CategorizeFunction implements Function {
/** Use as a literal value to indicate behaviour of threshold boundary */
public static final String SUCCEEDING = "succeeding";
/** Use as a literal value to indicate behaviour of threshold boundary */
public static final String PRECEDING = "preceding";
/**
* Use as a PropertyName when defining a color map.
* The "Raterdata" is expected to apply to only a single band; if multiple
* bands are provided it is probably a mistake; but we will use the maximum
* value (since we are working against a threshold).
*/
public static final String RASTER_DATA = "Rasterdata";
private final List<Expression> parameters;
private final Literal fallback;
/**
* Make the instance of FunctionName available in
* a consistent spot.
*/
public static final FunctionName NAME = new Name();
/**
* Describe how this function works.
* (should be available via FactoryFinder lookup...)
*/
public static class Name implements FunctionName {
public int getArgumentCount() {
return 2; // indicating unbounded, 2 minimum
}
public List<String> getArgumentNames() {
return Arrays.asList(new String[]{
"LookupValue",
"Value",
"Threshold 1", "Value 1",
"Threshold 2", "Value 2",
"succeeding or preceding"
});
}
public String getName() {
return "Categorize";
}
};
public CategorizeFunction() {
this( new ArrayList<Expression>(), null);
}
public CategorizeFunction(List<Expression> parameters, Literal fallback) {
this.parameters = parameters;
this.fallback = fallback;
}
public String getName() {
return NAME.getName();
}
public List<Expression> getParameters() {
return Collections.unmodifiableList(parameters);
}
public Object accept(ExpressionVisitor visitor, Object extraData) {
return visitor.visit(this, extraData);
}
public Object evaluate(Object object) {
return evaluate(object, Object.class);
}
public <T> T evaluate(Object object, Class<T> context) {
final Expression lookupExp = parameters.get(0);
final String belongsTo = queryThreshdoldBelongsTo(object);
Expression currentExp = parameters.get(1);
final List<Expression> splits;
if (parameters.size() == 2) {
return currentExp.evaluate(object, context);
} else if (parameters.size() % 2 == 0) {
splits = parameters.subList(2, parameters.size());
} else {
splits = parameters.subList(2, parameters.size() - 1);
}
FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2(null);
for (int i = 0; i < splits.size(); i += 2) {
Expression threshholdExp = splits.get(i);
Expression rangedExp = splits.get(i + 1);
String lookupValue = lookupExp.evaluate(object, String.class);
//we deal with a raster data
if(lookupValue.equalsIgnoreCase(RASTER_DATA)){
Double bandValue = new Double(object.toString());
Double threshholdValue = threshholdExp.evaluate(object, Double.class);
if (PRECEDING.equals(belongsTo)) {
if(bandValue > threshholdValue){
currentExp = rangedExp;
}else{
break;
}
} else {
if(bandValue >= threshholdValue){
currentExp = rangedExp;
}else{
break;
}
}
}
//we deal with something else, a mistake ? can it happen ?
else{
Filter isIncludedInThreshold;
if (PRECEDING.equals(belongsTo)) {
isIncludedInThreshold = ff.greater(lookupExp, threshholdExp);
} else {
isIncludedInThreshold = ff.greaterOrEqual(lookupExp, threshholdExp);
}
if (isIncludedInThreshold.evaluate(object)) {
currentExp = rangedExp;
} else {
break;
}
}
}
return currentExp.evaluate(object, context);
}
/**
* There is no great way to check if the last parameter
* is intended to be the optional ThreshholdBelongsTo
* or not (since it is an optional parameter).
* <p>
* We can figure out if "succeeding" or "preceding" is
* being provided by checking the number of parameters.
* @param object
* @return PRECEDING or SUCCEEDING after checking if any information was provided.
*/
private String queryThreshdoldBelongsTo(Object object) {
if (parameters.size() == 2 && parameters.size() % 2 == 0) {
return SUCCEEDING; // user has not specified anything
}
Expression lastParameter = parameters.get(parameters.size() - 1);
String lastValue = lastParameter.evaluate(object, String.class);
if (PRECEDING.equalsIgnoreCase(lastValue)) {
return PRECEDING;
} else if (SUCCEEDING.equalsIgnoreCase(lastValue)) {
return SUCCEEDING;
} else {
// warning?
return SUCCEEDING; // default
}
}
public Literal getFallbackValue() {
return fallback;
}
}