PercentageTextField.java

/* (c) 2016 Open Source Geospatial Foundation - all rights reserved
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.geoserver.web.wicket;

import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;

import org.apache.wicket.markup.html.form.TextField;
import org.apache.wicket.model.IModel;
import org.apache.wicket.util.convert.IConverter;

/**
 * A TextField for {@code java.lang.Double} representation as a percentage.
 * 
 * @author Jody Garnett (Boundless)
 */
public class PercentageTextField extends TextField<Double> {
    private static final long serialVersionUID = -4589385113632745745L;

    private int maximumFractionDigits = 1;
    
    private IConverter<Double> percentConverter = new IConverter<Double>() {
        private static final long serialVersionUID = -8409029711658542273L;
        @Override
        public String convertToString(Double value, Locale locale) {
            NumberFormat format = formatter(locale);            
            return value == null? null : format.format(value);
        }
        @Override
        public Double convertToObject(String value, Locale locale) {
            if (value == null || value.trim().length() == 0) {
                return null;
            }
            if( !value.endsWith("%")){
                value += "%";
            }
            NumberFormat format = formatter(locale);            
            Number parsed;
            try {
                parsed = format.parse(value);
            } catch (ParseException e) {
                error(e.getMessage());
                return null;
            }
            return Double.valueOf(parsed.doubleValue());
        }
    };
    
    public PercentageTextField(String id) {
        super(id, Double.class);
    }
    public PercentageTextField(String id, IModel<Double> model) {
        super(id, model, Double.class);
    }

    private NumberFormat formatter(Locale locale) {
        NumberFormat format = NumberFormat.getPercentInstance(locale);
        format.setMaximumFractionDigits(maximumFractionDigits);
        
        return format;
    }
    public void setMaximumFractionDigits(int maximumFractionDigits) {
        this.maximumFractionDigits = maximumFractionDigits;
    }
    
    @SuppressWarnings("unchecked")
    @Override
    public <C> IConverter<C> getConverter(Class<C> type) {
        if( Double.class.isAssignableFrom(type)){
            return (IConverter<C>) percentConverter;
        }
        return super.getConverter(type);
    }
}