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The main module contains the GeoTools public interfaces that are used by other GeoTools modules (and GeoTools applications). Where possible we make use industry standard terms as provided by OGC and ISO standards. The formal GeoTools public api consists of gt-metadata, jts and the gt-main module. The main module contains the default implementations that are available provided to other GeoTools modules using our factory system. Factories are obtained from an appropriate FactoryFinder, giving applications a chance configure the factory used using the Factory Hints facilities. FilterFactory ff = CommonFactoryFinder.getFilterFactory(); Expression expr = ff.add( expression1, expression2 ); If you find yourself using implementation specific classes chances are you doing it wrong: Expression expr = new AddImpl( expression1, expressiom2 );

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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2013-2016, 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.styling.visitor;

import java.util.HashMap;
import java.util.Map;
import javax.measure.Unit;
import javax.measure.UnitConverter;
import javax.measure.quantity.Length;
import org.geotools.measure.Units;
import org.opengis.filter.expression.Expression;
import org.opengis.filter.expression.Literal;
import si.uom.SI;
import systems.uom.common.USCustomary;

/**
 * Helper class that allows rescaling to pixels numbers that might carry a unit specification along
 * with them, handling the case where real world units should not be rescaled (dpi rescaling) as
 * well as the simpler case where everything should be rescaled (uom rescaling)
 */
enum RescalingMode {
    /** Rescales the values and maintains the units */
    KeepUnits {
        @Override
        public String rescaleToStringInternal(double scaleFactor, Measure measure) {
            double rescaled = measure.value * scaleFactor;
            String rescaledString;
            if (rescaled == (int) rescaled) {
                rescaledString = String.valueOf((int) rescaled);
            } else {
                rescaledString = String.valueOf(rescaled);
            }
            if (measure.isPixelInPixelDefault()) {
                return rescaledString;
            } else {
                return rescaledString + UNIT_SYMBOLS.get(measure.uom);
            }
        }
    },

    /** Only rescales pixel values */
    Pixels {
        @Override
        public String rescaleToStringInternal(double scaleFactor, Measure measure) {
            if (measure.isRealWorldUnit()) {
                if (measure.isRealWorldUnitInPixelDefault()) {
                    return String.valueOf(measure.value) + UNIT_SYMBOLS.get(measure.uom);
                } else {
                    return String.valueOf(measure.value);
                }
            } else {
                return String.valueOf(measure.value * scaleFactor);
            }
        }

        @Override
        public Expression rescaleToExpression(Expression scaleFactor, Measure measure) {
            if (measure.isRealWorldUnit()) {
                return measure.expression;
            } else {
                return super.rescaleToExpression(scaleFactor, measure);
            }
        }
    },

    /**
     * Rescales feet and meter to pixel based on the scale factor (interpreted as a scale
     * denominator)
     */
    RealWorld {
        @Override
        public String rescaleToStringInternal(double scaleFactor, Measure measure) {
            return String.valueOf(
                    measure.value * computeRescaleMultiplier(scaleFactor, measure.uom));
        }

        /**
         * Computes a rescaling multiplier to be applied to an unscaled value.
         *
         * @param mapScale the mapScale in pixels per meter.
         * @param uom the unit of measure that will be used to scale.
         * @return the rescaling multiplier for the provided parameters.
         */
        double computeRescaleMultiplier(double mapScale, Unit uom) {
            // no scaling to do if UOM is PIXEL (or null, which stands for PIXEL as well)
            if (uom == null || uom.equals(Units.PIXEL)) return 1;

            if (uom == SI.METRE) {
                return mapScale;
            }

            // converts value from meters to given UOM
            UnitConverter converter = uom.getConverterTo(SI.METRE);
            return converter.convert(mapScale);
        }
    };

    public abstract String rescaleToStringInternal(double scaleFactor, Measure measure);

    public String rescaleToString(double scaleFactor, Measure measure) {
        if (measure.value == null) {
            throw new IllegalStateException(
                    "Cannot rescale to literal, the value is a generic expression, not a static value: "
                            + measure.expression);
        }

        return rescaleToStringInternal(scaleFactor, measure);
    }

    public Expression rescaleToExpression(Expression scaleFactor, Measure measure) {
        if (measure.value != null && scaleFactor instanceof Literal) {
            Double scale = scaleFactor.evaluate(null, Double.class);
            return Measure.ff.literal(rescaleToStringInternal(scale, measure));
        } else {
            // if it's an expression, there is still a chance the expression will have, at the
            // end,
            // a unit, so we have to delay the evaluation to later
            return Measure.ff.function(
                    "rescaleToPixels",
                    measure.expression,
                    Measure.ff.literal(measure.uom),
                    scaleFactor,
                    Measure.ff.literal(this));
        }
    }

    /**
     * Translates between units and their shortcuts (we can only get the full name from the unit
     * object
     */
    final Map UNIT_SYMBOLS =
            new HashMap() {
                {
                    put(Units.PIXEL, "px");
                    put(USCustomary.FOOT, "ft");
                    put(SI.METRE, "m");
                }
            };
}