Application: gvSIG desktop

/* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana

 *

 * Copyright (C) 2005 IVER T.I. and Generalitat Valenciana.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,USA.

 *

 * For more information, contact:

 *

 *  Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib??ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *      +34 963862235

 *   gvsig@gva.es

 *      www.gvsig.gva.es

 *

 *    or

 *

 *   IVER T.I. S.A

 *   Salamanca 50

 *   46005 Valencia

 *   Spain

 *

 *   +34 963163400

 *   dac@iver.es

 */

package com.iver.cit.gvsig.fmap.core;

import java.awt.geom.AffineTransform;

import com.iver.cit.gvsig.fmap.MapContext;

import com.iver.cit.gvsig.fmap.ViewPort;

/**

 * <p>This interface enables Cartographic support for those graphical elements that require

 * additional runtime information rather than the feature itself geometric definitions.<br></p>

 *

 * <p>It allows to realworld's measure units dimensioning.<br></p>

 *

 * <p>It also supplies a toolkit to perform operations with centralized static methods.

 * @see CartographicSupportToolkit inner class' methods<br></p>

 *

 * @author jaume dominguez faus - jaume.dominguez@iver.es

 */

public interface CartographicSupport {

        public static final int WORLD = 0;

        public static final int PAPER = 0;

        /**

         * Defines the unit used to express measures. It is the position of the unit in the <b>MapContext.NAMES</b> array.

         * @param unitIndex, the index of the unit in the MapContext.NAMES array

         */

        public abstract void setUnit(int unitIndex);

        /**

         * Returns the unit used to express measures. It is the position of the unit in the <b>MapContext.NAMES</b> array.

         * @returns an <b>int</b> with the index of the unit in the MapContext.NAMES array

         */

        public abstract int getUnit();

        /**

         * Returns the <b>Reference System</b> used to draw the elements of the image.<br>

         * <p>

         * The elements have to be scaled to <b>pixel</b> when the image is bein drawn in

         * order to compose the map. The elements of the map may define its size in

         * other units than pixel.<br>

         * </p>

         * <p><b>CartographicSupport</b> enables the elements to define the size in

         * measure units but these units may refer to different reference system. Two

         * kinds of Reference Systems are allowed in this context: <b>CartographicSupport.WORLD</b>,

         * and <b>CartographicSupport.PAPER</b>.

         * <br></p>

         * <p>

         * Depending on which <b>Reference System</b> is used the unit used by this element

         * refers to distances in the real world (then they are map's CRS-dependant)

         * or screen or printer output (then they are output DPI-dependant)<br>

         * </p>

         * <p>

         * In case the unit used is <b>pixel</b> then the reference system does not

         * have any effect since the source unit is the same than the target unit.

         * <br>

         * </p>

         * @return

         */

        public abstract int getReferenceSystem();

        /**

         * Sets the <b>Reference System</b> that defines how this units have to be

         * handled. Possible values are:

         * <ol>

         *   <li><b>CartographySupport.WORLD</b>: Defines that the unit values refer

         *   to distances in the world. So, the size of the element displayed <b>depends

         *   directly on the scale and CRS</b> used by the map. The size of the elements

         *   defined to use CartographicSupport.WORLD will match exactly to their

         *   actual size in the real world.</li>

         *   <li><b>CartographySupport.PAPER</b>: Defines that the unit values refer

         *   to the length that the element will have regardless where it appears. If

         *   ReferenceSystem is <b>CartographySupport.PAPER</b>, and the length is (e.g.)

         *   millimeters the element will be displayed with the <b>same</b> amount of

         *   millimeters of length whether in the <b>screen</b> or the <b>printer</b>

         *   (screen DPI and printer DPI must be correctly configured).</li>

         * </ol>

         */

        public void setReferenceSystem(int referenceSystem);

        class CartographicSupportToolkit {

                private static final int CONVERSION_ARRAY_LENGTH = MapContext.CHANGEM.length;

                /**

                 * <p><b>Computes the screen size (pixels)</b> of a given <b>length</b> according to the current's rendering

                 * context defined by an <b>affine transform</b> in the <b>X axis</b>. The value of the length is expressed in the

                 * units specified by <b>unitIndex</b>-th element of the <b>MapContext.NAMES</b> array.</p>

                 *

                 * <p>If the unitIndex is out of the MapContext.NAMES array range, (it is assumed that the

                 * distance units are already in pixel) then the input and output length values are

                 * equal.</p>

                 * @param length, the length to be transformed to screen units

                 * @param at, an affine transform with the current rendering context

                 * @param unitIndex, the unit in which the length is given

                 * @return

                 */

                public static double toScreenUnitXAxis(CartographicSupport graphicElement, double length, ViewPort viewPort) {

                        final int unitIndex = graphicElement.getUnit();

                        if (unitIndex >= CONVERSION_ARRAY_LENGTH || unitIndex < 0) return length;

                        return Math.abs(viewPort.getAffineTransform().getScaleX()*

                                        toViewPortUnits(length, unitIndex, viewPort));

                }

                /**

                 * <p><b>Computes the screen size (pixels)</b> of a given <b>length</b> according to the current's rendering

                 * context defined by an <b>affine transform</b> in the <b>Y axis</b>. The value of the length is expressed in the

                 * units specified by <b>unitIndex</b>-th element of the <b>MapContext.NAMES</b> array.</p>

                 *

                 * <p>If the unitIndex is out of the MapContext.NAMES array range, (it is assumed that the

                 * distance units are already in pixel) then the input and output length values are

                 * equal.</p>

                 * @param length, the length to be transformed to screen units

                 * @param at, an affine transform with the current rendering context

                 * @param unitIndex, the unit in which the length is given

                 * @return

                 */

                public static double toScreenUnitYAxis(CartographicSupport graphicElement, double length, ViewPort viewPort) {

                        final int unitIndex = graphicElement.getUnit();

                        if (unitIndex >= CONVERSION_ARRAY_LENGTH || unitIndex < 0) return length;

                        return Math.abs(viewPort.getAffineTransform().getScaleY()*

                                        toViewPortUnits(length, unitIndex, viewPort));

                }

                public static double toViewPortUnits(double length, int unit, ViewPort viewPort) {

                        int viewPortUnit = viewPort.getMapUnits();

                        if (viewPortUnit == unit) return length;

                        // for speed, only change if length is not in meters

                        if (unit != 1) length = length*MapContext.CHANGEM[unit];

                        // now length is in meters, translate it to viewport's units

                        if (viewPortUnit != 1) return length/MapContext.CHANGEM[viewPortUnit];

                        // viewport's units are meters too, no tranlation needed.

                        return length;

                }

                public static double toPaperUnits(double length, int unit, int dpi) {

                        // inch units used as canonical.

                        if (unit != 7) length = length*MapContext.CHANGE[unit];

                        // length is now in inches

                        return length*dpi;

                }

        }

}