skrueger/geotools/XMapPane.java

/*
 *    GeoTools - OpenSource mapping toolkit
 *    http://geotools.org
 *    (C) 2002-2006, GeoTools Project Managment Committee (PMC)
 *
 *    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 gtmig.org.geotools.swing;

/**
 * <b>Xulu:<br>
 *    Code taken from gt-2.4.5 to make some changes (marked with {@code xulu}),
 *    which can not be realized in a subclass:</b>
 *    <ul>
 *       <li>{@link #getMapArea()} declared as {@code final}<li>
 *       <li>some variables declared as {@code protected}</li>
 *       <li>minimal/maximal zoom scale</li>
 *       <li>zoom in and zoom out via mouse click realized by setMapArea(..)</li>
 *    </ul>
 * <br><br>
 * A simple map container that is a JPanel with a map in. provides simple
 * pan,zoom, highlight and selection The mappane stores an image of the map
 * (drawn from the context) and an image of the slected feature(s) to speed up
 * rendering of the highlights. Thus the whole map is only redrawn when the bbox
 * changes, selection is only redrawn when the selected feature changes.
 *
 *
 * @author Ian Turton
 *
 */

import java.awt.Color;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import javax.swing.JPanel;

import org.apache.log4j.Logger;
import org.geotools.map.MapContext;
import org.geotools.map.event.MapLayerListEvent;
import org.geotools.map.event.MapLayerListListener;
import org.geotools.renderer.GTRenderer;
import org.geotools.renderer.label.LabelCacheImpl;
import org.geotools.renderer.lite.LabelCache;
import org.geotools.renderer.lite.StreamingRenderer;
import org.opengis.filter.FilterFactory2;
import org.opengis.referencing.crs.CoordinateReferenceSystem;

import schmitzm.geotools.JTSUtil;
import schmitzm.swing.SwingUtil;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.GeometryFactory;

public class JMapPane extends JPanel implements MouseListener,
                MouseMotionListener, PropertyChangeListener, MapLayerListListener {
        private static Logger LOGGER = Logger.getLogger(JMapPane.class);

        private static final long serialVersionUID = -8647971481359690499L;

        public static final int Reset = 0;

        public static final int ZoomIn = 1;

        public static final int ZoomOut = 2;

        public static final int Pan = 3;

        public static final int Select = 4;

        /**
         * what renders the map
         */
        GTRenderer renderer;

        /**
         * the map context to render
         */
        MapContext context;

        /**
         * the area of the map to draw
         */
        protected Envelope mapArea;

        /**
         * the size of the pane last time we drew
         */
        protected Rectangle oldRect = null;

        /** We store the old mapArea for a moment to use it for the
        "quick scaled preview" in case of ZoomOut **/
        protected Envelope oldMapArea = null;

        /**
         * the base image of the map
         */
        protected BufferedImage baseImage, panningImage;

        /**
         * a factory for filters
         */
        FilterFactory2 ff;

        /**
         * a factory for geometries
         */
        GeometryFactory gf = new GeometryFactory(); // FactoryFinder.getGeometryFactory(null);

        private int state = ZoomIn;

        /**
         * how far to zoom in or out
         */
        private double zoomFactor = 2.0;

        boolean changed = true;

        LabelCache labelCache = new LabelCacheImpl();

        protected boolean reset = false;

        int startX;

        int startY;

        /**
         * If not <code>null</code>, the {@link JMapPane} will not allow to zoom/pan
         * out of that area
         **/
        private Envelope maxExtend = null;

        // /**
        // * Is max. 1 or 0 of the 2 axised allowed to extend the maxExtend? If
        // * <code>true</code> the extends has to be fully inside maxExtend
        // **/
        // boolean maxExtendForceMode = true;

        private boolean clickable;

        int lastX;

        int lastY;

        private Double maxZoomScale = Double.MIN_VALUE;
        private Double minZoomScale = Double.MAX_VALUE;

        /**
         * Wenn true, dann wurde PANNING via mouseDraged-Events begonnen. Dieses
         * Flag wird benutzt um nur einmal den passenden Cursor nur einmal zu
         * setzen.
         */
        private boolean panning_started = false;

        /**
         * This color is used as the default background color when painting a map.
         */
        private Color mapBackgroundColor = Color.WHITE;

        public JMapPane() {
                this(null, true, null, null);
        }

        /**
         * create a basic JMapPane
         * 
         * @param render
         *            - how to draw the map
         * @param context
         *            - the map context to display
         */
        public JMapPane(final GTRenderer render, final MapContext context) {
                this(null, true, render, context);
        }

        /**
         * full constructor extending JPanel
         * 
         * @param layout
         *            - layout (probably shouldn't be set)
         * @param isDoubleBuffered
         *            - a Swing thing I don't really understand
         * @param render
         *            - what to draw the map with
         * @param context
         *            - what to draw
         */
        public JMapPane(final LayoutManager layout, final boolean isDoubleBuffered,
                        final GTRenderer render, final MapContext context) {
                super(layout, isDoubleBuffered);

                ff = (FilterFactory2) org.geotools.factory.CommonFactoryFinder
                                .getFilterFactory(null);
                setRenderer(render);

                setContext(context);

                this.addMouseListener(this);
                this.addMouseMotionListener(this);
                setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));
        }

        /**
         * get the renderer
         */
        public GTRenderer getRenderer() {
                return renderer;
        }

        public void setRenderer(final GTRenderer renderer) {
                Map<Object, Object> hints = new HashMap<Object, Object>();

                this.renderer = renderer;
                // MS: Apply hint also for ShapeFileRenderer
                // if (renderer instanceof StreamingRenderer) {
                hints = renderer.getRendererHints();
                if (hints == null) {
                        hints = new HashMap<Object, Object>();
                }
                if (hints.containsKey(StreamingRenderer.LABEL_CACHE_KEY)) {
                        labelCache = (LabelCache) hints
                                        .get(StreamingRenderer.LABEL_CACHE_KEY);
                } else {
                        hints.put(StreamingRenderer.LABEL_CACHE_KEY, labelCache);
                }

                hints.put("memoryPreloadingEnabled", Boolean.TRUE);

                renderer.setRendererHints(hints);
                // }

                if (this.context != null) {
                        this.renderer.setContext(this.context);
                }
        }

        public MapContext getContext() {
                return context;
        }

        public void setContext(final MapContext context) {
                if (this.context != null) {
                        this.context.removeMapLayerListListener(this);
                }

                this.context = context;

                if (context != null) {
                        this.context.addMapLayerListListener(this);
                }

                if (renderer != null) {
                        renderer.setContext(this.context);
                }
        }

        public Envelope getMapArea() {
                return mapArea;
        }

        public void setMapArea(final Envelope mapArea) {
                this.mapArea = mapArea;
        }

        public int getState() {
                return state;
        }

        public void setState(final int state) {
                this.state = state;

                // System.out.println("State: " + state);
        }

        public double getZoomFactor() {
                return zoomFactor;
        }

        public void setZoomFactor(final double zoomFactor) {
                this.zoomFactor = zoomFactor;
        }

        protected void paintComponent(final Graphics g) {
                super.paintComponent(g);

                if ((renderer == null) || (mapArea == null)) {
                        return;
                }

                final Rectangle r = getBounds();
                final Rectangle dr = new Rectangle(r.width, r.height);

                if (!r.equals(oldRect) || reset) {
                        if (!r.equals(oldRect) && (mapArea == null)) {
                                try {
                                        mapArea = context.getLayerBounds();
                                } catch (final IOException e) {
                                        LOGGER.warn("context.getLayerBounds()", e);
                                }
                        }

                        if (mapArea != null) {
                                /* either the viewer size has changed or we've done a reset */
                                changed = true; /* note we need to redraw */
                                reset = false; /* forget about the reset */
                                oldRect = r; /* store what the current size is */

                                mapArea = JTSUtil.fixAspectRatio(r, mapArea, false);
                        }
                }

                if (!mapArea.equals(oldMapArea)) { /* did the map extent change? */
                        changed = true;
                        oldMapArea = mapArea;
                        // when we tell the context that the bounds have changed WMSLayers
                        // can refresh them selves
                        context.setAreaOfInterest(mapArea, context
                                        .getCoordinateReferenceSystem());
                }

                if (changed) { /* if the map changed then redraw */
                        changed = false;
                        
                        // The baseImage should not have alpha
                        baseImage = new BufferedImage(dr.width, dr.height,
                                        BufferedImage.TYPE_INT_RGB); 

                        final Graphics2D ig = baseImage.createGraphics();
                        ig.setBackground(getMapBackgroundColor());
                        ig.fillRect(0, 0, dr.width, dr.height);
                        
//                      /* System.out.println("rendering"); */
                        if (renderer.getContext() != null)
                                renderer.setContext(context);

                        // TODO is this clearing still needed? We already replace all that stuff whenever we change the style. Deactivated 31.10.09.. let's see 
//                      labelCache.clear(); // work around anoying labelcache bug

                        // draw the map
                        renderer.paint(ig, dr, mapArea);

                        panningImage = new BufferedImage(dr.width, dr.height, BufferedImage.TYPE_INT_RGB);

                }

                ((Graphics2D) g).drawImage(baseImage, 0, 0, this);
        }

        public void mouseClicked(final MouseEvent e) {
                if (mapArea == null)
                        return;
                // System.out.println("before area "+mapArea+"\nw:"+mapArea.getWidth()+"
                // h:"+mapArea.getHeight());
                final Rectangle bounds = this.getBounds();
                final double x = (double) (e.getX());
                final double y = (double) (e.getY());
                final double width = mapArea.getWidth();
                final double height = mapArea.getHeight();
                // xulu.sc
                // double width2 = mapArea.getWidth() / 2.0;
                // double height2 = mapArea.getHeight() / 2.0;
                final double width2 = width / 2.0;
                final double height2 = height / 2.0;
                // xulu.ec
                final double mapX = ((x * width) / (double) bounds.width)
                                + mapArea.getMinX();
                final double mapY = (((bounds.getHeight() - y) * height) / (double) bounds.height)
                                + mapArea.getMinY();

                /*
                 * System.out.println(""+x+"->"+mapX);
                 * System.out.println(""+y+"->"+mapY);
                 */

                /*
                 * Coordinate ll = new Coordinate(mapArea.getMinX(), mapArea.getMinY());
                 * Coordinate ur = new Coordinate(mapArea.getMaxX(), mapArea.getMaxY());
                 */
                double zlevel = 1.0;

                switch (state) {
                case Pan:
                        zlevel = 1.0;
                        // xulu.sc SK: return here.. a mouselistener is managing the PANNING
                        // break;
                        return;
                        // xulu.ec
                case ZoomIn:
                        zlevel = zoomFactor;

                        break;

                case ZoomOut:
                        zlevel = 1.0 / zoomFactor;

                        break;
                //
                // case Select:
                // doSelection(mapX, mapY, selectionLayer);
                //
                // return;

                default:
                        return;
                }

                final Coordinate ll = new Coordinate(mapX - (width2 / zlevel), mapY
                                - (height2 / zlevel));
                final Coordinate ur = new Coordinate(mapX + (width2 / zlevel), mapY
                                + (height2 / zlevel));
                // xulu.sc SK: Check for min/max scale
                // mapArea = new Envelope(ll, ur);
                final Envelope newMapArea = new Envelope(ll, ur);
                setMapArea(bestAllowedMapArea(newMapArea));
                // xulu.ec

                // sk.ec

                // System.out.println("after area "+mapArea+"\nw:"+mapArea.getWidth()+"
                // h:"+mapArea.getHeight());
                repaint();
        }

        public void mouseEntered(final MouseEvent e) {
        }

        public void mouseExited(final MouseEvent e) {
        }

        public void mousePressed(final MouseEvent e) {
                startX = e.getX();
                startY = e.getY();
                lastX = 0;
                lastY = 0;
        }

        public void mouseReleased(final MouseEvent e) {
                final int endX = e.getX();
                final int endY = e.getY();

                processDrag(startX, startY, endX, endY, e);
                lastX = 0;
                lastY = 0;

                /**
                 * Es wird nicht (mehr) gepannt!
                 */
                panning_started = false;
        }

        public void mouseDragged(final MouseEvent e) {
                final Graphics graphics = this.getGraphics();
                final int x = e.getX();
                final int y = e.getY();

                if ((state == JMapPane.Pan)
                                || ((e.getModifiersEx() & InputEvent.BUTTON3_DOWN_MASK) != 0)) {
                        /**
                         * SK: Der Cursor wird auf PANNING gesetzt.
                         */
                        if (panning_started == false) {
                                panning_started = true;
                                setCursor(SwingUtil.PANNING_CURSOR);
                        }

                        // move the image with the mouse
                        if ((lastX > 0) && (lastY > 0)) {
                                final int dx = lastX - startX;
                                final int dy = lastY - startY;
                                // System.out.println("translate "+dx+","+dy);
                                final Graphics2D g2 = panningImage.createGraphics();
                                g2.setBackground(getMapBackgroundColor()); 

                                g2.clearRect(0, 0, this.getWidth(), this.getHeight());
                                g2.drawImage(baseImage, dx, dy, this);
                                graphics.drawImage(panningImage, 0, 0, this);
                        }

                        lastX = x;
                        lastY = y;
                } else

                if ((state == JMapPane.ZoomIn) || (state == JMapPane.ZoomOut)) {

                        graphics.setXORMode(Color.WHITE);

                        if ((lastX > 0) && (lastY > 0)) {
                                drawRectangle(graphics);
                        }

                        // draw new box
                        lastX = x;
                        lastY = y;
                        drawRectangle(graphics);
                }
                // else if (state == JMapPane.Select && selectionLayer != null) {
                //
                // // construct a new bbox filter
                // final Rectangle bounds = this.getBounds();
                //
                // final double mapWidth = mapArea.getWidth();
                // final double mapHeight = mapArea.getHeight();
                //
                // final double x1 = ((this.startX * mapWidth) / (double) bounds.width)
                // + mapArea.getMinX();
                // final double y1 = (((bounds.getHeight() - this.startY) * mapHeight) /
                // (double) bounds.height)
                // + mapArea.getMinY();
                // final double x2 = ((x * mapWidth) / (double) bounds.width)
                // + mapArea.getMinX();
                // final double y2 = (((bounds.getHeight() - y) * mapHeight) / (double)
                // bounds.height)
                // + mapArea.getMinY();
                // final double left = Math.min(x1, x2);
                // final double right = Math.max(x1, x2);
                // final double bottom = Math.min(y1, y2);
                // final double top = Math.max(y1, y2);
                //
                // String name = selectionLayer.getFeatureSource().getSchema()
                // .getDefaultGeometry().getName();
                //
                // if (name == "") {
                // name = "the_geom";
                // }
                // final Filter bb = ff.bbox(ff.property(name), left, bottom, right,
                // top,
                // getContext().getCoordinateReferenceSystem().toString());
                // if (selectionManager != null) {
                // selectionManager.selectionChanged(this, bb);
                // }
                //
                // graphics.setXORMode(Color.green);
                //
                // /*
                // * if ((lastX > 0) && (lastY > 0)) { drawRectangle(graphics); }
                // */
                //
                // // draw new box
                // lastX = x;
                // lastY = y;
                // drawRectangle(graphics);
                // }

        }

        // sk.cs
        // private void processDrag(int x1, int y1, int x2, int y2) {
        // sk.ce
        protected void processDrag(final int x1, final int y1, final int x2,
                        final int y2, final MouseEvent e) {

                /****
                 * If no layers exist, we ignore the drag.
                 */
                if (context.getLayerCount() <= 0) {
                        return;
                }

                // System.out.println("processing drag from " + x1 + "," + y1 + " -> "
                // + x2 + "," + y2);
                if ((x1 == x2) && (y1 == y2)) {
                        if (isClickable()) {
                                mouseClicked(new MouseEvent(this, 0, new Date().getTime(), 0,
                                                x1, y1, y2, false));
                        }

                        return;
                }

                final Rectangle bounds = this.getBounds();

                final double mapWidth = mapArea.getWidth();
                final double mapHeight = mapArea.getHeight();

                final double startX = ((x1 * mapWidth) / (double) bounds.width)
                                + mapArea.getMinX();
                final double startY = (((bounds.getHeight() - y1) * mapHeight) / (double) bounds.height)
                                + mapArea.getMinY();
                final double endX = ((x2 * mapWidth) / (double) bounds.width)
                                + mapArea.getMinX();
                final double endY = (((bounds.getHeight() - y2) * mapHeight) / (double) bounds.height)
                                + mapArea.getMinY();

                if ((state == JMapPane.Pan) || (e.getButton() == MouseEvent.BUTTON3)) {
                        // move the image with the mouse
                        // calculate X offsets from start point to the end Point
                        final double deltaX1 = endX - startX;

                        // System.out.println("deltaX " + deltaX1);
                        // new edges
                        final double left = mapArea.getMinX() - deltaX1;
                        final double right = mapArea.getMaxX() - deltaX1;
                        final double deltaY1 = endY - startY;

                        // System.out.println("deltaY " + deltaY1);
                        final double bottom = mapArea.getMinY() - deltaY1;
                        final double top = mapArea.getMaxY() - deltaY1;
                        final Coordinate ll = new Coordinate(left, bottom);
                        final Coordinate ur = new Coordinate(right, top);
                        // xulu.sc
                        // mapArea = fixAspectRatio(this.getBounds(), new Envelope(ll, ur));

                        setMapArea(bestAllowedMapArea(new Envelope(ll, ur)));
                        // xulu.ec
                } else if (state == JMapPane.ZoomIn) {

                        // Zu kleine Flächen sollen nicht gezoomt werden.
                        // sk.bc
                        if ((Math.abs(x1 - x2) * Math.abs(y2 - y1)) < 150)
                                return;
                        // sk.ec

                        drawRectangle(this.getGraphics());
                        // make the dragged rectangle (in map coords) the new BBOX
                        final double left = Math.min(startX, endX);
                        final double right = Math.max(startX, endX);
                        final double bottom = Math.min(startY, endY);
                        final double top = Math.max(startY, endY);
                        final Coordinate ll = new Coordinate(left, bottom);
                        final Coordinate ur = new Coordinate(right, top);
                        // xulu.sc

                        // mapArea = fixAspectRatio(this.getBounds(), new Envelope(ll, ur));
                        setMapArea(bestAllowedMapArea(new Envelope(ll, ur)));

                } else if (state == JMapPane.ZoomOut) {
                        drawRectangle(this.getGraphics());

                        // make the dragged rectangle in screen coords the new map size?
                        final double left = Math.min(startX, endX);
                        final double right = Math.max(startX, endX);
                        final double bottom = Math.min(startY, endY);
                        final double top = Math.max(startY, endY);
                        final double nWidth = (mapWidth * mapWidth) / (right - left);
                        final double nHeight = (mapHeight * mapHeight) / (top - bottom);
                        final double deltaX1 = left - mapArea.getMinX();
                        final double nDeltaX1 = (deltaX1 * nWidth) / mapWidth;
                        final double deltaY1 = bottom - mapArea.getMinY();
                        final double nDeltaY1 = (deltaY1 * nHeight) / mapHeight;
                        final Coordinate ll = new Coordinate(mapArea.getMinX() - nDeltaX1,
                                        mapArea.getMinY() - nDeltaY1);
                        final double deltaX2 = mapArea.getMaxX() - right;
                        final double nDeltaX2 = (deltaX2 * nWidth) / mapWidth;
                        final double deltaY2 = mapArea.getMaxY() - top;
                        final double nDeltaY2 = (deltaY2 * nHeight) / mapHeight;
                        final Coordinate ur = new Coordinate(mapArea.getMaxX() + nDeltaX2,
                                        mapArea.getMaxY() + nDeltaY2);
                        // xulu.sc
                        // mapArea = fixAspectRatio(this.getBounds(), new Envelope(ll, ur));
                        setMapArea(bestAllowedMapArea(new Envelope(ll, ur)));

                        // xulu.ec
                }
                // else if (state == JMapPane.Select && selectionLayer != null) {
                // final double left = Math.min(startX, endX);
                // final double right = Math.max(startX, endX);
                // final double bottom = Math.min(startY, endY);
                // final double top = Math.max(startY, endY);
                //
                // String name = selectionLayer.getFeatureSource().getSchema()
                // .getDefaultGeometry().getLocalName();
                //
                // if (name == "") {
                // name = "the_geom";
                // }
                // final Filter bb = ff.bbox(ff.property(name), left, bottom, right,
                // top,
                // getContext().getCoordinateReferenceSystem().toString());
                // // System.out.println(bb.toString());
                // if (selectionManager != null) {
                // selectionManager.selectionChanged(this, bb);
                // }
                // /*
                // * FeatureCollection fc; selection = null; try { fc =
                // * selectionLayer.getFeatureSource().getFeatures(bb); selection =
                // * fc; } catch (IOException e) { e.printStackTrace(); }
                // */
                // }

                // xulu.so
                // setMapArea(mapArea);
                // xulu.eo
                repaint();
        }

        private boolean isClickable() {
                return clickable;
        }

        public void propertyChange(final PropertyChangeEvent evt) {
                final String prop = evt.getPropertyName();

                if (prop.equalsIgnoreCase("crs")) {
                        context.setAreaOfInterest(context.getAreaOfInterest(),
                                        (CoordinateReferenceSystem) evt.getNewValue());
                }
        }

        public boolean isReset() {
                return reset;
        }

        public void setReset(final boolean reset) {
                this.reset = reset;
        }

        public void layerAdded(final MapLayerListEvent event) {
                changed = true;

                if (context.getLayers().length == 1) { // the first one

                        try {
                                // xulu.sc
                                // mapArea = context.getLayerBounds();
                                mapArea = context.getAreaOfInterest();
                                if (mapArea == null)
                                        mapArea = context.getLayerBounds();
                                // xulu.ec
                        } catch (final IOException e) {
                                LOGGER.error(e);
                        }

                        reset = true;
                }

                repaint();
        }

        public void layerRemoved(final MapLayerListEvent event) {
                changed = true;
                repaint();
        }

        public void layerChanged(final MapLayerListEvent event) {
                changed = true;
                // System.out.println("layer changed - repaint");
                repaint();
        }

        public void layerMoved(final MapLayerListEvent event) {
                changed = true;
                repaint();
        }

        protected void drawRectangle(final Graphics graphics) {
                // undraw last box/draw new box
                final int left = Math.min(startX, lastX);
                final int right = Math.max(startX, lastX);
                final int top = Math.max(startY, lastY);
                final int bottom = Math.min(startY, lastY);
                final int width = right - left;
                final int height = top - bottom;
                // System.out.println("drawing rect("+left+","+bottom+","+ width+","+
                // height+")");
                graphics.drawRect(left, bottom, width, height);
        }

        /**
         * if clickable is set to true then a single click on the map pane will zoom
         * or pan the map.
         * 
         * @param clickable
         */
        public void setClickable(final boolean clickable) {
                this.clickable = clickable;
        }

        public void mouseMoved(final MouseEvent e) {
        }

        // xulu.sn
        /**
         * Korrigiert den {@link Envelope} aka {@code mapArea} auf die beste
         * erlaubte Flaeche damit die Massstabsbeschaenkungen noch eingehalten
         * werden, FALLS der uebergeben Envelope nicht schon gueltig sein sollte.<br/>
         * Since 21. April 09: Before thecalculation starts, the aspect ratio is
         * corrected. This change implies, that setMapArea() will most of the time
         * not allow setting to a wrong aspectRatio.
         * 
         * @author <a href="mailto:[email protected]">Stefan Alfons
         *         Kr&uuml;ger</a>
         */
        public Envelope bestAllowedMapArea(Envelope env) {
                if (getWidth() == 0)
                        return env;
                if (env == null)
                        return env;

                Envelope newArea = null;

                /**
                 * Correct the aspect Ratio before we check the rest. Otherwise we might
                 * easily fail. We allow to grow here, because we don't check against
                 * the maxExtend
                 */
                env = JTSUtil.fixAspectRatio(this.getBounds(), env, true);

                final double scale = env.getWidth() / getWidth();
                final double centerX = env.getMinX() + env.getWidth() / 2.;
                final double centerY = env.getMinY() + env.getHeight() / 2.;
                double newWidth2 = 0;
                double newHeight2 = 0;
                if (scale < getMaxZoomScale()) {
                        // ****************************************************************************
                        // Wir zoomen weiter rein als erlaubt => Anpassen des envelope
                        // ****************************************************************************
                        newWidth2 = getMaxZoomScale() * getWidth() / 2.;
                        newHeight2 = getMaxZoomScale() * getHeight() / 2.;
                } else if (scale > getMinZoomScale()) {
                        // ****************************************************************************
                        // Wir zoomen weiter raus als erlaubt => Anpassen des envelope
                        // ****************************************************************************
                        newWidth2 = getMinZoomScale() * getWidth() / 2.;
                        newHeight2 = getMinZoomScale() * getHeight() / 2.;
                } else {
                        // ****************************************************************************
                        // Die mapArea / der Envelope ist ist gueltig! Keine Aenderungen
                        // ****************************************************************************
                        newArea = env;
                }

                if (newArea == null) {

                        final Coordinate ll = new Coordinate(centerX - newWidth2, centerY
                                        - newHeight2);
                        final Coordinate ur = new Coordinate(centerX + newWidth2, centerY
                                        + newHeight2);

                        newArea = new Envelope(ll, ur);
                }

                Envelope maxAllowedExtend = getMaxExtend();
                while (maxAllowedExtend != null && !maxAllowedExtend.contains(newArea)
                                && newArea != null && !newArea.isNull()
                                && !Double.isNaN(newArea.getMinX())
                                && !Double.isNaN(newArea.getMaxX())
                                && !Double.isNaN(newArea.getMinY())
                                && !Double.isNaN(newArea.getMaxY())) {
                        /*
                         * If a maxExtend is set, we have to honour that...
                         */

                        // Exceeds top? Move down and maybe cut
                        if (newArea.getMaxY() > maxAllowedExtend.getMaxY()) {
                                double divY = newArea.getMaxY() - maxAllowedExtend.getMaxY();
                                // LOGGER.debug("Moving area down by " + divY);

                                newArea = new Envelope(new Coordinate(newArea.getMinX(),
                                                newArea.getMinY() - divY), new Coordinate(newArea
                                                .getMaxX(), newArea.getMaxY() - divY));

                                if (newArea.getMinY() < maxAllowedExtend.getMinY()) {
                                        // LOGGER.debug("Now it exeeds the bottom border.. cut!");
                                        // And cut the bottom if it moved out of the area
                                        newArea = new Envelope(new Coordinate(newArea.getMinX(),
                                                        maxAllowedExtend.getMinY()), new Coordinate(newArea
                                                        .getMaxX(), newArea.getMaxY()));

                                        // LOGGER.debug("and fix aspect ratio");

                                        newArea = JTSUtil.fixAspectRatio(this.getBounds(), newArea,
                                                        false);
                                }
                        }

                        // Exceeds bottom? Move up and maybe cut
                        if (newArea.getMinY() < maxAllowedExtend.getMinY()) {
                                double divY = newArea.getMinY() - maxAllowedExtend.getMinY();
                                // LOGGER.debug("Moving area up by " + divY);

                                newArea = new Envelope(new Coordinate(newArea.getMinX(),
                                                newArea.getMinY() - divY), new Coordinate(newArea
                                                .getMaxX(), newArea.getMaxY() - divY));

                                if (newArea.getMaxY() > maxAllowedExtend.getMaxY()) {
                                        // LOGGER.debug("Now it exeeds the top border.. cut!");
                                        // And cut the bottom if it moved out of the area
                                        newArea = new Envelope(new Coordinate(newArea.getMinX(),
                                                        newArea.getMinY()), new Coordinate(newArea
                                                        .getMaxX(), maxAllowedExtend.getMaxY()));

                                        // LOGGER.debug("and fix aspect ratio");

                                        newArea = JTSUtil.fixAspectRatio(this.getBounds(), newArea,
                                                        false);
                                }
                        }

                        // Exceeds to the right? move and maybe cut
                        if (newArea.getMaxX() > maxAllowedExtend.getMaxX()) {

                                // Move left..
                                double divX = newArea.getMaxX() - maxAllowedExtend.getMaxX();
                                // LOGGER.debug("Moving area left by " + divX);

                                newArea = new Envelope(new Coordinate(newArea.getMinX() - divX,
                                                newArea.getMinY()), new Coordinate(newArea.getMaxX()
                                                - divX, newArea.getMaxY()));

                                if (newArea.getMinX() < maxAllowedExtend.getMinX()) {
                                        // LOGGER.debug("Now it exeeds the left border.. cut!");
                                        // And cut the left if it moved out of the area
                                        newArea = new Envelope(new Coordinate(maxAllowedExtend
                                                        .getMinX(), newArea.getMinY()), new Coordinate(
                                                        newArea.getMaxX(), newArea.getMaxY()));

                                        // LOGGER.debug("and fix aspect ratio");

                                        newArea = JTSUtil.fixAspectRatio(this.getBounds(), newArea,
                                                        false);
                                }
                        }

                        // Exceeds to the left? move and maybe cut
                        if (newArea.getMinX() < maxAllowedExtend.getMinX()) {

                                // Move right..
                                double divX = newArea.getMinX() - maxAllowedExtend.getMinX();
                                // LOGGER.debug("Moving area right by " + divX);

                                newArea = new Envelope(new Coordinate(newArea.getMinX() - divX,
                                                newArea.getMinY()), new Coordinate(newArea.getMaxX()
                                                - divX, newArea.getMaxY()));

                                if (newArea.getMaxX() > maxAllowedExtend.getMaxX()) {
                                        // LOGGER.debug("Now it exeeds the right border.. cut!");
                                        // And cut the left if it moved out of the area
                                        newArea = new Envelope(new Coordinate(newArea.getMinX(),
                                                        newArea.getMinY()), new Coordinate(maxAllowedExtend
                                                        .getMaxX(), newArea.getMaxY()));

                                        // LOGGER.debug("and fix aspect ratio");

                                        newArea = JTSUtil.fixAspectRatio(this.getBounds(), newArea,
                                                        false);
                                }
                        }

                }

                return newArea;
        }

        /**
         * Retuns the minimum allowed zoom scale. This is the bigger number value of
         * the two. Defaults to {@link Double}.MAX_VALUE
         * 
         * @author <a href="mailto:[email protected]">Stefan Alfons
         *         Kr&uuml;ger</a>
         */
        public Double getMinZoomScale() {
                return minZoomScale;
        }

        /**
         * Retuns the maximum allowed zoom scale. This is the smaller number value
         * of the two. Defaults to {@link Double}.MIN_VALUE
         * 
         * @author <a href="mailto:[email protected]">Stefan Alfons
         *         Kr&uuml;ger</a>
         */
        public Double getMaxZoomScale() {
                return maxZoomScale;
        }

        /**
         * Set the maximum allowed zoom scale. This is the smaller number value of
         * the two. If <code>null</code> is passed, Double.MINVALUE are used which
         * mean there is no restriction.
         * 
         * @author <a href="mailto:[email protected]">Stefan Alfons
         *         Kr&uuml;ger</a>
         */
        public void setMaxZoomScale(final Double maxZoomScale) {
                this.maxZoomScale = maxZoomScale == null ? Double.MIN_VALUE
                                : maxZoomScale;
        }

        /**
         * Set the minimum (nearest) allowed zoom scale. This is the bigger number
         * value of the two. If <code>null</code> is passed, Double.MAXVALUE are
         * used which mean there is no restriction.
         * 
         * 
         * @author <a href="mailto:[email protected]">Stefan Alfons
         *         Kr&uuml;ger</a>
         */
        public void setMinZoomScale(final Double minZoomScale) {
                this.minZoomScale = minZoomScale == null ? Double.MAX_VALUE
                                : minZoomScale;
        }

        /**
         * Defines an evelope of the viwable area. The JMapPane will never show
         * anything outside of this extend.
         * 
         * @param maxExtend
         *            <code>null</code> to not have this restriction.
         */
        public void setMaxExtend(Envelope maxExtend) {
                this.maxExtend = maxExtend;
        }

        /**
         * Returns the evelope of the viewable area. The JMapPane will never show
         * anything outside of this extend. If this has been set to
         * <code>null</code> via {@link #setMaxExtend(Envelope)}, it tries to return
         * quickly the context's bounds. It it takes to long to determine the
         * context bounds, <code>null</code> is returned.
         * 
         * @param maxExtend
         *            <code>null</code> to not have this restriction.
         */

        public Envelope getMaxExtend() {
                if (maxExtend == null) {
                        try {
                                return JTSUtil.fixAspectRatio(this.getBounds(),
                                                // Kartenbereich um 10% vergroessern
                                                JTSUtil.expandEnvelope(context.getLayerBounds(), 0.1),
                                                true);
                        } catch (IOException e) {
                                LOGGER
                                                .warn(
                                                                "maxExtend == null; failed to getLayerBounds of context",
                                                                e);
                        }
                }
                return maxExtend;
        }

        /**
         * Set the background color of the map. 
         * @param if <code>null</code>, white is used.
         */
        public void setMapBackgroundColor(Color bgColor) {
                if (bgColor == null) bgColor = Color.WHITE;
                this.mapBackgroundColor = bgColor;
        }

        /**
         * Returns the background {@link Color} of the map pane. Default is white.
        **/
        public Color getMapBackgroundColor() {
                return mapBackgroundColor;
        }

}