overviewmaparealayer.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

// **********************************************************************
// 
// <copyright>
// 
//  BBN Technologies
//  10 Moulton Street
//  Cambridge, MA 02138
//  [phone]
// 
//  Copyright (C) BBNT Solutions LLC. All rights reserved.
// 
// </copyright>
// **********************************************************************
// 
// $Source: /cvs/distapps/openmap/src/openmap/com/bbn/openmap/layer/OverviewMapAreaLayer.java,v $
// $RCSfile: OverviewMapAreaLayer.java,v $
// $Revision: 1.3.2.1 $
// $Date: 2004/10/14 18:27:03 $
// $Author: dietrick $
// 
// **********************************************************************

package com.bbn.openmap.layer;

import com.bbn.openmap.LatLonPoint;
import com.bbn.openmap.Layer;
import com.bbn.openmap.event.OverviewMapStatusListener;
import com.bbn.openmap.event.ProjectionEvent;
import com.bbn.openmap.omGraphics.DrawingAttributes;
import com.bbn.openmap.omGraphics.OMGraphic;
import com.bbn.openmap.omGraphics.OMRect;
import com.bbn.openmap.proj.Cylindrical;
import com.bbn.openmap.proj.Projection;

import java.awt.Graphics;
import java.awt.Point;
import java.util.Properties;

/**
 * A class used to draw the rectangle representing the area covered by
 * the source MapBean projection. Used by the OverviewMapHandler. The
 * layer responds to DrawingAttributes properties being set, which are
 * forwarded on to the coverage box rectangle.
 */
public class OverviewMapAreaLayer extends Layer implements
        OverviewMapStatusListener {

    OMRect rectangle;
    float sourceScale;
    float overviewScale;
    LatLonPoint ul;
    LatLonPoint lr;

    DrawingAttributes boxAttributes = DrawingAttributes.getDefaultClone();

    /**
     * Listening to the overview MapBean.
     */
    public void projectionChanged(ProjectionEvent pEvent) {
        Projection proj = pEvent.getProjection();

        // HACK for big world problem...
        if (rectangle == null) {
            rectangle = new OMRect();
            boxAttributes.setTo(rectangle);
        }
        if (ul != null || lr != null) {

            if (proj instanceof Cylindrical) {
                Point ulp = proj.forward(ul);
                Point lrp = proj.forward(lr);
                rectangle.setLocation(ulp.x, ulp.y, lrp.x, lrp.y);
                rectangle.setLineType(OMGraphic.LINETYPE_STRAIGHT);
            } else {
                //  HACK Would be nice if we didn't run into the
                //  big-world problem.
                rectangle.setLocation(ul.getLatitude(),
                        ul.getLongitude(),
                        lr.getLatitude(),
                        lr.getLongitude(),
                        OMGraphic.LINETYPE_RHUMB);
            }
            rectangle.generate(proj);
        }

        overviewScale = proj.getScale();
    }

    /**
     * Set with the projection of the source MapBean, before changing
     * the projection of the overview MapBean. That way, the rectangle
     * coordinates are set before they get generated().
     */
    public void setSourceMapProjection(Projection proj) {
        ul = proj.getUpperLeft();
        lr = proj.getLowerRight();
        sourceScale = proj.getScale();
    }

    /**
     * Get the area rectangle.
     */
    public OMRect getOverviewMapArea() {
        return rectangle;
    }

    public void paint(Graphics g) {
        if (rectangle != null && overviewScale > sourceScale)
            rectangle.render(g);
    }

    public void setProperties(String prefix, Properties props) {
        super.setProperties(prefix, props);
        boxAttributes.setProperties(prefix, props);
        // Cause a rebuild if this is called after
        // the first projection change.
        rectangle = null;
    }

    public Properties getProperties(Properties props) {
        props = super.getProperties(props);
        boxAttributes.getProperties(props);
        return props;
    }

    public Properties getPropertyInfo(Properties props) {
        props = super.getPropertyInfo(props);
        boxAttributes.getPropertyInfo(props);
        return props;
    }

}