omcircle.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/omGraphics/OMCircle.java,v $
// $RCSfile: OMCircle.java,v $
// $Revision: 1.5.2.3 $
// $Date: 2005/01/10 16:59:43 $
// $Author: dietrick $
// 
// **********************************************************************

package com.bbn.openmap.omGraphics;

import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import java.io.Serializable;
import java.util.ArrayList;

import com.bbn.openmap.LatLonPoint;
import com.bbn.openmap.proj.Length;
import com.bbn.openmap.proj.Projection;

/**
 * Graphic object that represents a circle or an ellipse.
 * <p>
 * <h3>NOTE:</h3>
 * See the <a
 * href="com.bbn.openmap.proj.Projection.html#poly_restrictions">
 * RESTRICTIONS </a> on Lat/Lon polygons/polylines which apply to
 * circles as well. Not following the guidelines listed may result in
 * ambiguous/undefined shapes! Similar assumptions apply to the other
 * vector graphics that we define: polys, rects, lines.
 * <p>
 * We currently do not allow LatLon ellipses, only XY.
 * <p>
 * These assumptions are virtually the same as those on the more
 * generic OMPoly graphic type.
 * <p>
 * 
 * @see OMPoly
 */
public class OMCircle extends OMArc implements Serializable {

    /**
     * The simplest constructor for an OMCircle, and it expects that
     * all fields will be filled in later. Rendertype is
     * RENDERTYPE_UNKNOWN.
     */
    public OMCircle() {
        super();
    }

    /**
     * Create a OMCircle, positioned with a lat-lon center and x-y
     * axis. Rendertype is RENDERTYPE_OFFSET.
     * 
     * @param latPoint latitude of center point, decimal degrees
     * @param lonPoint longitude of center point, decimal degrees
     * @param w horizontal diameter of circle/ellipse, pixels
     * @param h vertical diameter of circle/ellipse, pixels
     */
    public OMCircle(float latPoint, float lonPoint, int w, int h) {
        this(latPoint, lonPoint, 0, 0, w, h);
    }

    /**
     * Create a OMCircle, positioned with a x-y center with x-y axis.
     * Rendertype is RENDERTYPE_XY.
     * 
     * @param x1 window position of center point from left of window,
     *        in pixels
     * @param y1 window position of center point from top of window,
     *        in pixels
     * @param w horizontal diameter of circle/ellipse, pixels
     * @param h vertical diameter of circle/ellipse, pixels
     */
    public OMCircle(int x1, int y1, int w, int h) {
        super(x1, y1, w, h, 0f, 360f);
    }

    /**
     * Create a OMCircle, positioned at a Lat-lon location, x-y
     * offset, x-y axis. Rendertype is RENDERTYPE_OFFSET.
     * 
     * @param latPoint latitude of center of circle/ellipse.
     * @param lonPoint longitude of center of circle/ellipse.
     * @param offset_x1 # pixels to the right the center will be moved
     *        from lonPoint.
     * @param offset_y1 # pixels down that the center will be moved
     *        from latPoint.
     * @param w horizontal diameter of circle/ellipse, pixels.
     * @param h vertical diameter of circle/ellipse, pixels.
     */
    public OMCircle(float latPoint, float lonPoint, int offset_x1,
            int offset_y1, int w, int h) {
        super(latPoint, lonPoint, offset_x1, offset_y1, w, h, 0f, 360f);
    }

    /**
     * Creates an OMCircle with a Lat-lon center and a lat-lon axis.
     * Rendertype is RENDERTYPE_LATLON.
     * 
     * @param latPoint latitude of center point, decimal degrees
     * @param lonPoint longitude of center point, decimal degrees
     * @param radius distance in decimal degrees (converted to radians
     *        internally).
     */
    public OMCircle(float latPoint, float lonPoint, float radius) {
        this(latPoint, lonPoint, radius, Length.DECIMAL_DEGREE, -1);
    }

    /**
     * Create an OMCircle with a lat/lon center and a physical
     * distance radius. Rendertype is RENDERTYPE_LATLON.
     * 
     * @param latPoint latitude of center of circle in decimal degrees
     * @param lonPoint longitude of center of circle in decimal
     *        degrees
     * @param radius distance
     * @param units com.bbn.openmap.proj.Length object.
     */
    public OMCircle(float latPoint, float lonPoint, float radius, Length units) {
        this(latPoint, lonPoint, radius, units, -1);
    }

    /**
     * Create an OMCircle with a lat/lon center and a physical
     * distance radius. Rendertype is RENDERTYPE_LATLON.
     * 
     * @param latPoint latitude of center of circle in decimal degrees
     * @param lonPoint longitude of center of circle in decimal
     *        degrees
     * @param radius distance
     * @param units com.bbn.openmap.proj.Length object specifying
     *        units.
     * @param nverts number of vertices for the poly-circle (if &lt;
     *        3, value is generated internally)
     */
    public OMCircle(float latPoint, float lonPoint, float radius, Length units,
            int nverts) {
        this(new LatLonPoint(latPoint, lonPoint), radius, units, nverts);
    }

    /**
     * Create an OMCircle with a lat/lon center and a physical
     * distance radius. Rendertype is RENDERTYPE_LATLON.
     * 
     * @param center LatLon center of circle
     * @param radius distance
     * @param units com.bbn.openmap.proj.Length object specifying
     *        units for distance.
     * @param nverts number of vertices for the poly-circle(if &lt; 3,
     *        value is generated internally)
     */
    public OMCircle(LatLonPoint center, float radius, Length units, int nverts) {
        super(center, radius, units, nverts, 0f, 360f);
    }

    /**
     * Helper function that helps the generate method figure out if
     * the center point should be in the generate shape - if it's not,
     * the code knows that there is a problem with the poles, and the
     * polar correction code needs to be run.
     */
    protected boolean shouldCenterBeInShape() {
        return true;
    }

    /**
     * An internal method designed to fetch the Shape to be used for
     * an XY or OFFSET OMCircles. This method is smart enough to take
     * the calculated position information and make a call to
     * Ellipse2D.Float.
     */
    protected Shape createArcShape(float x, float y, float fwidth, float fheight) {
        return new Ellipse2D.Float(x, y, fwidth, fheight);
    }

    /**
     * An internal method designed to fetch the ArrayList for LATLON
     * OMCircles. This method is smart enough to take the calculated
     * position information and make a call to
     * Projection.forwardCircle.
     */
    protected ArrayList getCoordLists(Projection proj, LatLonPoint center,
                                      float radius, int nverts) {
        return proj.forwardCircle(center, /* radians */
                true,
                radius,
                nverts,
                !isClear(fillPaint));
    }

    protected boolean hasLineTypeChoice() {
        return false;
    }
}