webextent.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.web.data.geometry;

import com.esri.adf.web.data.geometry.WebPoint;
import com.esri.adf.web.data.geometry.WebPolygon;
import com.esri.adf.web.data.geometry.WebRing;

/**
 * Geometry extent type that extends the ADF {@link com.esri.adf.web.data.geometry.WebExtent}
 * type and adds capabilities, such as conversion to a {@link WebPolygon}
 */
public class WebExtent extends com.esri.adf.web.data.geometry.WebExtent {
	private static final long serialVersionUID = -8012409567364871347L;

	/**
	 * Constructor to create a {@link WebExtent} from a 
	 * {@link com.esri.adf.web.data.geometry.WebExtent}
	 * @param adfExtent
	 */
	public WebExtent(com.esri.adf.web.data.geometry.WebExtent adfExtent) {
		this.setSpatialReference(adfExtent.getSpatialReference());
		this.setMaxX(adfExtent.getMaxX());
		this.setMaxY(adfExtent.getMaxY());
		this.setMinX(adfExtent.getMinX());
		this.setMinY(adfExtent.getMinY());
	}
	
	/**
	 * Converts the {@link com.esri.adf.web.data.geometry.WebExtent} type
	 * to a {@link WebPolygon}
	 * @return The {@link WebExtent} converted to a {@link WebPolygon}
	 */
	public WebPolygon toWebPolygon() {
		double minx = this.getMinX();
		double miny = this.getMinY();
		double maxx = this.getMaxX();
		double maxy = this.getMaxY();

		WebPoint ll = new WebPoint(minx, miny);
		WebPoint ul = new WebPoint(minx, maxy);
		WebPoint ur = new WebPoint(maxx, maxy);
		WebPoint lr = new WebPoint(maxx, miny);

		WebRing wr = new WebRing();
		wr.addPoint(ll);
		wr.addPoint(ul);
		wr.addPoint(ur);
		wr.addPoint(lr);
		wr.addPoint(ll);
			
		WebPolygon wp = new WebPolygon();
		wp.addRing(wr);
	
		return wp;
	}
	
	/**
	 * Calculates and returns the center point of the extent.
	 * WARNING: This calculation does not work for extents crossing the 
	 * North or South pole and 180 degrees longitude.
	 * @return {@link WebPoint} representing the center point
	 */
	public WebPoint getCenterPoint() {
		WebPoint center = new WebPoint();
		
	    double x1 = getMinX();
	    double x2 = getMaxX();
	    double y1 = getMinY();
	    double y2 = getMaxY();
	    center.setX((x1 + x2) / 2);
	    center.setY((y1 + y2) / 2);		
	    center.setSpatialReference(this.getSpatialReference());
	    
	    return center;
	}
	
	/**
	 * Adjust the extent to the specified aspect ration for width and heigh
	 * so that the extent is adjust 
	 * @param width
	 * @param height
	 * @return
	 */
	public WebExtent getAdjustedExtent(int width, int height) {
	    com.esri.solutions.jitk.web.data.geometry.WebExtent adjustedExt = 
	    	new com.esri.solutions.jitk.web.data.geometry.WebExtent(this);

	    double extWidth = getWidth();
	    double extHeigth = getHeight();
	    
	    if ((extWidth <= 0) || (extWidth <= 0) || (extWidth <= 0) || (extWidth <= 0)) {
	    	new Exception("Extent dimesion and passed dimesions can not equal to or less than zero");
	    }
	    
	    double mapAspectRation = (double) width / (double) height;
	    double extAspectRation = extWidth / extHeigth;
	    
	    double shrinkFactor = 1.0;
	    WebPoint center = adjustedExt.getCenterPoint();	 
	    
	    /*
	     * aspect ration = width / height
	     * 
	     * If map aspect ratio > extent aspect ratio
	     *      shrink extent height
	     * Else
	     * 		shrink extent width
	     */	    
	    
	    if (mapAspectRation > extAspectRation) {
    		shrinkFactor = extAspectRation * (1 / mapAspectRation);

    		double yzoom = ( (extHeigth * shrinkFactor) / (double) 2.0);
    		adjustedExt.setMaxY(center.getY() + yzoom);
    		adjustedExt.setMinY(center.getY() - yzoom);	        	
	    } else {
	    	shrinkFactor = mapAspectRation * (1 / extAspectRation);
	    	
	    	double xzoom = ( (extWidth * shrinkFactor) / (double) 2.0);
    		adjustedExt.setMaxX(center.getX() + xzoom);
    		adjustedExt.setMinX(center.getX() - xzoom);	    	
	    }
	    
	    return adjustedExt;
	}	
	
	/**
	 * Centers the extent at the specified {@link WebPoint}
	 * @param mapPoint Point to center on
	 * @param zoomFactor Zoom factor of the centering operation
	 */
	public void centerAt(WebPoint mapPoint, double zoomFactor) {
	    double x1 = getMinX();
	    double x2 = getMaxX();
	    double y1 = getMinY();
	    double y2 = getMaxY();
	    double cx = (x1 + x2) / 2;
	    double cy = (y1 + y2) / 2;
	    double dx = mapPoint.getX() - cx;
	    double dy = mapPoint.getY() - cy;
	    double xzoom = (1 - zoomFactor) * getWidth() / 2;
	    double yzoom = (1 - zoomFactor) * getHeight() / 2;
	    
	    this.putCoords(x1 + dx + (xzoom * x1), y1 + dy + (yzoom * y1), x2 + dx - (xzoom * x2), y2 + dy - (yzoom * y2));
	}	
}