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关于MapXtreme for Java鹰眼实现思路及代码

2012-08-30 21:26 369 查看

两个思路：
1.客户断每次操作地图后发起两次请求：取主地图和鹰眼地图，鹰眼地图根据主地图窗口在临时图层生成一个方框
2.页面初始化的时候从服务器获取一张小图（鹰眼图，可以是事先做好的，也可以通过MapJ生成），同时获得这张鹰眼图的minx,miny,maxx,maxy,zoom，每次操作地图后通过主地图的minx,miny,maxx,maxy，然后在页面上根据这几对坐标和zoom生成一个div叠加到鹰眼图上

推荐第二种方式，减少服务器的压力！

第一种方式我已经不怎么用了，代码也找不到，网上的一段：

private void responsebound(MapJ mymap, MapJ boundmap, HttpServletResponse response)
{
ServletOutputStream sout = null;
try
{
Layer anlayer = boundmap.getLayers().elementAt(0);
FeatureFactory ff = boundmap.getFeatureFactory();
PrimaryKey pk = new PrimaryKey(new Attribute(101));
Rendition rend = RenditionImpl.getDefaultRendition();
rend.setvalue(Rendition.STROKE, Color.red);
rend.setvalue(Rendition.STROKE_WIDTH, 2);
rend.setvalue(Rendition.FILL_OPACITY, new Float(0.0D));
DoublePoint p1 = new DoublePoint(0.0D, 0.0D);
DoublePoint p2 = new DoublePoint(imgsizex, 0.0D);
DoublePoint p3 = new DoublePoint(imgsizex, imgsizey);
DoublePoint p4 = new DoublePoint(0.0D, imgsizey);
DoublePoint mp1 = mymap.transformScreenToNumeric(p1);
DoublePoint mp2 = mymap.transformScreenToNumeric(p2);
DoublePoint mp3 = mymap.transformScreenToNumeric(p3);
DoublePoint mp4 = mymap.transformScreenToNumeric(p4);
double p[] = new double[10];
p[0] = mp1.x;
p[1] = mp1.y;
p[2] = mp2.x;
p[3] = mp2.y;
p[4] = mp3.x;
p[5] = mp3.y;
p[6] = mp4.x;
p[7] = mp4.y;
p[8] = mp1.x;
p[9] = mp1.y;
Feature ft = ff.createRegion(p, rend, null, null, pk);
PrimaryKey spk[] = {
new PrimaryKey(new Attribute(101))
};
Vector col = new Vector();
FeatureSet ftset = anlayer.searchByPrimaryKey(col, spk, null);
PrimaryKey primarykey;
if(ftset == null)
primarykey = anlayer.addFeature(ft);
else
anlayer.replaceFeature(pk, ft);
boundmap.setDeviceBounds(new DoubleRect(0.0D, 0.0D, smallimgsizex, smallimgsizey));
boundmap.setDistanceUnits(mymap.getDistanceUnits());
if(mymap.getZoom() / boundmap.getZoom() >= 0.80000000000000004D)
{
boundmap.setZoom(mymap.getZoom() * 1.25D);
boundmap.setCenter(mymap.getCenter());
} else
{
boundmap.setZoom(resetzoom);
boundmap.setCenter(resetpoint);
}
}
catch(Exception e)
{
e.printStackTrace();
}
response.setContentType("image/jpeg");
try
{
sout = response.getOutputStream();
ImageRequestComposer irc = ImageRequestComposer.create(boundmap, 65535, Color.white, "image/jpeg");
MapXtremeImageRenderer renderer = new MapXtremeImageRenderer(mapxtremeurl);
renderer.render(irc);
renderer.toStream(sout);
}
catch(Exception e)
{
e.printStackTrace();
}
try
{
if(sout != null)
sout.close();
}
catch(Exception exception) { }
}

第二种方式就是javascript了：
var ViewScaleX = (boundMap_RX-boundMap_LX)/boundMap_W;
var ViewScaleY = (boundMap_TY-boundMap_BY)/boundMap_H;

var xView1 = (map.LX-boundMap_LX)/ViewScaleX;
var xView2 = boundMap_W - (boundMap_RX - map.RX)/ViewScaleX;
var yView1 = (boundMap_TY - map.TY)/ViewScaleY;
var yView2 = boundMap_H-(map.BY-boundMap_BY)/ViewScaleY;
var Height = yView2-yView1;
var Width = xView2-xView1;

改变鹰眼方框的大小(boundMap_BOX , Width , Height);
移动鹰眼方块(boundMap_BOX , parseInt(boundimg.border)+xView1 , parseInt(boundimg.border)+yView1);

archive 评论：

第一种方法要能够准确实现鹰眼矩形
而第二种方法对于独立坐标系是可以使用的，如果使用大地坐标系而且显示范围较大时（如：整个世界）很难准确实现鹰眼矩形（除非你能够在客户端实现投影匹配）

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