一个屏幕坐标和地图坐标转换的js代码

2022-07-15 80酷酷网 80kuku.com

　　js|转换

一个屏幕坐标和地图坐标转换的js代码

在开发webgis的时候在客户端经常要处理屏幕坐标和地图坐标的转换关系，特别是现在 web2.0时代，要求ie 交互和展现更加丰富，对坐标转换要求就更多了。因此在项目中写了个通用的转换 javascript代码。在实际项目得到了较好的应用
具体代码如下（需要prototype.js的支持）

/*
*共有三个类
*whpoint 点
*whrect 矩形
*whcoordchange坐标转换类
*/

whpoint=Class.create();

whpoint.prototype={
initialize:function(x,y){
this.x=x;
this.y=y;
}
};

whrect=Class.create();
whrect.prototype={
initialize:function(pointmin,pointmax){
this.point1=pointmin;
this.point2=pointmax;
this.width=this.point2.x-this.point1.x;
this.height=this.point2.y-this.point1.y;

getwidth:function(){
return this.point2.x-this.point1.x;
},

setwidth:function(newwidth){

this.width=newwidth;
},

getheight:function(){
return this.point2.y-this.point1.y;
},

setheight:function(newheight){
this.height=newheight;
},

setpointmax:function(pointmax){
this.point2=pointmax;
},

setpointmin:function(pointmin){
this.point1=pointmin;
},

getminx:function(){

return this.point1.x;
},
getminy:function(){
return this.point1.y;
},
getmaxx:function(){

return this.point2.x
},

getmaxy:function(){

return this.point2.y;
}

};

whcoordchange=Class.create();

whcoordchange.prototype={
initialize:function(screenrect,maprect){
this.screenrect=screenrect;
this.maprect=maprect;

},
getmapextent:function(screenpoint,twidth,theight){
var screenbl_x=screenpoint.x-twidth/2;
var screenbl_y=screenpoint.y+theight/2;
var tempscreenblp=new whpoint(screenbl_x,screenbl_y);
var resmapblp=this.screentomap(tempscreenblp);

var screenur_x=screenpoint.x+twidth/2;
var screenur_y=screenpoint.y-theight/2;
var tempscreenurp=new whpoint(screenur_x,screenur_y);
var resmapurp=this.screentomap(tempscreenurp);

return new whrect(resmapblp,resmapurp);

},

screentomap:function(screenpoint){

var resmapx=this.maprect.getminx()+

this.maprect.getwidth()*(screenpoint.x-this.screenrect.getminx())/this.screenrect.getwidth();
var resmapy=this.maprect.getmaxy()-

this.maprect.getheight()*(screenpoint.y-this.screenrect.getminy())/this.screenrect.getheight();

return new whpoint(resmapx,resmapy);
},

maptoscreen:function(mappoint){
var resscreenx=this.screenrect.getminx()+

this.screenrect.getwidth()*(mappoint.x-this.maprect.getminx())/this.maprect.getwidth();
var resscreeny=this.screenrect.getminy()+

this.screenrect.getheight()*(this.maprect.getmaxy()-mappoint.y)/this.maprect.getheight();
return new whpoint(Math.ceil(resscreenx),Math.ceil(resscreeny));

}

};

//////////////////////////////////////
/////////////////////////////////

实际页面中的应用实例


    var scminp=new whpoint(10,10);
    var scmaxp=new whpoint(400,300);
    var screct=new whrect(scminp,scmaxp);

     var mminp=new whpoint(120.235,30.235);
    var mmaxp=new whpoint(120.265,30.265);

    var mrect=new whrect(mminp,mmaxp);

    //建立屏幕坐标和地图坐标的对应关系注意应该是鹰眼的范围对应地图的范围
    var mycoordchange=new whcoordchange(screct,mrect);

    var scpoint1=new whpoint(10,300);
    var mapscpoint1=mycoordchange.screentomap(scpoint1);

    alert(mapscpoint1.x+";"+mapscpoint1.y);

     var mapoint1=new whpoint(120.250,30.250);
    var scmapoint1=mycoordchange.maptoscreen(mapoint1);

    alert(scmapoint1.x+";"+scmapoint1.y);

    //根据屏幕坐标点相应鹰眼redbox的 width 和 height 获取相应的地图extent,
    var maprect=mycoordchange.getmapextent(scmapoint1,195,145);

    alert (maprect.getminx()+";" + maprect.getminy()+";"+maprect.getmaxx()+";"+ maprect.getmaxy());