如何实现OpenLayers目测功能


发布日期 ： 2026-01-08 01:22:12 UTC

访问量： 185 次浏览

OpenLayers怎么实现目测

这个例子可以计算两条直线的距离，可以计算多边形的面积。

下面把代码贴出来。

[Java] view plaincopyprint?

[JScript] view plaincopyprint?

看到这句话了吗？OpenLayers版本不同，可能没有这个measure.js。  
[JScript] view plaincopyprint?
现在把这个js贴出来，拷贝到您的网站中，这个功能就能实现了。  
[JScript] view plaincopyprint?

[JScript] view plaincopyprint?
/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD   
* license.  See http://svn.openlayers.org/trunk/openlayers/license.txt for the   
* full text of the license. */    

/**   
* @requires OpenLayers/Control.js   
* @requires OpenLayers/Feature/Vector.js   
*/    

/**   
* Class: OpenLayers.Control.Measure   
* Allows for drawing of features for measurements.   
*   
* Inherits from:   
*  -    
*/    
OpenLayers.Control.Measure = OpenLayers.Class(OpenLayers.Control, {    

/**   
* APIProperty: handlerOptions   
* {Object} Used to set non-default properties on the control's handler   
*/    
handlerOptions: null,    

/**   
* APIProperty: onMeasure   
* {Function} After a geometry is drawn, onMeasure is called with three   
*     arguments: the geometry, its length, and its area.   
*/    
onMeasure: function() {},    

/**   
* Property: callbacks   
* {Object} The functions that are sent to the handler for callback   
*/    
callbacks: null,    

/**   
* Property: displayUnits   
* {String} Units for output.  Must be one of 'in', 'ft', 'mi', 'm', 'km',   
*     or 'dd'.  If null, displayUnits will be assumed to be the same as   
*     map units.   
*/    
displayUnits: null,    

/**   
* Constructor: OpenLayers.Control.Measure   
*    
* Parameters:   
* handler - {}    
* options - {Object}    
*/    
initialize: function(handler, options) {    
OpenLayers.Control.prototype.initialize.apply(this, [options]);    
this.callbacks = OpenLayers.Util.extend(    
{done: this.measureGeometry, point: this.partialMeasure},    
this.callbacks    
);    
this.handler = new handler(this, this.callbacks, this.handlerOptions);    
},    

/**   
* Method: measureGeometry   
*/    
measureGeometry: function(geometry) {    
var area = this.getArea(geometry);    
var length = this.getLength(geometry);    
this.onMeasure(geometry, length, area, this.displayUnits);    
},    

/**   
* Method: getArea   
*/    
getArea: function(geometry) {    
var area = geometry.getArea();    
var inPerDisplayUnit = OpenLayers.INCHES_PER_UNIT[this.displayUnits];    
if(inPerDisplayUnit) {    
var inPerMapUnit = OpenLayers.INCHES_PER_UNIT[this.map.units];    
area *= Math.pow((inPerMapUnit / inPerDisplayUnit), 2);    
}    
return area;    
},    

/**   
* Method: getLength   
*/    
getLength: function(geometry) {    
var length = geometry.getLength();    
var inPerDisplayUnit = OpenLayers.INCHES_PER_UNIT[this.displayUnits];    
if(inPerDisplayUnit) {    
var inPerMapUnit = OpenLayers.INCHES_PER_UNIT[this.map.units];    
length *= (inPerMapUnit / inPerDisplayUnit);    
}    
return length;    
},    

CLASS_NAME: "OpenLayers.Control.Measure"    
});  

                        

                            

                            
                                
                                    本文链接
                                
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                            如何实现OpenLayers目测功能
                        

                    
                
                

                    

                        

                            
                            
                        

                    

                

            
        
        

            

    
        
        

            

                

                    
                        
                            
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