重写 geturl Openlayers中使用TileCache加载预切割图片作为基础地图图层

Openlayers中使用TileCache加载预切割图片作为基础地图图层

博客分类：
• OpenLayers

Java代码

1. /**
2. *对自定义规则切割的图片进行拼装的类
3. */
4. SimpleTileCache=OpenLayers.Class(OpenLayers.Layer.TileCache,{
5. initialize:function(name,url,options){
6. vartempoptions=OpenLayers.Util.extend(
7. {'format':'image/png',isBaseLayer:true},options);
8. OpenLayers.Layer.TileCache.prototype.initialize.apply(this,[name,url,{},tempoptions]);
9. this.extension=this.format.split('/')[1].toLowerCase();
10. this.extension=(this.extension=='jpg')?'jpeg':this.extension;
11. this.transitionEffect="resize";
12. this.buffer=2;
13. },
14. /**
15. *按地图引擎切图规则实现的拼接方式
16. */
17. getURL:function(bounds){
18. varres=this.map.getResolution();
19. varbbox=this.map.getMaxExtent();
20. varsize=this.tileSize;
21. //计算列号
22. vartileX=Math.round((bounds.left-bbox.left)/(res*size.w));
23. //计算行号
24. vartileY=Math.round((bbox.top-bounds.top)/(res*size.h));
25. //当前的等级
26. vartileZ=this.map.zoom;
27. if(tileX<0)tileX=tileX+Math.round(bbox.getWidth()/bounds.getWidth());
28. if(tileY<0)tileY=tileY+Math.round(bbox.getHeight()/bounds.getHeight());
29. returnthis.getTilePic(tileX,tileY,tileZ);
30. },
31. getTilePic:function(tileX,tileY,tileZ){
32. vardir='';
33. if(tileZ>6){
34. vardelta=Math.pow(2,tileZ-5);
35. varrowDir='R'+Math.floor(tileY/delta);
36. varcolDir='C'+Math.floor(tileX/delta);
37. dir=tileZ+"/"+rowDir+"/"+colDir+"/";
38. }else{
39. dir=tileZ+'/';
40. }
41. vartileNo=tileZ+"-"+tileX+"-"+tileY;
42. varsUrl=this.url+dir+tileNo+'.png';
43. returnsUrl;
44. },
45. clone:function(obj){
46. if(obj==null){
47. obj=newSimpleTileCache(this.name,this.url,this.options);
48. }
49. obj=OpenLayers.Layer.TileCache.prototype.clone.apply(this,[obj]);
50. returnobj;
51. },
52. CLASS_NAME:"SimpleTileCache"
53. });

/**
 * 对自定义规则切割的图片进行拼装的类
 */
SimpleTileCache=OpenLayers.Class(OpenLayers.Layer.TileCache,{
	initialize:function(name,url,options){
		var tempoptions = OpenLayers.Util.extend(
{'format': 'image/png',isBaseLayer:true},options);			        
		OpenLayers.Layer.TileCache.prototype.initialize.apply(this,[name, url, {}, tempoptions]);
		this.extension = this.format.split('/')[1].toLowerCase();
		this.extension = (this.extension == 'jpg') ? 'jpeg' : this.extension;
		this.transitionEffect="resize";
		this.buffer=2;		
	},
	/**
     *   按地图引擎切图规则实现的拼接方式
	 */
	getURL: function(bounds) {		    
		var res   = this.map.getResolution();			        
		var bbox  = this.map.getMaxExtent();
		var size  = this.tileSize;
		//计算列号		        
		var tileX = Math.round((bounds.left - bbox.left) / (res * size.w));
           //计算行号
		var tileY = Math.round((bbox.top-bounds.top) / (res * size.h));	
		//当前的等级			
		var tileZ = this.map.zoom;				        						        
		if(tileX<0) tileX=tileX+Math.round(bbox.getWidth()/bounds.getWidth());       
		if(tileY<0)  tileY=tileY+Math.round(bbox.getHeight()/bounds.getHeight());			        
		return	this.getTilePic(tileX,tileY,tileZ);
	},
	getTilePic: function(tileX,tileY,tileZ){
		var dir = '';
		if(tileZ > 6) {
			var delta       = Math.pow(2,tileZ-5);	    
			var rowDir   = 'R'+ Math.floor(tileY /delta);
			var colDir   = 'C'+Math.floor(tileX /delta);
			dir      = tileZ  + "/" + rowDir + "/" + colDir + "/";
		} else {
			dir= tileZ + '/';
		}				    
		var tileNo  = tileZ + "-" + tileX + "-" + tileY;
		var sUrl = this.url + dir + tileNo + '.png';
		return sUrl;
	},
	clone: function (obj) { 
		if (obj == null) {
		obj = new SimpleTileCache(this.name,this.url,this.options);
		}
		obj = OpenLayers.Layer.TileCache.prototype.clone.apply(this, [obj]);
		return obj;
	},
	CLASS_NAME: "SimpleTileCache"
});