1.作用:
聚簇类是用于前端显示优化,使POI点要素显示更为美观。大量的Marker距离太近会引起压盖而对浏览或者操作产生不便,因此,一般在超过1K点的时候,用此类。、
2.使用方式:
1: // cluster layer that uses OpenLayers style clustering
2: clusterLayer = new ClusterLayer({
3: "data": photoInfo.data,
4: "distance": 100,
5: "id": "clusters",
6: "labelColor": "#fff",
7: "labelOffset": 10,
8: "resolution": map.extent.getWidth() / map.width,
9: "singleColor": "#888",
10: "maxSingles":1999,
11: "singleTemplate": popupTemplate
12: });
13: var defaultSym = new SimpleMarkerSymbol().setSize(4);
14: var renderer = new ClassBreaksRenderer(defaultSym, "clusterCount");
15:
16: var picBaseUrl = "http://static.arcgis.com/images/Symbols/Shapes/";
17: var blue = new PictureMarkerSymbol(picBaseUrl + "BluePin1LargeB.png", 32, 32).setOffset(0, 15);
18: var green = new PictureMarkerSymbol(picBaseUrl + "GreenPin1LargeB.png", 64, 64).setOffset(0, 15);
19: var red = new PictureMarkerSymbol(picBaseUrl + "RedPin1LargeB.png", 72, 72).setOffset(0, 15);
20: renderer.addBreak(0, 2, blue);
21: renderer.addBreak(2, 200, green);
22: renderer.addBreak(200, 1001, red);
23:
24: clusterLayer.setRenderer(renderer);
25: map.addLayer(clusterLayer);
构造函数源码重点:
return declare([GraphicsLayer], {
constructor:
function(options) {
//
options:
// data:
Object[]
// Array of
objects. Required. Object are
required to have properties named x, y and attributes. The x and y coordinates
have to be numbers that represent a points
coordinates.要素对象集合是必要字段。而要素是Json格式,有三个key,x,y,attributes,坐标值之外的属性数据全部放在attributes字段里。
// distance: Number?
// Optional. The max number of pixels between points to
group points in the same cluster. Default value is
50.该字段是设定两点之间小于多少个像素值就被归类于同一个簇中
默认值是50.
// labelColor:
String?
// Optional.
Hex string or array of rgba values used as the color for cluster labels. Default
value is #fff (white).
//
labelOffset: String?
// Optional. Number of pixels to shift a cluster label
vertically. Defaults to -5 to align labels with circle symbols. Does
not work in IE.
// resolution:
Number
// Required.
Width of a pixel in map coordinates. Example of how to calculate:
// map.extent.getWidth()
/ map.width
//
showSingles: Boolean?
// Optional. Whether or graphics should be displayed
when a cluster graphic is clicked. Default is
true.
// singleSymbol:
MarkerSymbol?
//
Marker Symbol (picture or simple). Optional. Symbol to use for graphics that
represent single points. Default is a small gray
SimpleMarkerSymbol.
//
singleTemplate: PopupTemplate?
// PopupTemplate</a>. Optional. Popup template
used to format attributes for graphics that represent single points. Default
shows all attributes as "attribute = value" (not
recommended).
// maxSingles:
Number?
// Optional.
Threshold(阈值) for whether or not to show graphics for points in a cluster.
Default is 1000.
// webmap:
Boolean?
// Optional.
Whether or not the map is from an ArcGIS.com webmap. Default is
false.
// spatialReference:
SpatialReference?
//
Optional. Spatial reference for all graphics in the layer. This has to match the
spatial reference of the map. Default is 102100. Omit this if the map uses
basemaps in web mercator.
官方实例在这。点击下载