Openlayers中使用Cluster实现缩放地图时图层聚合与取消聚合

刺骨的言语ヽ痛彻心扉 2023-10-01 10:40 58阅读 0赞

## 场景 ##

Openlayers中实现地图上打点并显示图标和文字：

[Openlayers中实现地图上打点并显示图标和文字\_BADAO\_LIUMANG\_QIZHI的博客-CSDN博客\_openlayers 打点][Openlayers_BADAO_LIUMANG_QIZHI_-CSDN_openlayers]

上面实现加载显示离线地图并显示图标元素的效果后。

实现当多个元素堆积在一起时实现聚合显示效果。

![watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBA6Zy46YGT5rWB5rCT5rCU6LSo_size_20_color_FFFFFF_t_70_g_se_x_16][]

并且伴随着地图的缩放实现自动聚合显示和取消聚合。

![6f59087863b44c73acbc237be8ca0150.gif][]

注：

博客：  
[BADAO\_LIUMANG\_QIZHI的博客\_霸道流氓气质\_CSDN博客-C\#,SpringBoot,架构之路领域博主][BADAO_LIUMANG_QIZHI_CSDN_-C_SpringBoot]  
关注公众号  
霸道的程序猿  
获取编程相关电子书、教程推送与免费下载。

## 实现 ##

1、随机创建一些要素

// 随机创建要素
            var clusterSource = new ol.source.Vector();
            debugger
            for (var i = 1; i <= 10; i++) {
                var coordinates = [-11551949.709486058 + Math.random(), 5533080.7247905275 + Math.random()];
                var feature = new ol.Feature(new ol.geom.Point(coordinates));
                clusterSource.addFeature(feature);
            }
            for (var i = 1; i <= 20; i++) {
                var coordinates = [-11553949.709486058 + Math.random(), 5527080.7247905275 + Math.random()];
                var feature = new ol.Feature(new ol.geom.Point(coordinates));
                clusterSource.addFeature(feature);
            }

这里的坐标值是从地图上获取的一些坐标值，然后通过对x和y随机增加随机数，构造一组10和一组20个的要素。

2、新建聚合图层数据源

// 聚合图层数据源
            var clusterSourceForLayer = new ol.source.Cluster({
                source: clusterSource,
                distance: 100
            })

这里的distance就是设置的聚合的距离。

3、新建聚合图层

// 聚合图层
            var clusterLayer = new ol.layer.Vector({
                source: clusterSourceForLayer,
                style: function (feature, resolution) {
                    var size = feature.get('features').length;
                    if (size == 1) {
                        return new ol.style.Style({
                            image: new ol.style.Icon({
                                scale: 0.8,
                                src: './icon/house.png',
                                anchor: [0.48, 0.52]
                            }),
                            text: new ol.style.Text({
                                font: 'normal 12px 黑体',
                                // // 对其方式
                                textAlign: 'center',
                                // 基准线
                                textBaseline: 'middle',
                                offsetY: -35,
                                offsetX: 0,
                                backgroundFill: new ol.style.Stroke({
                                    color: 'rgba(0,0,255,0.7)',
                                }),
                                // 文本填充样式
                                fill: new ol.style.Fill({
                                    color: 'rgba(236,218,20,1)'
                                }),
                                padding: [5, 5, 5, 5],
                                text: `霸道的程序猿`,
                            })
                        });
                    } else {
                        return new ol.style.Style({
                            image: new ol.style.Circle({
                                radius: 30,
                                stroke: new ol.style.Stroke({
                                    color: 'white'
                                }),
                                fill: new ol.style.Fill({
                                    color: 'blue'
                                })
                            }),
                            text: new ol.style.Text({
                                text: size.toString(),
                                fill: new ol.style.Fill({
                                    color: 'white'
                                })
                            })
                        });
                    }
                }
            });

注意这里的核心的代码就是

style: function (feature, resolution) {
           var size = feature.get('features').length;
               if (size == 1) {
    
     	        }else{
    
     	        }

如果size大于1则返回聚合样式，反之则返回图片样式。

4、将聚合图层添加进地图

//View 视图管理器，主要用来管理地图视图，分辨率或旋转，中心、投影、分辨率、缩放级别等。
            var view = new ol.View({
                //中心点
                center: [-11549894, 5533433],
                //缩放等级
                zoom: 11,
                //投影坐标系
                projection: projection,
                //边界
                extent: [-20037508.34, -20037508.34, 20037508.34, 20037508.34]
            });
    
            //Map Openlayers的核心组件，包含图层、交互事件、UI控制元素等。
            var map = new ol.Map({
                layers: [layer, clusterLayer],
                target: 'map',
                view: view
            });

5、除此之外的代码就是离线加载瓦片地图的代码，完整代码

<!doctype html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <title>OpenLayers example</title>
        <link rel="stylesheet" href="lib/ol65/ol.css" type="text/css">
        <style>
            html,
            body,
            #map {
                padding: 0;
                margin: 0;
                width: 100%;
                height: 100%;
                overflow: hidden;
            }
        </style>
    </head>
    
    <body>
        <div id="map"></div>
        <script type="text/javascript" src="lib/ol65/ol.js"></script>
        <script type="text/javascript">
            var source = new ol.source.XYZ({
                tileUrlFunction: function (xyz, obj1, obj2) {
                    if (!xyz)
                        return "";
                    var z = xyz[0];
                    var x = Math.abs(xyz[1]);
                    var y = Math.abs(xyz[2]);
                    var xyz_convert = self.convert_(z, x, y);
                    x = xyz_convert[0];
                    y = xyz_convert[1];
                    z = xyz_convert[2];
                    var shift = z / 2;
                    var half = 2 << shift;
                    var digits = 1;
                    if (half > 10)
                        digits = parseInt(Math.log(half) / Math.log(10)) + 1;
                    var halfx = parseInt(x / half);
                    var halfy = parseInt(y / half);
                    x = parseInt(x);
                    y = parseInt(y) - 1;
                    var url = "./images/EPSG_900913" + "_" + self.padLeft_(2, z) + "/" + self.padLeft_(digits,
                            halfx) + "_" + self.padLeft_(digits, halfy) + "/" + self.padLeft_(2 * digits, x) +
                        "_" + self.padLeft_(2 * digits, y) + "." + 'png';
                    return url;
                }
            });
    
            //projections投影坐标系转换相关的操作
            var projection = new ol.proj.Projection({
                code: 'EPSG:900913',
                units: 'm',
                axisOrientation: 'neu'
            });
    
            //Layers 图层管理类，用来管理图层信息。主要包括Tile，Image，Vector，VectorTile等图层。
            var layer = new ol.layer.Tile({
                source: source
            });
    
            // 随机创建要素
            var clusterSource = new ol.source.Vector();
            debugger
            for (var i = 1; i <= 10; i++) {
                var coordinates = [-11551949.709486058 + Math.random(), 5533080.7247905275 + Math.random()];
                var feature = new ol.Feature(new ol.geom.Point(coordinates));
                clusterSource.addFeature(feature);
            }
            for (var i = 1; i <= 20; i++) {
                var coordinates = [-11553949.709486058 + Math.random(), 5527080.7247905275 + Math.random()];
                var feature = new ol.Feature(new ol.geom.Point(coordinates));
                clusterSource.addFeature(feature);
            }
    
            // 聚合图层数据源
            var clusterSourceForLayer = new ol.source.Cluster({
                source: clusterSource,
                distance: 100
            })
            // 聚合图层
            var clusterLayer = new ol.layer.Vector({
                source: clusterSourceForLayer,
                style: function (feature, resolution) {
                    var size = feature.get('features').length;
                    if (size == 1) {
                        return new ol.style.Style({
                            image: new ol.style.Icon({
                                scale: 0.8,
                                src: './icon/house.png',
                                anchor: [0.48, 0.52]
                            }),
                            text: new ol.style.Text({
                                font: 'normal 12px 黑体',
                                // // 对其方式
                                textAlign: 'center',
                                // 基准线
                                textBaseline: 'middle',
                                offsetY: -35,
                                offsetX: 0,
                                backgroundFill: new ol.style.Stroke({
                                    color: 'rgba(0,0,255,0.7)',
                                }),
                                // 文本填充样式
                                fill: new ol.style.Fill({
                                    color: 'rgba(236,218,20,1)'
                                }),
                                padding: [5, 5, 5, 5],
                                text: `霸道的程序猿`,
                            })
                        });
                    } else {
                        return new ol.style.Style({
                            image: new ol.style.Circle({
                                radius: 30,
                                stroke: new ol.style.Stroke({
                                    color: 'white'
                                }),
                                fill: new ol.style.Fill({
                                    color: 'blue'
                                })
                            }),
                            text: new ol.style.Text({
                                text: size.toString(),
                                fill: new ol.style.Fill({
                                    color: 'white'
                                })
                            })
                        });
                    }
                }
            });
    
            //View 视图管理器，主要用来管理地图视图，分辨率或旋转，中心、投影、分辨率、缩放级别等。
            var view = new ol.View({
                //中心点
                center: [-11549894, 5533433],
                //缩放等级
                zoom: 11,
                //投影坐标系
                projection: projection,
                //边界
                extent: [-20037508.34, -20037508.34, 20037508.34, 20037508.34]
            });
    
            //Map Openlayers的核心组件，包含图层、交互事件、UI控制元素等。
            var map = new ol.Map({
                layers: [layer, clusterLayer],
                target: 'map',
                view: view
            });
    
            //xy行列转换
            function convert_(zoomLevel, x, y) {
                var extent = Math.pow(2, zoomLevel);
                if (x < 0 || x > extent - 1) {
                    console.log("The X coordinate is not sane: " + x);
                    return;
                }
                if (y < 0 || y > extent - 1) {
                    console.log("The Y coordinate is not sane: " + y);
                    return;
                }
                // openlayers 6.0版本
                var gridLoc = [x, extent - y, zoomLevel];
    
                // openlayers 4.5版本
                // var gridLoc = [x, extent - y + 1, zoomLevel];
                return gridLoc;
            }
    
            //字符截取
            function padLeft_(num, val) {
                return (new Array(num).join('0') + val).slice(-num);
            }
        </script>
    </body>
    
    </html>

[Openlayers_BADAO_LIUMANG_QIZHI_-CSDN_openlayers]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/118631046
[watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBA6Zy46YGT5rWB5rCT5rCU6LSo_size_20_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/bc2020c0273744ac9a00fea4da7a5687.jpg?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA6Zy46YGT5rWB5rCT5rCU6LSo,size_20,color_FFFFFF,t_70,g_se,x_16
[6f59087863b44c73acbc237be8ca0150.gif]: https://img-blog.csdnimg.cn/6f59087863b44c73acbc237be8ca0150.gif
[BADAO_LIUMANG_QIZHI_CSDN_-C_SpringBoot]: https://blog.csdn.net/badao_liumang_qizhi