【GIS交互:单击要素】openlayers单击获取要素的两种方式

已被阅读 3198 次 | 文章分类:OpenLayers | 2021-07-08 00:08

openlayers提供了两种单击要素的方式 getFeaturesAtPixel,interaction.Select();这里说的单击就是拾取要素,能够通过事件获得单击要素空间信息和属性信息的意思;

1 效果

效果1和效果2

小白GIS

小白GIS

2 第一种 通过单击事件singleclick 结合像素拾取

首先生成两个点

                                        
// 注意图层顺序,定义越前的图层 会被后面图层盖着    
        new layer.Tile({
            source: new source.OSM()
        }),
        new layer.Vector({
            source: new source.Vector({
                features: [
                    new ol.Feature({
                        geometry: new geom.Point([121.478815, 31.24161])
                    }),
                    new ol.Feature({
                        geometry: new geom.Point([120.160318, 30.293255]),
                        name: '杭州市'
                    })]
            })
        })
                                        
                                    
                                        
let clickFeature = null;
map.on("singleclick", function (e) {
    var features = map.getFeaturesAtPixel(e.pixel, { hitTolerance: 1 });
    var pt_style = function (_feature) {
        return new style.Style({
            image: new style.Circle({
                radius: 5,
                fill: new style.Fill({
                    color: 'red'
                }),
                stroke: new style.Stroke({ //边界样式
                    color: 'black',
                    width: 1
                })
            }),
            text: new style.Text({
                textAlign: 'left',              // 位置
                offsetX: '8',                    // 水平方向偏移量
                offsetY: '8',                   // 垂直方向偏移量
                font: '13px Microsoft YaHei',   // 字体属性
                text: _feature.get('name'),    // 显示内容
                fill: new style.Fill({       // 字体颜色
                    color: 'red'
                }),
                stroke: new style.Stroke({   // 字体轮廓
                    color: 'black',
                    width: 1
                })
            })
        });
    }
    if (clickFeature) {
        clickFeature.setStyle(null);
    }
    if (features.length > 0) {
        features[0].setStyle(pt_style(features[0]));
        clickFeature = features[0];
    }
})
                                        
                                    

3 第二种 定义选择器事件

                                        
var selectClick = new interaction.Select();
    map.addInteraction(selectClick);
    selectClick.on('select', function(e) {
        var features=e.target.getFeatures().getArray();
        if(features.length>0){
            var coor=features[0].getGeometry().getCoordinates();
            alert(coor);
        }   
    })
                                        
                                    

具体样式设计,跟上面一样

4 结合单击显示弹出框

原理是获取单击要素的坐标,然后新建弹出框在该位置

全部代码如下

                                        
 import * as ol from 'ol';
 import * as geom from 'ol/geom'
 import * as layer from 'ol/layer';
 import * as source from 'ol/source';
 import * as interaction from 'ol/interaction';
 import 'ol/ol.css';
var map = new ol.Map({
    target:'map',
    layers:[
        // 注意图层顺序,定义越前的图层 在越下层
        new layer.Tile({
            source:new source.OSM()
        }),
        new layer.Vector({
            source: new source.Vector({
                features:[
                    new ol.Feature({
                        geometry:new geom.Point([121.478815,31.24161]),
                        name:'上海市'
                }),
                    new ol.Feature({
                        geometry:new geom.Point([120.160318,30.293255]),
                        name:'杭州市'
                    })]        
            })
        })
    ],
    view:new ol.View({
        center:[121.478815,31.24161],
        zoom:10,
        projection:	'EPSG:4326'	
    })
});
// 创建一个div
var div_popup;
function createPopupDiv(){
    div_popup=document.createElement('div');
    div_popup.id="popup"; 
    div_popup.className="popup"; 
    div_popup.style.cssText ="display:block;background:black;color:white;border:solid 1px;"
    document.body.appendChild(div_popup);
}
createPopupDiv();
// 创建一个overlay层
var popup = new ol.Overlay({
    element: document.getElementById('popup'),
    autoPan:true,
    autoPanMargin:100,
    positioning:'center-left',
    offset:[10,-5]
});
 
var selectClick = new interaction.Select();
map.addInteraction(selectClick);
 
selectClick.on('select', function(e) {
    var features=e.target.getFeatures().getArray();
    if(features.length>0){
        var element = popup.getElement();
        var coor=features[0].getGeometry().getCoordinates();
        var property=features[0].getProperties();
        var type=features[0].getGeometry().getType();
        var hdms="点名:"+property["name"];
        hdms=hdms+"<br/>";
        hdms = hdms+"几何类型:"+type;
        hdms=hdms+"<br/>";
        hdms = hdms+"位置:"+coor[0]+"-"+coor[1];
        element.innerHTML=hdms;
        map.addOverlay(popup);
        popup.setPosition(coor);
    }else{
        map.removeOverlay(popup);
    }
})
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 import * as ol from 'ol';
 import * as geom from 'ol/geom'
 import * as layer from 'ol/layer';
 import * as source from 'ol/source';
 import * as interaction from 'ol/interaction';
 import 'ol/ol.css';
var map = new ol.Map({
    target:'map',
    layers:[
        // 注意图层顺序,定义越前的图层 在越下层
        new layer.Tile({
            source:new source.OSM()
        }),
        new layer.Vector({
            source: new source.Vector({
                features:[
                    new ol.Feature({
                        geometry:new geom.Point([121.478815,31.24161]),
                        name:'上海市'
                }),
                    new ol.Feature({
                        geometry:new geom.Point([120.160318,30.293255]),
                        name:'杭州市'
                    })]        
            })
        })
    ],
    view:new ol.View({
        center:[121.478815,31.24161],
        zoom:10,
        projection:	'EPSG:4326'	
    })
});
// 创建一个div
var div_popup;
function createPopupDiv(){
    div_popup=document.createElement('div');
    div_popup.id="popup"; 
    div_popup.className="popup"; 
    div_popup.style.cssText ="display:block;background:black;color:white;border:solid 1px;"
    document.body.appendChild(div_popup);
}
createPopupDiv();
// 创建一个overlay层
var popup = new ol.Overlay({
    element: document.getElementById('popup'),
    autoPan:true,
    autoPanMargin:100,
    positioning:'center-left',
    offset:[10,-5]
});
 
var selectClick = new interaction.Select();
map.addInteraction(selectClick);
 
selectClick.on('select', function(e) {
    var features=e.target.getFeatures().getArray();
    if(features.length>0){
        var element = popup.getElement();
        var coor=features[0].getGeometry().getCoordinates();
        var property=features[0].getProperties();
        var type=features[0].getGeometry().getType();
        var hdms="点名:"+property["name"];
        hdms=hdms+"<br/>";
        hdms = hdms+"几何类型:"+type;
        hdms=hdms+"<br/>";
        hdms = hdms+"位置:"+coor[0]+"-"+coor[1];
        element.innerHTML=hdms;
        map.addOverlay(popup);
        popup.setPosition(coor);
    }else{
        map.removeOverlay(popup);
    }
})

                                        
                                    

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