OpenLayers 6.15.1设置declutter:false后图标标签裁剪问题求解

我使用OpenLayers 6.15.1，需要在地图上展示一个点图层并设置declutter: false——因为不想让用户必须缩放才能发现存在更多要素。但最外侧的图标及其标签被裁剪了，该如何解决？

裁剪情况示例 #

• 图标下方裁剪：
• 图标右侧裁剪：
• 图标左上角裁剪：

我创建了一个可调试的示例，同时附上样式和图层代码：

样式代码 #

var size = 0;
var placement = 'point';
var style_Civici = function(feature, resolution){
    var context = {
        feature: feature,
        variables: {}
    };
    var value = ""
    var labelText = "";
    size = 0;
    var labelFont = "13.0px 'MS Shell Dlg 2', sans-serif";
    var labelFill = "#e31a1c";
    var bufferColor = "#ffffff";
    var bufferWidth = 3.0;
    var textAlign = "left";
    var offsetX = 8;
    var offsetY = 3;
    var placement = 'point';
    if (feature.get("numcivico") !== null) {
        labelText = String(feature.get("numcivico"));
    }
    var style = [ new ol.style.Style({
        image: new ol.style.Circle({radius: 4.0 + size,
            stroke: new ol.style.Stroke({color: 'rgba(35,35,35,1.0)', lineDash: null, lineCap: 'butt', lineJoin: 'miter', width: 0}), fill: new ol.style.Fill({color: 'rgba(227,26,28,0.9490196078431372)'})}),
        text: createTextStyle(feature, resolution, labelText, labelFont,
                              labelFill, placement, bufferColor,
                              bufferWidth)
    })];

    return style;
};

图层代码 #

var format_Civici = new ol.format.GeoJSON();
var features_Civici = format_Civici.readFeatures(json_Civici, 
            {dataProjection: 'EPSG:4326', featureProjection: 'EPSG:25832'});
var jsonSource_Civici = new ol.source.Vector({
                attributions: "<img src='styles/legend/Civici.png' /> <b>Civici</b>"
            });
jsonSource_Civici.addFeatures(features_Civici);
var lyr_Civici = new ol.layer.Vector({
                declutter: false,
                source:jsonSource_Civici, 
                style: style_Civici,
                permalink: "Civici",
                popuplayertitle: "Civici",
                interactive: true,
                title: "<img src='styles/legend/Civici.png' /> Civici"
            });
var extent_Civici = jsonSource_Civici.getExtent();
lyr_Civici.setProperties('extent');
lyr_Civici.set('extent' , extent_Civici);

更新 #

删除图层中与extent相关的最后三行代码后，问题得以解决。请问如何在保留图层extent定义的同时，避免图标被裁剪？

内容的提问来源于stack exchange，提问作者andreaordonselli