前言
要素标注是一个常用功能,就是将要素信息如名称等显示在地图上,方便查找和使用。在OpenLayers
中要素标注很灵活,使用起来也很方便,可以修改标注样式以及标注权限。在本文中主要介绍如何修改文本放置样式和文字样式
1. 创建标注要素
在地图上创建三组点要素,第一组只设置textAlign
文本框放置属性,其值有"start"、"end"、"left"、"right"、"center"
;第二组在第一组的基础上,设置justify
属性,用于调整文本放置属性,其值有"left"、"center"、"right"
;第三组在第二组的基础上修改justify
属性,观察文本样式变化。
css
const features = [ // 第一组 { geometry: new ol.geom.Point([94.11434654171987, 28.972402471968656]),
textAlign: "left" // 标注文本框位于point右边,point右边是标注文本框
}, {
geometry: new ol.geom.Point([103.45228063165628, 28.972402471968656]),
textAlign: "center" // 标注文本框位于point中心
},
{
geometry: new ol.geom.Point([112.03997466732001, 28.972402471968656]),
textAlign: "right" // 标注文本框位于point左边,point左边是标注文本框
},
// 第二组
{
geometry: new ol.geom.Point([94.11434654171987, 26.972402471968656]),
textAlign: "left", // 文本对齐
justify: "center" // 文本框内的文本对齐
}, {
geometry: new ol.geom.Point([103.45228063165628, 26.972402471968656]),
textAlign: "center",
justify: "center"
},
{
geometry: new ol.geom.Point([112.03997466732001, 26.972402471968656]),
textAlign: "right",
justify: "center"
},
// 第三组
{
geometry: new ol.geom.Point([94.11434654171987, 24.972402471968656]),
textAlign: "left",
justify: "left"
}, {
geometry: new ol.geom.Point([103.45228063165628, 24.972402471968656]),
textAlign: "center",
justify: "left"
},
{
geometry: new ol.geom.Point([112.03997466732001, 24.972402471968656]),
textAlign: "right",
justify: "left"
},
]
2. 创建样式函数
创建样式函数设置标注文本框和文本样式,fill
属性设置文本填充色,backgroundFill
属性设置文本框背景颜色,backgroundStroke
属性设置文本框线框颜色,padding
属性设置文本框内边距。一些其他样式属性请参考:[https://openlayers.org/en/v9.2.4/apidoc/module-ol_style_Text-Text.html](https://openlayers.org/en/v9.2.4/apidoc/module-ol_style_Text-Text.html)
php
function createStyle({ textAlign, justify }) {
return new ol.style.Style({
image: new ol.style.Circle({
radius: 10, // 单位像素
fill: new ol.style.Fill({
color: "rgba(255, 0, 0, 0.1)"
}),
stroke: new ol.style.Stroke({
color: "red",
width: 1.5 // 单位像素
})
}),
text: new ol.style.Text({
font: '16px sans-serif',
textAlign,
justify,
text: `Justify text inside boxntextAlign: ${textAlign}` +
(justify ? `\njustify: ${justify}` : ''),
fill: new ol.style.Fill({
color: [148, 0, 211, 1],
}),
backgroundFill: new ol.style.Fill({
color: [128, 0, 128, 0.25]
}),
// 设置边框边线色
backgroundStroke: new ol.style.Stroke({
color: [255, 182, 193, 0.5],
width: 2.5,
lineJoin: 'miter',
lineCap: "round"
}),
padding: [10, 10, 10, 10], // 文本框内间距
// offsetX: 100
})
})
}
3. 创建标注图层
根据点要素创建点图层并添加到地图中,然后调用setStyle
方法设置要素样式进行标注。
php
const vectorPoints = new ol.layer.Vector({
source: new ol.source.Vector({
features: new ol.Collection(
features.map(featureOptions => {
const feature = new ol.Feature({
geometry: featureOptions.geometry
})
// 设置要素样式
feature.setStyle(createStyle(featureOptions))
return feature
})
),
format: new ol.format.GeoJSON()
})
})
map.addLayer(vectorPoints)
4. 完整代码
其中libs
文件夹下的包需要更换为自己下载的本地包或者引用在线资源。本示例引用了layui
组件,请自行替换。
xml
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>OpenLayers 要素标注</title>
<meta charset="utf-8" />
<link rel="stylesheet" href="../../css/ol9.2.4.css">
<link rel="stylesheet" href="../../libs/layui/css/layui.css">
<script src="../../js/config.js"></script>
<script src="../../libs/js/proj4.js"></script>
<script src="../../libs/js/ol9.2.4.js"></script>
<script src="../../libs/layui/layui.js"></script>
<script src="../../libs/js/geotiff.min.js"></script>
<style>
* {
padding: 0;
margin: 0;
font-size: 14px;
font-family: '微软雅黑';
}
html,
body {
width: 100%;
height: 100%;
}
#map {
position: absolute;
top: 50px;
bottom: 0;
width: 100%;
}
#top-content {
position: absolute;
width: 100%;
height: 50px;
line-height: 50px;
background: linear-gradient(135deg, #ff00cc, #ffcc00, #00ffcc, #ff0066);
color: #fff;
text-align: center;
font-size: 32px;
}
#top-content span {
font-size: 32px;
}
</style>
</head>
<body>
<div id="top-content">
<span>OpenLayers 要素标注</span>
</div>
<div id="map" title="地图显示"></div>
</body>
</html>
<script>
//地图投影坐标系
const projection = ol.proj.get('EPSG:3857');
//==============================================================================//
//============================天地图服务参数简单介绍==============================//
//================================vec:矢量图层==================================//
//================================img:影像图层==================================//
//================================cva:注记图层==================================//
//======================其中:_c表示经纬度投影,_w表示球面墨卡托投影================//
//==============================================================================//
const TDTImgLayer = new ol.layer.Tile({
title: "天地图影像图层",
source: new ol.source.XYZ({
url: "http://t0.tianditu.com/DataServer?T=img_w&x={x}&y={y}&l={z}&tk=" + TDTTOKEN,
attibutions: "天地图影像描述",
crossOrigin: "anoymous",
wrapX: false
})
})
const TDTImgCvaLayer = new ol.layer.Tile({
title: "天地图影像注记图层",
source: new ol.source.XYZ({
url: "http://t0.tianditu.com/DataServer?T=cia_w&x={x}&y={y}&l={z}&tk=" + TDTTOKEN,
attibutions: "天地图注记描述",
crossOrigin: "anoymous",
wrapX: false
})
})
const map = new ol.Map({
target: "map",
loadTilesWhileInteracting: true,
view: new ol.View({
center: [102.845864, 25.421639],
zoom: 6.5,
worldsWrap: false,
minZoom: 1,
maxZoom: 20,
projection: 'EPSG:4326',
}),
layers: [TDTImgLayer],
// 地图默认控件
controls: ol.control.defaults.defaults({
zoom: false,
attribution: true,
rotate: true
})
})
map.on('click', evt => {
console.log("获取地图坐标:", evt.coordinate)
})
const features = [
// 第一组
{
geometry: new ol.geom.Point([94.11434654171987, 28.972402471968656]),
textAlign: "left" // 标注文本框位于point右边,point右边是标注文本框
}, {
geometry: new ol.geom.Point([103.45228063165628, 28.972402471968656]),
textAlign: "center" // 标注文本框位于point中心
},
{
geometry: new ol.geom.Point([112.03997466732001, 28.972402471968656]),
textAlign: "right" // 标注文本框位于point左边,point左边是标注文本框
},
// 第二组
{
geometry: new ol.geom.Point([94.11434654171987, 26.972402471968656]),
textAlign: "left", // 文本对齐
justify: "center" // 文本框内的文本对齐
}, {
geometry: new ol.geom.Point([103.45228063165628, 26.972402471968656]),
textAlign: "center",
justify: "center"
},
{
geometry: new ol.geom.Point([112.03997466732001, 26.972402471968656]),
textAlign: "right",
justify: "center"
},
// 第三组
{
geometry: new ol.geom.Point([94.11434654171987, 24.972402471968656]),
textAlign: "left",
justify: "left"
}, {
geometry: new ol.geom.Point([103.45228063165628, 24.972402471968656]),
textAlign: "center",
justify: "left"
},
{
geometry: new ol.geom.Point([112.03997466732001, 24.972402471968656]),
textAlign: "right",
justify: "left"
},
]
function createStyle({ textAlign, justify }) {
return new ol.style.Style({
image: new ol.style.Circle({
radius: 10, // 单位像素
fill: new ol.style.Fill({
color: "rgba(255, 0, 0, 0.1)"
}),
stroke: new ol.style.Stroke({
color: "red",
width: 1.5 // 单位像素
})
}),
text: new ol.style.Text({
font: '16px sans-serif',
textAlign,
justify,
text: `Justify text inside boxntextAlign: ${textAlign}` +
(justify ? `\njustify: ${justify}` : ''),
fill: new ol.style.Fill({
color: [148, 0, 211, 1],
}),
backgroundFill: new ol.style.Fill({
color: [128, 0, 128, 0.25]
}),
// 设置边框边线色
backgroundStroke: new ol.style.Stroke({
color: [255, 182, 193, 0.5],
width: 2.5,
lineJoin: 'miter',
lineCap: "round"
}),
padding: [10, 10, 10, 10], // 文本框内间距
// offsetX: 100 // X方向偏移100px
})
})
}
const vectorPoints = new ol.layer.Vector({
source: new ol.source.Vector({
features: new ol.Collection(
features.map(featureOptions => {
const feature = new ol.Feature({
geometry: featureOptions.geometry
})
// 设置要素样式
feature.setStyle(createStyle(featureOptions))
return feature
})
),
format: new ol.format.GeoJSON()
})
})
map.addLayer(vectorPoints)
</script>
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