升级到最新版openlayers5.2,重新写量测方法，官网examples里面有实现好的代码，但是项目是基于vue的模块化开发，官网的例子直接引入不是很合适，并且官网的例子是可以一直连续的测量，而项目中需要测量一次的方法，所以需要对官网例子做一些改进，在此mark一下，有同样需要的朋友们直接拿走不谢o(￣︶￣)o
效果图如下所示：
image.png
实现Measure.js
import Draw from 'ol/interaction/Draw'
import VectorSource from 'ol/source/Vector';
import VectorLayer from 'ol/layer/Vector';
import TileLayer from 'ol/layer/Tile';
import OSM from 'ol/source/OSM';
import {
unByKey
} from 'ol/Observable.js';
import Overlay from 'ol/Overlay';
import {
getArea,
getLength
} from 'ol/sphere.js';
import View from 'ol/View';
import {
LineString,
Polygon
} from 'ol/geom.js';
import {
Circle as CircleStyle,
Fill,
Stroke,
Style
} from 'ol/style.js';
export default{
measure(map, measureType) {
/**
* Currently drawn feature.
* @type {module:ol/Feature~Feature}
*/
var sketch;
/**
* The help tooltip element.
* @type {Element}
*/
var helpTooltipElement;
/**
* Overlay to show the help messages.
* @type {module:ol/Overlay}
*/
var helpTooltip;
/**
* The measure tooltip element.
* @type {Element}
*/
var measureTooltipElement;
/**
* Overlay to show the measurement.
* @type {module:ol/Overlay}
*/
var measureTooltip;
/**
* Message to show when the user is drawing a polygon.
* @type {string}
*/
var continuePolygonMsg = '继续点击绘制多边形';
/**
* Message to show when the user is drawing a line.
* @type {string}
*/
var continueLineMsg = '继续点击绘制线';
createMeasureTooltip();
createHelpTooltip();
/**
* Handle pointer move.
* @param {module:ol/MapBrowserEvent~MapBrowserEvent} evt The event.
*/
var pointerMoveHandler = function (evt) {
if (evt.dragging) {
return;
}
/** @type {string} */
var helpMsg = '请点击开始绘制';
if (sketch) {
var geom = (sketch.getGeometry());
if (geom instanceof Polygon) {
helpMsg = continuePolygonMsg;
} else if (geom instanceof LineString) {
helpMsg = continueLineMsg;
}
}
helpTooltipElement.innerHTML = helpMsg;
helpTooltip.setPosition(evt.coordinate);
helpTooltipElement.classList.remove('hidden');
};
map.on('pointermove', pointerMoveHandler);
map.getViewport().addEventListener('mouseout', function () {
helpTooltipElement.classList.add('hidden');
});
var draw;
var formatLength = function (line) {
var length = getLength(line);
var output;
if (length > 100) {
output = (Math.round(length / 1000 * 100) / 100) +
' ' + 'km';
} else {
output = (Math.round(length * 100) / 100) +
' ' + 'm';
}
return output;
};
var formatArea = function (polygon) {
var area = getArea(polygon);
var output;
if (area > 10000) {
output = (Math.round(area / 1000000 * 100) / 100) +
' ' + 'km2';
} else {
output = (Math.round(area * 100) / 100) +
' ' + 'm2';
}
return output;
};
var source;
// var layer ;
// 获取存放feature的vectorlayer层。map初始化的时候可以添加好了
for(let layerTmp of map.getLayers().getArray()){
if(layerTmp.get("name")=="feature"){
// layer = layerTmp;
// layerTmp.setSource(null)
source= layerTmp.getSource();
}
}
function addInteraction() {
var type = (measureType == 'area' ? 'Polygon' : 'LineString');
draw = new Draw({
source: source,
type: type,
style: new Style({
fill: new Fill({
color: 'rgba(255, 255, 255, 0.2)'
}),
stroke: new Stroke({
color: 'rgba(0, 0, 0, 0.5)',
lineDash: [10, 10],
width: 2
}),
image: new CircleStyle({
radius: 5,
stroke: new Stroke({
color: 'rgba(0, 0, 0, 0.7)'
}),
fill: new Fill({
color: 'rgba(255, 255, 255, 0.2)'
})
})
})
});
map.addInteraction(draw);
var listener;
draw.on('drawstart',
function (evt) {
// set sketch
sketch = evt.feature;
/** @type {module:ol/coordinate~Coordinate|undefined} */
var tooltipCoord = evt.coordinate;
listener = sketch.getGeometry().on('change', function (evt) {
var geom = evt.target;
var output;
if (geom instanceof Polygon) {
output = formatArea(geom);
tooltipCoord = geom.getInteriorPoint().getCoordinates();
} else if (geom instanceof LineString) {
output = formatLength(geom);
tooltipCoord = geom.getLastCoordinate();
}
measureTooltipElement.innerHTML = output;
measureTooltip.setPosition(tooltipCoord);
});
}, this);
draw.on('drawend',
function () {
measureTooltipElement.className = 'tooltip tooltip-static';
measureTooltip.setOffset([0, -7]);
// unset sketch
sketch = null;
// unset tooltip so that a new one can be created
measureTooltipElement = null;
createMeasureTooltip();
unByKey(listener);
map.un('pointermove', pointerMoveHandler);
map.removeInteraction(draw);
helpTooltipElement.classList.add('hidden');
}, this);
}
function createHelpTooltip() {
if (helpTooltipElement) {
helpTooltipElement.parentNode.removeChild(helpTooltipElement);
}
helpTooltipElement = document.createElement('div');
helpTooltipElement.className = 'tooltip hidden';
helpTooltip = new Overlay({
element: helpTooltipElement,
offset: [15, 0],
positioning: 'center-left'
});
map.addOverlay(helpTooltip);
}
function createMeasureTooltip() {
if (measureTooltipElement) {
measureTooltipElement.parentNode.removeChild(measureTooltipElement);
}
measureTooltipElement = document.createElement('div');
measureTooltipElement.className = 'tooltip tooltip-measure';
measureTooltip = new Overlay({
element: measureTooltipElement,
offset: [0, -15],
positioning: 'bottom-center'
});
map.addOverlay(measureTooltip);
}
// 量测调用
addInteraction();
}
}
以上代码为官网例子的重构，可以一直多次进行测量。
若只想要进行一次量测则在drawend事件中添加
map.un('pointermove', pointerMoveHandler);
map.removeInteraction(draw);
helpTooltipElement.classList.add('hidden');
改为
draw.on('drawend',
function () {
measureTooltipElement.className = 'tooltip tooltip-static';
measureTooltip.setOffset([0, -7]);
// unset sketch
sketch = null;
// unset tooltip so that a new one can be created
measureTooltipElement = null;
createMeasureTooltip();
unByKey(listener);
map.un('pointermove', pointerMoveHandler);
map.removeInteraction(draw);
helpTooltipElement.classList.add('hidden');
}, this);
}
即可。
调用
然后直接
import Measure from "./Measure";
...
Measure.measure(this.map, type);
...
就可以调用啦，type值为LineString时为距离测量，area时为面积测量