图层层级（Z-Index）

正方形图层层级
三角形图层层级

本示例演示使用 Z-index 设置图层层级顺序.

本示例中有两个可管理图层（正方形和三角形；可管理图层指的是可操作）和一个非管理图层（五角星）。
Z-index 决定了渲染的顺序；地图的渲染参数为：{正方形: 1, 三角形: 0, 五角星: unmanaged}，渲染顺序为三角形，正方形，以及顶层的五角星。

main.js

import Feature from 'ol/Feature.js';
import Map from 'ol/Map.js';
import Point from 'ol/geom/Point.js';
import VectorLayer from 'ol/layer/Vector.js';
import VectorSource from 'ol/source/Vector.js';
import View from 'ol/View.js';
import {Fill, RegularShape, Stroke, Style} from 'ol/style.js';

const stroke = new Stroke({color: 'black', width: 1});

const styles = {
  'square': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'blue'}),
      stroke: stroke,
      points: 4,
      radius: 80,
      angle: Math.PI / 4,
    }),
  }),
  'triangle': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'red'}),
      stroke: stroke,
      points: 3,
      radius: 80,
      rotation: Math.PI / 4,
      angle: 0,
    }),
  }),
  'star': new Style({
    image: new RegularShape({
      fill: new Fill({color: 'green'}),
      stroke: stroke,
      points: 5,
      radius: 80,
      radius2: 4,
      angle: 0,
    }),
  }),
};

function createLayer(coordinates, style, zIndex) {
  const feature = new Feature(new Point(coordinates));
  feature.setStyle(style);

  const source = new VectorSource({
    features: [feature],
  });

  const vectorLayer = new VectorLayer({
    source: source,
  });
  vectorLayer.setZIndex(zIndex);

  return vectorLayer;
}

const layer0 = createLayer([40, 40], styles['star']);
const layer1 = createLayer([0, 0], styles['square'], 1);
const layer2 = createLayer([0, 40], styles['triangle'], 0);

const layers = [];
layers.push(layer1);
layers.push(layer2);

const map = new Map({
  layers: layers,
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 18,
  }),
});

layer0.setMap(map);

function bindInputs(id, layer) {
  const idxInput = document.getElementById('idx' + id);
  idxInput.onchange = function () {
    layer.setZIndex(parseInt(this.value, 10) || 0);
  };
  idxInput.value = String(layer.getZIndex());
}
bindInputs(1, layer1);
bindInputs(2, layer2);

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Layer Z-Index</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div>
      <label for="idx1">
        <input type="number" id="idx1"></input>
        Square layer Z-index
      </label></br>

      <label for="idx2">
        <input type="number" id="idx2"></input>
        Triangle layer Z-index
      </label>
    </div>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="./resources/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "layer-z-index",
  "dependencies": {
    "ol": "7.3.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}