原文链接及内容

原文链接：https://openlayers.org/en/latest/examples/layer-z-index.html

运行界面

有两个受管控的图层层(正方形和三角形)和一个非管控图层(星形)。
zIndex决定了渲染顺序;对于{square: 1, triangle: 0, star: unmanaged}索引，渲染顺序是三角形、正方形、星形，后渲染的图层位于先渲染图层上方。

注意：图层将首先按zIndex排序，然后按位置(添加顺序)排序。当某个图层使用其setMap()方法时，则该图层的索引值为Infinity(无穷大)，具体参考API文档：https://openlayers.org/en/latest/apidoc/module-ol_layer_Vector-VectorLayer.html。

main.js代码如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
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);

界面布局文件index.html代码如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
<!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="https://cdn.jsdelivr.net/npm/elm-pep@1.0.6/dist/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>