原文地址：https://xiaozhuanlan.com/topic/6591843207 版权归原作者所有
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
<title>Custom DynamicLayer - 4.12</title>
<link rel="stylesheet" href="https://js.arcgis.com/4.12/esri/themes/light/main.css" />
<style>
html,
body,
#viewDiv {
padding: 0;
margin: 0;
height: 100%;
100%;
}
</style>
<script src="https://js.arcgis.com/4.12/"></script>
</head>
<body>
<div id="viewDiv"></div>
<script>
require([
"esri/Map",
"esri/Basemap",
"esri/views/MapView",
"esri/layers/BaseDynamicLayer",
"esri/layers/TileLayer",
"esri/core/urlUtils"
], function (Map, Basemap, MapView, BaseDynamicLayer, TileLayer) {
//自定义叠加图片图层
var CustomImageOverlayLayer = BaseDynamicLayer.createSubclass({
properties: {
picUrl: null,
extent: null,
image: null,
canvas: null,
},
// Override the getImageUrl() method to generate URL
// to an image for a given extent, width, and height.
getImageUrl: function (extent, width, height) {
//新Image对象，可以理解为DOM
if (!this.image) {
this.image = new Image();
}
this.image.src = this.picUrl;
// 创建canvas DOM元素，并设置其宽高和图片一样
if (!this.canvas) {
this.canvas = canvas = document.createElement("canvas");
}
this.canvas.width = 2000;
this.canvas.height = 2000;
//左上角坐标转换屏幕坐标,为了获取canvas绘制图片的起点
var mapPoint = {
x: this.extent.xmin,
y: this.extent.ymax,
spatialReference: {
wkid: 4326
}
};
var screenPoint = view.toScreen(mapPoint);
//根据extent范围计算canvas绘制图片的宽度以及高度
//左下角
var leftbottom = {
x: this.extent.xmin,
y: this.extent.ymin,
spatialReference: {
wkid: 4326
}
};
var screen_leftbottom = view.toScreen(leftbottom);
//右上角
var righttop = {
x: this.extent.xmax,
y: this.extent.ymax,
spatialReference: {
wkid: 4326
}
};
var screen_righttop = view.toScreen(righttop);
this.canvas.getContext("2d").drawImage(this.image, screenPoint.x, screenPoint.y, Math.abs(screen_righttop.x - screen_leftbottom.x), Math.abs(screen_righttop.y - screen_leftbottom.y));
return this.canvas.toDataURL("image/png");
}
});
var layer = new TileLayer({
url: "http://server.arcgisonline.com/arcgis/rest/services/ESRI_Imagery_World_2D/MapServer"
});
var imgBasemap = new Basemap({
baseLayers: [layer]
});
map = new Map({
basemap: imgBasemap,
});
view = new MapView({
container: "viewDiv",
map: map,
center: [113.36795152905626, 23.1278045049863],
zoom: 12
});
view.when(function () {
var ImageOverlayLayer = new CustomImageOverlayLayer({
picUrl: "0.png",
extent: { xmin: 113.3596, ymin: 23.1239, xmax: 113.3748, ymax: 23.1354 }
});
map.add(ImageOverlayLayer);
//地图移动刷新,防止地图初始化时候，图片叠加图层加载刷新不过来
setTimeout(function () {
var center = view.center.clone();
center.x -= 0.001;//底图是经纬度
view.center = center;
view.goTo(view.center,
{
speedFactor: 0.1,
easing: "linear" //linear, in-cubic, out-cubic, in-out-cubic, in-expo, out-expo, in-out-expo
});
}, 500);
}, function (error) {
console.log("The view's resources failed to load: ", error);
});
});
</script>
</body>
</html>