百度地图之实现海量闪烁点（基于经纬度）
html:
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<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>海量闪烁点</title>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=oWbN3CdN6Bpnucw9Xi8eWHD380KUSLP6"></script>
<script src="http://lbsyun.baidu.com/jsdemo/data/points-sample-data.js"></script>
</head>
<body>
<div id="map"></div>
<div id="pointBox"></div>
</body>
</html>
css:
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html,
body {
margin: 0;
width: 100%;
height: 100%;
background: #ffffff;
}
#map {
width: 100%;
height: 100%;
}
.anchorBL {
display: none
}
#pointBox {
position: fixed;
padding: 2px 15px;
z-index: 9999;
text-align: center;
background: rgba(0, 0, 0, .6);
color: #efefef;
line-height: 32px;
font-size: 18px;
border-radius: 5px;
top: 100px;
left: 100px;
white-space: nowrap;
display: none;
}
#pointBox::after {
position: absolute;
border-left: 10px solid transparent;
border-right: 10px solid transparent;
border-top: 10px solid rgba(0, 0, 0, .6);
content: "";
position: absolute;
width: 0;
top: 100%;
left: 50%;
margin-left: -10px;
z-index: 9999;
}
js：(重点来了)
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var map = new BMap.Map("map", {}); // 创建Map实例
var pointBox = document.getElementById('pointBox');
map.centerAndZoom(new BMap.Point(105.000, 38.000), 5); // 初始化地图,设置中心点坐标和地图级别
map.enableScrollWheelZoom(); //启用滚轮放大缩小
map.enableDragging();
var mapStyle = {
// features: ["road", "building", "water", "land"], //隐藏地图上的poi
style: "dark" //设置地图风格为高端黑
}
map.setMapStyle(mapStyle);
if (document.createElement('canvas').getContext) {
var BW = 0, //canvas width
BH = 0, //canvas height
stars = [], //存储所有星星对象的数组
timer = 5000, //定时器
rs = [], //最新的结果
py = null, //偏移
canvas = null, //画布元素
ctx = null; // 实例化画布
function Star(options) {
this.init(options);
}
Star.prototype.init = function(options) {
this.x = ~~(options.x);
this.y = ~~(options.y);
this.px = options.lng;
this.py = options.lat;
this.size = ~~(options.size);
this.maxSize = this.size > 6 ? 6 : this.size;
// 重算点大小
this.initSize();
}
// 重算点大小，循环时,让其闪烁
Star.prototype.initSize = function(size) {
if (~~(0.5 + Math.random() * 7) == 1) {
this.size = 0;
} else {
this.size = this.maxSize;
}
}
Star.prototype.render = function(i) {
if (this.x < 0 || this.y < 0 || this.x > BW || this.y > BH) {
return;
}
// 画布绘图 - 开始
ctx.beginPath();
var gradient = ctx.createRadialGradient(this.x, this.y, 0, this.x, this.y, this.size);
gradient.addColorStop(0, "rgba(7,120,249,1)");
gradient.addColorStop(1, "rgba(7,120,249,0.3)");
ctx.fillStyle = gradient;
ctx.arc(this.x, this.y, this.size, Math.PI * 2, false);
ctx.fill();
// 画布绘图 - 结束
// 重置点的大小
this.initSize();
}
function render() {
renderAction();
setTimeout(render, 180);
}
// 画布,设置点的数据
function renderAction() {
// 清除画布数据
ctx.clearRect(0, 0, BW, BH);
// 画布显示的样式
ctx.globalCompositeOperation = "lighter";
// 在画布设置已知的点
for (var i = 0, len = stars.length; i < len; ++i) {
if (stars[i]) {
stars[i].render(i);
}
}
}
//要判断事件对象发生的位置，事件对象e的layerX和layerY属性表示Canvas内部坐标系中的坐标
function getEventPosition(ev) {
var x, y;
if (ev.layerX || ev.layerX == 0) {
x = ev.layerX;
y = ev.layerY;
} else if (ev.offsetX || ev.offsetX == 0) { // Opera
x = ev.offsetX;
y = ev.offsetY;
}
return {
x: x,
y: y
};
}
// 复杂的自定义覆盖物
function ComplexCustomOverlay(point) {
this._point = point;
}
ComplexCustomOverlay.prototype = new BMap.Overlay();
ComplexCustomOverlay.prototype.initialize = function(map) {
this._map = map;
// 实例化画布
canvas = this.canvas = document.createElement("canvas");
canvas.style.cssText = "position:absolute;left:0;top:0;";
ctx = canvas.getContext("2d");
var size = map.getSize();
// 设置画布大小
canvas.width = BW = size.width;
canvas.height = BH = size.height;
// 将画布嵌入地图
map.getPanes().labelPane.appendChild(canvas);
var d_find = false;
// 监听画布事件 - 鼠标移动
canvas.addEventListener('mousemove', function(e) {
var p = getEventPosition(e);
d_find = stars.find(function(val) {
var size = val.maxSize;
var d_x = (p.x >= (val.x - size / 2)) && (p.x <= (val.x + size / 2));
var d_y = (p.y >= (val.y - size / 2)) && (p.y <= (val.y + size / 2));
return d_x && d_y;
});
if (!d_find) {
pointBox.style.display = 'none';
return canvas.style.cursor = 'auto';
}
pointBox.style.display = 'block';
var pbox_w = pointBox.offsetWidth / 2;
var pbox_h = pointBox.offsetHeight;
pointBox.style.left = (d_find.x - pbox_w) + 'px';
pointBox.style.top = (d_find.y - pbox_h - 20) + 'px';
pointBox.innerText = 'x:' + d_find.px + ', y:' + d_find.py;
canvas.style.cursor = 'pointer';
});
// 监听画布事件 - 鼠标单击
// canvas.addEventListener('click', function(e) {
// if (!d_find) {
// return false;
// }
// console.log(d_find);
// });
return this.canvas;
}
ComplexCustomOverlay.prototype.draw = function() {
var map = this._map;
var bounds = map.getBounds();
var sw = bounds.getSouthWest();
var ne = bounds.getNorthEast();
var pixel = map.pointToOverlayPixel(new BMap.Point(sw.lng, ne.lat));
py = pixel;
// 放大缩小时,重绘闪烁点
if (rs.length > 0) {
showStars(rs);
}
}
// 实例化自定义覆盖物
var myCompOverlay = new ComplexCustomOverlay();
// 将覆盖物放置地图
map.addOverlay(myCompOverlay);
/**
* 请求定位数据,并在地图上绘制出
* @param 请求的时间
* @param 成功后执行的回调函数
*
*/
var requestMgr = {
request: function(successCbk) {
rs = data.data;
showStars(rs);
if (successCbk) {
successCbk();
}
// var xhr = new XMLHttpRequest();
// xhr.onreadystatechange = function() {
// if (xhr.readyState == 4 && xhr.status == 200) {
// rs = JSON.parse(xhr.responseText);
// showStars(rs);
// if (successCbk) {
// successCbk();
// }
// }
// }
// xhr.open("GET", url, true);
// xhr.send(null);
}
}
//显示闪烁点
function showStars(rs) {
// stars.length = 0;
stars = [];
var temp = {};
for (var i = 0, len = rs.length; i < len; i++) {
var item = rs[i];
var px = map.pointToOverlayPixel({
lng: item[0],
lat: item[1]
});
var s = new Star({
x: px.x - py.x,
y: px.y - py.y,
lng: item[0],
lat: item[1],
size: 6
});
stars.push(s);
//}
}
canvas.style.left = py.x + "px";
canvas.style.top = py.y + "px";
renderAction();
}
function startCbk() {
requestMgr.request(function() {
// 5秒重新获取数据
// setTimeout(function() {
// console.log(1);
// startCbk();
// }, timer);
});
};
// 初始化,置入定时器,使其循环,实现闪烁效果
render();
// 请求数据
startCbk();
} else {
alert('请在chrome、safari、IE8+以上浏览器运行该程序');
}
觉得可以的话就赏一下吧