根据他人的程序修改的，原文是如何利用百度地图JSAPI画带箭头的线？
在此，使用两条平行线表示路线。
1.坐标计算：
2.代码如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>值班员主界面</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<style type="text/css">
body,html {
100%;
height: 100%;
margin: 0;
font-family: "微软雅黑";
}
#allmap {
height: 100%;
100%;
}
</style>
<script type="text/javascript"
src="http://api.map.baidu.com/api?v=2.0&ak=Tv58ayKXGwWUzEcg2WoBw1qQrIkVww9B"></script>
<!-- ak表示的是百度地图的key值 -->
</head>
<body>
<div id="allmap"></div>
</body>
</html>
<script type="text/javascript">
var routeLine = [
"114.402781,30.498467", "114.402759,30.498304",
"114.402723,30.498086", "114.402683,30.497872",
"114.402647,30.497627", "114.402543,30.49751",
"114.402341,30.497569", "114.402265,30.497592",
"114.401367,30.497751", "114.400917,30.497806",
"114.400792,30.497829", "114.400644,30.497849",
"114.400446,30.497872", "114.400194,30.497915",
"114.400096,30.497934", "114.400028,30.497771",
"114.40001,30.497569", "114.400001,30.497456",
"114.400006,30.49725", "114.399988,30.497106",
"114.399925,30.496946", "114.399898,30.49688",
"114.399884,30.496849", "114.399875,30.496818", ];
var point_local = new BMap.Point(114.399916, 30.493214); //屏幕中心点坐标
// 初始化百度地图API功能
// 创建Map实例,并设置地图允许的最小/大级别(可选)
var map = new BMap.Map("allmap");
var localhost_Icon = new BMap.Icon("images/Point_local.png",
new BMap.Size(32, 49), {anchor: new BMap.Size(16, 48)
});
//设置引用图标的名字以及大小，并设置图片相对于所加的点的位置
map.centerAndZoom(point_local, 16); // 初始化地图,设置中心点坐标(经度，纬度)和地图缩放级别
map.enableScrollWheelZoom(true); // 开启鼠标滚轮缩放
map.addOverlay(new BMap.Marker(point_local, {icon: localhost_Icon}));
drawRouteLine(routeLine); // 描绘轨迹线路
////////////////////////////////////////////////////
// 描绘轨迹线路
function drawRouteLine(routeLine) {
if(routeLine.length<2) return;
var routeLineArray = [];
for ( var i = 0; i < routeLine.length; i++) {
var x = routeLine[i].split(",")[0];
var y = routeLine[i].split(",")[1];
routeLineArray[i] = new BMap.Point(x, y);
}
var polyline = new BMap.Polyline(routeLineArray, {strokeColor:"red", strokeWeight:2, strokeOpacity:0.5}); //创建折线
// map.addOverlay(polyline);
var linePoint = polyline.getPath(); //线的坐标串
var length = 1; //管子半径
var LinePointUp=new Array(), LinePointDown=new Array();
for (var i=0; i<linePoint.length; i++) {
var pixelStart;
var pixelEnd;
var PixelArr;
if(i==0){
pixelStart = map.pointToPixel(linePoint[i+1]); //坐标转换为可视区域坐标
pixelEnd = map.pointToPixel(linePoint[i]);
}else {
pixelStart = map.pointToPixel(linePoint[i-1]);
pixelEnd = map.pointToPixel(linePoint[i]);
}
//计算偏差点坐标
PixelArr = getPixel(pixelStart, pixelEnd, length);
var pixelPointa = map.pixelToPoint(new BMap.Pixel(PixelArr[0],PixelArr[1]));
var pixelPointb = map.pixelToPoint(new BMap.Pixel(PixelArr[2],PixelArr[3]));
if(i==0){ //第一个点需要交换处理
var pixelPointTem = pixelPointa;
pixelPointa=pixelPointb;
pixelPointb=pixelPointTem;
}
LinePointUp[i] = pixelPointa;
LinePointDown[i] = pixelPointb;
}
var PixelLine1a = new BMap.Polyline(
LinePointUp, {strokeColor:"green", strokeWeight:2, strokeOpacity:0.5});
map.addOverlay(PixelLine1a);
var PixelLine2b = new BMap.Polyline(
LinePointDown, {strokeColor:"green", strokeWeight:2, strokeOpacity:0.5});
map.addOverlay(PixelLine2b);
}
function getPixel(pixelStart, pixelEnd, length){
var r = length; //管子半径
var delta = 0; //主线斜率，垂直时无斜率
var param = 0; //代码简洁考虑
var pixelXa, pixelYa, pixelXb, pixelYb;
//计算偏差点坐标
if (pixelEnd.x - pixelStart.x == 0) { //斜率不存在是时
if (pixelEnd.y > pixelStart.y) {
pixelXa = pixelEnd.x-r;
pixelXb = pixelEnd.x+r;
}else{
pixelXa = pixelEnd.x+r;
pixelXb = pixelEnd.x-r;
}
pixelYa = pixelEnd.y; pixelYb = pixelEnd.y;
} else { //斜率存在时
delta = (pixelEnd.y - pixelStart.y)/(pixelEnd.x-pixelStart.x); //斜率
param = Math.sqrt(delta * delta + 1);
//已知直角三角形两个点坐标及其中一个角，求另外一个点坐标算法
if (pixelEnd.x > pixelStart.x) { //第一、四象限
pixelXa = pixelEnd.x-r*delta/param; pixelYa = pixelEnd.y+r/param;
pixelXb = pixelEnd.x+r*delta/param; pixelYb = pixelEnd.y-r/param;
}else{ //第二、三象限
pixelXa = pixelEnd.x+r*delta/param; pixelYa = pixelEnd.y-r/param;
pixelXb = pixelEnd.x-r*delta/param; pixelYb = pixelEnd.y+r/param;
}
}
return [pixelXa,pixelYa, pixelXb, pixelYb];
}
////////////////////////////////////////////////////////
</script>现在的问题：在拐角的转折做的不好，特别是在外角部分。