function parsePath(info){
let { path, zoom, offset } = info;
var steps = path.steps;
var lineArr = [];
steps.forEach(function(item, index){
var tmparr = item.polyline.split(";");
var tmp = tmparr.map(function(val){
return val.split(",");
});
lineArr = lineArr.concat(tmp);
});
var pxarr = lineArr.map(function(item){
return project({
lng : item[0],
lat : item[1]
}, 20);
});
var pas = [];
var ratio = Math.pow(2, 20 - zoom);
pxarr.forEach(function(item, index){
if(index % 4 === 0) {
pas.push([((item.x - offset.x) /ratio).toFixed(6),((item.y - offset.y)/ratio).toFixed(6)]);
}
});
return pas;
}
function pathLength(pas) {
var len = 0;
var i = 1;
if(pas && pas.length) {
for( i; i<pas.length; i++){
var a = pas[i][0] - 0 - pas[i-1][0];
var b = pas[i][1] - 0 - pas[i-1][1];
len += Math.sqrt( a * a + b * b );
}
}
return len;
}
function fetchPath(opt){
var from = opt.origin.x + "," + opt.origin.y;
var to = opt.dest.x + "," + opt.dest.y
var url = "http://restapi.amap.com/v3/direction/driving?key=ac92f92386cfe54122ae34476aafb03e&extensions=base&strategy=" + parseInt(1 + 20 * Math.random()) + "&origin=" + from + "&destination=" + to;
fetch(url)
.then( (res) => {
return res.json();
})
.then( (json) => {
return {
path : json.route.paths[0],
zoom : opt.zoom,
offset : opt.offset
};
})
.then( parsePath )
.then( (pas) => {
var len = pathLength(pas);
postMessage({
path : pas,
len : len,
opt : opt
});
});
}
