javascript 从 MySQL 数据库在 Google Maps API v3 上绘制多个多边形
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Drawing Multiple Polygons on Google Maps API v3 from MySQL database
提问by nBishop
So, I am attempting to draw multiple polygons onto a google map via polygon spatial data from my MySQL table. I have a php script that outputs the following XML based off my table data.
所以，我试图通过我的 MySQL 表中的多边形空间数据将多个多边形绘制到谷歌地图上。我有一个 php 脚本，它根据我的表数据输出以下 XML。
<subdivision name="Auburn Hills">
<coord lat="39.00748" lng="-92.323222"/>
<coord lat="39.000843" lng="-92.323523"/>
<coord lat="39.000509" lng="-92.311592"/>
<coord lat="39.007513" lng="-92.311378"/>
<coord lat="39.00748" lng="-92.323222"/>
</subdivision>
<subdivision name="Vanderveen">
<coord lat="38.994206" lng="-92.350645"/>
<coord lat="38.985033" lng="-92.351074"/>
<coord lat="38.984699" lng="-92.343092"/>
<coord lat="38.981163" lng="-92.342234"/>
<coord lat="38.984663" lng="-92.3335"/>
<coord lat="38.993472" lng="-92.333179"/>
<coord lat="38.994206" lng="-92.350645"/>
</subdivision>
My issue is that the javascript I am using to try and draw each shape onto the map is returning odd coordinates. using an alert, I can see that the array that is meant to store the coordinates for the "new google.maps.Polygon" is returning the first latitude and longitude pair for each shape and drawing a line segment as opposed to the full polygon. The problematic javascript is below.
我的问题是我用来尝试在地图上绘制每个形状的 javascript 返回奇数坐标。使用警报，我可以看到用于存储“新 google.maps.Polygon”坐标的数组正在返回每个形状的第一个纬度和经度对，并绘制一条线段而不是完整的多边形。有问题的javascript如下。
function initialize() {
var mapOptions = {
...
};
var map = new google.maps.Map(document.getElementById('map-canvas'),
mapOptions);
var arr = new Array();
var polygons = [];
downloadUrl("subdivision-coordinates.php", function(data) {
var xml = data.responseXML;
var subdivision = xml.documentElement.getElementsByTagName("subdivision");
for (var i = 0; i < subdivision.length; i++) {
var coordinates = xml.documentElement.getElementsByTagName("subdivision")[i].getElementsByTagName("coord");
arr.push( new google.maps.LatLng(
parseFloat(coordinates[i].getAttribute("lat")),
parseFloat(coordinates[i].getAttribute("lng"))
));
polygons.push(new google.maps.Polygon({
paths: arr,
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35
}));
polygons[polygons.length-1].setMap(map);
}
});
}
function downloadUrl(url, callback) {
..blah..blah stuff from google
}
function doNothing() {}
google.maps.event.addDomListener(window, 'load', initialize);
The issue seems to be clearly related to how I am pushing the data into the array "arr". I've tried a few different methods of handling it and nothing seems to be working (I am admittedly a novice when it comes to javascript). Any advice would be greatly appreciated!
这个问题似乎与我如何将数据推送到数组“arr”中有关。我尝试了几种不同的处理方法，但似乎没有任何效果（无可否认，我是 JavaScript 的新手）。任何建议将不胜感激！
回答by geocodezip
The google.maps.Polygonpaths property takes an array of arrays of google.maps.LatLngs. You need to process through each subdivision as its own array and either push it as a separate path into the one polygon or (as below) create a new polygon for each.
所述google.maps.Polygon路径属性采用google.maps.LatLngs的数组的数组。您需要将每个细分作为其自己的数组进行处理，并将其作为单独的路径推入一个多边形中，或者（如下所示）为每个细分创建一个新的多边形。
var subdivision = xml.getElementsByTagName("subdivision");
for (var i = 0; i < subdivision.length; i++) {
arr = [];
var coordinates = xml.documentElement.getElementsByTagName("subdivision")[i].getElementsByTagName("coord");
for (var j=0; j < coordinates.length; j++) {
arr.push( new google.maps.LatLng(
parseFloat(coordinates[j].getAttribute("lat")),
parseFloat(coordinates[j].getAttribute("lng"))
));
bounds.extend(arr[arr.length-1])
}
polygons.push(new google.maps.Polygon({
paths: arr,
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35
}));
polygons[polygons.length-1].setMap(map);
}
code snippet:
代码片段：
function initialize() {
var mapOptions = {
zoom: 5,
center: new google.maps.LatLng(40, -117),
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
var arr = new Array();
var polygons = [];
var bounds = new google.maps.LatLngBounds();
// downloadUrl("subdivision-coordinates.php", function(data) {
var xml = xmlParse(xmlString);
var subdivision = xml.getElementsByTagName("subdivision");
// alert(subdivision.length);
for (var i = 0; i < subdivision.length; i++) {
arr = [];
var coordinates = xml.documentElement.getElementsByTagName("subdivision")[i].getElementsByTagName("coord");
for (var j = 0; j < coordinates.length; j++) {
arr.push(new google.maps.LatLng(
parseFloat(coordinates[j].getAttribute("lat")),
parseFloat(coordinates[j].getAttribute("lng"))
));
bounds.extend(arr[arr.length - 1])
}
polygons.push(new google.maps.Polygon({
paths: arr,
strokeColor: '#FF0000',
strokeOpacity: 0.8,
strokeWeight: 2,
fillColor: '#FF0000',
fillOpacity: 0.35
}));
polygons[polygons.length - 1].setMap(map);
}
// });
map.fitBounds(bounds);
}
var xmlString = '<subdivisions><subdivision name="Auburn Hills"><coord lat="39.00748" lng="-92.323222"/><coord lat="39.000843" lng="-92.323523"/><coord lat="39.000509" lng="-92.311592"/><coord lat="39.007513" lng="-92.311378"/><coord lat="39.00748" lng="-92.323222"/></subdivision><subdivision name="Vanderveen"><coord lat="38.994206" lng="-92.350645"/><coord lat="38.985033" lng="-92.351074"/><coord lat="38.984699" lng="-92.343092"/><coord lat="38.981163" lng="-92.342234"/><coord lat="38.984663" lng="-92.3335"/><coord lat="38.993472" lng="-92.333179"/><coord lat="38.994206" lng="-92.350645"/></subdivision><subdivisions>';
/**
* Parses the given XML string and returns the parsed document in a
* DOM data structure. This function will return an empty DOM node if
* XML parsing is not supported in this browser.
* @param {string} str XML string.
* @return {Element|Document} DOM.
*/
function xmlParse(str) {
if (typeof ActiveXObject != 'undefined' && typeof GetObject != 'undefined') {
var doc = new ActiveXObject('Microsoft.XMLDOM');
doc.loadXML(str);
return doc;
}
if (typeof DOMParser != 'undefined') {
return (new DOMParser()).parseFromString(str, 'text/xml');
}
return createElement('div', null);
}
google.maps.event.addDomListener(window, 'load', initialize);#map-canvas,
body,
html {
height: 100%;
width: 100%;
}<script src="http://maps.google.com/maps/api/js"></script>
<div id="map-canvas"></div>