画一个圆圈谷歌静态地图 [英] Drawing a circle Google Static Maps

问题描述

我有一个在 v3 api 上绘制的 Google Maps Circle.当用户在那里绘制圆(或多边形，如果他们选择)，他们可以将数据保存到服务器.如果用户选择了径向搜索，则中心坐标和以英尺为单位的半径将存储到数据库中.这意味着当用户重新加载搜索时，它可以再次穿过圆圈(如下所示).

I have a Google Maps Circle drawn on v3 api. When the user has plotted there circle (or polygon if they choose), they can save the data to the server. If the user has picked a radial search, the Centre coordinates and the radius in feet is stored to the database. This means when the user reloads his search, it can pull through the circle again (like below).

但是，我遇到了 1 个问题，即用户选择他们想要使用的搜索.如果他们画了一个多边形，它会很好地加载多边形，如果它是一个圆形，它会穿过中心的标记.但是我需要的是静态地图中的一个函数来绘制一个圆圈.

I'm having 1 problem, however, which is when the user selects what search they would like to use. It loads the polygon fine, if they drew a polygon, and if it's a circle it pulls through the marker on the center. However what I need is a function in static maps to draw a circle.

推荐答案

游戏有点晚了，但我没有找到解决问题的方法(只有服务器端 php，没有 javascript).我最终到达那里并在这里详细说明了我的方法:http://jomacinc.com/map-radius/短版如下.

A bit late in the game, but nothing I found solved my issue (serverside php only, no javascript). I ended up getting there in the end and have detailed my method here: http://jomacinc.com/map-radius/ and the short version is below.

此 PHP 函数将返回一个编码的多段线字符串，该字符串包含 lat/lng 点在指定点周围的圆中，并在指定半径处.该函数需要 Gabriel Svennerberg 的 PHP 折线编码类，可在此处获得 (http://www.svennerberg.com/examples/折线/PolylineEncoder.php.txt).

This PHP function will return an encoded polyline string of lat/lng points in a circle around the specified point, and at the specified radius. The function requires Gabriel Svennerberg’s PHP polyline encoding class available here (http://www.svennerberg.com/examples/polylines/PolylineEncoder.php.txt).

function GMapCircle($Lat,$Lng,$Rad,$Detail=8){
 $R    = 6371;

 $pi   = pi();

 $Lat  = ($Lat * $pi) / 180;
 $Lng  = ($Lng * $pi) / 180;
 $d    = $Rad / $R;

 $points = array();
 $i = 0;

 for($i = 0; $i <= 360; $i+=$Detail):
   $brng = $i * $pi / 180;

   $pLat = asin(sin($Lat)*cos($d) + cos($Lat)*sin($d)*cos($brng));
   $pLng = (($Lng + atan2(sin($brng)*sin($d)*cos($Lat), cos($d)-sin($Lat)*sin($pLat))) * 180) / $pi;
   $pLat = ($pLat * 180) /$pi;

   $points[] = array($pLat,$pLng);
 endfor;

 require_once('PolylineEncoder.php');
 $PolyEnc   = new PolylineEncoder($points);
 $EncString = $PolyEnc->dpEncode();

 return $EncString['Points'];
}

您现在可以使用上面的函数来创建静态地图了.

You can now the use the above function to create a static map.

/* set some options */
$MapLat    = '-42.88188'; // latitude for map and circle center
$MapLng    = '147.32427'; // longitude as above
$MapRadius = 100;         // the radius of our circle (in Kilometres)
$MapFill   = 'E85F0E';    // fill colour of our circle
$MapBorder = '91A93A';    // border colour of our circle
$MapWidth  = 640;         // map image width (max 640px)
$MapHeight = 480;         // map image height (max 640px)

/* create our encoded polyline string */
$EncString = GMapCircle($MapLat,$MapLng, $MapRadius);

/* put together the static map URL */
$MapAPI = 'http://maps.google.com.au/maps/api/staticmap?';
$MapURL = $MapAPI.'center='.$MapLat.','.$MapLng.'&size='.$MapWidth.'x'.$MapHeight.'&maptype=roadmap&path=fillcolor:0x'.$MapFill.'33%7Ccolor:0x'.$MapBorder.'00%7Cenc:'.$EncString.'&sensor=false';

/* output an image tag with our map as the source */
echo '<img src="'.$MapURL.'" />'

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