使用Google地圖在多邊形內繪制較小的多邊形

Question

我正在嘗試在Google Maps（使用API​​的V3）上渲染形狀，這些形狀包含相同的形狀，但內部較小。 基本上是一個盒子內的一個盒子或一個多邊形內的一個多邊形。

對於矩形，我有以下代碼可以正常工作：

var drawEdgesRectangle = function (shape) {
  // shape is the original, parent rectangle

  var NE, SW, childNE, childSW, padding, diagonal, inner;

  // set padding constant to 1 (i.e. 1m distance all around) 
  padding = 1;

  // get diagonal distance from corner
  diagonal = Math.sqrt(2) * padding;

  // get NE of parent
  NE = shape.bounds.getNorthEast();

  // get SW of parent
  SW = shape.bounds.getSouthWest();

  // get child NE, SW
  childNE = google.maps.geometry.spherical.computeOffset(NE, diagonal, 225);
  childSW = google.maps.geometry.spherical.computeOffset(SW, diagonal, 45);

  // render inner shape
  inner = new google.maps.Rectangle({
    strokeColor: 'white',
    strokeOpacity: 0.8,
    strokeWeight: 1,
    fillColor: 'black',
    fillOpacity: 0.35,
    map: map,
    bounds: new google.maps.LatLngBounds(
      childSW,
      childNE
    )
  });
}

當然，對多邊形執行此操作是另一回事。 我知道我可以使用getPaths()來獲取每一行的屬性，但是要弄清楚如何放置內部行，並且確實要弄清“內部”的位置在概念上對我來說非常困難。

我想知道如果使用Google API，我想實現的目標是否可行。

Answer 1

如果多邊形是“簡單的”（中心在多邊形的“內部”並且沒有凹入的邊），則一種選擇是做與矩形（類似於滿足這些條件的四邊形多邊形）相似的操作）：

使用幾何庫 ：

要包括它：

<script src="https://maps.googleapis.com/maps/api/js?v=3&libraries=geometry"></script>

代碼（假設全局“多邊形”等）：

var drawEdgesPoly = function() {
  // shape is the original, parent polygon

  var shape = poly;
  // set padding constant to 1 (i.e. 1m distance all around) 
  padding = 50;

  var vertices = shape.getPath();
  var polybounds = new google.maps.LatLngBounds();
  for (var i = 0; i < vertices.getLength(); i++) {
    polybounds.extend(vertices.getAt(i));
  }
  var center = polybounds.getCenter();
  if (centerMarker && centerMarker.setMap) {
    centerMarker.setMap(null);
  }
  centerMarker = new google.maps.Marker({
    position: center,
    map: map,
    icon: {
      url: "https://maps.gstatic.com/intl/en_us/mapfiles/markers2/measle.png",
      size: new google.maps.Size(7, 7),
      anchor: new google.maps.Point(4, 4)
    }
  });
  if (polylines && (polylines.length > 0)) {
    for (var i = 0; i < polylines.length; i++) {
      polylines[i].setMap(null);
    }
  }
  polylines = [];
  var newPath = [];
  for (var i = 0; i < vertices.getLength(); i++) {
    polylines.push(new google.maps.Polyline({
      path: [center, vertices.getAt(i)],
      map: map,
      strokeWidth: 2,
      strokeColor: 'red'
    }));
    newPath[i] = google.maps.geometry.spherical.computeOffset(vertices.getAt(i),
      padding,
      google.maps.geometry.spherical.computeHeading(vertices.getAt(i), center));
  }
  if (inner && inner.setMap)
    inner.setMap(null);
  // render inner shape
  inner = new google.maps.Polygon({
    strokeColor: 'white',
    strokeOpacity: 0.8,
    strokeWeight: 1,
    fillColor: 'black',
    fillOpacity: 0.35,
    map: map,
    editable: false,
    path: newPath
  });
};

概念證明小提琴在代碼片段或jsfiddle中玩多邊形以查看約束。

 var map; var infoWindow; var poly; var inner; var polylines = []; var centerMarker; var paths = [ [ new google.maps.LatLng(38.872886, -77.054720), new google.maps.LatLng(38.872602, -77.058046), new google.maps.LatLng(38.870080, -77.058604), new google.maps.LatLng(38.868894, -77.055664), new google.maps.LatLng(38.870598, -77.053346) ] ]; function initialize() { var mapOptions = { center: new google.maps.LatLng(38.8714, -77.0556), zoom: 15 }; map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions); poly = new google.maps.Polygon({ paths: paths, strokeWeight: 3, fillColor: '#55FF55', fillOpacity: 0.5, editable: true }); poly.setMap(map); drawEdgesPoly(); google.maps.event.addListener(poly.getPath(), 'insert_at', drawEdgesPoly); google.maps.event.addListener(poly.getPath(), 'remove_at', drawEdgesPoly); google.maps.event.addListener(poly.getPath(), 'set_at', drawEdgesPoly); // Define an info window on the map. infoWindow = new google.maps.InfoWindow(); } google.maps.event.addDomListener(window, 'load', initialize); var drawEdgesPoly = function() { // shape is the original, parent polygon var shape = poly; // set padding constant to 1 (ie 1m distance all around) padding = 50; var vertices = shape.getPath(); var polybounds = new google.maps.LatLngBounds(); for (var i = 0; i < vertices.getLength(); i++) { polybounds.extend(vertices.getAt(i)); } var center = polybounds.getCenter(); if (centerMarker && centerMarker.setMap) { centerMarker.setMap(null); } centerMarker = new google.maps.Marker({ position: center, map: map, icon: { url: "https://maps.gstatic.com/intl/en_us/mapfiles/markers2/measle.png", size: new google.maps.Size(7, 7), anchor: new google.maps.Point(4, 4) } }); if (polylines && (polylines.length > 0)) { for (var i = 0; i < polylines.length; i++) { polylines[i].setMap(null); } } polylines = []; var newPath = []; for (var i = 0; i < vertices.getLength(); i++) { polylines.push(new google.maps.Polyline({ path: [center, vertices.getAt(i)], map: map, strokeWidth: 2, strokeColor: 'red' })); newPath[i] = google.maps.geometry.spherical.computeOffset(vertices.getAt(i), padding, google.maps.geometry.spherical.computeHeading(vertices.getAt(i), center)); } if (inner && inner.setMap) inner.setMap(null); // render inner shape inner = new google.maps.Polygon({ strokeColor: 'white', strokeOpacity: 0.8, strokeWeight: 1, fillColor: 'black', fillOpacity: 0.35, map: map, editable: false, path: newPath }); }; 

 html, body, #map-canvas { height: 100%; width: 100%; } 

 <script src="https://maps.googleapis.com/maps/api/js?v=3&libraries=geometry"></script> <div id="map-canvas" style="height:100%; width:100%;"></div>