將Android GoogleMap放在一個點上，同時縮放得足以包含另一個點

Question

我想要一個類似於雷達屏幕的東西，該屏幕集中在用戶所在的位置，同時縮放足以包含v2 api的目標點。現在，我使用

bounds = new LatLngBounds.Builder().include(destPos) 
       .include(yourPos).build(); 
     map.animateCamera(CameraUpdateFactory.newLatLngBounds(bounds, 50)); 

但這中心在兩個點之間的某一點，並放大到包括。有沒有一種方法可以像我想要的那樣簡單？或者我必須或多或少地從頭開始並做一些數學運算（例如，計算兩點之間的距離，計算LatLngBounds的lat/lng，以便用戶位於定義的矩形的中心並且矩形的邊緣包括目的地 - 考慮地圖/屏幕尺寸）？

這是我有：

這是我想要的東西：

Answer 1

你自己的答案是過於複雜。

您需要計算位置另一側的點，並將其包含在LatLngBounds中。

LatLng otherSidePos = new LatLng(2 * yourPos.latitude - destPos.latitude, 2 * yourPos.longitude - destPos.longitude); 
bounds = new LatLngBounds.Builder().include(destPos) 
       .include(otherSidePos).build(); 
     map.animateCamera(CameraUpdateFactory.newLatLngBounds(bounds, padding)); 

注意：您不想將50像素作爲填充進行硬編碼。它在不同的設備上看起來不同。改用密度獨立的像素。

Answer 2

我想通了，如何做到這一點的硬路上面給出。我選擇了LatLngBounds的一個方形區域來簡化軸承編號（只要它適合在屏幕中，這對我來說是可以的：你可以計算出軸承從中心到非方形矩形的角點與一些更多的三角）。我還添加了一些填充，因爲點之間的距離將與從中心到東北角的對角線相同，並且這將大於從中心到頂邊的距離，這將意味着第二個點可能在頂部邊緣之上並且不可見（如果是，例如正北）。我借巨資從http://www.movable-type.co.uk/scripts/latlong.html和calculating Lat and Long from Bearing and Distance，

這是我對獲得的LatLngBounds方法：

public LatLngBounds getBounds(double lat1, double lng1, double lat2, 
     double lng2) { 

    // defines a square area with point lat1,lng1 at center and includes 
    // point 
    // lat2, long2 with a buffer between edge and second point 

    // get distance between two points 
    float[] results = new float[1]; 

    Location.distanceBetween(lat1, lng1, lat2, lng2, results); 
    double d = results[0]; 

    d = (d * 1.5); // add padding. The shortest distance to an edge of the 
//square box is d * cos(45 degrees). Thus it's possible that the second point will be out of the box. To compensate I make the radius larger (d * 1/cos(45) = d * 1.41). I put a bit extra so that the second point isn't right on the edge of the screen. 

    long R = 6371000; // distance of earth's radius in meters 

    d = d /(double) R; 

    lat1 = Math.toRadians(lat1); // Current lat point converted to radians 
    lng1 = Math.toRadians(lng1); // Current long point converted to radians 

    // calculate northeast corner of LatLngBounds 

    double brng = Math.toRadians(45); // bearing from center to northeast in 
             // radians 

    double resultLat1 = Math.asin(Math.sin(lat1) * Math.cos(d) 
      + Math.cos(lat1) * Math.sin(d) * Math.cos(brng)); 

    double resultLng1 = lng1 
      + Math.atan2(Math.sin(brng) * Math.sin(d) * Math.cos(lat1), 
        Math.cos(d) - Math.sin(lat1) * Math.sin(resultLat1)); 

    resultLat1 = Math.toDegrees(resultLat1); 
    resultLng1 = Math.toDegrees(resultLng1); 

    Log.i("My Code", "resultLat1: " + resultLat1 + " resultLng1: " + resultLng1); 

    LatLng northEast = new LatLng(resultLat1, resultLng1); 

    // calculate southwest corner of LatLngBounds. Everything is the same 
    // except the bearing value 

    brng = Math.toRadians(225); // bearing from center to southwest corner 
           // in radians 
    double resultLat2 = Math.asin(Math.sin(lat1) * Math.cos(d) 
      + Math.cos(lat1) * Math.sin(d) * Math.cos(brng)); 

    double resultLng2 = lng1 
      + Math.atan2(Math.sin(brng) * Math.sin(d) * Math.cos(lat1), 
        Math.cos(d) - Math.sin(lat1) * Math.sin(resultLat2)); 

    resultLat2 = Math.toDegrees(resultLat2); 
    resultLng2 = Math.toDegrees(resultLng2); 

    Log.i("My Code", "resultLat2: " + resultLat2 + " resultLng2: " + resultLng2); 

    LatLng southWest = new LatLng(resultLat2, resultLng2); 

    LatLngBounds bounds = new LatLngBounds(southWest, northEast); 

    return bounds; 
} 

Answer 3

用於縮放以包含所有標記而不更改相機目標（地圖中心）。

LatLngBounds.Builder builder = new LatLngBounds.Builder(); 
for (Marker marker : markers) { 
    builder.include(marker.getPosition()); 
} 
LatLngBounds bounds = builder.build(); 

LatLng currentLoc = _googleMapView.getCameraPosition().target; 

//make sure that centre location doesn't change 
double deltaLat = Math.max(Math.abs(bounds.southwest.latitude - currentLoc.latitude), 
       Math.abs(bounds.northeast.latitude - currentLoc.latitude)); 

double deltaLon = Math.max(Math.abs(bounds.southwest.longitude - currentLoc.longitude), 
       Math.abs(bounds.northeast.longitude - currentLoc.longitude)); 

LatLngBounds.Builder displayBuilder = new LatLngBounds.Builder(); 
displayBuilder.include(currentLoc); //not necessary but hey 
displayBuilder.include(new LatLng(currentLoc.latitude + deltaLat, currentLoc.longitude + deltaLon)); 
displayBuilder.include(new LatLng(currentLoc.latitude - deltaLat, currentLoc.longitude - deltaLon)); 

_googleMapView.moveCamera(CameraUpdateFactory.newLatLngBounds(displayBuilder.build(), 0));