android - MKCoordinateRegionMakeWithDistance 在 Android 中等效

Question

我们可以在 iPhone 的 map 上设置特定位置的周边区域，如下所示

CLLocationCoordinate2D coord = {latitude:37.09024, longitude:-95.712891};
CLLocationDistance latitudinalMeters;
latitudinalMeters =NoOfMiles * 1609.344;
CLLocationDistance longitudinalMeters;
longitudinalMeters = NoOfMiles * 1609.344;
mapViewHome.region = MKCoordinateRegionMakeWithDistance(coord, latitudinalMeters, longitudinalMeters); 

Android有没有等价的方法？

Answer 1

此代码不是产品质量。改用克里斯在此处评论中的建议:https://issuetracker.google.com/issues/35823607#comment4

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这个问题最初是针对 Maps API v1 提出的。此答案适用于 v2，但可以轻松更改为 v1，所以...

没有简单的方法来做到这一点。

您可能想要 request this feature on gmaps-api-issues .

由于等待在 Google 方面实现此功能可能需要几个月的时间，所以这就是我要做的:

private static final double ASSUMED_INIT_LATLNG_DIFF = 1.0;
private static final float ACCURACY = 0.01f;

public static LatLngBounds boundsWithCenterAndLatLngDistance(LatLng center, float latDistanceInMeters, float lngDistanceInMeters) {
    latDistanceInMeters /= 2;
    lngDistanceInMeters /= 2;
    LatLngBounds.Builder builder = LatLngBounds.builder();
    float[] distance = new float[1];
    {
        boolean foundMax = false;
        double foundMinLngDiff = 0;
        double assumedLngDiff = ASSUMED_INIT_LATLNG_DIFF;
        do {
            Location.distanceBetween(center.latitude, center.longitude, center.latitude, center.longitude + assumedLngDiff, distance);
            float distanceDiff = distance[0] - lngDistanceInMeters;
            if (distanceDiff < 0) {
                if (!foundMax) {
                    foundMinLngDiff = assumedLngDiff;
                    assumedLngDiff *= 2;
                } else {
                    double tmp = assumedLngDiff;
                    assumedLngDiff += (assumedLngDiff - foundMinLngDiff) / 2;
                    foundMinLngDiff = tmp;
                }
            } else {
                assumedLngDiff -= (assumedLngDiff - foundMinLngDiff) / 2;
                foundMax = true;
            }
        } while (Math.abs(distance[0] - lngDistanceInMeters) > lngDistanceInMeters * ACCURACY);
        LatLng east = new LatLng(center.latitude, center.longitude + assumedLngDiff);
        builder.include(east);
        LatLng west = new LatLng(center.latitude, center.longitude - assumedLngDiff);
        builder.include(west);
    }
    {
        boolean foundMax = false;
        double foundMinLatDiff = 0;
        double assumedLatDiffNorth = ASSUMED_INIT_LATLNG_DIFF;
        do {
            Location.distanceBetween(center.latitude, center.longitude, center.latitude + assumedLatDiffNorth, center.longitude, distance);
            float distanceDiff = distance[0] - latDistanceInMeters;
            if (distanceDiff < 0) {
                if (!foundMax) {
                    foundMinLatDiff = assumedLatDiffNorth;
                    assumedLatDiffNorth *= 2;
                } else {
                    double tmp = assumedLatDiffNorth;
                    assumedLatDiffNorth += (assumedLatDiffNorth - foundMinLatDiff) / 2;
                    foundMinLatDiff = tmp;
                }
            } else {
                assumedLatDiffNorth -= (assumedLatDiffNorth - foundMinLatDiff) / 2;
                foundMax = true;
            }
        } while (Math.abs(distance[0] - latDistanceInMeters) > latDistanceInMeters * ACCURACY);
        LatLng north = new LatLng(center.latitude + assumedLatDiffNorth, center.longitude);
        builder.include(north);
    }
    {
        boolean foundMax = false;
        double foundMinLatDiff = 0;
        double assumedLatDiffSouth = ASSUMED_INIT_LATLNG_DIFF;
        do {
            Location.distanceBetween(center.latitude, center.longitude, center.latitude - assumedLatDiffSouth, center.longitude, distance);
            float distanceDiff = distance[0] - latDistanceInMeters;
            if (distanceDiff < 0) {
                if (!foundMax) {
                    foundMinLatDiff = assumedLatDiffSouth;
                    assumedLatDiffSouth *= 2;
                } else {
                    double tmp = assumedLatDiffSouth;
                    assumedLatDiffSouth += (assumedLatDiffSouth - foundMinLatDiff) / 2;
                    foundMinLatDiff = tmp;
                }
            } else {
                assumedLatDiffSouth -= (assumedLatDiffSouth - foundMinLatDiff) / 2;
                foundMax = true;
            }
        } while (Math.abs(distance[0] - latDistanceInMeters) > latDistanceInMeters * ACCURACY);
        LatLng south = new LatLng(center.latitude - assumedLatDiffSouth, center.longitude);
        builder.include(south);
    }
    return builder.build();
}

用法:

LatLngBounds bounds = AndroidMapsExtensionsUtils.boundsWithCenterAndLatLngDistance(new LatLng(51.0, 19.0), 1000, 2000);
map.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, 0));

注意事项:

• 此代码尚未经过全面测试，可能不适用于边缘情况
• 您可能想要调整私有(private)常量以使其执行得更快
• 您可以删除计算 LatLng south 的第 3 部分，并像计算经度一样这样做:这对于较小的 latDistance 值来说是准确的(假设您不会看到 100 公里以下的差异)
• 代码很丑，请随意重构