android - 将 LatLngBounds 缩小 5%

Question

好吧，在阅读了 Antonio 的评论后，我在我的代码中接受了这个。现在，无论我提交的百分比是多少，它仍然认为我的对象在边界框之外。

My Position 是传入的marker。

LatLngBounds bounds = mMap.getProjection().getVisibleRegion().latLngBounds;
LatLngBounds newBounds = reduceBy(bounds, 0.05d);

        if(newBounds.contains(myPosition.getPosition())) {
            //If the item is within the the bounds of the screen
        } else{
            //If the marker is off screen
            zoomLevel -= 1;}
    }
    return zoomLevel;
}


public LatLngBounds reduceBy(LatLngBounds bounds, double percentage) {
    double distance = SphericalUtil.computeDistanceBetween(bounds.northeast, bounds.southwest);
    double reduced = distance * percentage;

    double headingNESW = SphericalUtil.computeHeading(bounds.northeast, bounds.southwest);
    LatLng newNE = SphericalUtil.computeOffset(bounds.northeast, reduced/2d, headingNESW);

    double headingSWNE = SphericalUtil.computeHeading(bounds.southwest, bounds.northeast);
    LatLng newSW = SphericalUtil.computeOffset(bounds.southwest, reduced/2d, headingSWNE);

    return LatLngBounds.builder().include(newNE).include(newSW).build();
}

}

我已经设置了所有的缩放级别，但有时我会遇到像这样的点，它仍然在边界内，只是标记不在屏幕上。我想要一个稍微小一点的边界框来检测这一点，然后仅在这些情况下缩小一个级别。

Answer 1

您可以使用 Google Maps API Utility Library 中的 SphericalUtil 类进行计算:

public LatLngBounds reduceBy(LatLngBounds bounds, double percentage) {
    double distance = SphericalUtil.computeDistanceBetween(bounds.northeast, bounds.southwest);
    double reduced = distance * percentage;

    double headingNESW = SphericalUtil.computeHeading(bounds.northeast, bounds.southwest);
    LatLng newNE = SphericalUtil.computeOffset(bounds.northeast, reduced/2d, headingNESW);

    double headingSWNE = SphericalUtil.computeHeading(bounds.southwest, bounds.northeast);
    LatLng newSW = SphericalUtil.computeOffset(bounds.southwest, reduced/2d, headingSWNE);

    return LatLngBounds.builder().include(newNE).include(newSW).build();
}

要将边界缩小 5%(对角线)，您可以:

LatLngBounds newBounds = reduceBy(bounds, 0.05d);