（谷歌地图）检查 LatLng 是否在可见区域经度的 80% 以内答案

【问题标题】：(Google Maps) Check if LatLng is within 80% of the visible region longitude（谷歌地图）检查 LatLng 是否在可见区域经度的 80% 以内
【发布时间】：2019-04-11 15:36:14
【问题描述】：

我有一个 android 布局，它有一个谷歌地图布局，底部覆盖着一个小的 LinearLayout。当用户选择地图上的标记时，这个小布局变得可见。现在，我想知道所选标记是否在选择时被小布局覆盖，比如它是否在地图经度可见区域的前 80% 范围内。我玩过maps.getProjection().getVisibleRegion()，但我不确定我从这里去哪里。提前感谢

【问题讨论】：

标签： android google-maps android-layout google-maps-markers

【解决方案1】：

要检查 80%（或更多）的标记是否与您的小布局重叠，最好使用屏幕坐标，而不是 LatLng。您应该得到屏幕y 标记的坐标，标记height 和height 的“小布局”，而不是检查标记的y 坐标是否比小布局顶部的y 坐标大80%。

所以用这样的东西：

public class MainActivity extends AppCompatActivity implements OnMapReadyCallback {

    private static final String TAG = MainActivity.class.getSimpleName();

    static final LatLng KYIV = new LatLng(50.450000, 30.523610);

    private GoogleMap mGoogleMap;
    private SupportMapFragment mMapSupportedFragment;
    private LinearLayout mSmallLinearLayout;
    private RelativeLayout mRootLayout;
    private Marker mMarker;
    private int mRootLayoutHeight;
    private int mSmallLayoutHeight;
    private int mMarkerWidth = 100;
    private int mMarkerHeight = 100;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRootLayout = (RelativeLayout) findViewById(R.id.root_layout);
        mSmallLinearLayout = (LinearLayout) findViewById(R.id.small_bottom_layout);

        mMapSupportedFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map_fragment);
        mMapSupportedFragment.getMapAsync(MainActivity.this);

    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mGoogleMap = googleMap;

        mRootLayout.post(new Runnable() {
            @Override
            public void run() {
                mRootLayoutHeight = mRootLayout.getHeight();
            }
        });

        mSmallLinearLayout.post(new Runnable() {
            @Override
            public void run() {
                mSmallLayoutHeight = mSmallLinearLayout.getHeight();
            }
        });

        mMarker = mGoogleMap.addMarker(new MarkerOptions()
                .position(KYIV)
                .icon(getMarkerIcon(mMarkerWidth, mMarkerHeight)));

        mGoogleMap.setOnCameraIdleListener(new GoogleMap.OnCameraIdleListener() {
            @Override
            public void onCameraIdle() {
                if (isMarkerOverlayed()) {
                    // do you magic here:
                    Toast.makeText(MainActivity.this, "Overlapped", Toast.LENGTH_SHORT).show();
                };
            }
        });

    }

    private boolean isMarkerOverlayed() {
        boolean overlayed = false;

        LatLng markerLocation = mMarker.getPosition();
        Projection projection = mGoogleMap.getProjection();
        Point markerScreenPosition = projection.toScreenLocation(markerLocation);

        int smallLayoutTopY = mRootLayoutHeight - mSmallLayoutHeight;

        // 0.8 is 80% of marker height
        if (markerScreenPosition.y >= smallLayoutTopY + 0.8 * mMarkerHeight &&
            markerScreenPosition.y < mRootLayoutHeight) {
            overlayed = true;
        }

        return overlayed;
    }

    private BitmapDescriptor getMarkerIcon(int width, int height) {

        final Drawable iconDrawable = getResources().getDrawable(R.drawable.ic_marker);
        final Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        iconDrawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        iconDrawable.draw(canvas);

        return BitmapDescriptorFactory.fromBitmap(bitmap);
    }

}

你得到了类似的东西：

【讨论】：

非常感谢。这才是真正帮助我的。虽然我做了一些调整，但这一次给了我一个想法。
@MetaSnarf 不客气！当然，这不是您任务的解决方案，只是方法。

【解决方案2】：

在确认地图已加载后尝试这样的操作：

LatLngBounds.Builder builder = new LatLngBounds.Builder();

LatLngBounds bounds = builder.build();
LatLng ne = bounds.northeast;
LatLng sw = bounds.southwest;

Point neBoundInPx = mGoogleMap.getProjection().toScreenLocation(ne);
Point swBoundInPx = mGoogleMap.getProjection().toScreenLocation(sw);

Point newBottomBoundInPx = new Point (neBoundInPx.x , swBoundInPx.y - bottomLinearLayout.getHeight());

LatLng newBottomBoundInPxLatLng = mGoogleMap.getProjection().fromScreenLocation(newBottomBoundInPx);

if(placeLatLng.latitude <= ne.latitude &&
        placeLatLng.longitude >= sw.longitude &&
        placeLatLng.latitude >= newBottomBoundInPxLatLng.latitude &&
        placeLatLng.longitude <= ne.longitude) {
            //Yor place is above the linearLayout at the Bottom.
}

【讨论】：