谷歌地图文字叠加 - Android

Question

I am trying to colour some building on Google Maps like this:

I am able to overlay a polygon object on top of the building but Im not able to apply a label on top of it (Building's ID).

How can overlay text on buildings like it's shown in the image above with Android?

Answer 1

I know this question is a bit old, but I just figured out how to do this for my own project and thought I'd share. The method is to create a bitmap image of your text, and then display it as a GroundOverlay on your polygon with a zIndex greater than the polygon.

If you've got the list of LatLngs for your polygon you can do the following:

private void showText(List<LatLng> latLngList) {
    LatLngBounds.Builder builder = new LatLngBounds.Builder();
    for (LatLng latLng : latLngList) {
        builder.include(latLng);
    }

    googleMap.addGroundOverlay(new GroundOverlayOptions()
            .positionFromBounds(builder.build())
            .image(
                    BitmapDescriptorFactory.fromBitmap(
                            getBitmapFromView()
                    )
            )
            .zIndex(100)
    );
}

The .zIndex(100) part is important since you'll want the text to be displayed over your polygon. (I'm not actually sure what the maximum z index is but 100 works).

Here's the method to transform a layout into a bitmap.

private Bitmap getBitmapFromView() {
    View customView = ((LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.my_text_layout, null);
    customView.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);
    customView.layout(0, 0, customView.getMeasuredWidth(), customView.getMeasuredHeight());
    customView.buildDrawingCache();
    Bitmap returnedBitmap = Bitmap.createBitmap(customView.getMeasuredWidth(), customView.getMeasuredHeight(),
            Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(returnedBitmap);
    canvas.drawColor(Color.WHITE, PorterDuff.Mode.SRC_IN);
    Drawable drawable = customView.getBackground();
    if (drawable != null) {
        drawable.draw(canvas);
    }
    customView.draw(canvas);
    return returnedBitmap;
}

If you just want the text, then your layout 'R.layout.my_text_layout' can just be a layout with a TextView.