A ground overlay is an image that is fixed to a map. A ground overlay has the following properties:

Position

There are two ways to specify the position of the ground overlay:

• Using a location: You must provide an image of the ground overlay, a LatLng to which the anchor will be fixed and the width of the overlay (in meters). The anchor is, by default, 50% from the top of the image and 50% from the left of the image. This can be changed. You can optionally provide the height of the overlay (in meters). If you do not provide the height of the overlay, it will be automatically calculated to preserve the proportions of the image.
• Using a Bounds: You must provide a LatLngBounds which will contain the image.

You must specify the position of the ground overlay before it is added to the map, otherwise an IllegalArgumentException will be thrown when the ground overlay is added to the map. Furthermore, you must only specify the position using one of these methods in the GroundOverlayOptions object; otherwise an IllegalStateException will be thrown when specifying using a second method.

Image

The image (as an BitmapDescriptor) to be used for this overlay. The image will be scaled to fit the position provided. You must specify an image before adding the ground overlay to the map; if not an IllegalArgumentException will be thrown when it is added to the map.

Bearing

The amount that the image should be rotated in a clockwise direction. The center of the rotation will be the image's anchor. This is optional and the default bearing is 0, i.e., the image is aligned so that up is north.

zIndex

The order in which this ground overlay is drawn with respect to other overlays (including Polylines and TileOverlays, but not Markers). An overlay with a larger zIndex is drawn over overlays with smaller zIndexes. The order of overlays with the same zIndex value is arbitrary. This is optional and the default zIndex is 0.

Transparency

Transparency of the ground overlay in the range [0..1] where 0 means the overlay is opaque and 1 means the overlay is fully transparent. If the specified bitmap is already partially transparent, the transparency of each pixel will be scaled accordingly (for example, if a pixel in the bitmap has an alpha value of 200 and you specify the transparency of the ground overlay as 0.25, then the pixel will be rendered on the screen with an alpha value of 150). Specification of this property is optional and the default transparency is 0 (opaque).

Visibility

Indicates if the ground overlay is visible or invisible, i.e. whether it is drawn on the map. An invisible ground overlay is not drawn, but retains all of its other properties. This is optional and the default visibility is true, i.e., visible.

Clickability

If you want to handle events fired when the user clicks the ground overlay, set this property to true. You can change this value at any time. The default is false. If this property is set to true, your app will receive notifications to the GoogleMap.OnGroundOverlayClickListener registered through GoogleMap.setOnGroundOverlayClickListener(GoogleMap.OnGroundOverlayClickListener).

Tag

An Object associated with the ground overlay. For example, the Object can contain data about what the ground overlay represents. This is easier than storing a separate Map<GroundOverlay, Object>. As another example, you can associate a String ID corresponding to the ID from a data set. Google Maps SDK for Android neither reads nor writes this property.

Methods in this class must be called on the Android UI thread. If not, an IllegalStateException will be thrown at runtime.

Example

GoogleMap map = ...; // get a map.
 BitmapDescriptor imageDescriptor = ...; // get an image.
 LatLngBounds bounds = ...; // get a bounds
 // Adds a ground overlay with 50% transparency.
 GroundOverlay groundOverlay = map.addGroundOverlay(new GroundOverlayOptions()
     .image(imageDescriptor)
     .positionFromBounds(bounds)
     .transparency(0.5));