Google Maps API v2 Usage - TechGeekD/android_guides GitHub Wiki
This guide will instruct you on how use the Google Maps API v2 library to create a map within your application's activities and/or fragments.
For full setup instructions, see our Google Maps Setup Guide. Assuming you have added the GoogleMap v2 MapFragment to your layout, you should first run this method onCreate(). In my case, I am using the SupportMapFragment, either will work.
protected void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mapFragment == null) {
mapFragment = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map));
// Check if we were successful in obtaining the map.
if (mapFragment != null) {
mapFragment.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap map) {
loadMap(map);
}
});
}
}
}
// The Map is verified. It is now safe to manipulate the map.
protected void loadMap(GoogleMap googleMap) {
if (googleMap != null) {
// ... use map here
}
}After you have run that it is safe for you to begin adding markers.
The Maps API allows you to configure the initial state of the map including type, position, controls, and much more:
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
map:cameraBearing="112.5"
map:cameraTargetLat="-33.796923"
map:cameraTargetLng="150.922433"
map:cameraTilt="30"
map:cameraZoom="13"
map:mapType="normal"
map:uiCompass="false"
map:uiRotateGestures="true"
map:uiScrollGestures="false"
map:uiTiltGestures="true"
map:uiZoomControls="false"
map:uiZoomGestures="true"/>See the official docs for more configuration options.
The map location center and zoom can be manipulated using the moveCamera or animateCamera which both take a CameraUpdate object. For example, to retarget the camera to a new latitude and longitude we can do:
LatLng latLng = new LatLng(latitude, longitude);
CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLng(latLng);
map.animateCamera(cameraUpdate);Check the CameraUpdateFactory for the available camera update types including newLatLng, newLatLngZoom, zoomTo, and more.
We can add a marker to the map with the following code specifying the position (LatLng), icon (BitmapDescriptor), title, and snippet:
// Set the color of the marker to green
BitmapDescriptor defaultMarker =
BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN);
// listingPosition is a LatLng point
LatLng listingPosition = new LatLng(-33.867, 151.206);
// Create the marker on the fragment
Marker mapMarker = mapFragment.addMarker(new MarkerOptions()
.position(listingPosition)
.title("Some title here")
.snippet("Some description here")
.icon(defaultMarker));We can attach a click handler to a marker once the map is loaded with:
protected void loadMap(GoogleMap googleMap) {
if (googleMap != null) {
// Attach marker click listener to the map here
map.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
public boolean onMarkerClick(Marker marker) {
// Handle marker click here
}
});
// ...
}
}Markers have limited information and associating a marker to the underlying data model can be difficult without creating an associated hash map to track the mappings between a marker's id and the associated data model. Refer to this stackoverflow post for specifics.
We can also use custom markers based on any arbitrary drawable with:
// Define custom marker
BitmapDescriptor customMarker =
BitmapDescriptorFactory.fromResource(R.drawable.house_flag);See the BitmapDescriptorFactory docs for other colors or icon loading options. Review the official markers guide for additional marker customization options.
You can use the following code to bring up an AlertDialog for users to type a message on MapLongClick event. On completion, we can add a marker to the map which when pressed displays the message typed.
First, we need to create a new xml file in res/layout/message_item.xml which will be displayed as the alert window:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layout_root"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp" >
<TextView
android:id="@+id/tvTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="20dp"
android:text="Title:" />
<EditText
android:id="@+id/etTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/etSnippet"
android:layout_alignBottom="@+id/tvTitle"
android:layout_toRightOf="@+id/tvTitle" >
</EditText>
<TextView
android:id="@+id/tvSnippet"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/tvTitle"
android:paddingTop="20dp"
android:text="Snippet:" />
<EditText
android:id="@+id/etSnippet"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/tvSnippet"
android:layout_below="@+id/tvTitle"
android:layout_toRightOf="@+id/tvSnippet" >
</EditText>
</RelativeLayout>If we want to setup a long click listener, we need to implement the OnMapLongClickListener in our Activity and setup the listener for the map:
public class MapDemoActivity extends AppCompatActivity implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener,
OnMapLongClickListener {
...
protected void loadMap(GoogleMap googleMap) {
map = googleMap;
if (map != null) {
// Attach long click listener to the map here
map.setOnMapLongClickListener(this);
// ...
}
}
...
// Fires when a long press happens on the map
@Override
public void onMapLongClick(final LatLng point) {
Toast.makeText(this, "Long Press", Toast.LENGTH_LONG).show();
// Custom code here...
}
}Make sure to have your activity implement from the OnMapLongClickListener for this to work properly. Now, when we run this, we should see a toast when the user long clicks on the map.
Next, let's trigger an alert dialog which will be displayed to accept input from the user within MapDemoActivity:
// ...
@Override
public void onMapLongClick(LatLng point) {
Toast.makeText(getApplicationContext(), "Long Press", Toast.LENGTH_LONG).show();
// Custom code here...
// Display the alert dialog
showAlertDialogForPoint(point);
}
// Display the alert that adds the marker
private void showAlertDialogForPoint(final LatLng point) {
// inflate message_item.xml view
View messageView = LayoutInflater.from(MapDemoActivity.this).
inflate(R.layout.message_item, null);
// Create alert dialog builder
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
// set message_item.xml to AlertDialog builder
alertDialogBuilder.setView(messageView);
// Create alert dialog
final AlertDialog alertDialog = alertDialogBuilder.create();
// Configure dialog button (OK)
alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// Define color of marker icon
BitmapDescriptor defaultMarker =
BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN);
// Extract content from alert dialog
String title = ((EditText) alertDialog.findViewById(R.id.etTitle)).
getText().toString();
String snippet = ((EditText) alertDialog.findViewById(R.id.etSnippet)).
getText().toString();
// Creates and adds marker to the map
Marker marker = map.addMarker(new MarkerOptions()
.position(point)
.title(title)
.snippet(snippet)
.icon(defaultMarker));
}
});
// Configure dialog button (Cancel)
alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) { dialog.cancel(); }
});
// Display the dialog
alertDialog.show();
}
// ...When we run the app now, the long click on the map should trigger a dialog which allows us to enter text which will be associated with a map marker.
To implement the falling pin animation, add a marker to the desired position in map and then call this function with that marker. This function uses a Handler to animate the marker over time by [setting the anchor](https://developer.android.com/reference/com/google/android/gms/maps/model/Marker.html#setAnchor\(float, float)).
private void dropPinEffect(final Marker marker) {
// Handler allows us to repeat a code block after a specified delay
final android.os.Handler handler = new android.os.Handler();
final long start = SystemClock.uptimeMillis();
final long duration = 1500;
// Use the bounce interpolator
final android.view.animation.Interpolator interpolator =
new BounceInterpolator();
// Animate marker with a bounce updating its position every 15ms
handler.post(new Runnable() {
@Override
public void run() {
long elapsed = SystemClock.uptimeMillis() - start;
// Calculate t for bounce based on elapsed time
float t = Math.max(
1 - interpolator.getInterpolation((float) elapsed
/ duration), 0);
// Set the anchor
marker.setAnchor(0.5f, 1.0f + 14 * t);
if (t > 0.0) {
// Post this event again 15ms from now.
handler.postDelayed(this, 15);
} else { // done elapsing, show window
marker.showInfoWindow();
}
}
});
}Review the repeating periodic tasks guide for a better understanding of the Handler pattern used above to animate the marker over time.
Next, in private void showAlertDialogForPoint add the call to dropPinEffect(marker); at the end to animate the placement of the marker:
// Display the alert that adds the marker
private void showAlertDialogForPoint(final LatLng point) {
// ...
alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// Define color of marker icon
BitmapDescriptor defaultMarker = BitmapDescriptorFactory
.defaultMarker(BitmapDescriptorFactory.HUE_GREEN);
// Extract content from alert dialog
String title = ((EditText) alertDialog.findViewById(R.id.etTitle))
.getText().toString();
String snippet = ((EditText) alertDialog.findViewById(R.id.etSnippet))
.getText().toString();
// Creates and adds marker to the map
Marker marker = map.addMarker(new MarkerOptions().position(point)
.title(title).snippet(snippet).icon(defaultMarker));
// Animate marker using drop effect
// --> Call the dropPinEffect method here
dropPinEffect(marker);
}
});
// ...
}If you want to use your own layout instead of the default options, you can do so by creating your own InfoWindowAdapter seen below. Create a layout file in res/layout/custom_info_window.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
android:orientation="vertical" >
<TextView
android:id="@+id/tv_info_window_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#ff669900"
android:textStyle="bold"
android:singleLine="true" />
<TextView
android:id="@+id/tv_info_window_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#ff0099cc"
android:text="Hours" />
</LinearLayout>And here is the code you need to implement your own InfoWindowAdpapter class.
class CustomWindowAdapter implements InfoWindowAdapter{
LayoutInflater mInflater;
public CustomWindowAdapter(LayoutInflater i){
mInflater = i;
}
// This defines the contents within the info window based on the marker
@Override
public View getInfoContents(Marker marker) {
// Getting view from the layout file
View v = mInflater.inflate(R.layout.custom_info_window, null);
// Populate fields
TextView title = (TextView) v.findViewById(R.id.tv_info_window_title);
title.setText(marker.getTitle());
TextView description = (TextView) v.findViewById(R.id.tv_info_window_description);
description.setText(marker.getSnippet());
// Return info window contents
return v;
}
// This changes the frame of the info window; returning null uses the default frame.
// This is just the border and arrow surrounding the contents specified above
@Override
public View getInfoWindow(Marker marker) {
return null;
}
}You would use this by setting your InfoWindowAdapter to this new class after you have initialized your map. In the case of our example running this line after calling loadMap() in onCreate().
map.setInfoWindowAdapter(new CustomWindowAdapter(getLayoutInflater()));This will use the custom adapter to create the information window, allowing us to customize how the information is displayed.
If you are loading remote images into an InfoWindow, there is a common problem where the image doesn't load properly the first time you open the window for each item. The hacky solution is to refresh the window after a delay. The better solution is to trigger the window to refresh after the image is finished downloading.
When creating a custom information window on the map, the developer can choose to override either getInfoContents (as shown above) which allows you to customize just the contents of the window but still keep the default info window frame and background. If instead the desired behavior is to provide a view that will be used for the entire info window, we need to override getInfoWindow instead of getInfoContents. Note that only one of these can be overridden for a particular adapter. See further discussion in this stackoverflow post, this infowindow tutorial or on the official google docs.
The map supports arbitrary drawing of lines and various shapes on the surface including polylines (connected lines), polygons (enclosed regions) and circles. For additional details on drawing shapes on the map, check out the official maps guide.
Drawing polylines allows us to connect multiple dots using lines. To draw these connecting lines, simply specify each coordinate that should be connected.
// Instantiates a new Polyline object and adds points to define a rectangle
PolylineOptions rectOptions = new PolylineOptions()
.add(new LatLng(37.35, -122.0))
.add(new LatLng(37.45, -122.0)) // North of the previous point, but at the same longitude
.add(new LatLng(37.45, -122.2)) // Same latitude, and 30km to the west
.add(new LatLng(37.35, -122.2)) // Same longitude, and 16km to the south
.add(new LatLng(37.35, -122.0)); // Closes the polyline.
// Get back the mutable Polyline
Polyline polyline = myMap.addPolyline(rectOptions);Polygons are designed to define regions within a closed loop with the interior filled in:
// Instantiates a new Polygon object and adds points to define a rectangle
PolygonOptions rectOptions = new PolygonOptions()
.add(new LatLng(37.35, -122.0),
new LatLng(37.45, -122.0),
new LatLng(37.45, -122.2),
new LatLng(37.35, -122.2),
new LatLng(37.35, -122.0))
.strokeColor(Color.RED).fillColor(Color.BLUE));
// Get back the mutable Polygon
Polygon polygon = myMap.addPolygon(rectOptions);Drawing circles requires specifying the center and radius of the circle:
// Instantiates a new CircleOptions object and defines the center and radius
CircleOptions circleOptions = new CircleOptions()
.center(new LatLng(37.4, -122.1))
.radius(1000)); // In meters
// Get back the mutable Circle
Circle circle = myMap.addCircle(circleOptions);For additional details on drawing shapes on the map, check out the official maps guide.
Ground overlays are image overlays that are tied to latitude/longitude coordinates, so they move when you drag or zoom the map.
A tile overlay, sometimes called a tile layer, is a collection of images that are displayed on top of the base map tiles.
In addition to the standard "normal" map, there are several other map types available including Terrain (MAP_TYPE_TERRAIN), Hybrid (MAP_TYPE_HYBRID), and Satellite (MAP_TYPE_SATELLITE). To set the type, call setMapType with one of the following options:
mapFragment.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap map) {
// Once map is loaded
// Supported types include: MAP_TYPE_NORMAL, MAP_TYPE_SATELLITE
// MAP_TYPE_TERRAIN, MAP_TYPE_HYBRID
map.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
}
});The various types are illustrated below:
For additional features such as heat maps, marker clusters, calculating distances and more be sure to check out the maps utility library. Watch this video introduction for a brief overview.