Rotate MapView in Android
I am writing an Android app where one of the features is that the map will rotate according to the compass (i.e. if the phone is pointing east, the map will be oriented so that the east side of the map is on top). Previous answers that I have found suggested over writing the onDraw() method in mapView, however, the api changed the method to final so it cannot be overwritten. As a result I have tried to overwrite the dispatchDraw() method like so:
Note:
-compass is a boolean that if true, rotate the view
-bearing is a float variable that has the degrees that the view should rotate
protected void dispatchDraw(Canvas canvas) {
canvas.save();
if (compass) {
final float w = this.getWidth();
final float h = this.getHeight();
final float scaleFactor = (float)(Math.sqrt(h * h + w * w) / Math.min(w, h));
final float centerX = w / 2.0f;
final float centerY = h / 2.0f;
canvas.rotate(bearing, centerX, centerY);
canvas.scale(scaleFactor, scaleFactor, centerX, centerY);
}
super.dispatchDraw(canvas);
canvas.restore();
}
Solution 1:
Thanks to pheelicks and Nikita Koksharov answers, I manage to turn on/off the rotation of a mapview according to the compass.
First you will need the two inner class of MapViewCompassDemo.java found at: Android_SDK_ Tools\add-ons\addon-google_apis-google-#\samples\MapsDemo\src\com\example\android\apis\view\
RotateView
SmoothCanvas
Extract the inner class RotateView to RotateView.java and add SmoothCanvas as a inner class of RotateView.java instead of MapViewCompassDemo.java
public class RotateView extends ViewGroup implements SensorListener {
...
static final class SmoothCanvas extends Canvas {
...
}//end SmoothCanvas
}//end RotateView
maplayout.xml :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map_layout_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:id="@+id/rotating_view"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.google.android.maps.MapView
android:id="@+id/map_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:apiKey="##### YOUR MAP KEY HERE ######"
android:clickable="true" />
</LinearLayout>
<ToggleButton
android:id="@+id/button_compass"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:onClick="onClick"
android:textOff="compass off"
android:textOn="compass on" />
</RelativeLayout>
The MapActivity
/**
* Example activity on how to display a google map view rotation with compass
* To make it work you need to add:
* - <uses-library android:name="com.google.android.maps" /> in the manifest.xml file
* - Your Android Maps API Key from https://developers.google.com/android/maps-api- signup
* - Set the project build target to "Google APIs"
* - Extract/Add the two inner classes RotateView and SmoothCanvas of MapViewCompassDemo.java found at:
* ..\Android\Android SDK Tools\add-ons\addon-google_apis-google-#\samples\MapsDemo\src\com\example\android\apis\view\
*
* @author hsigmond - touchboarder.com -
*
*/
public class MapViewRotationWithCompass extends MapActivity {
private MapView mMapView;
private MyLocationOverlay mMyLocationOverlay = null;
private boolean mModeCompass = false;
private SensorManager mSensorManager;
private LinearLayout mRotateViewContainer;
private RotateView mRotateView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.maplayout);
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
mRotateViewContainer = (LinearLayout) findViewById(R.id.rotating_view);
mRotateView = new RotateView(this);
// Sign Up for the Android Maps API at:
// https://developers.google.com/android/maps-api-signup
// Add the Android Maps API key to the MapView in the maplayout.xml file
mMapView = (MapView) findViewById(R.id.map_view);
mMyLocationOverlay = new MyLocationOverlay(this, mMapView);
}
@SuppressWarnings("deprecation")
public void onClick(View v) {
switch (v.getId()) {
case R.id.button_compass:
if (mMyLocationOverlay.isCompassEnabled()) {
mSensorManager.unregisterListener(mRotateView);
mRotateView.removeAllViews();
mRotateViewContainer.removeAllViews();
mRotateViewContainer.addView(mMapView);
mMyLocationOverlay.disableCompass();
mModeCompass = false;
} else {
mRotateViewContainer.removeAllViews();
mRotateView.removeAllViews();
mRotateView.addView(mMapView);
mRotateViewContainer.addView(mRotateView);
mMapView.setClickable(true);
mSensorManager.registerListener(mRotateView,
SensorManager.SENSOR_ORIENTATION,
SensorManager.SENSOR_DELAY_UI);
mMyLocationOverlay.enableCompass();
mModeCompass = true;
}
break;
}
}
@SuppressWarnings("deprecation")
@Override
public void onResume() {
super.onResume();
if (mModeCompass) {
mMyLocationOverlay.enableCompass();
mSensorManager.registerListener(mRotateView,
SensorManager.SENSOR_ORIENTATION,
SensorManager.SENSOR_DELAY_UI);
}
}
@Override
public void onPause() {
super.onPause();
mMyLocationOverlay.disableCompass();
}
@SuppressWarnings("deprecation")
@Override
protected void onStop() {
mSensorManager.unregisterListener(mRotateView);
super.onStop();
}
@Override
protected boolean isRouteDisplayed() {
return (false);// Don't display a route
}
}
Update: Rotating Google MapView with Compass Example Project: https://www.dropbox.com/sh/c1encbc2lr63qd9/6C1C4hsrlT
Solution 2:
From the docs:
protected void dispatchDraw (Canvas canvas)
Called by draw to draw the child views. This may be overridden by derived classes to gain control just before its children are drawn (but after its own view has been drawn).
So overriding dispatchDraw is no good as the main map view has already been drawn
One solution might be to add the MapView as a child of another CustomView (a sub-class of ViewGroup) and then use the dispatchDraw method of CustomView to draw the MapView (now a child) rotated. So in xml you'd do something like:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<com.example.CustomView
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<com.google.android.maps.MapView
android:id="@+id/mapview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:apiKey="XXXXXXXXXXXXXXXXX"/>
</com.example.CustomView>
</RelativeLayout>
Solution 3:
It should be something like this:
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.save(Canvas.MATRIX_SAVE_FLAG);
if (compass) {
// rotate the canvas with the pivot on the center of the screen
canvas.rotate(-azimuth, getWidth() * 0.5f, getHeight() * 0.5f);
super.dispatchDraw(canvas);
canvas.restore();
}
}
Solution 4:
Take a look at MapsDemo examples in ANDROID_SDK\add-ons\addon-google_apis-google_inc_-7\samples\MapsDemo. It has rotation map demo.
Solution 5:
This answer applies to Google Maps api v2.
It is possible by registering your application with Sensor Listener for Orientation and get the
angle relative to true north inside onSensorChanged and update camera accordingly.
Angle can be used for bearing. Following code can be used:
Instead of using Sensor.TYPE_ORIENTATION try using getOrinetation api. Sensor.TYPE_ORIENTATION
has been deprecated.
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
if (sensorManager != null)
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
SensorManager.SENSOR_DELAY_GAME);
}
public void onSensorChanged(SensorEvent event) {
float degree = Math.round(event.values[0]);
Log.d(TAG, "Degree ---------- " + degree);
updateCamera(degree);
}
private void updateCamera(float bearing) {
CameraPosition oldPos = googleMap.getCameraPosition();
CameraPosition pos = CameraPosition.builder(oldPos).bearing(bearing)
.build();
googleMap.moveCamera(CameraUpdateFactory.newCameraPosition(pos));
}