Develop Reference

How do I draw a line Overlay on Google Maps Android

I am trying to draw a line on my maps project, but can't get the line to draw. Where and how do I declare the overlay? I've tried various methods, but can't get it to work. ie, code just displays errors in Eclipse. What I am NOT trying to do is draw a route from A to B, but rather draw the route as I am moving.
// Creating a MapView
public class Gpstrack extends MapActivity {
private MapView map;
private MapController controller;
private Projection projection;
ArrayList<GeoPoint> geoPointsArray = new ArrayList<GeoPoint>();
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initMapView();
initMyLocation();
TabHost.TabSpec spec;
TabHost th = (TabHost)findViewById(R.id.tabhost);
th.setup();
spec = th.newTabSpec("tag1");
spec.setContent(R.id.map_Tab);
spec.setIndicator("Map");
th.addTab(spec);
spec = th.newTabSpec("tag2");
spec.setContent(R.id.log_Tab);
spec.setIndicator("Log");
th.addTab(spec);
spec = th.newTabSpec("tag3");
spec.setContent(R.id.details_Tab);
spec.setIndicator("Details");
th.addTab(spec);
spec = th.newTabSpec("tag4");
spec.setContent(R.id.student_Tab);
spec.setIndicator("Student Info");
th.addTab(spec);
}
#Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
//Map and Controls
private void initMapView() {
map = (MapView) findViewById(R.id.mvMain);
controller = map.getController();
map.setSatellite(true);
//map.setStreetView(true);
map.setBuiltInZoomControls(true);
}
//Creates an Overlay that marks current position
private void initMyLocation() {
final MyLocationOverlay overlay = new MyLocationOverlay(this, map);
overlay.enableMyLocation();
overlay.enableCompass();
overlay.runOnFirstFix(new Runnable() {
public void run() {
controller.setZoom(17);
controller.animateTo(overlay.getMyLocation());
map.getOverlays().add(overlay);
}
});
}
//Experiment
class MyOverlay extends Overlay {
public void draw(Canvas canvas, MapView mapv, boolean shadow) {
super.draw(canvas, mapv, shadow);
Projection projection = mapv.getProjection();
Path p = new Path();
for (int i = 0; i < geoPointsArray.size(); i++) {
if (i == geoPointsArray.size() -1) {
break;
}
Point from = new Point();
Point to = new Point();
projection.toPixels(geoPointsArray.get(i), from);
projection.toPixels(geoPointsArray.get(i + 1), to);
p.moveTo(from.x, from.y);
p.lineTo(to.x, to.y);
}
Paint mPaint = new Paint();
mPaint.setStyle(Style.STROKE);
mPaint.setColor(Color.GREEN);
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(5);
canvas.drawPath(p, mPaint);
mapv.invalidate();
super.draw(canvas, mapv, shadow);
}
}
}

Have you tried with this demo to implement the Google Map Overlay?

In you overlay class you can draw line like this
public class MapOverlay extends com.google.android.maps.Overlay
{
Canvas canvas;
#Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
long when)
{
// TODO Auto-generated method stub
super.draw(canvas, mapView, shadow);
this.canvas=canvas;
Point screenpoint = new Point();
mapView.getProjection().toPixels(p, screenpoint);
Bitmap bmp = BitmapFactory.decodeResource(
getResources(), R.drawable.pushpin);
canvas.drawBitmap(bmp, canvas.getWidth()/4,
canvas.getHeight()/4, null);
Paint paint = new Paint();
paint.setColor(Color.BLACK);
canvas.drawLine(canvas.getWidth()/4, canvas.getHeight()/4,
canvas.getWidth()/2, canvas.getHeight()/2, paint);
return true;
}
return true;
}
}
the draw line function is like
public void drawLine (float startX, float startY,
float stopX, float stopY, Paint paint)
Since: API Level 1 Draw a line segment with the specified start and stop x,y coordinates, using the specified paint.
Parameters
startX The x-coordinate of the start point of the line
startY The y-coordinate of the start point of the line
paint The paint used to draw the line
and you can reffer this quetion if you want to draw a path
J2ME/Android/BlackBerry - driving directions, route between two locations

I think you should try this link Drawing a line/path on Google Maps
and this one J2ME/Android/BlackBerry - driving directions, route between two locations .I think this should help you.

Line is not coming according to geopoint

Through my main java file I am calling overlay and than I am passing the geopoint, and the lines is coming so wierd not even close. Starts from top corner and goes to the middle of the screen.
java1:
public class TourmapActivity extends MapActivity {
private MapView mapView;
private MyOverlay myOverlay;
private List<Overlay> mapOverlays;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
mapOverlays = mapView.getOverlays();
myOverlay = new MyOverlay(mapView);
mapOverlays.add(myOverlay);
}
#Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}
java2:
public class MyOverlay extends Overlay {
private Point point1;
private Point point2;
private Projection projection;
public MyOverlay(MapView mapView){
projection = mapView.getProjection();
}
public void draw(Canvas canvas, MapView mapView, boolean shadow){
super.draw(canvas, mapView, shadow);
Paint paint = new Paint();
paint.setDither(true);
paint.setColor(Color.BLUE);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(2);
point1 = new Point();
point2 = new Point();
Path path = new Path();
//43.26082327999097, -79.92047309875488 jhe
float longitude = 43.26082327999097f; // first point
float latitude = -79.92047309875488f;
//43.26347189172956, -79.91776943206787 student center
float longitude_1 = 43.26347189172956f; // second point
float latitude_1 = -79.91776943206787f;
GeoPoint geoPoint1 = new GeoPoint((int)(longitude * 1E6), (int)(latitude * 1E6));
GeoPoint geoPoint2 = new GeoPoint((int)(longitude_1 * 1E6), (int)(latitude_1* 1E6));
projection.toPixels(geoPoint1, point1);
projection.toPixels(geoPoint2, point2);
path.lineTo(point1.x, point1.y);
path.lineTo(point2.x, point2.y);
canvas.drawPath(path, paint);
}
}

You should look at the documentation for Path, specifically for lineTo and moveTo.
So you want to change
path.lineTo(point1.x, point1.y);
to
path.moveTo(point1.x, point1.y);

draw path between two points on google maps

I am working on Android Google maps. I gone through
http://csie-tw.blogspot.com/2009/06/android-driving-direction-route-path.html
I am not able to draw full Path between two points if the distance is more than 200KM. How can i draw full path between two points? is there any issue with license, if there is any license issue how can i approach to get license.
Thanks

I managed to draw a path between two points using Google map android API v2. I posted its solution at that link. Answer : Draw path between two points using Google Maps Android API v2

/** Called when the activity is first created. */
private List<Overlay> mapOverlays;
private Projection projection;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
linearLayout = (LinearLayout) findViewById(R.id.zoomview);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
mapOverlays = mapView.getOverlays();
projection = mapView.getProjection();
mapOverlays.add(new MyOverlay());
}
#Override
protected boolean isRouteDisplayed() {
return false;
}
class MyOverlay extends Overlay{
public MyOverlay(){
}
public void draw(Canvas canvas, MapView mapv, boolean shadow){
super.draw(canvas, mapv, shadow);
Paint mPaint = new Paint();
mPaint.setDither(true);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(2);
GeoPoint gP1 = new GeoPoint(19240000,-99120000);
GeoPoint gP2 = new GeoPoint(37423157, -122085008);
Point p1 = new Point();
Point p2 = new Point();
Path path = new Path();
Projection projection.toPixels(gP1, p1);
projection.toPixels(gP2, p2);
path.moveTo(p2.x, p2.y);
path.lineTo(p1.x,p1.y);
canvas.drawPath(path, mPaint);
}

Connect points on map with lines

I have three gps points in android app. How to set on map connect first and second with red and second and third with blue line ? How to connect any two points on map, draw line between them?

Here's a minimal implementation (2 points only, no markers) using a map overlay and mapView.getProjection() fro you to expand upon:
public class HelloGoogleMaps extends MapActivity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MapController mMapController;
MapView mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
mMapController = mapView.getController();
mMapController.setZoom(18);
// Two points in Mexico about 1km apart
GeoPoint point1 = new GeoPoint(19240000,-99120000);
GeoPoint point2 = new GeoPoint(19241000,-99121000);
mMapController.setCenter(point2);
// Pass the geopoints to the overlay class
MapOverlay mapOvlay = new MapOverlay(point1, point2);
mapView.getOverlays().add(mapOvlay);
}
public class MapOverlay extends com.google.android.maps.Overlay {
private GeoPoint mGpt1;
private GeoPoint mGpt2;
protected MapOverlay(GeoPoint gp1, GeoPoint gp2 ) {
mGpt1 = gp1;
mGpt2 = gp2;
}
#Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
long when) {
super.draw(canvas, mapView, shadow);
Paint paint;
paint = new Paint();
paint.setColor(Color.RED);
paint.setAntiAlias(true);
paint.setStyle(Style.STROKE);
paint.setStrokeWidth(2);
Point pt1 = new Point();
Point pt2 = new Point();
Projection projection = mapView.getProjection();
projection.toPixels(mGpt1, pt1);
projection.toPixels(mGpt2, pt2);
canvas.drawLine(pt1.x, pt1.y, pt2.x, pt2.y, paint);
return true;
}
}
#Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}
.

Creating Custom Overlay on the map

I am trying to replicate this feature of Maps in Android:
You can see that on the map, there's a Circle depicting the range that the user has selected.
In my application, I'll also want a dragger to reside on the perimeter of the circle, which can be dragged to redefine radius.
If someone could tell me how to draw custom drawable overlays and 2D graphics over map, I can do other things on my own.
Thanks!
The full application can be reached at this link

Okay, I tried to do things on my Own, and put this code to get the above effect:
public class MarkerOverlay extends Overlay {
Geocoder geoCoder = null;
public MarkerOverlay() {
super();
}
#Override
public boolean onTap(GeoPoint geoPoint, MapView mapView){
selectedLatitude = geoPoint.getLatitudeE6();
selectedLongitude = geoPoint.getLongitudeE6();
return super.onTap(geoPoint,mapView);
}
#Override
public void draw(Canvas canvas, MapView mapV, boolean shadow){
if(shadow){
Projection projection = mapV.getProjection();
Point pt = new Point();
projection.toPixels(globalGeoPoint,pt);
GeoPoint newGeos = new GeoPoint(selectedLat+(100),selectedLong); // adjust your radius accordingly
Point pt2 = new Point();
projection.toPixels(newGeos,pt2);
float circleRadius = Math.abs(pt2.y-pt.y);
Paint circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
circlePaint.setColor(0x30000000);
circlePaint.setStyle(Style.FILL_AND_STROKE);
canvas.drawCircle((float)pt.x, (float)pt.y, circleRadius, circlePaint);
circlePaint.setColor(0x99000000);
circlePaint.setStyle(Style.STROKE);
canvas.drawCircle((float)pt.x, (float)pt.y, circleRadius, circlePaint);
Bitmap markerBitmap = BitmapFactory.decodeResource(getApplicationContext().getResources(),R.drawable.pin);
canvas.drawBitmap(markerBitmap,pt.x,pt.y-markerBitmap.getHeight(),null);
super.draw(canvas,mapV,shadow);
}
}
}
This let me have following effect:
The calculation used may not be what you want.
Its just for demonstration purposes. Real range/distance calculation requires the use of bearing too and has some specific formula.
Let me know if you have any questions regarding this.

Extend the class ItemizedOverlay to override the draw() method. The Canvas where overlays are drawn is passed to that method and you can call drawCircle or anything that's needed to make your range dragger appear.

An example code to draw a pushpin with the circle:
public class MapDemoActivity extends MapActivity {
MapView mapView;
MapController mc;
GeoPoint p;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mapView = (MapView) findViewById(R.id.mapView);
LinearLayout zoomLayout = (LinearLayout)findViewById(R.id.zoom);
View zoomView = mapView.getZoomControls();
zoomLayout.addView(zoomView,
new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
mapView.displayZoomControls(true);
mc = mapView.getController();
String coordinates[] = {"28.38", "77.12"};
double lat = Double.parseDouble(coordinates[0]);
double lng = Double.parseDouble(coordinates[1]);
p = new GeoPoint(
(int) (lat * 1E6),
(int) (lng * 1E6));
mc.animateTo(p);
mc.setZoom(8);
//---Add a location marker---
MapOverlay mapOverlay = new MapOverlay();
List<Overlay> listOfOverlays = mapView.getOverlays();
listOfOverlays.clear();
listOfOverlays.add(mapOverlay);
mapView.invalidate();
}
class MapOverlay extends com.google.android.maps.Overlay
{
#Override
public boolean draw(Canvas canvas, MapView mapView,
boolean shadow, long when)
{
super.draw(canvas, mapView, shadow);
//---translate the GeoPoint to screen pixels---
Point screenPts = new Point();
mapView.getProjection().toPixels(p, screenPts);
//--------------draw circle----------------------
Point pt=mapView.getProjection().toPixels(p,screenPts);
Paint circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
circlePaint.setColor(0x30000000);
circlePaint.setStyle(Style.FILL_AND_STROKE);
canvas.drawCircle(screenPts.x, screenPts.y, 50, circlePaint);
//---add the marker---
Bitmap bmp = BitmapFactory.decodeResource(
getResources(), R.drawable.pin);
canvas.drawBitmap(bmp, screenPts.x, screenPts.y-bmp.getHeight(), null);
super.draw(canvas,mapView,shadow);
return true;
}
}
#Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}