You can't attach your own Canvas to the view, you need to draw in to the view's existing canvas. You'd normally do that by deriving from the class and implementing onDraw().You could also try drawing in to a transparent view on top of the MapView, though I'm not sure how that would work with touch events.
On Sun, Jun 21, 2009 at 5:45 AM, mnish <[email protected]> wrote: > > I have initialized paint now. The nullpointerexception is solved by > this. But i still can't see any line on the map. As you said I have to > attach the canvas to the view or so. I have read the links you > supplied. But I dont understand it. I need to use the MapView and draw > lines on it. How can i do this. Could you please show me in a simple > way how i can do this? > > thank you > > On Jun 21, 4:55 am, Marco Nelissen <[email protected]> wrote: > > The problem is those last two lines: canvas = new Canvas(); > > canvas.drawLine(p1.x, p1.y, p2.x, p2.y, paint); > > > > That creates a new Canvas, then draws in to it. The problem with that is > > that the Canvas isn't "attached" to anything, so you're essentially > drawing > > in to something that is not visible. > > You should probably have a look at: > http://developer.android.com/reference/android/view/View.html#onDraw(...) > > > > On Sat, Jun 20, 2009 at 7:14 PM, nEx.Software <[email protected] > >wrote: > > > > > > > > > In your code, I am not seeing anywhere that you have initialized > > > paint. That would be the first place I'd look. > > > > > On Jun 20, 5:50 pm, mnish <[email protected]> wrote: > > > > Hello, > > > > I have a problem with drawing lines between two points on google map. > > > > I get nullpointerexception on this line of code: > > > > canvas.drawLine(p1.x, p1.y, p2.x, p2.y, paint); > > > > > > I know this is a very basic thing, but I don't know not much about it > > > > and I really really need your help. > > > > > > here is were i call this method: > > > > > > @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(on); > > > > mapOverlays = mapView.getOverlays(); > > > > drawable = > > > this.getResources().getDrawable(R.drawable.circle); > > > > itemizedoverlay = new HelloItemizedOverlay(drawable); > > > > Projection projection = mapView.getProjection(); > > > > > > Double lat1 = 30.342833*1E6, lon1 = -91.719033*1E6; > > > > Double lat2 = -37.5262180*1E6, lon2 = > 175.8060710*1E6; > > > > point1 = new GeoPoint(lat1.intValue(), > lon1.intValue()); > > > > point2 = new GeoPoint(lat2.intValue(), > lon2.intValue()); > > > > p1 = new Point(); > > > > p2 = new Point(); > > > > projection.toPixels(point1, p1); > > > > projection.toPixels(point2, p2); > > > > canvas = new Canvas(); > > > > canvas.drawLine(p1.x, p1.y, p2.x, p2.y, paint); > > > > > > } > > > > > > Any help is more than welcome. > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
