Efficient Map Overlays in Android Google Map

Question

I want to do the following and am kind of stuck on these for a few days:

1. I was trying to draw polylines (I have encoded polylines, but have

Answer 1

I have the same problem. We are developing an iphone app and an android app at the same time. I have 2500 + map overlays. No problem on iphone; a huge performance hit on android when calling populate() after adding all overlays. (Of course, my first try was to call populate() every time after adding an overlay; a typical mistake due to google's tutorial. Now I am calling populate() just once, after all 2500+ overlays have been added to the ItemizedOverlay.)

So the single populate() call takes over 40 seconds to complete on an htc hero device. I had to put in a busy indicator; no progress bar is possible because we cannot get any information about the progress of populate().

I tried another solution: not use ItemizedOverlay but add overlays by hand, subclassing Overlay. Result: indeed it is much faster to add all those overlays to the map; however, the map becomes unusable due to constant calling of the draw() method on each overlay. In my draw method, I tried to optimize as much as possible; I do not create a bitmap every time. My draw() method looks like this:

public void draw(android.graphics.Canvas canvas, MapView mapView, boolean shadow)  {
// our marker bitmap already includes shadow.
// centerPoint is the geopoint where we need to put the marker.
 if (!shadow) {
  Point point = new Point();  
  mapView.getProjection().toPixels(centerPoint, point);
  canvas.drawBitmap(markerBitmap, point.x, point.y, null);
 }

}

Here markerBitmap is precomputed. I don't know what else I could optimize. Is there some kind of populate() call required if we are not using ItemizedOverlay??? I could not find any good answers for that.

Right now I resort to caching the ItemizedOverlay once it has been created in a background thread. This way at least the user does not have to wait every time.