Drawing an image as a map overlay

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This draws an image centered around the given geographical point in a map. Add as many of this as you want to your map.

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import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Point; import com.google.android.maps.GeoPoint; import com.google.android.maps.MapView; import com.google.android.maps.Overlay; public class DrawableMapOverlay extends Overlay { private static final double MAX_TAP_DISTANCE_KM = 3; // Rough approximation - one degree = 50 nautical miles private static final double MAX_TAP_DISTANCE_DEGREES = MAX_TAP_DISTANCE_KM * 0.5399568 * 50; private final GeoPoint geoPoint; private final Context context; private final int drawable; /** * @param context the context in which to display the overlay * @param geoPoint the geographical point where the overlay is located * @param drawable the ID of the desired drawable */ public CamerasMapOverlay(Context context, GeoPoint geoPoint, int drawable) { this.context = context; this.geoPoint = geoPoint; this.drawable = drawable; } @Override public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) { super.draw(canvas, mapView, shadow); // Convert geo coordinates to screen pixels Point screenPoint = new Point(); mapView.getProjection().toPixels(geoPoint, screenPoint); // Read the image Bitmap markerImage = BitmapFactory.decodeResource(context.getResources(), drawable); // Draw it, centered around the given coordinates canvas.drawBitmap(markerImage, screenPoint.x - markerImage.getWidth() / 2, screenPoint.y - markerImage.getHeight() / 2, null); return true; } @Override public boolean onTap(GeoPoint p, MapView mapView) { // Handle tapping on the overlay here return true; } } In the activity which has your MapView: MapView map = (MapView) findViewById(R.id.mapview); MapController mapController = map.getController(); List<Overlay> overlays = map.getOverlays(); overlays.add(new DrawableMapOverlay(this, point, R.drawable.my_drawable); map.invalidate();
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You are calling the constructor "CamerasMapOverlay" instead of DrawableMapOverlay. Just a quibble, but eclipse don't like it...


Reply · April 15, 2011, 8:40 p.m.