That sounded like an excellent suggestion so I gave it a try. The new
code looks like this:
mapController.zoomToSpan(latitudeDelta, longitudeDelta);
/*
* If the MapView has not been drawn yet, we won't be able to retrieve
an
* accurate zoom level. We have to queue up the work to make the
adjustment,
* if necessary.
*/
mapView.post(new Runnable() {
public void run() {
if (mapView.getZoomLevel() > 20) {
mapView.getController().setZoom(20);
}
}
});
And, that still didn't work although I fully expected it to. But,
after debugging it awhile I noticed some strange behavior that I did
not expect. First, I wanted to check that my runnable got queued up
OK, and it ran when I expected it to run. It did not. Before I
explain what I observed let me first explain my activity / view
structure.
Tabbed Activity w/ 3 tabs
- Tab 1 - ListActivity
- Tab 2 - MapActivity
- Tab 3 - Plain 'Ol Activity
So the sequence I did was:
1. Enter Tabbed Activity, ListActivity in Tab 1 is shown by default.
2. Click on Tab2, the MapActivity.
I would have expected the Runnable to be executed at this point.
3. Click 'back' to exit Tabbed Activity.
4. Re-enter Tabbed Activity, again ListActivity in Tab 1 is shown by
default.
And, this is the point at which the Runnable was executed. I am at a
loss as to why.
P.S. I must have misunderstood getMaxZoomLevel() because that didn't
return what I thought it would which is the zoom level at which you
still get the satellite imagery and not the blank white screen w/ grey
X's. So, I went back and hard-coded to zoom level 20.
On Sep 1, 4:29 pm, Steve Howard wrote:
> The zoom may be deferred if the MapView hasn't been drawn yet. Have you
> tried putting your logic in a Runnable and post()ing it to the MapView?
>
> Steve
>
> On Sun, Aug 29, 2010 at 7:18 PM, Chad McQuillen
> wrote:
>
>
>
> > My application has a MapView which shows a collection of items in a
> > satellite view. I use the MapController's zoomToSpan() method to
> > initialize the zoom level of MapView. I later discovered that the
> > MapView was showing a blank white screen with grey X's (zoom'd too
> > far, zoom out once and everything looks as expected) for the use case
> > when the collection of item's locations were very close to each
> > other. So, I modified the code from this:
>
> > mapController.zoomToSpan(latitudeDelta, longitudeDelta);
>
> > to this:
>
> > mapController.zoomToSpan(latitudeDelta, longitudeDelta);
>
> > if (mapView.getZoomLevel() > mapView.getMaxZoomLevel()) {
> > mapController.setZoom(mapView.getMaxZoomLevel());
> > }
>
> > but, I still got the same result. I added some debug before and after
> > the zoomToSpan() to retrieve the zoom level from MapView and noticed
> > that the zoom level did not change. I'm guessing somehow that the
> > work is queued up??
>
> > I don't know if this information is important or not to this problem,
> > but I'll also mention that the MapView is created from a MapActivity
> > which is hosted in the tab host of a TabActivity that contains three
> > tabs, one of which is the map. I searched this forum and elsewhere
> > and haven't seen anyone encounter such a problem before. I'm hoping
> > someone can point me in the right direction.
>
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