scrollTo / scrollToAndCenter using different coordinates after scaling about mapview

[Starcross]

Thanks for you help. I have it working using the scale now.

I think I got confused as I am porting over from TileView, where I was able to call defineBounds, then scrollToAndCenter without making any transformations.

[p-lr]

Hi, it's possible that the jump is caused by using wrong coordinates for scrollTo. I need a working example to figure out what's going on. Could you fork the demo app and reproduce the issue?

[Starcross]

I've created a fork here

There's a button on the first fragment that calls scrollToAndCenter with fixed pixel co-ordinates.

If you zoom in a bit at a time and click the button, you should see it jumps to a different place each time. It's more noticeable the more you zoom in.

[p-lr]

That's because the scroll is affected by the scale.

[p-lr]

8192 is the size of the map at scale 1. So 4096 corresponds to the center of the map, at scale 1.
If you want the button to center on the map, use this:

button.setOnClickListener{
      mapView.scrollToAndCenter((4096 * mapView.scale).toInt(), (4096 * mapView.scale).toInt())
}

[p-lr]

Alternatively, a common use case is to center on a marker. That's when defineBounds is handy. For an example, have a look at MapMarkersFragment. Suppose you set bounds like this: mapView.defineBounds(0.0, 0.0, 1.0, 1.0), and you add a marker at the center:

mapView.addMarker(marker, 0.5, 0.5)

You can then center on that marker using the moveToMarker api: mapView.moveToMarker(marker, destinationScale = 0.8, shouldAnimate = true)