restrict max zoom to real map

Hello.

Yes, it is possible to implement, for example, in such ways (below).
The general idea is that all "no map data" tiles have the same image.

1. Intercept the request to download the tile, download the tile and check the checksum of the data. If the checksum matches the "no map data" tile, then set the status - error.
http://infinity-code.com/doxygen/online … 5a04ae9f94
2. Subscribe to OnlineMapsTile.OnTileDownloaded and OnlineMapsCache.OnLoadedFromCache. When the tile is loaded, check the colors of several pixels (for example, 3-5 pixels in different places of the image). If the colors of the image match the colors of "no map data" image, set the status - error.

Have struggled to make this work.
I can detect pixel color (only tried 1 pixel) but do not get call to downloaded or cache functions when map shows "no map data" image.
In the area I am working, zoom level 20 shows no data.
But zoom level 20 never gets to Tile or cache functions
Code and output below:

As a side note, I don't seem to be getting zoom in completed notification either, related ?

void Start () {
        //few other things
        OnlineMapsLocationService locationService = OnlineMapsLocationService.instance; //used in other code
        OnlineMaps.instance.OnChangeZoom += OnChangeZoom;
        OnlineMapsTile.OnTileDownloaded += OnTileDownloaded;
        OnlineMapsCache.instance.OnLoadedFromCache += OnLoadedFromCache;
//more stuff
}
    public void OnTileDownloaded(OnlineMapsTile tile)
    {
        Debug.Log("Tile DOwnloaded at zoom: " + OnlineMaps.instance.zoom);

        Color colTextPix;
        colTextPix = tile.texture.GetPixel(1, 1);
        Debug.Log("colour of pixel downloaded" + colTextPix);
    }

    public void OnLoadedFromCache(OnlineMapsTile tile)
    {
        Debug.Log("Tile from Cache zoom: " + OnlineMaps.instance.zoom);
        Color colTextPix;
        colTextPix = tile.texture.GetPixel(1, 1);
        Debug.Log("colour of pixel cached" + colTextPix);
    }
   
        public void OnChangeZoom()
    {
        // When the zoom changes you will see in the console new zoom.
         Debug.Log("zoom" + OnlineMaps.instance.zoom);
        //debug never reports "zoom" change above
       //code below not run
        if (OnlineMaps.instance.zoom > HZoomMax) OnlineMaps.instance.zoom = HZoomMax;
        HZoomCurrent = OnlineMaps.instance.zoom;
        testZoomedImage();
    }

Output: note: zoom 20 has no output, but shows "no data" on screen and zoom 20 in "map" inside inspector:
Debug (shortened version, as get returns from several tiles each time moved or zoomed):

Tile from Cache zoom: 18
colour of pixel cachedRGBA(0.784, 0.753, 0.702, 1.000)
Tile from Cache zoom: 19
colour of pixel cachedRGBA(0.831, 0.820, 0.753, 1.000)

any suggestions greatly appreciated ?
PS will try again with new version from today

I made a script (below) that works for me (Provider - ArcGIS / WorldImagery).
OnChangeZoom works on all zoom levels (including 19 and 20).
If you use another provider, just change the colors.

But this requires a slight modification of the source code Online Maps.
OnlineMapsTileSetControl.cs (line: 1600) from:

OnlineMapsTile currentTile = tile;

to:

OnlineMapsTile currentTile = tile;
if (currentTile != null && currentTile.status != OnlineMapsTileStatus.loaded) currentTile = null;

OnlineMapsBuffer.cs (line: 421) from:

if (!tile.hasColors)

to:

if (!tile.hasColors || tile.status != OnlineMapsTileStatus.loaded)

I give you changes so that you do not wait for the new version to be available.
The next version of Online Maps will contain these changes.

Script:

using UnityEngine;

public class DetectNoDataTiles:MonoBehaviour
{
    private Color32 c1 = new Color32(204, 204, 204, 255);
    private Color32 c2 = new Color32(201, 201, 201, 255);

    private void Start()
    {
        OnlineMaps.instance.OnChangeZoom += OnChangeZoom;
        OnlineMapsTile.OnTileDownloaded += OnTileLoaded;
        OnlineMapsCache.instance.OnLoadedFromCache += OnTileLoaded;
    }

    public void OnTileLoaded(OnlineMapsTile tile)
    {
        Color32 p1, p2, p3;
        if (OnlineMaps.instance.target == OnlineMapsTarget.tileset)
        {
            p1 = tile.texture.GetPixelBilinear(0, 0);
            p2 = tile.texture.GetPixelBilinear(0.5f, 0.5f);
            p3 = tile.texture.GetPixelBilinear(1, 1);
        }
        else
        {
            p1 = tile.colors[0];
            p2 = tile.colors[32896];
            p3 = tile.colors[65535];
        }
        

        if (ColorEqual(p1, c1) &&
            ColorEqual(p2, c2) &&
            ColorEqual(p3, c1)) tile.status = OnlineMapsTileStatus.error;
    }

    public static bool ColorEqual(Color32 c1, Color32 c2)
    {
        if (c1.r != c2.r) return false;
        if (c1.g != c2.g) return false;
        if (c1.b != c2.b) return false;
        if (c1.a != c2.a) return false;
        return true;
    }

    public void OnChangeZoom()
    {
        Debug.Log("zoom" + OnlineMaps.instance.zoom);
    }
}