WebTiledLayer invisible at some zoom levels

JustinSteventon

Hi folks,

I am running into an issue with my app where my tiled layers sometimes are not visible, depending on the zoom level.

Starting with the SDK example with an empty basemap, I add a layer and then set the viewpoint. Many scales work fine, but sometimes it does not. For example if I do this inside the setMapView API:

    if (!mapView || mapView == m_mapView) {
        return;
    }
    m_mapView = mapView;
    m_mapView->setMap(m_map);
   
    auto layer = new WebTiledLayer("https://{subDomain}.tile.openstreetmap.org/{level}/{col}/{row}.png", QStringList { "a", "b", "c" });
    m_map->basemap()->baseLayers()->append(layer);

    connect(m_map, &Map::loadStatusChanged, this, [&](LoadStatus loadStatus)
    {
        if (loadStatus == LoadStatus::Loaded)
        {
            auto point = Point(-109.37801138359127, -27.102741576507512, SpatialReference::wgs84());
            auto viewpoint = Viewpoint(point, 701.4829384369524);
            m_mapView->setViewpointAsync(viewpoint, 0.0);
       }
    });

    emit mapViewChanged();

 

Some observations:
1. Zooming in/out brings the tiles back
2. Other layer types (like ArcGISTiledLayer) work fine
3. If the initial map constructor is set like this "m_map(new Map(BasemapStyle::OsmStandard, this))", then that works.
4. I believe this happens on all platforms

Thanks!

Mapbug.zip

MichaelDavidsonPM_0-1738016783525.png

JamesBallard1

@JustinSteventon here's another idea. You can wait for the draw status to be completed the very first time, and then zoom to the viewpoint you want. There is a momentary stutter since the map appears at one scale and then immediately zooms in, but this avoids any delay. There may be other things you can do to hide the map's visibility until the zoom happens.

connect(m_map, &Map::loadStatusChanged, this, [&](LoadStatus loadStatus)
{
    if (loadStatus != LoadStatus::Loaded)
    {
        return;
    }

    connect(m_mapView, &MapQuickView::drawStatusChanged, this, [this](DrawStatus drawStatus)
    {
        // once draw status has completed the first time, set the viewpoint to the desired location
        // which is outside the supported scale location for the service
        if (drawStatus == DrawStatus::Completed)
        {
            auto point2 = Point(-109.37801138359127, -27.102741576507512, SpatialReference::wgs84());
            auto viewpoint2 = Viewpoint(point2, 701.4829384369524);
            m_mapView->setViewpointAsync(viewpoint2, 0.0);
            // do this one time only
            disconnect(m_mapView, &MapQuickView::drawStatusChanged, this, nullptr);
        }
    });

    auto point = Point(-109.37801138359127, -27.102741576507512, SpatialReference::wgs84());
    auto viewpoint = Viewpoint(point, 1128.5);
    m_mapView->setViewpointAsync(viewpoint, 0.0);
});