Dynamically adding/removing GraphicOverlays

BrianLoehr

I'm using Esri.ArcGISRuntime.Maui v200.0.0. Admittedly I am new to using Esri so maybe there is a more obvious solution: I am wanting to dynamically add  and remove site pins on the map. First attempt was to reuse the initial set of Graphic objects and just build a new GraphicsOverlay and only add the Graphics desired. Then null out the GraphicsOverlays collection and add a new one. This resulted in the Object Already Owned exception.

Second attempt is to create a new GraphicsOverlay along with a new Graphic object for each item and add it to the GraphicsOverlays collection. Removing a GraphicOverlay is as simple as identifying the particular GraphicOverlay and removing it from the GraphicOverlays collection. In this manner I can add and remove as many as desired. 

The question is - is this a viable way to perform the action I desire? Will there be significant memory or performance issues if adding 100's or 1000's of objects?

// code from view model (using MVVM)

private static SimpleMarkerSymbol _pinSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Diamond, Color.OrangeRed, 12);

private static readonly MapPoint[] _sitePoints = new[]
        {
            new MapPoint(-97.7805, 30.4027, SpatialReferences.Wgs84),
            new MapPoint(-97.8005, 30.4227, SpatialReferences.Wgs84),
            new MapPoint(-97.8205, 30.4427, SpatialReferences.Wgs84),
            new MapPoint(-97.8100, 30.4227, SpatialReferences.Wgs84),
            new MapPoint(-97.7900, 30.4027, SpatialReferences.Wgs84)
        };

private void AddPin()
{
    if (GraphicsOverlays == null)
        return;

    if (GraphicsOverlays.Count == 5)
        return;

    // how many pins right now?
    var pinCount = GraphicsOverlays.Count;
    var newPinIndex = pinCount;

    var pinOverlay = new GraphicsOverlay();
    var newGraphic = new Graphic(_sitePoints[newPinIndex], _pinSymbol);
    pinOverlay.Graphics.Add(newGraphic);
    GraphicsOverlays.Add(pinOverlay);
}

private Task RemoveLatestPinLocation()
{
    if (GraphicsOverlays == null)
        return Task.CompletedTask;

    int count = GraphicsOverlays.Count;
    if (count == 0)
        return Task.CompletedTask;

    // update overlay
    var removePinIndex = count - 1;
    var overlayToRemove = GraphicsOverlays.ElementAt(removePinIndex);
    if (overlayToRemove == null)
        return Task.CompletedTask;

    GraphicsOverlays.Remove(overlayToRemove);

    return Task.CompletedTask;
}

 

SitePins.gif

BrianLoehr

Thank you @MatveiStefarov for your quick response and detailed reply!