Map interaction client/Grid layer

Creating the grid layer

• The grid layer is accessed through the grid layer interface, IMariaGridLayer (_gridLayer).

Create an view model class (GridViewModel) for the grid layer, inheriting ViewModelBase, implementing the initialization event handler and a "Grids" field for access to the Grid Layer.

public class GridViewModel  : ViewModelBase
{
   private readonly IMariaGridLayer _gridLayer;

   public GridViewModel(IMariaGridLayer gridLayer)
   {
       _gridLayer = gridLayer;
       _gridLayer.LayerInitialized += GridLayerOnLayerInitialized;
   }
   private void GridLayerOnLayerInitialized()
   {
       NotifyPropertyChanged(() => Grids);
   }
   public ObservableCollection`<IGridRenderer>` Grids
   {
      get { return _gridLayer.Grids; }
      set { _gridLayer.Grids = value; }
   }
}

Then, create the grid layer and include the GridViewModel in the declarations and constructor of the main view model (MariaWindowViewModel).

public GridViewModel  GridViewModel  { get; set; }
private readonly IMariaGridLayer _gridLayer;
. . .
_gridLayer = new TPG.Maria.GridLayer.GridLayer();
GridViewModel = new GridViewModel(_gridLayer);
Layers.Add(_gridLayer);

Changing grid display

To change the grid settings, add a pushbutton to your main window -- and bind it to the GridViewModel.

`<Button Content="Switch Grid!" Command="{Binding GridViewModel.SwitchGrid}"/>`

Add command handling to the GridViewModel.

private DelegateCommand _switchGrid;
public ICommand SwitchGrid { get { return _switchGrid; } }
 . . .
private int cnt = 0;
private void OnSwitchGrid(object a)
{
    var item = cnt % (Grids.Count + 1);
    for (var i = 0; i < Grids.Count; i++)
    {
        Grids[i].Visible = i == item;
    }
    cnt++;
}

… and set the delegate in the constructor.

_switchGrid = new DelegateCommand(OnSwitchGrid);

You should now be able to step through the different grid types.

This is a very simple example. In a real application you would probably use a drop down button or another control allowing multiple selection of grid types.