GeoStream renderers

The Render method of GeoStreamRenderer is just like the Render method of the IMapRenderer interface that is used to draw on a map that shows data from local GBFS files. Implement this method to draw on the map.

public override void Render(Graphics graphics, RenderContext rc) {

    // If we are zoomed a long way out, don't draw anything
    if (rc.Map.Zoom > 2000) {
        return;
    }
    // Calculate a reachable area to draw on the map.
    ReachableArea walkableInAnHour = 
            ReachableArea.WithinTimeSpan(new LatLon(34.1018, -118.2973),
                                         new TimeSpan(1, 0, 0), 
                                         new RoutingStrategyForPedestrian());

    PolygonFence reachable = walkableInAnHour.ComputeConvexPolygon();
    reachable.RenderBrush = new System.Drawing.SolidBrush(Color.FromArgb(80, Color.Blue));
    reachable.RenderPen = new System.Drawing.Pen(Color.Blue, 1);
    // Polygon Fences are drawn in the Prelabelling render mode
    // because there are no modes on the server, set the mode here.
    rc.Mode = RenderMode.PreLabelling;
    // use the render method of the reachable area to draw on the map.
    reachable.Render(graphics, rc);
}

The ExpiresAfter property controls how long the tiles your renderer creates can remain in the GeoStream tile cache before they expire. This value must be at least one minute.

public override TimeSpan ExpiresAfter {
     get {
         return TimeSpan.FromMinutes(1);
     }
 }

The DataDependentCache property indicates whether the renderer generates tiles that depend on data from the currently-loaded GBFS file. By default, this property is false. If you change this value to true, then any time the GBFS file changes, the GeoStream server generates new tiles rather than using cached versions. You do not need to override this property if your renderer does not use data from the current GBFS file.

The Bounds property indicates the area of the map that the renderer draws on. By default, this property is null, indicating that the renderer can draw anywhere on the map. If your renderer only draws within a limited geographic area, you can improve performance by supplying a bounding box as the value of Bounds. When Bounds is non-null, the Render method is not called for any tile requests that do not overlap the bounding box. This can significantly improve performance.

The CacheId property lets you implement your renderer so that it draws different things depending on arguments from the client. By making the value of CacheId dependent on the same arguments that your Render method uses, you ensure that the GeoStream server only uses cached tiles that were generated using the same arguments as the current request.

public override string CacheId {
     get {
         return Request.Params["color"];
     }
 }

Your renderer class must be added to an aspx file. The aspx page must have its "async" attribute set to true. You must place the aspx file in the renderers subfolder of your GeoStream server's root directory (by default, this is C:\Program Files\Telogis\GeoBase\GeoStream\server\renderers).

Note
If the renderers folder does not exist, you can add it to the root directory of your GeoStream tile server. However, it must be named renderers.

Although a GeoStream renderer generates a tile layer, similar to a WMS tile layer, you do not need to add the layers your renderers produce to the layers.config file. The GeoStream server automatically finds your renderer as long as it is in the renderers folder.