private Drawing RenderTile(IProjection projection, Rect currentTile, Extent mapArea)
{
var degrees = CalculateDegreeLines(mapArea.ZoomLevel);
var tileArea = projection.ToGeoArea(currentTile, mapArea);
var drawing = new DrawingGroup();
Geo.SetArea(drawing, tileArea);
var linePen = new Pen(Brushes.Red, 1);
linePen.Freeze();
using (var context = drawing.Open())
{
context.PushClip(new RectangleGeometry(currentTile));
var outerRect = projection.ToRect(projection.World, mapArea);
context.DrawRectangle(null, linePen, outerRect);
for (var lat = 0.0; lat <= projection.World.NorthEast.Latitude; lat += degrees)
{
var start = projection.ToPoint(new GeoPoint(lat, projection.World.NorthEast.Longitude), mapArea);
var end = projection.ToPoint(new GeoPoint(lat, projection.World.NorthWest.Longitude), mapArea);
context.DrawLine(linePen, start, end);
if (lat <= 0)
{
continue;
}
start = projection.ToPoint(new GeoPoint(-lat, projection.World.NorthEast.Longitude), mapArea);
end = projection.ToPoint(new GeoPoint(-lat, projection.World.NorthWest.Longitude), mapArea);
context.DrawLine(linePen, start, end);
}
for (var lon = 0.0; lon <= projection.World.NorthEast.Longitude; lon += degrees)
{
var start = projection.ToPoint(new GeoPoint(projection.World.NorthEast.Latitude, lon), mapArea);
var end = projection.ToPoint(new GeoPoint(projection.World.SouthEast.Latitude, lon), mapArea);
context.DrawLine(linePen, start, end);
if (lon <= 0)
{
continue;
}
start = projection.ToPoint(new GeoPoint(projection.World.NorthEast.Latitude, -lon), mapArea);
end = projection.ToPoint(new GeoPoint(projection.World.SouthEast.Latitude, -lon), mapArea);
context.DrawLine(linePen, start, end);
}
context.Pop();
}
drawing.Freeze();
return(drawing);
}