/// <summary>
/// Get tile envelope in WGS-84 coordinates
/// </summary>
/// <param name="x">x index</param>
/// <param name="y">y index</param>
/// <param name="zoom">zoom</param>
/// <returns>Envelope in WGS-84</returns>
private static Envelope GetTileEnvelope(int x, int y, int zoom)
{
var currTopLeftPixXY = TileCalculator.TileXYToTopLeftPixelXY(x, y);
var currTopLeftCoord = TileCalculator.PixelXYToLatLong((int)currTopLeftPixXY.X,
(int)currTopLeftPixXY.Y, zoom);
var currBtmRightPixXY = TileCalculator.TileXYToBottomRightPixelXY(x,
y);
var currBtmRightCoord = TileCalculator.PixelXYToLatLong((int)currBtmRightPixXY.X,
(int)currBtmRightPixXY.Y, zoom);
return(new Envelope(currTopLeftCoord, currBtmRightCoord));
}
public Tiles GetTiles(Envelope envelope, Rectangle bounds, BackgroundWorker bw)
{
var mapTopLeft = envelope.TopLeft();
var mapBottomRight = envelope.BottomRight();
//Clip the coordinates so they are in the range of the web mercator projection
mapTopLeft.Y = TileCalculator.Clip(mapTopLeft.Y, TileCalculator.MinLatitude, TileCalculator.MaxLatitude);
mapTopLeft.X = TileCalculator.Clip(mapTopLeft.X, TileCalculator.MinLongitude, TileCalculator.MaxLongitude);
mapBottomRight.Y = TileCalculator.Clip(mapBottomRight.Y, TileCalculator.MinLatitude, TileCalculator.MaxLatitude);
mapBottomRight.X = TileCalculator.Clip(mapBottomRight.X, TileCalculator.MinLongitude, TileCalculator.MaxLongitude);
var zoom = TileCalculator.DetermineZoomLevel(envelope, bounds);
var topLeftTileXY = TileCalculator.LatLongToTileXY(mapTopLeft, zoom);
var btmRightTileXY = TileCalculator.LatLongToTileXY(mapBottomRight, zoom);
var tileMatrix = new Bitmap[(int)(btmRightTileXY.X - topLeftTileXY.X) + 1, (int)(btmRightTileXY.Y - topLeftTileXY.Y) + 1];
var po = new ParallelOptions {
MaxDegreeOfParallelism = -1
};
Parallel.For((int)topLeftTileXY.Y, (int)btmRightTileXY.Y + 1, po,
(y, loopState) => Parallel.For((int)topLeftTileXY.X, (int)btmRightTileXY.X + 1, po,
(x, loopState2) =>
{
if (bw.CancellationPending)
{
loopState.Stop();
loopState2.Stop();
return;
}
var currEnv = GetTileEnvelope(x, y, zoom);
tileMatrix[x - (int)topLeftTileXY.X, y - (int)topLeftTileXY.Y] = GetTile(x, y, currEnv, zoom);
}
));
return(new Tiles(tileMatrix,
GetTileEnvelope((int)topLeftTileXY.X, (int)topLeftTileXY.Y, zoom), // top left tile = tileMatrix[0,0]
GetTileEnvelope((int)btmRightTileXY.X, (int)btmRightTileXY.Y, zoom) // bottom right tile = tileMatrix[last, last]
));
}