public TileRange DownloadTiles(BoundingBox bbox, ImageryProvider provider, int minTilesPerImage = 4)
{
TileRange tiles = new TileRange(provider);
BoundingBox mapBbox = null;
PointInt topLeft = new PointInt();
PointInt bottomRight = new PointInt();
// optimal zoom calculation (maybe there's a direct way)
// calculate the size of the full bbox at increasing zoom levels
// until the full image would be greater than a tile
int zoom = 0;
do
{
zoom++;
// coords are pixels in global map image (see TileUtils.MapSize(zoom))
topLeft = TileUtils.LatLongToPixelXY(bbox.yMax, bbox.xMin, zoom);
bottomRight = TileUtils.LatLongToPixelXY(bbox.yMin, bbox.xMax, zoom);
mapBbox = new BoundingBox(topLeft.X, bottomRight.X, topLeft.Y, bottomRight.Y);
}while (zoom < provider.MaxZoom &&
(mapBbox.Width < provider.TileSize * minTilesPerImage && mapBbox.Height < provider.TileSize * minTilesPerImage));
// now we have the minimum zoom without image
// we can know which tiles are needed
tiles.Start = new MapTileInfo(TileUtils.PixelXYToTileXY(topLeft.X, topLeft.Y), zoom);
tiles.End = new MapTileInfo(TileUtils.PixelXYToTileXY(bottomRight.X, bottomRight.Y), zoom);
tiles.AreaOfInterest = mapBbox;
// downdload tiles
Stopwatch swDownload = Stopwatch.StartNew();
_logger?.LogTrace("Starting images download");
// 2 max download threads
var options = new ParallelOptions()
{
MaxDegreeOfParallelism = provider.MaxDegreeOfParallelism
};
var range = tiles.EnumerateRange().ToList();
_logger.LogInformation($"Downloading {range.Count} tiles...");
Parallel.ForEach(range, options, tileInfo =>
{
Uri tileUri = BuildUri(provider, tileInfo.X, tileInfo.Y, tileInfo.Zoom);
_logger?.LogInformation($"Downloading {tileUri}");
var contentbytes = _httpClient.GetByteArrayAsync(tileUri).Result;
tiles.Add(new MapTile(contentbytes, provider.TileSize, tileUri, tileInfo));
}
);
swDownload.Stop();
_logger?.LogInformation($"DownloadImages done in : {swDownload.Elapsed:g}");
return(tiles);
}
public TileRange ComputeBoundingBoxTileRange(BoundingBox bbox, ImageryProvider provider, int minTilesPerImage = 4)
{
TileRange tiles = new TileRange(provider);
BoundingBox mapBbox;
PointInt topLeft;
PointInt bottomRight;
// optimal zoom calculation (maybe there's a direct way)
// calculate the size of the full bbox at increasing zoom levels
// until the full image would be greater than a tile
int zoom = 0;
int maxSize = provider.TileSize * minTilesPerImage;
do
{
zoom++;
// coords are pixels in global map image (see TileUtils.MapSize(zoom))
topLeft = TileUtils.LatLongToPixelXY(bbox.yMax, bbox.xMin, zoom);
bottomRight = TileUtils.LatLongToPixelXY(bbox.yMin, bbox.xMax, zoom);
mapBbox = new BoundingBox(topLeft.X, bottomRight.X, topLeft.Y, bottomRight.Y);
}while (zoom < provider.MaxZoom &&
(mapBbox.Width < maxSize || mapBbox.Height < maxSize));
// now we have the minimum zoom without image
// we can know which tiles are needed
tiles.Start = new MapTileInfo(TileUtils.PixelXYToTileXY(topLeft.X, topLeft.Y), zoom);
tiles.End = new MapTileInfo(TileUtils.PixelXYToTileXY(bottomRight.X, bottomRight.Y), zoom);
tiles.AreaOfInterest = mapBbox;
return(tiles);
}
public byte[] GenerateTile(int x, int y, int zoom)
{
byte[] tileBytes = null;
var font = SixLabors.Fonts.SystemFonts.CreateFont("Arial", 12);
var corner = TileUtils.TileXYToPixelXY(x, y);
var latLong = TileUtils.PixelXYToLatLong(corner.X, corner.Y, zoom);
var latLongOffset = TileUtils.PixelXYToLatLong(corner.X + TileSize, corner.Y + TileSize, zoom);
var graticules = graticuleService.DrawCore(latLong, latLongOffset);
using (Image <Rgba32> outputImage = new Image <Rgba32>(this.TileSize, this.TileSize))
{
string tileText = $"{x}/{y}/{zoom}{Environment.NewLine}";
outputImage.Mutate(o => o
.Fill(Rgba32.White)
.DrawText(tileText, font, Rgba32.Black, new PointF(10, 10))
);
outputImage.Mutate(o => DrawGraticules(o, graticules, corner, zoom));
// Test
if (DebugPoint != null)
{
var testPixel = TileUtils.LatLongToPixelXY(DebugPoint.Latitude, DebugPoint.Longitude, zoom);
var testTile = TileUtils.PixelXYToTileXY(testPixel.X, testPixel.Y);
// Draw test pixel
if (testTile.X == x && testTile.Y == y)
{
var basex = TileUtils.TileXYToPixelXY(x, y);
var ptLoc = new PointF(testPixel.X - basex.X, testPixel.Y - basex.Y);
outputImage.Mutate(o =>
o.DrawLines(Rgba32.Blue, 1f,
new PointF[] { new PointF(ptLoc.X - 10, ptLoc.Y - 10), new PointF(ptLoc.X + 10, ptLoc.Y + 10) })
.DrawLines(Rgba32.Blue, 1f,
new PointF[] { new PointF(ptLoc.X - 10, ptLoc.Y + 10), new PointF(ptLoc.X + 10, ptLoc.Y - 10) }));
}
}
using (MemoryStream ms = new MemoryStream())
{
outputImage.SaveAsPng(ms);
tileBytes = ms.ToArray();
}
}
return(tileBytes);
}