/// <summary>
/// Renders the layer
/// </summary>
/// <param name="g">Graphics object reference</param>
/// <param name="map">Map which is rendered</param>
public override void OnRender(System.Drawing.Graphics g, IMap map)
{
MapTransform mapTransform = new MapTransform(new PointF((float)Map.Center.X, (float)Map.Center.Y), (float)Map.PixelSize, Map.Image.Width, Map.Image.Height);
string level = BruTile.Utilities.GetNearestLevel(Schema.Resolutions, Map.PixelSize);
IEnumerable <TileInfo> tileInfos = Schema.GetTileInfos(mapTransform.Extent, level);
var graphics = Graphics.FromImage(Image);
//log.DebugFormat("Downloading tiles:");
foreach (var tileInfo in tileInfos)
{
var bytes = cache.Find(tileInfo.Index);
if (bytes == default(byte[]))
{
try
{
//log.DebugFormat("row: {0}, column: {1}, level: {2}", tileInfo.Index.Row, tileInfo.Index.Col, tileInfo.Index.Level);
bytes = TileSource.GetTile(tileInfo);
cache.Add(tileInfo.Index, bytes);
}
catch (WebException e)
{
//log once per 45 seconds max
if ((DateTime.Now - lastErrorLogged) > TimeSpan.FromSeconds(45))
{
log.Error("Can't fetch tiles from the server", e);
lastErrorLogged = DateTime.Now;
}
}
}
else
{
//log.DebugFormat("row: {0}, column: {1}, level: {2} (cached)", tileInfo.Index.Row, tileInfo.Index.Col, tileInfo.Index.Level);
}
if (bytes == null)
{
continue;
}
using (var bitmap = new Bitmap(new MemoryStream(bytes)))
{
var rectangle = mapTransform.WorldToMap(tileInfo.Extent.MinX, tileInfo.Extent.MinY,
tileInfo.Extent.MaxX, tileInfo.Extent.MaxY);
DrawTile(Schema, level, graphics, bitmap, rectangle);
}
}
}
private IList <IFeature> GetFeaturesInTile(TileInfo tileInfo)
{
if (TileSource == null)
{
return(null);
}
var features = _cache?.Find(tileInfo.Index);
// Is tile in cache?
if (features == null)
{
// No, tile not in cache, so get tile data new
// Calc tile offset relative to upper left corner
double factor = (tileInfo.Extent.MaxX - tileInfo.Extent.MinX) / 4096.0;
var tileData = TileSource.GetTile(tileInfo);
if (tileData == null)
{
// Tile isn't in this source, so construct one from lower zoom level
var maxZoom = int.Parse(BruTile.Utilities.GetNearestLevel(TileSource.Schema.Resolutions, TileSource.Schema.Resolutions[(TileSource.Schema.Resolutions.Count - 1).ToString()].UnitsPerPixel));
// Get bounds of this tile
var bounds = new BoundingBox(new Point(tileInfo.Extent.MinX, tileInfo.Extent.MinY), new Point(tileInfo.Extent.MaxX, tileInfo.Extent.MaxY));
// Calc new TileInfo
var zoom = int.Parse(tileInfo.Index.Level);
// If zoom is ok, than there are no tile informations for this tile
if (zoom <= maxZoom)
{
return(null);
}
var tileX = tileInfo.Index.Col;
var tileY = tileInfo.Index.Row;
while (zoom > maxZoom)
{
zoom--;
tileX = tileX >> 1;
tileY = tileY >> 1;
}
var newTileInfo = new TileInfo {
Index = new TileIndex(tileX, tileY, zoom.ToString())
};
// Now get features for this overview tile
var newFeatures = GetFeaturesInTile(newTileInfo);
// Extract all features, which belong to small tile
features = new List <IFeature>();
foreach (var feature in newFeatures)
{
if (feature is VectorTileFeature vft)
{
if (vft.Bounds.Intersects(bounds))
{
features.Add(vft);
}
}
}
// Save for later use
if (_cache != null)
{
_cache.Add(tileInfo.Index, features);
}
}
if (features == null && tileData != null)
{
// Parse tile and convert it to a feature list
Stream stream = new MemoryStream(tileData);
if (IsGZipped(stream))
{
stream = new GZipStream(stream, CompressionMode.Decompress);
}
features = VectorTileParser.Parse(tileInfo, stream);
// Save for later use
if (_cache != null && features.Count > 0)
{
_cache.Add(tileInfo.Index, features);
}
stream = null;
}
}
System.Diagnostics.Debug.WriteLine($"Cached Tile Level={tileInfo.Index.Level}, Col={tileInfo.Index.Col}, Row={tileInfo.Index.Row}");
return(features);
}