/// <summary>
/// Notifies this layer that the current mapview has changed.
/// </summary>
/// <param name="map"></param>
/// <param name="zoomFactor"></param>
/// <param name="center"></param>
/// <param name="view"></param>
/// <param name="extraView"></param>
protected internal override void ViewChanged(Map map, float zoomFactor, GeoCoordinate center, View2D view, View2D extraView)
{
// calculate the current zoom level.
var zoomLevel = (int)System.Math.Round(map.Projection.ToZoomLevel(zoomFactor), 0);
if (zoomLevel >= _minZoomLevel && zoomLevel <= _maxZoomLevel)
{
// build the bounding box.
var viewBox = view.OuterBox;
// build the tile range.
var range = TileRange.CreateAroundBoundingBox(new GeoCoordinateBox(map.Projection.ToGeoCoordinates(viewBox.Min[0], viewBox.Min[1]),
map.Projection.ToGeoCoordinates(viewBox.Max[0], viewBox.Max[1])), zoomLevel);
OsmSharp.Logging.Log.TraceEvent("LayerMBTile", OsmSharp.Logging.TraceEventType.Verbose, string.Format("Requesting {0} tiles for view.", range.Count));
// request all missing tiles.
lock (_connection)
{ // make sure the connection is accessed synchronously.
// TODO: Investigate the SQLite multithreaded behaviour..
// TODO: this a very naive way of loading these tiles. Find a way to query SQLite more efficiently
// TODO: find a way to have some cached tiles.
foreach (var tile in range.EnumerateInCenterFirst())
{
Image2D value;
if (_cache.TryGet(tile, out value))
{
// Tile is already in cache. We used TryGet, and not TryPeek, to inform the cache
// that we intend to use the datum in question.
continue;
}
Tile invertTile = tile.InvertY();
var tiles = _connection.Query <tiles>("SELECT * FROM tiles WHERE zoom_level = ? AND tile_column = ? AND tile_row = ?",
invertTile.Zoom, invertTile.X, invertTile.Y);
foreach (var mbTile in tiles)
{
var box = tile.ToBox(_projection);
var nativeImage = _nativeImageCache.Obtain(mbTile.tile_data);
var image2D = new Image2D(box.Min[0], box.Min[1], box.Max[1], box.Max[0], nativeImage);
image2D.Layer = (uint)(_maxZoomLevel - tile.Zoom);
lock (_cache)
{ // add the result to the cache.
_cache.Add(tile, image2D);
}
}
}
}
OsmSharp.Logging.Log.TraceEvent("LayerMBTile", Logging.TraceEventType.Information, "Cached tiles: {0}", _cache.Count);
}
}
/// <summary>
/// Response the specified myResp and tile.
/// </summary>
/// <param name="myResp">My resp.</param>
/// <param name="tile">Tile.</param>
private void Response(WebResponse myResp, Tile tile)
{
if (_cache == null)
{
return;
}
try
{
Stream stream = myResp.GetResponseStream();
byte[] image = null;
if (stream != null)
{
using (stream)
{
// there is data: read it.
var memoryStream = new MemoryStream();
stream.CopyTo(memoryStream);
image = memoryStream.ToArray();
memoryStream.Dispose();
var box = tile.ToBox(_projection);
var nativeImage = _nativeImageCache.Obtain(image);
var image2D = new Image2D(box.Min[0], box.Min[1], box.Max[1], box.Max[0], nativeImage);
image2D.Layer = (uint)(_maxZoomLevel - tile.Zoom);
lock (_cache)
{ // add the result to the cache.
_cache.Add(tile, image2D);
}
}
if (!_suspended)
{ // only raise the event when not suspended but do no throw away a tile, that would be a waste.
this.RaiseLayerChanged();
}
}
else
{
OsmSharp.Logging.Log.TraceEvent("LayerTile", Logging.TraceEventType.Error, "No response stream!");
}
}
catch (Exception ex)
{ // don't worry about exceptions here.
OsmSharp.Logging.Log.TraceEvent("LayerTile", Logging.TraceEventType.Error, ex.Message);
}
}
