MbTilesRasterTileSource¶
Namespace: ThinkGeo.Core
Raster tiles from a local MBTiles archive.
public sealed class MbTilesRasterTileSource : RasterTileSource, System.IDisposable
Inheritance object → RasterTileSource → MbTilesRasterTileSource
Implements IDisposable
Remarks:
MBTiles stores rows in the TMS order, counting from the south, while the renderer indexes tiles the slippy-map way, counting from the north. The flip happens here, so callers speak XYZ throughout.
Properties¶
MetadataJson¶
The archive's metadata table as one JSON object, read once at open: every row as a string value, with a "json" row's own content merged in, so a .mbtiles reads the same way PmTilesRasterTileSource.MetadataJson does.
public string MetadataJson { get; private set; }
Property Value¶
IsOpen¶
public bool IsOpen { get; }
Property Value¶
TileMatrixSet¶
Gets the tile grid this source PUBLISHES on: one TileMatrix per zoom level, indexed by zoom. The native grid, or the reprojection target when the tiles are being republished onto another grid.
public TileMatrixSet TileMatrixSet { get; }
Property Value¶
DrawsFallbackTiles¶
Gets or sets a value indicating whether a tile of this source, magnified from a shallower zoom, is worth showing while the tiles for the current one arrive.
public bool DrawsFallbackTiles { get; set; }
Property Value¶
Remarks:
True for imagery, and the default: a magnified aerial is a blurred version of the truth, in the right place, and it beats a hole in the map for the second or two the new tiles take.
Set it false for a source whose tiles are symbols drawn at a fixed size - a WMS of points or labels on nothing. Magnifying one of those does not blur it; it draws the symbols at the wrong size, beside the correctly sized ones in the cells that have already arrived. Measured on a service taking 1.2 s a tile, that is the whole of the transition. With this false the cells simply stay empty until their own tiles come, and whatever is under the layer shows through.
It says nothing about tiles that have arrived. A loaded tile always replaces the zoom beneath it across its whole footprint, transparent pixels included.
https://community.thinkgeo.com/t/bug-gpu-raster-tiles-from-previous-zooms-remain-visible/12479
TileSize¶
Gets the edge length, in pixels, of the tiles this source publishes.
public int TileSize { get; }
Property Value¶
MinDataZoom¶
The shallowest zoom level tiles exist at. A subclass that learns the range from the data - an archive header, a service capability - records it through at open.
public int MinDataZoom { get; }
Property Value¶
MaxDataZoom¶
The deepest zoom level tiles exist at; deeper views reuse this level's tiles (overzoom). See RasterTileSource.MinDataZoom.
public int MaxDataZoom { get; }
Property Value¶
Constructors¶
MbTilesRasterTileSource(string)¶
Initializes a source over the .mbtiles file at .
public MbTilesRasterTileSource(string filePath)
Parameters¶
filePath string
Methods¶
OpenAsync(CancellationToken)¶
public Task OpenAsync(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
Returns¶
GetTileImageAsyncCore(int, long, long, CancellationToken)¶
protected Task<Byte[]> GetTileImageAsyncCore(int zoom, long x, long y, CancellationToken cancellationToken)
Parameters¶
zoom int
x long
y long
cancellationToken CancellationToken
Returns¶
Dispose(bool)¶
Closes the archive.
protected void Dispose(bool disposing)
Parameters¶
disposing bool
Returns¶
Events¶
DataChanged¶
Raised when the tiles this source serves have changed - by RasterTileSource.Refresh(RectangleShape) - with the ground they changed over, null for all of it. The map listens and asks again.
public event EventHandler<TileSourceDataChangedEventArgs> DataChanged;