OpenStreetMapRasterTileSource¶

Namespace: ThinkGeo.Core

OpenStreetMap's public raster tiles, as an RasterTileSource.

public class OpenStreetMapRasterTileSource : XyzRasterTileSource, System.IDisposable

Inheritance object → RasterTileSource → XyzRasterTileSource → OpenStreetMapRasterTileSource
Implements IDisposable

Remarks:

An XyzRasterTileSource over OpenStreetMap's own hosts and nothing more - the server is an ordinary XYZ server, so the only thing this type adds is the three URLs and the two things the tile usage policy asks of every application: a descriptive HTTP user agent, which the constructor takes, and caching, which is why XyzRasterTileSource.TileCache is worth setting before the first tile.

Properties¶

TileSize¶

public int TileSize { get; }

Property Value¶

int

UserAgent¶

The HTTP user agent sent with every tile request. Public tile servers commonly require an identifying one.

public string UserAgent { get; set; }

Property Value¶

string

TileCache¶

Where fetched tiles are kept between runs. Null fetches every time; a public tile service's usage policy usually asks for one.

public RasterTileCache TileCache { get; set; }

Property Value¶

RasterTileCache

WebProxy¶

The proxy tile requests go through, or null for the system default.

public IWebProxy WebProxy { get; set; }

Property Value¶

IWebProxy

TimeoutInSeconds¶

How long one tile request may take before it is abandoned.

public int TimeoutInSeconds { get; set; }

Property Value¶

int

IsOpen¶

public bool IsOpen { get; }

Property Value¶

bool

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¶

TileMatrixSet

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¶

bool

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

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¶

int

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¶

int

Constructors¶

OpenStreetMapRasterTileSource()¶

Initializes a new instance with the default "OpenStreetMap" user agent.

public OpenStreetMapRasterTileSource()

OpenStreetMapRasterTileSource(string)¶

Initializes a new instance using the specified user agent.

public OpenStreetMapRasterTileSource(string userAgent)

Parameters¶

userAgent string

        How your application identifies itself. OpenStreetMap's usage policy asks for
        something descriptive; a generic one may be refused.

Events¶

SendingHttpRequest¶

Raised before each tile request is sent. Rewrite the request to inject an API key, a signed URL or authentication headers; set Cancel to skip the request. This is how keyed providers plug in without a dedicated class.

public event EventHandler<SendingHttpRequestMessageEventArgs> SendingHttpRequest;

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;