WfsAsyncLayer¶
Namespace: ThinkGeo.Core
Represents a web layer that asynchronously requests and renders data from a WFS 1.0 service.
public class WfsAsyncLayer : WebBasedAsyncFeatureLayer, IHttpRequestService
Inheritance object → LayerBase → AsyncLayer → AsyncFeatureLayer → WebBasedAsyncFeatureLayer → WfsAsyncLayer
Implements IHttpRequestService
Remarks:
This is the asynchronous counterpart to WfsFeatureLayer. WFS 1.0 remains in wide use - a great many municipal and national services publish nothing newer - so it gets an async layer of its own rather than being pointed at WfsV2AsyncLayer, which speaks only 2.0 and is not a substitute.
The service is read through a WfsAsyncFeatureSource. Styling is set on ; queries beyond the bounding box go to WfsAsyncLayer.FeatureSource directly, which offers the smaller set WFS 1.0 supports.
Properties¶
FeatureSource¶
Gets the WFS 1.0 source this layer draws from.
public AsyncFeatureSource FeatureSource { get; }
Property Value¶
ServiceLocationUrl¶
Gets or sets the base URL of the target WFS service.
public string ServiceLocationUrl { get; set; }
Property Value¶
TypeName¶
Gets or sets the feature type (layer) name that will be requested.
public string TypeName { get; set; }
Property Value¶
WfsNamespace¶
Gets or sets the namespace prefix used when building filter documents.
public WfsNamespace WfsNamespace { get; set; }
Property Value¶
GeometryType¶
Gets the kind of geometry this feature type holds - points, lines or areas.
public WellKnownType GeometryType { get; }
Property Value¶
Remarks:
Available once the layer is open, and WellKnownType.Invalid before that. See .
HttpClient¶
Gets or sets the client the source sends with. Left unset, the source makes one from WebBasedAsyncFeatureLayer.HttpMessageHandler, WebBasedAsyncFeatureLayer.WebProxy, WebBasedAsyncFeatureLayer.Credentials and WebBasedAsyncFeatureLayer.TimeoutInSeconds when it opens and disposes it when it closes; one set here belongs to the caller and is left alone.
public HttpClient HttpClient { get; set; }
Property Value¶
HttpMessageHandler¶
Gets or sets the handler the source builds its own client around.
public HttpMessageHandler HttpMessageHandler { get; set; }
Property Value¶
WebProxy¶
Gets or sets the proxy the source sends through.
public IWebProxy WebProxy { get; set; }
Property Value¶
TimeoutInSeconds¶
Gets or sets how long the source waits for a response, in seconds.
public int TimeoutInSeconds { get; set; }
Property Value¶
Credentials¶
Gets or sets the credentials the source sends with.
public ICredentials Credentials { get; set; }
Property Value¶
UserAgent¶
Gets or sets the User-Agent header the source sends.
public string UserAgent { get; set; }
Property Value¶
UpperScale¶
Gets or sets the largest scale at which the layer is drawn. Beyond it nothing is requested. AsyncFeatureLayer.ZoomLevelSet bands the styles by zoom level already; this is a blunt cut-off on top of it.
public double UpperScale { get; set; }
Property Value¶
LowerScale¶
Gets or sets the smallest scale at which the layer is drawn. See WebBasedAsyncFeatureLayer.UpperScale.
public double LowerScale { get; set; }
Property Value¶
ConcurrentAccess¶
Gets or sets how this layer behaves when more than one thread wants to draw it at once. This is its AsyncFeatureLayer.FeatureSource's value, exactly as FeatureLayer does it.
public ConcurrentAccess ConcurrentAccess { get; set; }
Property Value¶
ZoomLevelSet¶
Gets or sets the styles used to draw this layer, banded by zoom level.
public ZoomLevelSet ZoomLevelSet { get; set; }
Property Value¶
DrawingMarginInPixel¶
Gets or sets how far beyond the visible extent features are requested, in pixels.
public float DrawingMarginInPixel { get; set; }
Property Value¶
Remarks:
A margin keeps symbols and labels that straddle the edge of the view from being clipped. FeatureLayer defaults to 50 because widening a query against a local file costs almost nothing; here the default is 0, because every pixel of margin is extra extent a remote source has to answer for on every redraw. Raise it when clipped symbols at the edge of the view matter more than the traffic.
ProjectionConverter¶
Gets or sets the converter applied between the source's coordinate system and the map's.
public ProjectionConverter ProjectionConverter { get; set; }
Property Value¶
Name¶
Gets or sets the display name for the layer.
public string Name { get; set; }
Property Value¶
string
The name used to identify the layer within UI components such as legends.
Remarks:
The name is user defined. Assign a descriptive value so tooling such as legends and layer lists can surface a meaningful label to end users.
IsOpen¶
Gets a value indicating whether the layer is currently open.
public bool IsOpen { get; }
Property Value¶
bool
true if the layer has completed its open routine; otherwise, false.
Remarks:
This method is the concrete wrapper for the abstract method IsOpenCore. Various methods on the Layer require that it be in an open state. If one of those methods is called when the state is not open, then the method will throw an exception. To enter the open state, you must call the Layer Open method. The method will raise an exception if the current Layer is already open.
As this is a concrete public method that wraps a Core method, we reserve the right to add events and other logic to pre- or post-process data returned by the Core version of the method. In this way, we leave our framework open on our end, but also allow you the developer to extend our logic to suit your needs. If you have questions about this, please contact our support team as we would be happy to work with you on extending our framework.
IsVisible¶
Gets or sets a value indicating whether the layer is visible.
public bool IsVisible { get; set; }
Property Value¶
bool
true to draw the layer; otherwise, false.
Remarks:
If this property is set to false, the layer will not draw. We ensure this in the Draw method. This is useful for legends and other controls that control the visibility of layers.
Projection¶
Gets the projection of the layer.
public Projection Projection { get; set; }
Property Value¶
DrawingExceptionMode¶
Gets or sets how drawing exceptions are handled when the layer renders.
public DrawingExceptionMode DrawingExceptionMode { get; set; }
Property Value¶
Background¶
Gets or sets the background color used when rendering the layer.
public GeoColor Background { get; set; }
Property Value¶
GeoColor
The fill applied to areas not covered by layer content.
Transparency¶
Gets or sets the amount of transparency applied to the rendered image.
public float Transparency { get; set; }
Property Value¶
float
A value between 0 (fully transparent) and 255 (fully opaque).
Opacity¶
Gets or sets the opacity applied to the rendered image.
public float Opacity { get; set; }
Property Value¶
float
A value between 0.0 (fully transparent) and 1.0 (fully opaque).
BlueTranslation¶
Gets or sets the intensity adjustment applied to the blue channel.
public float BlueTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the blue channel translation.
RedTranslation¶
Gets or sets the intensity adjustment applied to the red channel.
public float RedTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the red channel translation.
GreenTranslation¶
Gets or sets the intensity adjustment applied to the green channel.
public float GreenTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the green channel translation.
KeyColors¶
Gets the collection of key colors that should be rendered as transparent.
public Collection<GeoColor> KeyColors { get; }
Property Value¶
Remarks:
Attempting to access this collection when the associated GeoCanvas does not support key colors (see GeoCanvas.SupportKeyColor) results in an exception. Add colors to this collection to ensure they render as transparent.
IsNegative¶
Gets or sets a value indicating whether the image should be rendered with inverted colors.
public bool IsNegative { get; set; }
Property Value¶
bool
true to invert the color channels; otherwise, false.
IsGrayscale¶
Gets or sets a value indicating whether the image should be converted to grayscale prior to rendering.
public bool IsGrayscale { get; set; }
Property Value¶
bool
true to apply a grayscale filter; otherwise, false.
HasBoundingBox¶
Gets a value indicating whether the layer supports retrieving its bounding box.
public bool HasBoundingBox { get; }
Property Value¶
Remarks:
When this property is false, calls to or GetFullExtent throw an exception. The default implementation returns false.
ThreadSafe¶
Gets or sets the threading guarantees provided by the layer implementation.
public ThreadSafetyLevel ThreadSafe { get; set; }
Property Value¶
ThreadSafetyLevel
The level of thread safety that callers can expect when interacting with the layer.
Remarks:
Replaced by LayerBase.ConcurrentAccess and kept only so that code written against it is told, by name, what to use instead. It does not compile, so there is never a question of which of the two a caller meant: there is one value, and it is the other one. That matters because the translation was lossy in one direction - writing ThreadSafetyLevel.Unsafe could only pick ConcurrentAccess.UnsafeLock, and would silently undo a layer or source that had said ConcurrentAccess.UnsafeClone.
ColorMappings¶
Gets the color translation map that will be applied when rendering the layer.
public Dictionary<GeoColor, GeoColor> ColorMappings { get; }
Property Value¶
Dictionary<GeoColor, GeoColor>
WrappingMode¶
Gets or sets how the layer wraps when the map extent crosses world boundaries.
public WrappingMode WrappingMode { get; set; }
Property Value¶
WrappingExtent¶
Gets or sets the geographic extent to use when wrapping is enabled.
public RectangleShape WrappingExtent { get; set; }
Property Value¶
Constructors¶
WfsAsyncLayer()¶
Initializes a new instance of the WfsAsyncLayer class.
public WfsAsyncLayer()
WfsAsyncLayer(string, string)¶
Initializes a new instance of the WfsAsyncLayer class using the specified service endpoint and feature type name.
public WfsAsyncLayer(string serviceLocationUrl, string typeName)
Parameters¶
serviceLocationUrl string
The base URL of the WFS service.
typeName string
The feature type (layer) name to request.
Methods¶
GetRasterContentTypeCore()¶
WFS responses are feature vectors rendered as cartography.
protected RasterContentType GetRasterContentTypeCore()
Returns¶
RasterContentType
The raster content type this layer produces.
GetBoundingBoxAsync(CancellationToken)¶
Returns the extent the service reports for this feature type.
public Task<RectangleShape> GetBoundingBoxAsync(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
A token that cancels the operation.
Returns¶
Task<RectangleShape>
The extent, or null when the service reports none.
Remarks:
WFS 1.0 has no per-type extent that can be read without a feature request, so this costs one round trip. It is asynchronous for that reason, unlike the synchronous GetBoundingBox on the layers that read theirs from a capabilities document.
GetCapabilitiesAsync(string, IWebProxy, HttpMessageHandler, CancellationToken)¶
Issues a WFS GetCapabilities request and returns the raw XML response as a string.
public static Task<string> GetCapabilitiesAsync(string url, IWebProxy webProxy, HttpMessageHandler httpMessageHandler, CancellationToken cancellationToken)
Parameters¶
url string
The base URL of the WFS service.
webProxy IWebProxy
The proxy the request goes through, or null for the system default proxy. Not used when is given: a handler carries its own proxy.
httpMessageHandler HttpMessageHandler
Optional handler for the request. The caller retains ownership; not disposed here.
cancellationToken CancellationToken
A token that can be used to cancel the request.
Returns¶
Task<string>
The GetCapabilities XML response.
Remarks:
The request asks for WFS 1.0, the version this layer speaks; the asynchronous counterpart of the static methods on WfsFeatureLayer.
GetCapabilitiesAsync(Uri, IWebProxy, HttpMessageHandler, CancellationToken)¶
Issues a WFS GetCapabilities request against the specified URI and returns the raw XML response as a string.
public static Task<string> GetCapabilitiesAsync(Uri serverUri, IWebProxy webProxy, HttpMessageHandler httpMessageHandler, CancellationToken cancellationToken)
Parameters¶
serverUri Uri
The base URI of the WFS service.
webProxy IWebProxy
The proxy the request goes through, or null for the system default proxy. Not used when is given: a handler carries its own proxy.
httpMessageHandler HttpMessageHandler
Optional handler for the request. The caller retains ownership; not disposed here.
cancellationToken CancellationToken
A token that can be used to cancel the request.
Returns¶
Task<string>
The GetCapabilities XML response.
GetLayersAsync(string, IWebProxy, HttpMessageHandler, CancellationToken)¶
Retrieves the collection of feature type names that are published by the specified WFS endpoint.
public static Task<Collection<string>> GetLayersAsync(string url, IWebProxy webProxy, HttpMessageHandler httpMessageHandler, CancellationToken cancellationToken)
Parameters¶
url string
The base URL of the WFS service.
webProxy IWebProxy
The proxy the request goes through, or null for the system default proxy. Not used when is given: a handler carries its own proxy.
httpMessageHandler HttpMessageHandler
Optional handler for the request. The caller retains ownership; not disposed here.
cancellationToken CancellationToken
A token that can be used to cancel the request.
Returns¶
Task<Collection<string>>
A collection that contains the discoverable feature type names.
Remarks:
The request asks for WFS 1.0, the version this layer speaks; the asynchronous counterpart of the static methods on WfsFeatureLayer.
GetLayersAsync(Uri, IWebProxy, HttpMessageHandler, CancellationToken)¶
Retrieves the collection of feature type names that are published by the WFS endpoint at the specified URI.
public static Task<Collection<string>> GetLayersAsync(Uri serverUri, IWebProxy webProxy, HttpMessageHandler httpMessageHandler, CancellationToken cancellationToken)
Parameters¶
serverUri Uri
The base URI of the WFS service.
webProxy IWebProxy
The proxy the request goes through, or null for the system default proxy. Not used when is given: a handler carries its own proxy.
httpMessageHandler HttpMessageHandler
Optional handler for the request. The caller retains ownership; not disposed here.
cancellationToken CancellationToken
A token that can be used to cancel the request.
Returns¶
Task<Collection<string>>
A collection that contains the discoverable feature type names.
Events¶
SendingHttpRequest¶
Raised before the source sends a request, with the request to inspect, change or cancel.
public event EventHandler<SendingHttpRequestMessageEventArgs> SendingHttpRequest;
ReceivedHttpResponse¶
Raised when the source has received a response, with the response to inspect or replace.
public event EventHandler<ReceivedHttpResponseMessageEventArgs> ReceivedHttpResponse;
DrawingException¶
Occurs when the DrawingException event is raised.
public event EventHandler<DrawingExceptionLayerEventArgs> DrawingException;
DrawnException¶
Occurs when the DrawnException event is raised.
public event EventHandler<DrawnExceptionLayerEventArgs> DrawnException;