GoogleMapsAsyncLayer¶

Namespace: ThinkGeo.Core

Represents an object that encapsulates a Google Map layer.

public class GoogleMapsAsyncLayer : WebBasedAsyncLayer

Inheritance Object → LayerBase → AsyncLayer → WebBasedAsyncLayer → GoogleMapsAsyncLayer

Remarks:

This class uses Google Static Maps API to implement url request.

Properties¶

PictureFormat¶

Gets or sets a value represents the image format of the image.

public GoogleMapsPictureFormat PictureFormat { get; set; }

Property Value¶

GoogleMapsPictureFormat

MapType¶

Gets or sets a value represents the map type of the GoogleMaps.

public GoogleMapsMapType MapType { get; set; }

Property Value¶

GoogleMapsMapType

Language¶

public string Language { get; set; }

Property Value¶

String

ClientId¶

Gets or sets a value to access the special features of Google Maps API Premier, you must provide a client ID when accessing any of the Premier API libraries or services. When registering for Google Maps API Premier, you will receive this client ID from Google Enterprise Support. All client IDs begin with a gme- prefix.

public string ClientId { get; set; }

Property Value¶

String

PrivateKey¶

Gets or sets a value that is unique to your client ID, please keep your key secure.

public string PrivateKey { get; set; }

Property Value¶

String

UriSigningSecret¶

public string UriSigningSecret { get; set; }

Property Value¶

String

ApiKey¶

public string ApiKey { get; set; }

Property Value¶

String

CustomParameters¶

public Dictionary<string, string> CustomParameters { get; }

Property Value¶

Dictionary<String, String>

TargetProjection¶

public Projection TargetProjection { get; set; }

Property Value¶

Projection

WebProxy¶

public IWebProxy WebProxy { get; set; }

Property Value¶

IWebProxy

TimeoutInSeconds¶

public int TimeoutInSeconds { get; set; }

Property Value¶

Int32

UpperThreshold¶

This property gets and sets the upper threshold in the scale at which to display the image.

public double UpperThreshold { get; set; }

Property Value¶

Double
This property gets the upper threshold in the scale at which to display the image.

Remarks:

Above the upper threshold in scale, the image will not be displayed. This, in conjunction with the LowerThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is 0. This means the image should always display.

LowerThreshold¶

This property gets and sets the lower threshold in the scale at which to display the image.

public double LowerThreshold { get; set; }

Property Value¶

Double
This property gets the lower threshold in the scale at which to display the image.

Remarks:

Below the lower threshold in scale, the image will not be displayed. This, in conjunction with the UpperThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is 0. This means the image should always display.

Credentials¶

This property gets or sets the base authentication interface for retrieving credentials for Web Client authentication.

public ICredentials Credentials { get; set; }

Property Value¶

ICredentials

UserAgent¶

This property allows you to specify a custom user-agent request header when making requests to a Web server. This header provides information about the client application or device and can be useful for server-side logging and analytics.

public string UserAgent { get; set; }

Property Value¶

String

Name¶

This property gets and sets the name for the layer.

public string Name { get; set; }

Property Value¶

String

Remarks:

The name is user defined. It is useful to set, as it may be used for higher level components such as legends, etc.

IsOpen¶

This property returns true if the Layer is open and false if it is not.

public bool IsOpen { get; }

Property Value¶

Boolean

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¶

This property gets and set the visible state of the layer.

public bool IsVisible { get; set; }

Property Value¶

Boolean

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.

DrawingTime¶

This property gets the last drawing time for the layer.

public TimeSpan DrawingTime { get; protected set; }

Property Value¶

TimeSpan

Remarks:

We track the drawing time for the layer and report it back in this method. This is useful for determining the speed of various layers.

Projection¶

Gets the projection of the layer.

public Projection Projection { get; set; }

Property Value¶

Projection

DrawingExceptionMode¶

public DrawingExceptionMode DrawingExceptionMode { get; set; }

Property Value¶

DrawingExceptionMode

Background¶

Gets and sets the background of the layer.

public GeoColor Background { get; set; }

Property Value¶

GeoColor

Transparency¶

This property gets and sets the amount of transparency to apply to the image.

public float Transparency { get; set; }

Property Value¶

Single
This property gets the amount of transparency to apply to the image.

Remarks:

None

BlueTranslation¶

This property gets and sets the amount of blue to apply to the image.

public float BlueTranslation { get; set; }

Property Value¶

Single
This property gets the amount of blue to apply to the image.

Remarks:

None

RedTranslation¶

This property gets and sets the amount of red to apply to the image.

public float RedTranslation { get; set; }

Property Value¶

Single
This property gets the amount of red to apply to the image.

Remarks:

None

GreenTranslation¶

This property gets and sets the amount of green to apply to the image.

public float GreenTranslation { get; set; }

Property Value¶

Single
This property gets the amount of green to apply to the image.

Remarks:

None

KeyColors¶

Gets a value represents a collection of key colors. If SupportKeyColor property is false, it will throw exception when you use KeyColors.

public Collection<GeoColor> KeyColors { get; }

Property Value¶

Collection<GeoColor>

Remarks:

It will make these colors transparent when draw image.

IsNegative¶

This property gets and sets whether the image should be converted to negative (inverse colors).

public bool IsNegative { get; set; }

Property Value¶

Boolean
This property gets and sets whether the image should be converted to negative (inverse colors).

Remarks:

None

IsGrayscale¶

This property gets and sets if the image should be converted to grayscale.

public bool IsGrayscale { get; set; }

Property Value¶

Boolean

        This property gets and sets if the image should be converted to grayscale.

Remarks:

None

HasBoundingBox¶

This property indicates whether a Layer has a BoundingBox or not. If it has no BoundingBox, it will throw an exception when you call the GetBoundingBox() and GetFullExtent() APIs.

public bool HasBoundingBox { get; }

Property Value¶

Boolean

Remarks:

The default value is false.

ThreadSafe¶

public ThreadSafetyLevel ThreadSafe { get; set; }

Property Value¶

ThreadSafetyLevel

ColorMappings¶

ColorMapping

public Dictionary<GeoColor, GeoColor> ColorMappings { get; }

Property Value¶

Dictionary<GeoColor, GeoColor>

WrappingMode¶

public WrappingMode WrappingMode { get; set; }

Property Value¶

WrappingMode

WrappingExtent¶

public RectangleShape WrappingExtent { get; set; }

Property Value¶

RectangleShape

Constructors¶

GoogleMapsAsyncLayer()¶

This is the constructor the for the class. If you use this constructor, then you need to set the required properties manually.

public GoogleMapsAsyncLayer()

Remarks:

None

GoogleMapsAsyncLayer(String)¶

This is the constructor the for the class.

public GoogleMapsAsyncLayer(string apiKey)

Parameters¶

apiKey String
The apiKey for the GoogleMapLayer.

Remarks:

This constructor initializes a new layer and assgin a license key.

GoogleMapsAsyncLayer(String, String)¶

This is the constructor the for the class.

public GoogleMapsAsyncLayer(string apiKey, string uriSigningSecret)

Parameters¶

apiKey String
The apiKey for the GoogleMapLayer.

uriSigningSecret String
The uriSigningSecret for the GoogleMapLayer.

Remarks:

This constructor initializes a new layer and assgin a license key and initilize a cache directory.

Methods¶

OpenAsyncCore(CancellationToken)¶

This method opens the Layer so that it is initialized and ready to use.

protected Task OpenAsyncCore(CancellationToken cancellationToken)

Parameters¶

cancellationToken CancellationToken

Returns¶

Task
None

Exceptions¶

InvalidOperationException
In the event you attempt to call this method on a Layer which has already been opened, it will throw an InvalidOperationException.

Remarks:

This abstract method is called from the concrete public method Open. The open method plays an important role, as it is responsible for initializing the Layer. Most methods on the Layer will throw an exception if the state of the Layer is not opened. When the map draws each layer, the layer will be opened as one of its first steps; then, after it is finished drawing with that layer, it will close it. In this way, we are sure to release all resources used by the Layer.

When implementing the abstract method, consider opening the FeatureSource or RasterSource. You will get a chance to close these in the Close method of the Layer.

CloseAsyncCore(CancellationToken)¶

This method closes the Layer and releases any resources it was using.

protected Task CloseAsyncCore(CancellationToken cancellationToken)

Parameters¶

cancellationToken CancellationToken

Returns¶

Task
None

Remarks:

This abstract method is called from the concrete public method Close. The close method plays an important role in the life cycle of the Layer. It may be called after drawing to release any memory and other resources that were allocated since the Open method was called.

If you override this method, it is recommended that you take the following things into account: This method may be called multiple times, so we suggest you write the method so that that a call to a closed Layer is ignored and does not generate an error. We also suggest that in the Close you free all resources that have been opened. Remember that the object will not be destroyed, but will be re-opened possibly in the near future.

DrawAsyncCore(GeoCanvas, Collection<SimpleCandidate>)¶

This method draws the Layer.

protected Task DrawAsyncCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)

Parameters¶

canvas GeoCanvas
This parameter is the view object or a NativeImage to draw on.

labelsInAllLayers Collection<SimpleCandidate>

        This parameter represents the labels used for collision detection and duplication
        checking.

Returns¶

Task
None

Remarks:

This method is the concrete wrapper for the abstract method DrawCore. This method draws the representation of the layer based on the extent you provided.

When implementing this abstract method, consider each feature and its column data values. You can use the full power of the GeoCanvas to do the drawing. If you need column data for a feature, be sure to override the GetRequiredColumnNamesCore and add the columns you need to the collection. In many of the styles, we add properties that allow the user to specify which field they need; then, in the GetRequiredColumnNamesCore, we read that property and add it to the collection.

DownloadImageAsyncCore(Double, Double, Double, RectangleShape, GeographyUnit, CancellationToken)¶

protected Task<Byte[]> DownloadImageAsyncCore(double width, double height, double scaleFactor, RectangleShape extent, GeographyUnit mapUnit, CancellationToken cancellationToken)

Parameters¶

width Double

height Double

scaleFactor Double

extent RectangleShape

mapUnit GeographyUnit

cancellationToken CancellationToken

Returns¶

Task<Byte[]>

GetPictureFormat()¶

Get picture format string which will use for request url.

public string GetPictureFormat()

Returns¶

String
Get picture format string which will use for request url.

Events¶

SendingHttpRequest¶

public event EventHandler<SendingHttpRequestMessageEventArgs> SendingHttpRequest;

ReceivedHttpResponse¶

public event EventHandler<ReceivedHttpResponseMessageEventArgs> ReceivedHttpResponse;

DrawingException¶

public event EventHandler<DrawingExceptionLayerEventArgs> DrawingException;

DrawnException¶

public event EventHandler<DrawnExceptionLayerEventArgs> DrawnException;