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Layer

Namespace: ThinkGeo.Core

This class is the base class for all types of Layers.

public abstract class Layer

Inheritance ObjectLayer

Remarks:

The Layer class is where all other types of layers are inherited from. It provides the base set of functionality. Though all Layers inherit from this class, we strongly suggest if you decide to create your own layer type that you consider inheriting from the higher level RasterLayer for image-based layers and FeatureLayer for feature-based layers. They provide a rich set of default operations for the various types of layers and are simple to inherit from.

As it is abstract, there are a number of methods you need to implement. The first is DrawCore. In this method, you are responsible for drawing the layer's representation. The other two required methods are OpenCore and CloseCore. These open and close the Layer. In the Open, you are responsible for getting the layer ready for drawing. You should open any file references, etc. In the Close, you need to clean up all file handles, close other objects etc. It is important that the Close puts the class in a state where it can be re-opened in the future. It is different than Dispose, as closed Layers will still exist and can be re-opened later in the mapping life cycle. Many methods (in the layer and in higher level objects) will require that the Layer be open before these methods are called, otherwise they will throw an exception.

Properties

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.

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.

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.

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.

Attribution

public string Attribution { get; set; }

Property Value

String

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.

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

ColorMappings

ColorMapping

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

Property Value

Dictionary<GeoColor, GeoColor>

DrawingExceptionMode

Gets or sets the DrawExceptionMode when exception happens.

public DrawingExceptionMode DrawingExceptionMode { get; set; }

Property Value

DrawingExceptionMode

ThreadSafe

public ThreadSafetyLevel ThreadSafe { get; set; }

Property Value

ThreadSafetyLevel

Projection

Gets the projection of the layer.

public Projection Projection { get; set; }

Property Value

Projection

Background

Gets and sets the background of the layer.

public GeoColor Background { get; set; }

Property Value

GeoColor

WrappingMode

public WrappingMode WrappingMode { get; set; }

Property Value

WrappingMode

WrappingExtent

public RectangleShape WrappingExtent { get; set; }

Property Value

RectangleShape

RequestDrawingInterval

public TimeSpan RequestDrawingInterval { get; set; }

Property Value

TimeSpan

Methods

OnRequestingDrawing(RequestingDrawingLayerEventArgs)

protected void OnRequestingDrawing(RequestingDrawingLayerEventArgs eventArgs)

Parameters

eventArgs RequestingDrawingLayerEventArgs

CloneDeep()

Create a copy of Layer using the deep clone process.

public Layer CloneDeep()

Returns

Layer
A cloned Layer.

Remarks:

The difference between deep clone and shallow clone is as follows: In shallow cloning, only the object is copied; the objects within it are not. By contrast, deep cloning copies the cloned object as well as all the objects within.

CloneDeepCore()

Create a copy of Layer using the deep clone process. The default implemenation uses serialization.

protected Layer CloneDeepCore()

Returns

Layer
A cloned Layer.

Remarks:

The difference between deep clone and shallow clone is as follows: In shallow cloning, only the object is copied; the objects within it are not. By contrast, deep cloning copies the cloned object as well as all the objects within.

LoadLayer(Uri)

public static Layer LoadLayer(Uri layerUri)

Parameters

layerUri Uri

Returns

Layer

LoadLayer(Stream)

public static Layer LoadLayer(Stream layerStream)

Parameters

layerStream Stream

Returns

Layer

Open()

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

public void Open()

Remarks:

This method is the concrete wrapper for the abstract method OpenCore. 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.

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.

OpenCore()

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

protected void OpenCore()

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.

Close()

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

public void Close()

Remarks:

This method is the concrete wrapper for the abstract method CloseCore. 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.


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.

CloseCore()

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

protected void CloseCore()

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.

GetBoundingBox()

This method returns the bounding box of the Layer.

public RectangleShape GetBoundingBox()

Returns

RectangleShape
This method returns the bounding box of the Layer.

Remarks:

This method is the concrete wrapper for the abstract method GetBoundingBoxCore. This method returns the bounding box of the RasterLayer.

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.

GetBoundingBoxCore()

This method returns the bounding box of the Layer.

protected RectangleShape GetBoundingBoxCore()

Returns

RectangleShape
This method returns the bounding box of the Layer.

Exceptions

InvalidOperationException
In the event you attempt to call this method on a layer which has not been opened, it will throw an InvalidOperationException.

Remarks:

This method returns the bounding box of the Layer.

Draw(GeoCanvas, Collection<SimpleCandidate>)

This method draws the Layer.

public void Draw(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.

Exceptions

ArgumentNullException
If you pass a null as the worldExtent, we will throw an ArgumentNullException.

ArgumentNullException
If you pass a null as the geoImageOrNativeImage, we will throw an ArgumentNullException.

ArgumentNullException
If you pass a null as the labeledInLayers, we will throw an ArgumentNullException.

ArgumentOutOfRangeException
If you pass in a mapUnit that is not defined in the enumeration, it will throw a ArgumentOutOfRangeException.

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.

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.

DrawWithColorTransformation(GeoCanvas, Collection<SimpleCandidate>, RectangleShape, Single, Single)

protected void DrawWithColorTransformation(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers, RectangleShape extent, float width, float height)

Parameters

canvas GeoCanvas

labelsInAllLayers Collection<SimpleCandidate>

extent RectangleShape

width Single

height Single

DrawException(GeoCanvas, Exception)

This method will draw on the view when the layer.Draw throw exception and the DrawExceptionMode is set to DrawException instead of ThrowException.

protected void DrawException(GeoCanvas canvas, Exception e)

Parameters

canvas GeoCanvas
The target view to draw the layer.

e Exception
The exception thrown when layer.Draw().

Remarks:

This method can be overriden its logic by rewrite the DrawExceptionCore.

DrawExceptionCore(GeoCanvas, Exception)

This method will draw on the view when the layer.Draw throw exception and the DrawExceptionMode is set to DrawException instead of ThrowException.

protected void DrawExceptionCore(GeoCanvas canvas, Exception e)

Parameters

canvas GeoCanvas
The target view to draw the layer.

e Exception
The exception thrown when layer.Draw().

OnDrawingException(DrawingExceptionLayerEventArgs)

protected void OnDrawingException(DrawingExceptionLayerEventArgs e)

Parameters

e DrawingExceptionLayerEventArgs

OnDrawnException(DrawnExceptionLayerEventArgs)

protected void OnDrawnException(DrawnExceptionLayerEventArgs e)

Parameters

e DrawnExceptionLayerEventArgs

DrawCore(GeoCanvas, Collection<SimpleCandidate>)

This method draws the Layer.

protected abstract void DrawCore(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.

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.

IsDrawingNeeded(Double)

public bool IsDrawingNeeded(double currentScale)

Parameters

currentScale Double

Returns

Boolean

IsDrawingNeededCore(Double)

protected bool IsDrawingNeededCore(double currentScale)

Parameters

currentScale Double

Returns

Boolean

DrawAttributionCore(GeoCanvas, String)

protected void DrawAttributionCore(GeoCanvas canvas, string attribution)

Parameters

canvas GeoCanvas

attribution String

OnDrawingAttribution(DrawingAttributionLayerEventArgs)

protected void OnDrawingAttribution(DrawingAttributionLayerEventArgs args)

Parameters

args DrawingAttributionLayerEventArgs

OnDrawnAttribution(DrawnAttributionLayerEventArgs)

protected void OnDrawnAttribution(DrawnAttributionLayerEventArgs args)

Parameters

args DrawnAttributionLayerEventArgs

OnDrawingProgressChanged(DrawingProgressChangedEventArgs)

protected void OnDrawingProgressChanged(DrawingProgressChangedEventArgs e)

Parameters

e DrawingProgressChangedEventArgs

RequestDrawing()

public void RequestDrawing()

RequestDrawing(RectangleShape)

public void RequestDrawing(RectangleShape extentToRefresh)

Parameters

extentToRefresh RectangleShape

RequestDrawing(IEnumerable<RectangleShape>)

public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh)

Parameters

extentsToRefresh IEnumerable<RectangleShape>

RequestDrawing(TimeSpan)

public void RequestDrawing(TimeSpan bufferTime)

Parameters

bufferTime TimeSpan

RequestDrawing(TimeSpan, RequestDrawingBufferTimeType)

public void RequestDrawing(TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)

Parameters

bufferTime TimeSpan

bufferTimeType RequestDrawingBufferTimeType

RequestDrawing(RectangleShape, TimeSpan)

public void RequestDrawing(RectangleShape extentToRefresh, TimeSpan bufferTime)

Parameters

extentToRefresh RectangleShape

bufferTime TimeSpan

RequestDrawing(RectangleShape, TimeSpan, RequestDrawingBufferTimeType)

public void RequestDrawing(RectangleShape extentToRefresh, TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)

Parameters

extentToRefresh RectangleShape

bufferTime TimeSpan

bufferTimeType RequestDrawingBufferTimeType

RequestDrawing(IEnumerable<RectangleShape>, TimeSpan)

public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh, TimeSpan bufferTime)

Parameters

extentsToRefresh IEnumerable<RectangleShape>

bufferTime TimeSpan

RequestDrawing(IEnumerable<RectangleShape>, TimeSpan, RequestDrawingBufferTimeType)

public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh, TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)

Parameters

extentsToRefresh IEnumerable<RectangleShape>

bufferTime TimeSpan

bufferTimeType RequestDrawingBufferTimeType

StartRequestDrawing()

protected void StartRequestDrawing()

OnRequestedDrawing(RequestedDrawingLayerEventArgs)

protected void OnRequestedDrawing(RequestedDrawingLayerEventArgs eventArgs)

Parameters

eventArgs RequestedDrawingLayerEventArgs

Events

DrawingProgressChanged

public event EventHandler<DrawingProgressChangedEventArgs> DrawingProgressChanged;

DrawingException

public event EventHandler<DrawingExceptionLayerEventArgs> DrawingException;

DrawnException

public event EventHandler<DrawnExceptionLayerEventArgs> DrawnException;

DrawingAttribution

public event EventHandler<DrawingAttributionLayerEventArgs> DrawingAttribution;

DrawnAttribution

public event EventHandler<DrawnAttributionLayerEventArgs> DrawnAttribution;

RequestedDrawing

public event EventHandler<RequestedDrawingLayerEventArgs> RequestedDrawing;

RequestingDrawing

public event EventHandler<RequestingDrawingLayerEventArgs> RequestingDrawing;