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RasterLayer

Namespace: ThinkGeo.Core

This abstract class is the basis for all image-based layers in the system.

public abstract class RasterLayer : Layer

Inheritance ObjectLayerRasterLayer

Remarks:

This abstract class is the basis for all image-based layers in the system. Its methods and properties deal with image manipulation. Currently, some classes that inherit from this are EcwRasterLayer, MrSidRasterLayer, GridRasterLayer and so on.

When creating your own RasterLayer, you need only to set a RasterSource and create a useful constructor; the class will take care of the rest. There are no required abstract members. It may be helpful for you to add additional properties specific to your Image.

Properties

ImageSource

This property gets and sets the Image used by the RasterLayer.

public RasterSource ImageSource { get; protected set; }

Property Value

RasterSource
This property gets the Image used by the RasterLayer.

Remarks:

The set for this property is protected and only intended to be used by developers who are creating their own ImageSources. This is the main property to set for developers who are creating their own RasterLayer derivatives.

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 double.min. 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 double.min. This means the image should always display.

ScaleFactor

The scale factor when drawing the primitive image. For example I am looking for an image with 100100px, If the ScaleFactor is set to 2, it means the component will get the image with 200200px. We want to keep it as 1 (by default) for most cases.

public double ScaleFactor { get; set; }

Property Value

Double

Projection

public Projection Projection { get; }

Property Value

Projection

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

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

GetHorizontalResolution()

This method returns the horizontal resolution of the image.

public float GetHorizontalResolution()

Returns

Single
This method returns the horizontal resolution of the image.

Exceptions

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

Remarks:

This method returns the horizontal resolution of the image.

GetVerticalResolution()

This method returns the vertical resolution of the image.

public float GetVerticalResolution()

Returns

Single
This method returns the vertical resolution of the image.

Exceptions

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

Remarks:

This method returns the vertical resolution of the image.

GetBoundingBoxCore()

This method returns the bounding box of the RasterLayer.

protected RectangleShape GetBoundingBoxCore()

Returns

RectangleShape
This method returns the bounding box of the RasterLayer.

Exceptions

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

Remarks:

This method returns the bounding box of the RasterLayer.

OpenCore()

This method opens the RasterLayer 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 image source which has already been opened, it will throw an InvalidOperationException.

Remarks:

The open method plays an important rol,e as it is responsible for initializing the RasterLayer. Most methods on the RasterLayer will throw an exception if the state of the RasterLayer is not opened. When the map draws each layer, it will open the RasterLayer 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 RasterLayer.

CloseCore()

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

protected void CloseCore()

Remarks:

The close method plays an important role in the life cycle of the RasterLayer. 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 RasterLayer 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.

IsDrawingNeededCore(Double)

protected bool IsDrawingNeededCore(double currentScale)

Parameters

currentScale Double

Returns

Boolean

DrawCore(GeoCanvas, Collection<SimpleCandidate>)

This method will draw the image from the NativeImage source based on the parameters provided.

protected void DrawCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)

Parameters

canvas GeoCanvas

        This parameter is the GeoCanvas used to Draw the RasterLayer.

labelsInAllLayers Collection<SimpleCandidate>
This parameter is not used for ImageLayers.

Remarks:

The DrawCore method will be called when the layer is being drawn. It will determine if the image is within the extent and the threshold defined. If these parameters are met, it will query the RasterSource for an image and then apply the other various properties (such as transparency, etc.) on the image. Lastly, it will draw the image on the NativeImage or native image passed into the method.

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;