Layer¶
Namespace: ThinkGeo.Core
This class is the base class for all types of Layers.
public abstract class Layer : LayerBase
Inheritance Object → LayerBase → Layer
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 from 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¶
RequestDrawingInterval¶
Gets or sets the interval between automatic draw requests. Obsolete.
public TimeSpan RequestDrawingInterval { 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¶
Boolean
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¶
Boolean
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.
DrawingTime¶
Gets the last recorded drawing time for the layer.
public TimeSpan DrawingTime { get; protected set; }
Property Value¶
TimeSpan
The duration of the most recent draw operation.
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¶
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¶
Single
A value between 0 (fully transparent) and 255 (fully opaque).
BlueTranslation¶
Gets or sets the intensity adjustment applied to the blue channel.
public float BlueTranslation { get; set; }
Property Value¶
Single
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¶
Single
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¶
Single
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¶
Boolean
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¶
Boolean
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.
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¶
Methods¶
OnDrawingProgressChanged(DrawingProgressChangedEventArgs)¶
Raises the Layer.DrawingProgressChanged event to notify listeners about rendering progress.
protected void OnDrawingProgressChanged(DrawingProgressChangedEventArgs e)
Parameters¶
e DrawingProgressChangedEventArgs
Progress information for the current draw pass.
LoadLayer(Uri)¶
Gets or sets the DrawExceptionMode when exception happens.
public static Layer LoadLayer(Uri layerUri)
Parameters¶
layerUri Uri
Returns¶
LoadLayer(Stream)¶
Deserializes a layer instance from the provided stream.
public static Layer LoadLayer(Stream layerStream)
Parameters¶
layerStream Stream
Returns¶
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 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.
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)¶
Draws the layer into an off-screen image so color translations and mappings can be applied before compositing.
protected void DrawWithColorTransformation(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers, RectangleShape extent, float width, float height)
Parameters¶
canvas GeoCanvas
The destination canvas that ultimately receives the transformed image.
labelsInAllLayers Collection<SimpleCandidate>
Labels participating in collision detection.
extent RectangleShape
The world extent corresponding to the off-screen image.
width Single
The width of the intermediate image in pixels.
height Single
The height of the intermediate image in pixels.
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.
RequestDrawing()¶
Requests that the layer refresh immediately using the default extent. Obsolete.
public void RequestDrawing()
RequestDrawing(RectangleShape)¶
Requests that the layer refresh the specified extent. Obsolete.
public void RequestDrawing(RectangleShape extentToRefresh)
Parameters¶
extentToRefresh RectangleShape
RequestDrawing(IEnumerable<RectangleShape>)¶
Requests that the layer refresh the specified extents. Obsolete.
public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh)
Parameters¶
extentsToRefresh IEnumerable<RectangleShape>
RequestDrawing(TimeSpan)¶
Requests that the layer refresh after the specified buffer time. Obsolete.
public void RequestDrawing(TimeSpan bufferTime)
Parameters¶
bufferTime TimeSpan
RequestDrawing(TimeSpan, RequestDrawingBufferTimeType)¶
Requests that the layer refresh after the specified buffer time using a custom interpretation. Obsolete.
public void RequestDrawing(TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)
Parameters¶
bufferTime TimeSpan
bufferTimeType RequestDrawingBufferTimeType
RequestDrawing(RectangleShape, TimeSpan)¶
Requests that the layer refresh the specified extent after the provided buffer time. Obsolete.
public void RequestDrawing(RectangleShape extentToRefresh, TimeSpan bufferTime)
Parameters¶
extentToRefresh RectangleShape
bufferTime TimeSpan
RequestDrawing(RectangleShape, TimeSpan, RequestDrawingBufferTimeType)¶
Requests that the layer refresh the specified extent after the provided buffer time using the given interpretation. Obsolete.
public void RequestDrawing(RectangleShape extentToRefresh, TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)
Parameters¶
extentToRefresh RectangleShape
bufferTime TimeSpan
bufferTimeType RequestDrawingBufferTimeType
RequestDrawing(IEnumerable<RectangleShape>, TimeSpan)¶
Requests that the layer refresh the specified extents after the provided buffer time. Obsolete.
public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh, TimeSpan bufferTime)
Parameters¶
extentsToRefresh IEnumerable<RectangleShape>
bufferTime TimeSpan
RequestDrawing(IEnumerable<RectangleShape>, TimeSpan, RequestDrawingBufferTimeType)¶
Requests that the layer refresh the specified extents after the provided buffer time using the given interpretation. Obsolete.
public void RequestDrawing(IEnumerable<RectangleShape> extentsToRefresh, TimeSpan bufferTime, RequestDrawingBufferTimeType bufferTimeType)
Parameters¶
extentsToRefresh IEnumerable<RectangleShape>
bufferTime TimeSpan
bufferTimeType RequestDrawingBufferTimeType
StartRequestDrawing()¶
Starts the legacy timer that periodically fires the Layer.RequestedDrawing event. Obsolete.
protected void StartRequestDrawing()
StopRequestDrawing()¶
Stops the timer created by and cleans up native resources. Obsolete.
protected void StopRequestDrawing()
OnRequestedDrawing(RequestedDrawingLayerEventArgs)¶
Raises the Layer.RequestedDrawing event so listeners can run custom drawing logic. Obsolete.
protected void OnRequestedDrawing(RequestedDrawingLayerEventArgs eventArgs)
Parameters¶
eventArgs RequestedDrawingLayerEventArgs
OnRequestingDrawing(RequestingDrawingLayerEventArgs)¶
Raises the Layer.RequestingDrawing event to let listeners cancel the legacy draw cycle. Obsolete.
protected void OnRequestingDrawing(RequestingDrawingLayerEventArgs eventArgs)
Parameters¶
eventArgs RequestingDrawingLayerEventArgs
Events¶
DrawingProgressChanged¶
Occurs as the layer reports drawing progress (useful for async or tiled rendering scenarios).
public event EventHandler<DrawingProgressChangedEventArgs> DrawingProgressChanged;
RequestedDrawing¶
Raised after the drawing buffer elapses so consumers can handle a legacy drawing cycle. Obsolete.
public event EventHandler<RequestedDrawingLayerEventArgs> RequestedDrawing;
RequestingDrawing¶
Raised before the drawing buffer elapses so consumers can cancel a legacy drawing operation. Obsolete.
public event EventHandler<RequestingDrawingLayerEventArgs> RequestingDrawing;
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;