GroupAsyncLayer¶
Namespace: ThinkGeo.Core
This class represents a Layer backed by a group of layers.
public class GroupAsyncLayer : AsyncLayer
Inheritance Object → LayerBase → AsyncLayer → GroupAsyncLayer
Remarks:
None
Properties¶
Layers¶
Gets the collection of child layers managed by the group.
public GeoCollection<LayerBase> Layers { get; }
Property Value¶
Remarks:
Add or remove layers from this collection to control the group's composition.
HasBoundingBox¶
This property checks to see if 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. In GroupLayer, we override this API and mark it as true.
public bool HasBoundingBox { get; }
Property Value¶
Remarks:
The default implementation in the base class returns false.
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.
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¶
Constructors¶
GroupAsyncLayer()¶
This is the default constructor for the class.
public GroupAsyncLayer()
Remarks:
GroupAsyncLayer(IEnumerable<LayerBase>)¶
This is a constructor for the class.
public GroupAsyncLayer(IEnumerable<LayerBase> layers)
Parameters¶
layers IEnumerable<LayerBase>
This parameter represents the layers in this class that you want to use.
Remarks:
This constructor gets the layer ready to use.
Methods¶
OpenAsyncCore()¶
This method opens the Layer so that it is initialized and ready to use.
protected Task OpenAsyncCore()
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, it will open the layer 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()¶
This method closes the FeatureSource and releases any resources it was using.
protected Task CloseAsyncCore()
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 the Core version of 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.
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.
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 are the labels used for collision detection and duplication checking.
Returns¶
Task
None
Remarks:
This abstract method is called from the concrete public method Draw. 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 to allow the user to specify which field they need; then, in the GetRequiredColumnNamesCore, we read that property and add it to the collection.
Events¶
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;