LayerBase¶
Namespace: ThinkGeo.Core
This class is the base class for all types of Layers.
public abstract class LayerBase
Inheritance object → LayerBase
Remarks:
The LayerBase 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 LayerBase 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.
Properties¶
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¶
bool
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¶
bool
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¶
float
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¶
float
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¶
float
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¶
float
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¶
bool
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¶
bool
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¶
GetRasterContentTypeCore()¶
Returns the default RasterContentType for this layer.
protected RasterContentType GetRasterContentTypeCore()
Returns¶
Remarks:
Subclasses override this to report the content type hint they can provide. The base implementation returns RasterContentType.Unspecified.
GetRasterContentType()¶
Gets the RasterContentType of the layer.
public RasterContentType GetRasterContentType()
Returns¶
GetRasterResamplingMode()¶
Gets the effective RasterResamplingMode for this layer.
protected RasterResamplingMode GetRasterResamplingMode()
Returns¶
IsDrawingNeeded(double)¶
Returns a value indicating whether the layer needs to be drawn at the specified map scale.
public bool IsDrawingNeeded(double currentScale)
Parameters¶
currentScale double
The current map scale.
Returns¶
bool
true if drawing is required; otherwise, false.
IsDrawingNeededCore(double)¶
Determines whether the layer needs to be redrawn for the provided scale.
protected bool IsDrawingNeededCore(double currentScale)
Parameters¶
currentScale double
The current map scale.
Returns¶
bool
true if drawing should proceed; otherwise, false.
DrawException(GeoCanvas, Exception)¶
Draws diagnostic content when Layer.Draw(GeoCanvas, Collection<SimpleCandidate>) throws and LayerBase.DrawingExceptionMode is set to DrawingExceptionMode.DrawException.
protected void DrawException(GeoCanvas canvas, Exception e)
Parameters¶
canvas GeoCanvas
The canvas onto which the diagnostic information is rendered.
e Exception
The exception thrown by the drawing routine.
Returns¶
Remarks:
Override to customize the diagnostic rendering.
DrawExceptionCore(GeoCanvas, Exception)¶
Draws diagnostic content when the drawing routine throws and LayerBase.DrawingExceptionMode requests visual feedback.
protected void DrawExceptionCore(GeoCanvas canvas, Exception e)
Parameters¶
canvas GeoCanvas
The canvas onto which the diagnostic information is rendered.
e Exception
The exception thrown by .
Returns¶
OnDrawingException(DrawingExceptionLayerEventArgs)¶
Performs on drawing exception.
protected void OnDrawingException(DrawingExceptionLayerEventArgs e)
Parameters¶
e DrawingExceptionLayerEventArgs
The e.
Returns¶
GetBoundingBox()¶
Returns the bounding box of the layer.
public RectangleShape GetBoundingBox()
Returns¶
RectangleShape
The geographic extent that encloses 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()¶
Returns the bounding box of the layer.
protected RectangleShape GetBoundingBoxCore()
Returns¶
RectangleShape
The geographic extent that encloses 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.
OnDrawnException(DrawnExceptionLayerEventArgs)¶
Performs on drawn exception.
protected void OnDrawnException(DrawnExceptionLayerEventArgs e)
Parameters¶
e DrawnExceptionLayerEventArgs
The e.
Returns¶
CloneDeep()¶
Create a copy of LayerBase using the deep clone process.
public LayerBase CloneDeep()
Returns¶
LayerBase
A cloned LayerBase.
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 LayerBase using the deep clone process. The default implemenation uses serialization.
protected LayerBase CloneDeepCore()
Returns¶
LayerBase
A cloned LayerBase.
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.
GenerateTileCacheAsync(IEnumerable<LayerBase>, FileRasterTileCache, TileMatrixSet, RectangleShape, GeographyUnit, int, int, Action<TileCacheGeneratedLayerBaseEventArgs>, float, OverwriteMode, CancellationToken)¶
Asynchronously generates and populates a file‐based raster tile cache for the given map layers over a specified geographic extent and zoom range.
public static Task GenerateTileCacheAsync(IEnumerable<LayerBase> layers, FileRasterTileCache fileTileCache, TileMatrixSet tileMatrixSet, RectangleShape cacheExtent, GeographyUnit cacheExtentUnit, int startZoom, int endZoom, Action<TileCacheGeneratedLayerBaseEventArgs> progress, float scaleFactor, OverwriteMode overwriteMode, CancellationToken cancellationToken)
Parameters¶
layers IEnumerable<LayerBase>
The collection of map layers to be rendered into the cache.
fileTileCache FileRasterTileCache
The instance where tiles will be stored.
tileMatrixSet TileMatrixSet
The defining the tile dimensions and scales for each zoom level.
cacheExtent RectangleShape
The bounding box (in world coordinates) that should be covered by the cache.
cacheExtentUnit GeographyUnit
The geographic unit of measure (e.g. ).
startZoom int
The starting zoom level (inclusive).
endZoom int
The ending zoom level (inclusive). Must be less than matrixSet.TileMatrices.Count.
progress Action<TileCacheGeneratedLayerBaseEventArgs>
Optional callback invoked after each tile is successfully cached. Receives a describing the tile and overall progress.
scaleFactor float
Factor by which to scale the rendered images (useful for HiDPI displays). Defaults to 1.0f.
overwriteMode OverwriteMode
Specifies whether existing cache files should be overwritten () or left intact (). Defaults to DoNotOverwrite.
cancellationToken CancellationToken
Token to observe while waiting for tasks to complete, and to cancel the operation if requested. A that completes when all required tiles have been generated and saved.
Returns¶
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;