RasterXyzTileAsyncLayer¶
Namespace: ThinkGeo.Core
Provides shared functionality for XYZ tile layers that return raster imagery.
public abstract class RasterXyzTileAsyncLayer : XyzTilesAsyncLayer
Inheritance Object → LayerBase → AsyncLayer → XyzTilesAsyncLayer → RasterXyzTileAsyncLayer
Properties¶
MinZoomOfTheData¶
Gets or sets the lowest zoom level available from the server or cache.
public int MinZoomOfTheData { get; set; }
Property Value¶
MaxZoomOfTheData¶
Gets or sets the highest zoom level available from the server or cache.
public int MaxZoomOfTheData { get; set; }
Property Value¶
RenderBeyondMinZoom¶
Gets or sets a value indicating whether tiles should be down-sampled beyond RasterXyzTileAsyncLayer.MinZoomOfTheData.
public bool RenderBeyondMinZoom { get; set; }
Property Value¶
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 0. 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 0. This means the image should always display.
UpperScale¶
This property gets and sets the upper threshold in the scale at which to display the image.
public double UpperScale { 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 0. This means the image should always display.
LowerScale¶
This property gets and sets the lower threshold in the scale at which to display the image.
public double LowerScale { 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 0. This means the image should always display.
RenderBeyondMaxZoom¶
Gets or sets a value indicating whether tiles should be up-sampled beyond RasterXyzTileAsyncLayer.MaxZoomOfTheData.
public bool RenderBeyondMaxZoom { get; set; }
Property Value¶
TileCache¶
Gets or sets the primary raster tile cache used for storing downloaded tiles.
public RasterTileCache TileCache { get; set; }
Property Value¶
ProjectedTileCache¶
Gets or sets the cache that stores reprojected tiles when a projection converter is in use.
public RasterTileCache ProjectedTileCache { get; set; }
Property Value¶
IsCacheOnly¶
Gets or sets a value indicating whether the layer should read exclusively from cache.
public bool IsCacheOnly { get; set; }
Property Value¶
ProjectionConverter¶
Gets or sets the projection converter used to transform coordinates during rendering.
public ProjectionConverter ProjectionConverter { get; set; }
Property Value¶
TileMatrixSet¶
Gets or sets the tile matrix set describing the XYZ grid.
public TileMatrixSet TileMatrixSet { get; set; }
Property Value¶
TileWidth¶
Gets or sets the TileWidth.
public int TileWidth { get; set; }
Property Value¶
TileHeight¶
Gets or sets the TileHeight.
public int TileHeight { get; set; }
Property Value¶
MaxExtent¶
This is the full extent of the matrix griding the xyz tiles. It's NOT the bounding box of the data itself.
public RectangleShape MaxExtent { get; set; }
Property Value¶
MapUnit¶
Gets or sets the MapUnit.
public GeographyUnit MapUnit { get; set; }
Property Value¶
HasBoundingBox¶
Gets or sets the HasBoundingBox.
public bool HasBoundingBox { get; }
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.
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¶
GetBoundingBoxCore()¶
Provides the overridable implementation that returns the bounding box that encloses the relevant geometry.
protected RectangleShape GetBoundingBoxCore()
Returns¶
RectangleShape
The result of the operation.
OpenAsyncCore(CancellationToken)¶
Provides the overridable implementation that asynchronously opens the instance and initializes the resources it depends on.
protected Task OpenAsyncCore(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
A cancellation or authentication token, depending on context.
Returns¶
Task
A task that represents the asynchronous operation.
CloseAsyncCore(CancellationToken)¶
Provides the overridable implementation that asynchronously closes the instance and releases any resources it holds.
protected Task CloseAsyncCore(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
A cancellation or authentication token, depending on context.
Returns¶
Task
A task that represents the asynchronous operation.
GetTileScaleCore()¶
Provides the overridable implementation that returns tile scale.
protected int GetTileScaleCore()
Returns¶
Int32
The result of the operation.
DrawAsyncCore(GeoCanvas, Collection<SimpleCandidate>)¶
Provides the overridable implementation that asynchronously draws onto and appends any label candidates to .
protected Task DrawAsyncCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)
Parameters¶
canvas GeoCanvas
The to draw to.
labelsInAllLayers Collection<SimpleCandidate>
A shared collection that receives label candidates generated during drawing.
Returns¶
Task
A task that represents the asynchronous operation.
GenerateTileCacheAsync(RectangleShape, Int32, Int32, Single, OverwriteMode, CancellationToken)¶
Asynchronously generates and caches tiles for a given extent across the specified zoom levels.
public Task GenerateTileCacheAsync(RectangleShape extent, int startZoom, int endZoom, float scaleFactor, OverwriteMode overwriteMode, CancellationToken cancellationToken)
Parameters¶
extent RectangleShape
The geographic area (in map coordinates) to generate tiles for.
startZoom Int32
The starting zoom level for which tiles should be generated.
endZoom Int32
The ending zoom level (inclusive) for which tiles should be generated.
scaleFactor Single
An optional scale multiplier to apply to each tile during generation. For example if the tile size is 256*256, the cached tile would be 512 * 512 if it's 2.0. It defaults to 1.0 (no scaling).
overwriteMode OverwriteMode
Specifies whether to overwrite existing tiles in the cache. If set to (by default), tiles that already exist on disk will be skipped.
cancellationToken CancellationToken
A cancellation token that can be used to cancel the operation before completion.
Returns¶
Task
A task representing the asynchronous operation.
Exceptions¶
Thrown if is not set or is not a .
Thrown if exceeds the number of available zoom levels in _zoomScales.
Thrown if the operation is canceled via the provided .
Remarks:
This method uses a throttled parallelism model to control concurrency and avoid overwhelming system resources. A maximum of 4 tile generation tasks are run concurrently using a SemaphoreSlim. Each tile is generated asynchronously and saved to the configured RasterXyzTileAsyncLayer.TileCache. TileCacheGenerated will be raised for each tile that is generated. Progress updates should be handled externally through events or UI bindings.
OnTileCacheGenerated(TileCacheGeneratedXyzTileAsyncLayerEventArgs)¶
Performs on tile cache generated.
protected void OnTileCacheGenerated(TileCacheGeneratedXyzTileAsyncLayerEventArgs e)
Parameters¶
e TileCacheGeneratedXyzTileAsyncLayerEventArgs
The e.
GetTileAsyncCore(Int32, Int64, Int64, Single, CancellationToken)¶
Provides the overridable implementation that returns tile async for the specified parameters.
protected abstract Task<RasterTile> GetTileAsyncCore(int zoomLevel, long x, long y, float resolutionFactor, CancellationToken cancellationToken)
Parameters¶
zoomLevel Int32
The zoom level.
x Int64
The x-coordinate, in pixels.
y Int64
The y-coordinate, in pixels.
resolutionFactor Single
The resolution factor.
cancellationToken CancellationToken
A cancellation or authentication token, depending on context.
Returns¶
Task<RasterTile>
A task that represents the asynchronous operation and provides the result.
IsDrawingNeededCore(Double)¶
Provides the overridable implementation that performs is drawing needed.
protected bool IsDrawingNeededCore(double currentScale)
Parameters¶
currentScale Double
The scale factor to apply.
Returns¶
Boolean
True if the condition is met; otherwise, false.
Events¶
TileCacheGenerated¶
Occurs each time a tile is generated during the execution of RasterXyzTileAsyncLayer.GenerateTileCacheAsync(RectangleShape, Int32, Int32, Single, OverwriteMode, CancellationToken).
public event EventHandler<TileCacheGeneratedXyzTileAsyncLayerEventArgs> TileCacheGenerated;
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;