MapStyleFeatureAsyncLayer¶
Namespace: ThinkGeo.Core
A classic layer that draws a style document over feature sources through the classic canvas styles: the same document and the same sources the GPU map is given, drawn onto whatever GeoCanvas it is handed - a bitmap, a printer, a vector PDF (PdfGeoCanvas).
public class MapStyleFeatureAsyncLayer : AsyncLayer
Inheritance object → LayerBase → AsyncLayer → MapStyleFeatureAsyncLayer
Remarks:
The CPU, vector counterpart of ThinkGeo.Gpu's MapStyleAsyncLayer, which takes the same three arguments and draws pixels. This one is a feature layer: each draw queries the sources for the canvas extent - no tiles are cut, so nothing is quantized and nothing seams.
The document is compiled by MapStyle, the compile every renderer shares, so which layers draw, which features pass the filters and what each property evaluates to are the GPU map's. The strokes and fills are GeoCanvas's, so it is not a pixel match. Raster, hillshade and heatmap layers are not drawn, and extrusions draw as their roofs.
The labels are the GPU map's: placed by its engine over tiles cut from the same sources, line labels walked glyph by glyph along their line, and drawn as text in the canvas's own fonts. They are placed first and claim their boxes in labelsInAllLayers, so a classic layer drawn after this one keeps clear of them; they do not give way to labels drawn before it.
The sources are queried directly, so give this layer sources of its own rather than the instances a GPU map is reading at the same time.
Properties¶
MapStyle¶
Gets the style document drawn.
public MapStyle MapStyle { get; }
Property Value¶
FeatureSources¶
Gets the feature sources drawn, keyed by source-layer name.
public GeoCollection<FeatureSource> FeatureSources { get; }
Property Value¶
SourceId¶
Gets the name the feature sources answer to in the style.
public string SourceId { 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¶
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.
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).
Opacity¶
Gets or sets the opacity applied to the rendered image.
public float Opacity { get; set; }
Property Value¶
float
A value between 0.0 (fully transparent) and 1.0 (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.
ConcurrentAccess¶
Gets or sets how this layer behaves when more than one thread wants to draw it at once, and what a caller who wants concurrency should therefore do with it.
public ConcurrentAccess ConcurrentAccess { get; set; }
Property Value¶
ConcurrentAccess
unless the layer says otherwise: callers take turns on the one instance, which is what the screen renderer has done with a layer that did not say otherwise since this question was first asked.
Remarks:
A FeatureLayer that is not given a value of its own answers with its FeatureLayer.FeatureSource's, so a layer and the source it reads through cannot disagree about this.
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.
Remarks:
Replaced by LayerBase.ConcurrentAccess and kept only so that code written against it is told, by name, what to use instead. It does not compile, so there is never a question of which of the two a caller meant: there is one value, and it is the other one. That matters because the translation was lossy in one direction - writing ThreadSafetyLevel.Unsafe could only pick ConcurrentAccess.UnsafeLock, and would silently undo a layer or source that had said ConcurrentAccess.UnsafeClone.
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¶
MapStyleFeatureAsyncLayer(MapStyle, GeoCollection<FeatureSource>, string)¶
Initializes a new instance over a style and the sources its layers name.
public MapStyleFeatureAsyncLayer(MapStyle mapStyle, GeoCollection<FeatureSource> featureSources, string sourceId)
Parameters¶
mapStyle MapStyle
The style document. Its layers name the sources by and the feature sources by their keys as "source-layer".
featureSources GeoCollection<FeatureSource>
The feature sources, keyed by the name the style gives as "source-layer".
sourceId string
The name the feature sources answer to in the style.
Methods¶
OpenAsyncCore(CancellationToken)¶
Opens the feature sources and compiles the style document.
protected Task OpenAsyncCore(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
Returns¶
CloseAsyncCore(CancellationToken)¶
Closes the feature sources.
protected Task CloseAsyncCore(CancellationToken cancellationToken)
Parameters¶
cancellationToken CancellationToken
Returns¶
DrawAsyncCore(GeoCanvas, Collection<SimpleCandidate>)¶
Draws the style's background, then its layers over the features inside the canvas extent, then its labels.
protected Task DrawAsyncCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)
Parameters¶
canvas GeoCanvas
labelsInAllLayers Collection<SimpleCandidate>
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;