FeatureLayer¶
Namespace: ThinkGeo.Core
This class represents a layer that is comprised of feature data.
public abstract class FeatureLayer : Layer, IFeatureLayer
Inheritance object → LayerBase → Layer → FeatureLayer
Implements IFeatureLayer
Remarks:
This abstract class is the basis for all feature-based layers in the system. Its methods and properties deal with feature data manipulation. Some of the classes that currently inherit from this are ShapeFileFeatureLayer, OracleFeatureLayer and so on.
When creating your own FeatureLayer, you need only to set a FeatureSource and create a useful constructor; the class will take care of the rest. There are no required abstract members. It may be helpful for you to add additional properties specific to your FeatureSource.
Properties¶
Projection¶
Gets the projection used by the underlying FeatureLayer.FeatureSource.
public Projection Projection { get; }
Property Value¶
EditTools¶
This property gets the EditTools that allow you to easily edit InternalFeatures in the Feature Layer.
public EditTools EditTools { get; protected set; }
Property Value¶
Remarks:
The EditTools are supplied as an easily accessible wrapper for the editing methods of the FeatureSource.
FeatureIdsToExclude¶
A collection of strings representing record id of features not to get in the Layer.
public Collection<string> FeatureIdsToExclude { get; }
Property Value¶
Remarks:
This string collection is a handy place to specify what records not to get from the source. Suppose you have a shape file of roads and you want to hide the roads within a particular rectangle, simply execute GetFeaturesInsideBoundingBox() and add the id of the return features to the collection and forget about them. Since you can set this by Layer it makes is easy to determine what to and what not to.
QueryTools¶
This property gets the QueryTools that allow you to easily query Features from the Feature Layer.
public QueryTools QueryTools { get; protected set; }
Property Value¶
Remarks:
Feature Layer. The QueryTools are supplied as an easily accessible wrapper for the query methods of the FeatureSource.
MaxRecordsToDraw¶
Gets or sets the maximum number of features that may be rendered per draw call.
public int MaxRecordsToDraw { get; set; }
Property Value¶
FeatureSource¶
This property gets the FeatureSource for the FeatureLayer.
public FeatureSource FeatureSource { get; set; }
Property Value¶
FeatureSource
This property gets the FeatureSource for the FeatureLayer.
Remarks:
The FeatureSource is the provider of data to the FeatureLayer. There are different FeatureSource classes to match the various ways that feature data is stored. It is important that, when you inherit from the FeatureLayer, in the constructor you set the FeatureSource you want to use.
DrawingQuality¶
This property gets and sets the general drawing quality for the FeatureLayer's view.
public DrawingQuality DrawingQuality { get; set; }
Property Value¶
This property gets the general drawing quality for the FeatureLayer's
Remarks:
The DrawingQuality enumeration allows you to control, in a macro sense, the drawing quality that will be used in the GeoCanvas. Each GeoCanvas, which is responsible for drawing of the features, may have its own specialized drawing quality properties. What the DrawingQuality enumeration does is define some general guidelines for each GeoCanvas. For example, if you set the DrawingQuality to HighSpeed, then inside of the PlatformGeoCanvas there is a profile for HighSpeed. This profile sets specific properties, such as the smoothing mode and composing drawing mode of the PlatformGeoCanvas. As each GeoCanvas may have different drawing quality properties, this offers a general way to control drawing quality and speed.
If you need complete control over how a specific GeoCanvas will draw, then you can set the DrawingQuality to Custom. This will tell the specific GeoCanvas to use the properties on its own object instead of one of the pre-defined profiles. If one of the profiles -- such as HighSpeed or HighQuality -- is set, then the specific GeoCanvas ignores its own properties for drawing quality.
ZoomLevelSet¶
This property gets and sets the ZoomLevelSet, which contains the specific zoom levels for the FeatureLayer.
public ZoomLevelSet ZoomLevelSet { get; set; }
Property Value¶
This property gets the ZoomLevelSet, which contains the specific zoom levels for
the FeatureLayer.
Remarks:
The ZoomLevelSet is a class that contains all of the ZoomLevels for the FeatureLayer. Each ZoomLevel contains the styles that are used to determine how to draw the InternalFeatures.
LabelDisplayMode¶
Gets or sets the labeling strategy to apply when drawing this layer.
public LabelDisplayMode LabelDisplayMode { get; set; }
Property Value¶
DrawingMarginInPixel¶
Gets or sets the pixel margin applied when requesting data for this layer.
public float DrawingMarginInPixel { get; set; }
Property Value¶
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¶
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.
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¶
OnDrawingFeatures(DrawingFeaturesEventArgs)¶
This method raises the DrawingFeatures event.
protected void OnDrawingFeatures(DrawingFeaturesEventArgs e)
Parameters¶
e DrawingFeaturesEventArgs
This parameter represents the event arguments for the event.
Returns¶
void
None
Remarks:
You can call this method from a derived class to enable it to raise the event. This may be useful if you plan to extend the FeatureLayer and you need access to the event. This event is meant to allow you to add or remove the features to be drawn.
OnDrawingWrappingFeatures(DrawingWrappingFeaturesFeatureLayerEventArgs)¶
Raises the FeatureLayer.DrawingWrappingFeatures event so derived classes can hook custom logic. Obsolete.
protected void OnDrawingWrappingFeatures(DrawingWrappingFeaturesFeatureLayerEventArgs e)
Parameters¶
e DrawingWrappingFeaturesFeatureLayerEventArgs
Returns¶
GetRasterContentTypeCore()¶
Feature layers draw vector cartographic content by default.
protected RasterContentType GetRasterContentTypeCore()
Returns¶
DrawCore(GeoCanvas, Collection<SimpleCandidate>)¶
This method will draw the FeatureLayer source based on the parameters provided.
protected void DrawCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)
Parameters¶
canvas GeoCanvas
This parameter is the GeoCanvas used to Draw the layer.
labelsInAllLayers Collection<SimpleCandidate>
This parameter is not used for ImageLayers.
Returns¶
void
None
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a FeatureLayer is not opened, it will throw an InvalidOperationException.
ArgumentNullException
If you pass a null as the labeledInLayers, we will throw an ArgumentNullException.
ArgumentNullException
If you pass a null as the worldExtent, we will throw an ArgumentNullException.
ArgumentNullException
If you pass a null as the image, we will throw an ArgumentNullException.
Remarks:
The DrawCore will be called when the layer is being drawn. It will check if the InternalFeatures are within the extent and whether it is within a defined zoom level. If these parameters are met, then it will apply the styles of the proper zoom level to the InternalFeatures for drawing. Lastly, it will draw InternalFeatures on the NativeImage or native image passed in to the method.
IsDrawingNeededCore(double)¶
Determines whether any zoom level contains valid styles for the supplied scale.
protected bool IsDrawingNeededCore(double currentScale)
Parameters¶
currentScale double
The scale currently being rendered.
Returns¶
bool
true if a zoom level is available and contains styles; otherwise, false.
SetupTools()¶
Initializes the FeatureLayer.EditTools and FeatureLayer.QueryTools helpers.
protected void SetupTools()
Returns¶
void
None
Remarks:
This method is the concrete wrapper for the abstract method SetupToolsCore. The SetupTools method allows you to create the QueryTool, EditTools and other tools you may need on your object. We created this method so that if you want to extend one of the tool classes, you can override the SetupToolsCore and create any class you want.
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.
SetupToolsCore()¶
Creates the actual tool instances that the FeatureLayer depends on.
protected void SetupToolsCore()
Returns¶
void
None
Remarks:
This method is the concrete wrapper for the abstract method SetupTools. The SetupTools method allows you to create the QueryTool, EditTools and other tools you may need on your object. We created this method so that if you want to extend one of the tool classes, you can override the SetupToolsCore and create any class you want.
OpenCore()¶
This method opens the FeatureLayer so that it is initialized and ready to use.
protected void OpenCore()
Returns¶
void
None
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a FeatureLayer 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 FeatureLayer. Most methods on the FeatureLayer will throw an exception if the state of the FeatureLayer is not opened. When the map draws each FeatureLayer, it will open the layer as one of its first steps, then after it is finished drawing with that FeatureLayer it will close it. In this way we are sure to release all resources used by the FeatureLayer.
CloseCore()¶
This method closes the FeatureSource and releases any resources it was using.
protected void CloseCore()
Returns¶
void
None
Remarks:
This protected virtual method is called from the concrete public method Close. The close method plays an important role in the life cycle of the FeatureLayer. 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 FeatureLayer 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 FeatureLayer.
protected RectangleShape GetBoundingBoxCore()
Returns¶
RectangleShape
This method returns the bounding box of the FeatureLayer.
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a FeatureLayer which has not been opened, it will throw an InvalidOperationException.
Remarks:
This method is called from the concrete public method GetBoundingBox. It returns the bounding box of the FeatureLayer.
GetWrappingFeaturesForDrawing(RectangleShape, IEnumerable<string>, RectangleShape)¶
Retrieves the features that should be rendered when wrapping is enabled for the specified drawing extent.
protected Collection<Feature> GetWrappingFeaturesForDrawing(RectangleShape drawingExtent, IEnumerable<string> returningColumnNames, RectangleShape wrappingExtent)
Parameters¶
drawingExtent RectangleShape
The map extent that is currently being rendered.
returningColumnNames IEnumerable<string>
Column names to hydrate for each feature.
wrappingExtent RectangleShape
The world extent that defines the wrapping bounds.
Returns¶
Collection<Feature>
A collection of features that represent the wrapped view of .
GetCeiling(double)¶
Returns rounded up to the nearest integer.
public double GetCeiling(double d)
Parameters¶
d double
Returns¶
Events¶
DrawingFeatures¶
This event is raised when features are about to be drawn in the layer.
public event EventHandler<DrawingFeaturesEventArgs> DrawingFeatures;
Remarks:
This event is raised when features are about to be drawn in the layer. In the event arguments, there is a collection of features to be drawn. You can easily add or remove items from this collection so that extra items will draw or not draw.
DrawingWrappingFeatures¶
Raised when wrapping features are about to be drawn. Deprecated; use FeatureLayer.DrawingFeatures instead.
public event EventHandler<DrawingWrappingFeaturesFeatureLayerEventArgs> DrawingWrappingFeatures;
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;