Table of Contents

Class InMemoryFeatureLayer

Namespace
ThinkGeo.Core
Assembly
ThinkGeo.Core.dll

This layer is backed by memory and is typically used for temporary features.

public class InMemoryFeatureLayer : FeatureLayer
Inheritance
InMemoryFeatureLayer
Inherited Members

Remarks

This layer is backed by memory and is typically used for temporary features. You can use the MapShapes layer for user-drawn InternalFeatures, InternalFeatures that come from an external device such as a GPS unit, or any InternalFeatures that are not saved to disk or a database.

Constructors

InMemoryFeatureLayer()

This is a constructor for the class.

public InMemoryFeatureLayer()

Remarks

If you use this constructor, then you need to specify the FeatureSource column manually.

InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn>) 

public InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn> featureSourceColumns)

Parameters

featureSourceColumns IEnumerable<FeatureSourceColumn>

InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn>, IEnumerable<BaseShape>)

This is a constructor for the class.

public InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn> featureSourceColumns, IEnumerable<BaseShape> shapes)

Parameters

featureSourceColumns IEnumerable<FeatureSourceColumn>

This parameter is the in this class that you want to use.

shapes IEnumerable<BaseShape>

This parameter represents the shapes in this class that you want to use.

Remarks

This constructor gets the layer ready to use.

InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn>, IEnumerable<Feature>)

This is a constructor for the class.

public InMemoryFeatureLayer(IEnumerable<FeatureSourceColumn> featureSourceColumns, IEnumerable<Feature> features)

Parameters

featureSourceColumns IEnumerable<FeatureSourceColumn>

This parameter is the FeatureSourceColumn in this class that you want to use.

features IEnumerable<Feature>

This parameter represents the features in this class that you want to use.

Remarks

This constructor gets the layer ready to use.

Properties

Columns

This property gets the columns of data for the InternalFeatures in this Layer.

public Collection<FeatureSourceColumn> Columns { get; }

Property Value

Collection<FeatureSourceColumn>

Remarks

You should set the column names for the data that the InternalFeatures will hold. For example, if you have some features that represent road signs, then one column you may want to add is "Sign Type". Then, for every Feature you add to the layer, you need to add the "Sign Type" and a value to the InternalFeatures' ColumnValues dictionary. If you provide this information, then you can use things like ValueStyles, Labeling, etc. based on the columns you have defined.

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 InMemoryFeatureLayer, we override this API and mark it as true.

public override bool HasBoundingBox { get; }

Property Value

bool

Remarks

The default implementation in the base class returns false.

InternalFeatures

This property gets the dictionary that holds your InternalFeatures.

public GeoCollection<Feature> InternalFeatures { get; }

Property Value

GeoCollection<Feature>

Remarks

The dictionary is a quick way to access your InternalFeatures. You can easily add, remove or edit features in this dictionary and they instantly take effect in the layer. You can always use the EditTools to do the same thing, but this is a shortcut, as the data is backed in memory so it is very pliable.

Methods

BuildIndex()

This method build a spatial index for a passed group of featurs which increases access speed.

public void BuildIndex()

Clear()

This method will clear all the features included in the feature source.

public void Clear()

Exceptions

InvalidOperationException

If you attempt to call this method on a feature source which is in a transaction, it will throw an InvalidOperationException.

InvalidOperationException

If you attempt to call this method on a feature source which is not opened, it will throw an InvalidOperationException.

GetColumns()

This method returns the columns of data for the InternalFeatures in this Layer.

public Collection<FeatureSourceColumn> GetColumns()

Returns

Collection<FeatureSourceColumn>

Remarks

You should set the column names for the data that the InternalFeatures will hold. For example, if you have some features that represent road signs, then one column you may want to add is "Sign Type". Then, for every Feature you add to the layer, you need to add the "Sign Type" and a value to the InternalFeatures' ColumnValues dictionary. If you provide this information, then you can use things like ValueStyles, Labeling, etc. based on the columns you have defined.

OpenCore()

This method opens the Layer so that it is initialized and ready to use.

protected override void OpenCore()

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, the layer will be opened 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.

Exceptions

InvalidOperationException

In the event you attempt to call this method on a Layer which has already been opened, it will throw an InvalidOperationException.