namespace SharpMap.Data.Providers

{

/// <summary>

/// Abstract class for providers which support the FilterMethod Delegate

/// </summary>

public abstract class FilterProvider

{

#region Delegates

/// <summary>

/// Filter Delegate Method

/// </summary>

/// <remarks>

/// The FilterMethod delegate is used for applying a method that filters data from the dataset.

/// The method should return 'true' if the feature should be included and false if not.

/// <para>See the <see cref="FilterDelegate"/> property for more info</para>

/// </remarks>

/// <seealso cref="FilterDelegate"/>

/// <param name="dr"><see cref="SharpMap.Data.FeatureDataRow"/> to test on</param>

/// <returns>true if this feature should be included, false if it should be filtered</returns>

public delegate bool FilterMethod(FeatureDataRow dr);

#endregion

/// <summary>

/// Filter Delegate Method for limiting the datasource

/// </summary>

/// <remarks>

/// <example>

/// Using an anonymous method for filtering all features where the NAME column starts with S:

/// <code lang="C#">

/// myShapeDataSource.FilterDelegate = new SharpMap.Data.Providers.ShapeFile.FilterMethod(delegate(SharpMap.Data.FeatureDataRow row) { return (!row["NAME"].ToString().StartsWith("S")); });

/// </code>

/// </example>

/// <example>

/// Declaring a delegate method for filtering (multi)polygon-features whose area is larger than 5.

/// <code>

/// myShapeDataSource.FilterDelegate = CountryFilter;

/// [...]

/// public static bool CountryFilter(SharpMap.Data.FeatureDataRow row)

/// {

/// if(row.Geometry.GetType()==typeof(GeoAPI.Geometries.IPolygon))

/// return ((row.Geometry as GeoAPI.Geometries.IPolygon).Area>5);

/// if (row.Geometry.GetType() == typeof(GeoAPI.Geometries.IMultiPolygon))

/// return ((row.Geometry as GeoAPI.Geometries.IMultiPolygon).Area > 5);

/// else return true;

/// }

/// </code>

/// </example>

/// </remarks>

/// <seealso cref="FilterMethod"/>

public FilterMethod FilterDelegate {get;set;}

}

}