Creating a plug-in data source

In this topic

• Creating a plug-in data source
• SimplePoint plug-in data source
• Implementing a plug-in workspace factory helper
• Implementing a plug-in workspace helper
• Implementing a plug-in dataset helper
• Implementing a plug-in cursor helper

Creating a plug-in data source

• Plug-in workspace factory helper
• Plug-in workspace helper
• Plug-in dataset helper
• Plug-in cursor helper

SimplePoint plug-in data source

Implementing a plug-in workspace factory helper

public UID WorkspaceFactoryTypeID
{
    get
    {
        UID wkspFTypeID=new UIDClass();
        wkspFTypeID.Value="{b8a25f89-2adc-43c0-ac2e-16b3a88e3915}"; //Proxy.
        return wkspFTypeID;
    }
}

Public ReadOnly Property WorkspaceFactoryTypeID() As UID Implements IPlugInWorkspaceFactoryHelper.WorkspaceFactoryTypeID
Get
Dim wkspFTypeID As UID=New UIDClass()
wkspFTypeID.Value="{b8a25f89-2adc-43c0-ac2e-16b3a88e3915}" 'Proxy.
Return wkspFTypeID
End Get
End Property

public IPlugInWorkspaceHelper OpenWorkspace(string wksString)
{
    if (System.IO.Directory.Exists(wksString))
    {
        SimplePointWksp openWksp=new SimplePointWksp(wksString);
        return (IPlugInWorkspaceHelper)openWksp;
    }
    return null;
}

Public Function OpenWorkspace(ByVal wksString As String) As IPlugInWorkspaceHelper Implements IPlugInWorkspaceFactoryHelper.OpenWorkspace
    If System.IO.Directory.Exists(wksString) Then
        Dim openWksp As SimplePointWksp=New SimplePointWksp(wksString)
        Return CType(openWksp, IPlugInWorkspaceHelper)
    End If
    Return Nothing
End Function

Implementing a plug-in workspace helper

public IPlugInDatasetHelper OpenDataset(string localName)
{
    if (m_sWkspPath == null)
        return null;
    SimplePointDataset ds=new SimplePointDataset(m_sWkspPath, localName);
    return (IPlugInDatasetHelper)ds;
}

Public Function OpenDataset(ByVal localName As String) As IPlugInDatasetHelper Implements IPlugInWorkspaceHelper.OpenDataset
    If m_sWkspPath Is Nothing Then
        Return Nothing
    End If
    Dim ds As SimplePointDataset=New SimplePointDataset(m_sWkspPath, localName)
    Return CType(ds, IPlugInDatasetHelper)
End Function

Implementing a plug-in dataset helper

public IFields get_Fields(int ClassIndex)
{
    IFieldEdit fieldEdit;
    IFields fields;
    IFieldsEdit fieldsEdit;
    IObjectClassDescription fcDesc;
    if (this.DatasetType == esriDatasetType.esriDTTable)
        fcDesc=new ObjectClassDescriptionClass();
    else
        fcDesc=new FeatureClassDescriptionClass();

    fields=fcDesc.RequiredFields;
    fieldsEdit=(IFieldsEdit)fields;

    fieldEdit=new FieldClass();
    fieldEdit.Length_2=1;
    fieldEdit.Name_2="ColumnOne";
    fieldEdit.Type_2=esriFieldType.esriFieldTypeString;
    fieldsEdit.AddField((IField)fieldEdit);

    //HIGHLIGHT: Add extra int column.
    fieldEdit=new FieldClass();
    fieldEdit.Name_2="Extra";
    fieldEdit.Type_2=esriFieldType.esriFieldTypeInteger;
    fieldsEdit.AddField((IField)fieldEdit);

    //HIGHLIGHT: Set shape field geometry definition.
    if (this.DatasetType != esriDatasetType.esriDTTable)
    {
        IField field=fields.get_Field(fields.FindField("Shape"));
        fieldEdit=(IFieldEdit)field;
        IGeometryDefEdit geomDefEdit=(IGeometryDefEdit)field.GeometryDef;
        geomDefEdit.GeometryType_2=geometryTypeByID(ClassIndex);
        ISpatialReference shapeSRef=this.spatialReference;

        #region M & Z
        //M.
        if ((ClassIndex >= 3 && ClassIndex <= 5) || ClassIndex >= 9)
        {
            geomDefEdit.HasM_2=true;
            shapeSRef.SetMDomain(0, 1000);
        }
        else
            geomDefEdit.HasM_2=false;

        //Z.
        if (ClassIndex >= 6)
        {
            geomDefEdit.HasZ_2=true;
            shapeSRef.SetZDomain(0, 1000);
        }
        else
            geomDefEdit.HasZ_2=false;
        #endregion 

        geomDefEdit.SpatialReference_2=shapeSRef;
    }

    return fields;
}

Public ReadOnly Property Fields(ByVal ClassIndex As Integer) As ESRI.ArcGIS.Geodatabase.IFields Implements ESRI.ArcGIS.Geodatabase.IPlugInDatasetHelper.Fields
Get
Dim fieldEdit As IFieldEdit
Dim flds As IFields
Dim fieldsEdit As IFieldsEdit
Dim fcDesc As IObjectClassDescription
If Me.DatasetType=esriDatasetType.esriDTTable Then
    fcDesc=New ObjectClassDescriptionClass()
Else
    fcDesc=New FeatureClassDescriptionClass()
End If

flds=fcDesc.RequiredFields
fieldsEdit=CType(flds, IFieldsEdit)

fieldEdit=New FieldClass()
fieldEdit.Length_2=1
fieldEdit.Name_2="ColumnOne"
fieldEdit.Type_2=esriFieldType.esriFieldTypeString
fieldsEdit.AddField(CType(fieldEdit, IField))

'HIGHLIGHT: Add extra int column.
fieldEdit=New FieldClass()
fieldEdit.Name_2="Extra"
fieldEdit.Type_2=esriFieldType.esriFieldTypeInteger
fieldsEdit.AddField(CType(fieldEdit, IField))

'HIGHLIGHT: Set shape field geometry definition.
If Me.DatasetType <> esriDatasetType.esriDTTable Then
    Dim field As IField=flds.Field(flds.FindField("Shape"))
    fieldEdit=CType(field, IFieldEdit)
    Dim geomDefEdit As IGeometryDefEdit=CType(field.GeometryDef, IGeometryDefEdit)
    geomDefEdit.GeometryType_2=geometryTypeByID(ClassIndex)
    Dim shapeSRef As ISpatialReference=Me.spatialReference
    
    ' #Region "M & Z."
    'M.
    If (ClassIndex >= 3 AndAlso ClassIndex <= 5) OrElse ClassIndex >= 9 Then
        geomDefEdit.HasM_2=True
        shapeSRef.SetMDomain(0, 1000)
    Else
        geomDefEdit.HasM_2=False
    End If
    
    'Z.
    If ClassIndex >= 6 Then
        geomDefEdit.HasZ_2=True
        shapeSRef.SetZDomain(0, 1000)
    Else
        geomDefEdit.HasZ_2=False
    End If
    ' #End Region.
    
    geomDefEdit.SpatialReference_2=shapeSRef
End If
Return flds
End Get
End Property

• FetchAll
• FetchByEnvelope
• FetchByID

public IPlugInCursorHelper FetchByEnvelope(int ClassIndex, IEnvelope env, bool
    strictSearch, string WhereClause, object FieldMap)
{
    if (this.DatasetType == esriDatasetType.esriDTTable)
        return null;

    //The envelope that is passed in always has the same spatial reference as the data.
    //For identify, it checks if search geometry intersects dataset bound
    //but not ITable.Search(pSpatialQueryFilter, bRecycle), and so on.
    //Check to see if the input envelope falls within the extent.
    IEnvelope boundEnv=this.Bounds;
    boundEnv.Project(env.SpatialReference);
    if (boundEnv.IsEmpty)
        return null;
    //Or raise an error?
    try
    {
        SimplePointCursor spatialCursor=new SimplePointCursor(m_fullPath,
            this.get_Fields(ClassIndex),  - 1, (System.Array)FieldMap, env,
            this.geometryTypeByID(ClassIndex));
        setMZ(spatialCursor, ClassIndex);

        return (IPlugInCursorHelper)spatialCursor;
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex.Message);
        return null;
    }
}

Public Function FetchByEnvelope(ByVal ClassIndex As Integer, ByVal env As ESRI.ArcGIS.Geometry.IEnvelope, ByVal strictSearch As Boolean, ByVal WhereClause As String, ByVal FieldMap As Object) As ESRI.ArcGIS.Geodatabase.IPlugInCursorHelper Implements ESRI.ArcGIS.Geodatabase.IPlugInDatasetHelper.FetchByEnvelope
    If Me.DatasetType=esriDatasetType.esriDTTable Then
        Return Nothing
    End If
    
    'The envelope that is passed in always has the same spatial reference as the data.
    'For identify, it checks if search geometry intersects dataset bound
    'but not ITable.Search(pSpatialQueryFilter, bRecycle), and so on.
    'Check to see if input envelope falls within the extent.
    Dim boundEnv As IEnvelope=Me.Bounds
    boundEnv.Project(env.SpatialReference)
    If boundEnv.IsEmpty Then
        Return Nothing 'Or raise an error?
    End If
    
    Try
    Dim spatialCursor As SimplePointCursor=New SimplePointCursor(m_fullPath, _
                                             Me.Fields(ClassIndex), _
                                             -1, _
                                             CType(FieldMap, System.Array), _
                                             env, _
                                             Me.geometryTypeByID(ClassIndex))
    setMZ(spatialCursor, ClassIndex)
    
    Return CType(spatialCursor, IPlugInCursorHelper)
    Catch ex As Exception
    System.Diagnostics.Debug.WriteLine(ex.Message)
    Return Nothing
    End Try
End Function

• Field map - Controls which attribute values are fetched by the cursor.
• Query envelope - Determines which rows are fetched by the cursor.
• File path - Tells the cursor where the data is.

public IPlugInCursorHelper FetchWithFilter(int ClassIndex, IEnvelope env, bool
    strictSearch, string whereClause, IFIDSet FIDSet, object FieldMap);

Public Function FetchWithFilter ( _
                                 ByVal ClassIndex As Integer, _
                                 ByVal env As IEnvelope, _
                                 ByVal strictSearch As Boolean, _
                                 ByVal WhereClause As String, _
                                 ByVal FIDSet As IFIDSet, _
                                 ByVal FieldMap As Object _
                                 ) As IPlugInCursorHelper

Implementing a plug-in cursor helper

public void NextRecord()
{
    if (m_bIsFinished)
    //Error has already thrown once.
        return ;

    //OID search has been performed.
    if (m_iOID >  - 1 && m_sbuffer != null)
    {
        m_pStreamReader.Close();
        m_bIsFinished=true;

        throw new COMException("End of SimplePoint Plugin cursor", E_FAIL);
    }
    else
    {
        //Read the file for text.
        m_sbuffer=ReadFile(m_pStreamReader, m_iOID);
        if (m_sbuffer == null)
        {
            //Finish reading and close the stream reader so resources will be released.
            m_pStreamReader.Close();
            m_bIsFinished=true;

            //Raise E_FAIL to notify end of cursor.
            throw new COMException("End of SimplePoint Plugin cursor", E_FAIL);
        }

        //Search by envelope or return all records and let post-filtering do 
        //the work for you (performance overhead).
        else if (m_searchEnv != null && !(m_searchEnv.IsEmpty))
        {
            this.QueryShape(m_wkGeom);
            IRelationalOperator pRelOp=(IRelationalOperator)m_wkGeom;
            if (!pRelOp.Disjoint((IGeometry)m_searchEnv))
                return ;
            //Valid record within search geometry. Stop advancing.
            else
                this.NextRecord();
        }
    }

Public Sub NextRecord() Implements IPlugInCursorHelper.NextRecord
    If m_bIsFinished Then 'Error has already thrown once.
        Return
    End If
    
    'OID search has been performed.
    If m_iOID > -1 AndAlso Not m_sbuffer Is Nothing Then
        m_pStreamReader.Close()
        m_bIsFinished=True
        
        Throw New COMException("End of SimplePoint Plugin cursor", E_FAIL)
    Else
        'Read the file for text.
        m_sbuffer=ReadFile(m_pStreamReader, m_iOID)
        If m_sbuffer Is Nothing Then
            'Finish reading and close the stream reader so resources will be released.
            m_pStreamReader.Close()
            m_bIsFinished=True
            
            'Raise E_FAIL to notify end of cursor.
            Throw New COMException("End of SimplePoint Plugin cursor", E_FAIL)
            'Search by envelope or return all records and let post-filtering do
            'the work for you (performance overhead).
        ElseIf Not m_searchEnv Is Nothing AndAlso Not (m_searchEnv.IsEmpty) Then
            Me.QueryShape(m_wkGeom)
            Dim pRelOp As IRelationalOperator=CType(m_wkGeom, IRelationalOperator)
            If (Not pRelOp.Disjoint(CType(m_searchEnv, IGeometry))) Then
                Return 'Valid record within search geometry. Stop advancing.
            Else
                Me.NextRecord()
            End If
        End If
    End If
End Sub

public void QueryShape(IGeometry pGeometry)
{
    if (pGeometry == null)
        return ;

    try
    {
        double x, y;
        x=Convert.ToDouble(m_sbuffer.Substring(0, 6));
        y=Convert.ToDouble(m_sbuffer.Substring(6, 6));

        #region set M and Z aware
        if (m_bZ)
            ((IZAware)pGeometry).ZAware=true;
        if (m_bM)
            ((IMAware)pGeometry).MAware=true;
        #endregion 

        //Insert (advanced) geometry construction.
        if (pGeometry is IPoint)
        {
            ((IPoint)pGeometry).PutCoords(x, y);
            if (m_bM)
                ((IPoint)pGeometry).M=m_iInterate;
            if (m_bZ)
                ((IPoint)pGeometry).Z=m_iInterate * 100;
        }
        else if (pGeometry is IPolyline)
            buildPolyline((IPointCollection)pGeometry, x, y);
        else if (pGeometry is IPolygon)
            buildPolygon((IPointCollection)pGeometry, x, y);
        else
            pGeometry.SetEmpty();
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(" Error: " + ex.Message);
        pGeometry.SetEmpty();
    }
}

Public Sub QueryShape(ByVal pGeometry As IGeometry) Implements IPlugInCursorHelper.QueryShape
    If pGeometry Is Nothing Then
        Return
    End If
    
    Try
    Dim x, y As Double
    x=Convert.ToDouble(m_sbuffer.Substring(0, 6))
    y=Convert.ToDouble(m_sbuffer.Substring(6, 6))
    
    ' #Region "set M and Z aware."
    If m_bZ Then
        CType(pGeometry, IZAware).ZAware=True
    End If
    If m_bM Then
        CType(pGeometry, IMAware).MAware=True
    End If
    ' #End Region.
    
    'Insert (advanced) geometry construction.
    If TypeOf pGeometry Is IPoint Then
        CType(pGeometry, IPoint).PutCoords(x, y)
        If m_bM Then
            CType(pGeometry, IPoint).M=m_iInterate
        End If
        If m_bZ Then
            CType(pGeometry, IPoint).Z=m_iInterate * 100
        End If
    ElseIf TypeOf pGeometry Is IPolyline Then
        buildPolyline(CType(pGeometry, IPointCollection), x, y)
    ElseIf TypeOf pGeometry Is IPolygon Then
        buildPolygon(CType(pGeometry, IPointCollection), x, y)
    Else
        pGeometry.SetEmpty()
    End If
    Catch ex As Exception
    System.Diagnostics.Debug.WriteLine(" Error: " & ex.Message)
    pGeometry.SetEmpty()
    End Try
End Sub

public int QueryValues(IRowBuffer Row)
{
    try
    {
        if (m_sbuffer == null)
            return  - 1;

        for (int i=0; i < m_fieldMap.GetLength(0); i++)
        {
            //Insert field map interpretation.
            if (m_fieldMap.GetValue(i).Equals( - 1))
                continue;

            IField valField=m_fields.get_Field(i);
            char parse=m_sbuffer[m_sbuffer.Length - 1];
            switch (valField.Type)
            {
                case esriFieldType.esriFieldTypeInteger:
                case esriFieldType.esriFieldTypeDouble:
                case esriFieldType.esriFieldTypeSmallInteger:
                case esriFieldType.esriFieldTypeSingle:
                    Row.set_Value(i, Convert.ToInt32(parse)); 
                        //Get ASCII code number for the character.
                    break;
                case esriFieldType.esriFieldTypeString:
                    Row.set_Value(i, parse.ToString());
                    break;
            }
        }
        return m_iInterate; //HIGHLIGHT: 2.3 QueryValues. Return OID.
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex.Message);
        return  - 1;
    }
}

Public Function QueryValues(ByVal Row As IRowBuffer) As Integer Implements IPlugInCursorHelper.QueryValues
    Try
    If m_sbuffer Is Nothing Then
        Return -1
    End If
    
    Dim i As Integer=0
    Do While i < m_fieldMap.GetLength(0)
        'Insert field map interpretation.
        If m_fieldMap.GetValue(i).Equals( -1) Then
            i +=1
            Continue Do
        End If
        
        Dim valField As IField=m_fields.Field(i)
        Dim parse As Char=m_sbuffer.Chars(m_sbuffer.Length - 1)
        Select Case valField.Type
            Case esriFieldType.esriFieldTypeInteger, esriFieldType.esriFieldTypeDouble, esriFieldType.esriFieldTypeSmallInteger, esriFieldType.esriFieldTypeSingle
                Row.Value(i)=Convert.ToInt32(parse) 'Get ASCII code number for the character.
            Case esriFieldType.esriFieldTypeString
                Row.Value(i)=parse.ToString()
        End Select
        i +=1
    Loop
    Return m_iInterate 'Return OID.
    Catch ex As Exception
    System.Diagnostics.Debug.WriteLine(ex.Message)
    Return -1
    End Try
End Function

See Also: