A Filter Dialog for a DataGridView

'' FILENAME:        DropDownExpression.vb
'' NAMESPACE:       PI.Dialogs.Filter
'' APPLICATION:     N/A
'' CREATED BY:      Luke Berg
'' CREATED:         8-15-06
'' REVISED BY:      Luke Berg
'' REVISED:         8-16-06
'' DESCRIPTION:     This represents an expression of a filter item that allows you to filter on
''                  a select group of items.

''' <summary>
'''   This represents an expression of a filter item that allows you to filter on
'''   a select group of items.
''' </summary>
''' <remarks>
'''  To use this expression, you will need to pass it the list of criteria with which to populate
'''  the criteria drop down list.
''' </remarks>
Public Class DropDownExpression

    ''' <summary>
    '''   The operands available for the expression
    ''' </summary>
    ''' <remarks></remarks>
    Private Enum Operands As Integer
        EqualTo = 0
        NotEqualTo = 1
    End Enum

    ''' <summary>
    '''   The datasource for the combobox of items to use as criteria
    ''' </summary>
    Public Property Items() As List(Of String)
        Get
            Return ComboBox1.DataSource
        End Get
        Set(ByVal value As List(Of String))
            ComboBox1.DataSource = value
        End Set
    End Property

    ''' <summary>
    '''  Basic constructor - no parameters
    ''' </summary>
    Public Sub New()

        ' This call is required by the Windows Form Designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.

    End Sub

    ''' <summary>
    '''  More advanced constructor
    ''' </summary>
    ''' <param name="items">The list of items add to the combobox of possible criteria</param>
    Public Sub New(ByVal field As String, ByVal items As List(Of String))

        ' This call is required by the Windows Form Designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.
        Me.Items = items
        Me.field = field

    End Sub

    ''' <summary>
    '''  Handles a selection of an operand
    ''' </summary>
    Public Sub OperandsList_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles OperandsList.SelectedIndexChanged
        SetValues()
    End Sub

    ''' <summary>
    '''  Handles the selection of a criteria from the possible list of criteria
    ''' </summary>
    Private Sub ComboBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.TextChanged
        SetValues()
    End Sub

    ''' <summary>
    '''  Sets the values of the expression's criteria, operand, inverse, readable operand, and readable criteria.
    '''  Called whenever the criteria or operand changes
    ''' </summary>
    Private Sub SetValues()

        '' Checks if nothing is set
        If ComboBox1.Text.Length = 0 Then
            Me._Filter = ""
            Me.RaiseFilterChanged()
            Exit Sub
        End If

        Select Case OperandsList.SelectedIndex
            Case Operands.EqualTo
                Me._Filter = Me.field & " = '" & ComboBox1.Text & "'"
            Case Operands.NotEqualTo
                Me._Filter = Me.field & " <> '" & ComboBox1.Text & "'"
        End Select

        '' Sets a readable version of the operand and readable version of the criteria
        Me.ReadableOperand = OperandsList.Text
        Me.ReadableCriteria = "'" & ComboBox1.Text & "'"

        '' Raises an event to indicate that the filter has changed.
        Me.RaiseFilterChanged()

    End Sub
End Class