createcontrol.vb

This application uses OleDb as a backhand communicator with the file to allow the user to : select,

Imports System
Imports System.Windows.Forms

Namespace DataEasy
    '/ <summary>
    '/ This Class Allows the user to develop his/her own controls
    '/ </summary>
    Public Class CreateControls
        Private Shared height As Integer
        Private Shared width As Integer
        Private Shared left As Integer
        Private Shared top As Integer 'So the controls will be placed in a line, one under the other
        Private Shared text As String
        Private Shared name As String
        'Note: Multiple controls may have the same name in .Net

        'MakeControl
        'Add the control to the form
        'AddControlToTheForm(myNewControl)
        Public Shared Function MakeControl(ByVal ControlType As String, ByVal cHeight As Integer, ByVal cWidth As Integer, ByVal cLeft As Integer, ByVal cTop As Integer, ByVal cText As String, ByVal cName As String) As Control
            'As there are four steps to follow
            'in order to create controls at runtime:
            'GET THE ASSEMBLY QUALIFIED NAME,
            'CREATE THE CONTROL,
            'SET THE CONTROL'S PROPERTIES and
            'ADD THE CONTROL TO THE FORM
            'I split method into four
            'methods doing exactly the specified
            'operations
            'Get the assembly qualified name
            Dim assemblyName As String
            assemblyName = GetAssemblyQualifiedName(ControlType)

            'Create the control
            Dim myNewControl As Control
            myNewControl = CreateControl(assemblyName)

            'Set it's properties like Name, 
            'Top, Left etc.
            height = cHeight
            width = cWidth
            left = cLeft
            top = cTop
            text = cText
            name = cName
            SetControlProperties(myNewControl)

            Return myNewControl
        End Function

        'GetAssemblyQualifiedName
        Private Shared Function GetAssemblyQualifiedName(ByVal ControlType As String) As String
            'In order to create a control 
            'at runtime you need to know:
            'THE CONTROL TYPE, 
            'THE NAME OF THE FILE that 
            'contains the type, 
            'THE VERION OF THE FILE, 
            'THE CULTURE and 
            'THE PUBLIC TOKEN KEY

            'It would be a better practice to 
            'declare this constants at the 
            'class level.
            'The reason why I placed this here
            'is olny that I wanted to make
            'this tutorial more easy to be 
            'followed and understood
            Dim TYPE_NAME As String = "System.Windows.Forms." + ControlType
            Const FILE_NAME As String = "System.Windows.Forms" 'REMARK! The name of the file without the type (.dll)
            Const VERSION_NUMBER As String = "1.0.3300.0"
            Const CULTURE As String = "neutral"
            Const TOKEN_KEY As String = "b77a5c561934e089"

            'Create the assembly qualified name
            Dim assemblyQualifiedName As String = TYPE_NAME + ", " + FILE_NAME + ", Version=" + VERSION_NUMBER + ", Culture=" + CULTURE + ", PublicKeyToken=" + TOKEN_KEY

            'return the assembly qualified name
            Return assemblyQualifiedName
        End Function

        'NOTE!
        'If you want to create a control 
        'deffined in an other library you
        'need to find the library version,
        'the culture and the token, presumming 
        'that you allready know the type of
        'control, and the library.
        'Do find this informations just
        'browse with WINDOWS EXPLORER
        'to the <WINDOWS DIR>\Assembly.
        'If you don't have this version of
        'System.Windows.Forms.dll
        'you shold also do the same way
        'to find your vesrion, culture and 
        'token

        'CreateControl
        Private Shared Function CreateControl(ByVal assemblyName As String) As Control
            'Get the button type
            Dim buttonType As Type = Type.GetType(assemblyName)

            'Get the button contructor
            'We search for the constructor
            'with no parameters
            Dim buttonCtor As System.Reflection.ConstructorInfo
            Dim typesCtorParams() As Type = Type.EmptyTypes
            buttonCtor = buttonType.GetConstructor(typesCtorParams)

            'Create the control by invoking
            'the constructor
            Dim paramsCtor() As Object = Nothing

            Dim myControl As Control = CType(buttonCtor.Invoke(paramsCtor), Control)
            'Return the control
            Return myControl
        End Function

        'SetControlProperties
        Private Shared Sub SetControlProperties(ByRef control As Control)
            'First increment the counter so the
            'next control will be visible
            '(otherwise it will be under
            'the previous control)
            'newControlsCounter++;
            'Set some properties
            control.Height = height
            control.Width = width
            control.Left = left
            control.Top = top 'So the controls will be placed in a line, one under the other
            control.Text = text
            control.Name = name 'Note: Multiple controls may have the same name in .Net
        End Sub
    End Class
    'CreateControls 'Add an event
    'NOTE!
    '1)
    'If you don't set any property
    'the control will be plased with
    'it's default properties.
    '
    'To create a control with it's
    'default properties comment all
    'the code within this method
    '2)
    'If you want to set some properties 
    'or handle some events that 
    'aren't inherited from
    'System.Windows.Forms.Control 
    '(such as you own-deffined control)
    'you have to cast the control
    'to a type that knows this properties
    'and events (such as your control type)
End Namespace