File To IntPtr

The Purpose of the below class is to convert a String to IntPtr

Public Class CairoIntPtr
    Inherits MarshalByRefObject
    Implements IDisposable

    Private _disposed As Boolean
    Private _handle As IntPtr

    Public Sub New(s As String)
        Dim func As Func(Of String, IntPtr) = Function(str)
                                                  Dim ptr As IntPtr = CType(Nothing, IntPtr)
                                                  ptr = System.Runtime.InteropServices.Marshal.StringToHGlobalUni(str)
                                                  Return ptr
                                              End Function
        Dim zero As Func(Of IntPtr) = Function() IntPtr.Zero
        _handle = If(Not String.IsNullOrEmpty(s), func(s), zero)
    End Sub

    Public ReadOnly Property Handle() As Integer
        Get
            Return Me._handle
        End Get
    End Property

    Public ReadOnly Property ToInt32 As Int32
        Get
            Return Convert.ToInt32(Me.Handle)
        End Get
    End Property

    Public ReadOnly Property ToInt64 As Int64
        Get
            Return Convert.ToInt64(Me.Handle)
        End Get
    End Property

    Private Sub DisposeInternal()
        If Me._handle <> 0 Then
            Dim action As Action(Of IntPtr) = Sub(ptr As IntPtr)
                                                  System.Runtime.InteropServices.Marshal.FreeHGlobal(ptr)
                                              End Sub
            action(_handle)
            Me._handle = 0
        End If
    End Sub

    Protected Overridable Sub Dispose(disposing As Boolean)
        If _disposed Then
            Return
        End If

        If disposing Then
            Me.DisposeInternal()
        End If

        _disposed = True
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        Return obj IsNot Nothing AndAlso obj.[GetType]() Is MyBase.[GetType]() AndAlso (CType(obj, CairoIntPtr))._handle = Me.Handle
    End Function

    Public Overrides Function GetHashCode() As Integer
        Return Me._handle.GetHashCode()
    End Function

    Protected Overrides Sub Finalize()
        Dispose(False)
        MyBase.Finalize()
    End Sub

    Public Sub Dispose() Implements IDisposable.Dispose
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub

End Class

The purpose of the below class is to convert IntPtr to File

Public Class CairoDataFile

    Private _data As Byte()
    Private _cairo As String
    Public Sub New(ptr As IntPtr)
        Dim func As Func(Of IntPtr, String) = Function(p) System.Runtime.InteropServices.Marshal.PtrToStringUni(p)
        _cairo = If(Nothing, func(ptr))
        Me._data = (If(Not String.IsNullOrEmpty(_cairo), (New Lazy(Of Byte())(Function() IO.File.ReadAllBytes(_cairo))).Value, (New Lazy(Of Byte())(Function() New Byte() {})).Value))
    End Sub

    Public ReadOnly Property ToText As String
        Get
            Return _cairo
        End Get
    End Property

    Public ReadOnly Property ToBytes As Byte()
        Get
            Return Me._data
        End Get
    End Property
    ' It is recommended to remove the below property, it is written for demonstration   purpose
    Public ReadOnly Property ToStream As IO.MemoryStream
        Get
            Return New IO.MemoryStream(ToBytes())
        End Get
    End Property

End Class

Usage:

Both classes may used together to read any file in computer

Example: Read an image from application directory and use it as background for the form

        Dim filePath As String = ".\tmp-0.gif"
        Dim ptr As IntPtr = New CairoIntPtr(filePath).Handle
        Dim cdf As New CairoDataFile(ptr)
        If IO.File.Exists(cdf.ToText) Then
            Me.BackgroundImageLayout = ImageLayout.Center
            Me.BackgroundImage = Image.FromStream(cdf.ToStream)
        End If