.NET GZip Class with extended functionality

Code

Public Class Example



    Public Event Progress(Position As Int64, Total As Int64)



    Public Sub ShowProgression(Position As Int64, Total As Int64)

        '...code...

    End Sub



    Public Function Compress(src() As Byte) As Byte()

        Using gzip As New GZipStream(CompressionLevel.Fastest, Buffer.VeryLarge, True)

            Return gzip.Compress(src, AddressOf Me.ShowProgression)

        End Using

    End Function



    Public Function Decompress(src() As Byte, Callback As GZipStream.ProgressCallback) As Byte()

        Using gzip As New GZipStream(CompressionLevel.Fastest, Buffer.Standard, True)

            Return gzip.Decompress(src, Sub(x, y) RaiseEvent Progress(x, y))

        End Using

    End Function



End Class

Code

Imports System.IO

Imports System.IO.Compression

Imports System.Runtime.InteropServices

Public NotInheritable Class GZipStream

    Inherits MemoryStream

    Public Enum Buffer As Int32

        Small = &HFF

        Standard = &HFFF

        Large = &HFFFF

        VeryLarge = &HFFFFF

    End Enum

    Public Delegate Sub ProgressCallback(Position As Int64, Total As Int64)

    Public Property Level As CompressionLevel

    Public Property BufferMaxSize As Int32

    Public Property BufferAutoSize As Boolean

    Sub New()

        Me.Level = CompressionLevel.Fastest

        Me.BufferMaxSize = DirectCast(Buffer.Standard, Int32)

        Me.BufferAutoSize = True

    End Sub

    Sub New(Buffer As Buffer)

        Me.Level = CompressionLevel.Fastest

        Me.BufferMaxSize = DirectCast(Buffer.Standard, Int32)

        Me.BufferAutoSize = False

    End Sub

    Sub New(Level As CompressionLevel)

        Me.Level = Level

        Me.BufferMaxSize = DirectCast(Buffer.Standard, Int32)

        Me.BufferAutoSize = False

    End Sub

    Sub New(BufferAutoSize As Boolean)

        Me.Level = Level

        Me.BufferMaxSize = DirectCast(Buffer.Standard, Int32)

        Me.BufferAutoSize = BufferAutoSize

    End Sub

    Sub New(Level As CompressionLevel, BufferSize As Buffer)

        Me.Level = Level

        Me.BufferMaxSize = DirectCast(BufferSize, Int32)

        Me.BufferAutoSize = False

    End Sub

    Sub New(Level As CompressionLevel, BufferSize As Buffer, BufferAutoSize As Boolean)

        Me.Level = Level

        Me.BufferMaxSize = DirectCast(BufferSize, Int32)

        Me.BufferAutoSize = BufferAutoSize

    End Sub

    Public Function Compress(source() As Byte, Progress As ProgressCallback) As Byte()

        Dim p As Integer = 0, Buffer As Byte() = New Byte(Me.AutoAdjustBuffer(source.Length - 1)) {}

        Using deflate As New DeflateStream(Me, Me.Level, True)

            Do

                Buffer = Me.Copy(source, p, Buffer, 0)

                If (p < source.Length) Then

                    deflate.Write(Buffer, 0, Buffer.Length)

                    p += Buffer.Length

                    Progress.Invoke(p, source.Length)

                End If

            Loop While p < source.Length

        End Using

        Progress.Invoke(0, 0)

        Return Me.ToArray

    End Function

    Public Function Decompress(source() As Byte, Progress As ProgressCallback) As Byte()

        Dim p As Int32 = 0, buffer As Byte() = New Byte(Me.AutoAdjustBuffer(source.Length - 1)) {}

        Using deflate As New DeflateStream(New MemoryStream(source), CompressionMode.Decompress)

            Do

                p = deflate.Read(buffer, 0, buffer.Length)

                If p > 0 Then

                    Progress.Invoke(deflate.BaseStream.Position - 1, deflate.BaseStream.Length - 1)

                    Me.Write(buffer, 0, p)

                End If

            Loop While p > 0

            Progress.Invoke(0, 0)

            Return Me.ToArray

        End Using

    End Function

    Private Function AutoAdjustBuffer(Length As Integer) As Integer

        If (Not Me.BufferAutoSize) Then Return Me.BufferMaxSize

        Dim n As Integer = &H400

        Do

            n += &H400

        Loop Until n >= Length Or n >= Me.BufferMaxSize

        Return n

    End Function

    Private Function Copy(source() As Byte, sourceindex As Int64, destination() As Byte, destinationindex As Int64) As Byte()

        If (destination.Length > (source.Length - sourceindex)) Then

            destination = New Byte(Convert.ToInt32((source.Length - sourceindex) - 1)) {}

        End If

        System.Array.Copy(source.ToArray, sourceindex, destination, destinationindex, destination.Length)

        Return destination

    End Function

End Class