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Animation – A class to extract all the frames of an animated image

Animation – A class to extract all the frames of an animated image

' This class loads an animated image and gives access to all its internal ' frames as Bitmap objects'' Example:'    ' load the animation and extract its frames'    Me.Cursor = Cursors.WaitCursor'    Dim anim As New Animation("D:SampleAnimation.gif")'    Me.Cursor = Cursors.Default'    ' get a reference to the first and last frame'    Dim firstFrame As Bitmap = anim.Frame(0)'    Dim lastFrame As Bitmap = anim.Frame(anim.FrameCount - 1)'    ' show the frames in two picture boxes'    PictureBox1.Image = firstFrame'    PictureBox2.Image = lastFrameClass Animation    Implements IDisposable    Dim m_Img As System.Drawing.Image    Dim m_Frames As New System.Collections.ArrayList    Dim m_FrameCount As Integer    Sub New(ByVal imgPath As String)        ' load the image        m_Img = System.Drawing.Image.FromFile(imgPath)        ' throw an exception and exit if this is not an animated image        If System.Drawing.ImageAnimator.CanAnimate(m_Img) = False Then            m_Img.Dispose()            Throw New ArgumentException("This is not an animated image")        End If        ' count the image's frames        Dim fdl As New Drawing.Imaging.FrameDimension(m_Img.FrameDimensionsList _            (0))        m_FrameCount = m_Img.GetFrameCount(fdl)        ' extract the first frame and start the animation to extract the other         ' single frames        AddCurrentFrame()        System.Drawing.ImageAnimator.Animate(m_Img, New EventHandler(AddressOf _            OnFrameChanged))        Do ' wait until all frames are loaded        Loop Until Done    End Sub    ' Return the total number of frames    Public ReadOnly Property FrameCount() As Integer        Get            Return m_FrameCount        End Get    End Property    ' Return the bitmap of the specified frame, stored in the private ArrayList    Public ReadOnly Property Frame(ByVal index As Integer) As _        System.Drawing.Bitmap        Get            Return DirectCast(m_Frames(index), System.Drawing.Bitmap)        End Get    End Property    Public Sub Dispose() Implements System.IDisposable.Dispose        StopAnimate()    End Sub    ' ==================== PRIVATE MEMBERS ====================    ' This method is raised when the current frame changes    Private Sub OnFrameChanged(ByVal sender As Object, ByVal e As EventArgs)        ' if the m_Frames array contains FrameCount bitmaps,        '  it means that the animation run through the end,         ' and now it is starting from the beginning again, so stop it        If Done Then            StopAnimate()            Exit Sub        End If        ' update the image to the new frame, and save it        System.Drawing.ImageAnimator.UpdateFrames(m_Img)        AddCurrentFrame()    End Sub    ' Add the current frame to the private ArrayList of bitmaps    Private Sub AddCurrentFrame()        ' create a new empty bitmap        Dim bmp As New System.Drawing.Bitmap(m_Img.Width, m_Img.Height)        ' retrieve a canvas object that allows to draw on the empty bitmap        Dim g As System.Drawing.Graphics = System.Drawing.Graphics.FromImage _            (DirectCast(bmp, System.Drawing.Image))        ' copy the original image on the canvas, and thus on the new bitmap        g.DrawImage(m_Img, 0, 0)        ' add the frame to the array        m_Frames.Add(bmp)    End Sub    ' Return True when the class has extracted all the frames    Private ReadOnly Property Done() As Boolean        Get            Return m_Frames.Count = FrameCount        End Get    End Property    ' Stop the animation and dispose the open image object    Private Sub StopAnimate()        System.Drawing.ImageAnimator.StopAnimate(m_Img, _            New EventHandler(AddressOf OnFrameChanged))        m_Img.Dispose()    End SubEnd Class

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