VB.NET PowerPoint - PPT-to-BMP Conversion

' Render PowerPoint Document to get a REImage collection.
Private Function GetPage(pageIndex As Integer) As BasePage Implements PPTXDocument.GetPage
End Function
Private Function toImage() As BaseImage Implements PPTXPage.toImage
End Function
Private Function toImage(height As Integer, width As Integer) As BaseImage Implements PPTXPage.toImage
End Function

' Convert PowerPoint slide to BMP using image conversion APIs.
Private Sub SaveImageFile(image As REImage, filePath As [String]) Implements REFile.SaveImageFile
End Sub

''' <summary>
''' Render PPTXDocument to image of BMP format
''' </summary>
''' <param name="PowerPointFilePath"></param>
''' <returns></returns>
Public Function RenderPPTXDocumentToBMP(PowerPointFilePath As [String]) As List(Of Stream)
	' A list of stream which contains the image data of the BMP image.
	Dim buffer As New List(Of Stream)()

	Dim doc As New PPTXDocument(PowerPointFilePath)
	For i As Integer = 0 To doc.GetPageCount() - 1
		Dim page As PPTXPage = DirectCast(doc.GetPage(i), PPTXPage)
		Dim temp As REImage = DirectCast(page.ToImage(), REImage)
		Dim imageStream As New MemoryStream()
		If temp IsNot Nothing Then
			temp.Convert(imageStream, ImageFormat.Bitmap)
			buffer.Add(imageStream)
		End If
	Next

	Return buffer
End Function