ASP.NET創(chuàng)建動(dòng)態(tài)縮略圖的方法

Function CreateJPEGThumbnail(ByVal inSourceFile As String, ByVal inDestinationFile As String, ByVal ThumbWidth As Integer, ByVal ThumbHeight As Integer) As Boolean
 Dim imageFile As System.Drawing.Image
 Dim outputFstream As New FileStream(inSourceFile, FileMode.Open, FileAccess.Read) 
 'Exposes a System.IO.Stream around a file, supporting both synchronous and asynchronous read and write operations.
 Dim ImageAbortCallBack As System.Drawing.Image.GetThumbnailImageAbort 
 'This method returns true if it decides that the System.Drawing.Image.GetThumbnailImage method should prematurely stop execution; otherwise, it returns false.
 imageFile = System.Drawing.Image.FromStream(outputFstream)
 ImageAbortCallBack = New System.Drawing.Image.GetThumbnailImageAbort(AddressOf ImageAbortDummyCallback)
 imageFile = imageFile.GetThumbnailImage(ThumbWidth, ThumbHeight, ImageAbortCallBack, IntPtr.Zero) 
 'IntPtr = A platform-specific type that is used to represent a pointer or a handle.
 imageFile.Save(inDestinationFile, System.Drawing.Imaging.ImageFormat.Jpeg)
 outputFstream.Close()
 outputFstream = Nothing
 imageFile = Nothing
End Function