[RESOLVED] Caching thumbnails

[olamm2k]

Well, I somehow missed that last post of yours - failed to get the email notification. Anyway, here's what I ended up doing:

<%@ Page Language="VB" Debug="False" Trace="False" %>
<%@Import Namespace="System.Drawing" %>
<%@Import Namespace="System.Drawing.Imaging" %>
<%@Import Namespace="System.Drawing.Drawing2D" %>
 
<script language="VB" runat="server">
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
  Dim strImage As String = Replace(Request.QueryString("image"), "%20", " ")
  Dim strAlbum as String = Replace(Request.QueryString("album"), "%20", " ")
 
  If strImage = String.Empty Or strAlbum = String.Empty Then Exit Sub
  If InStr(strImage, "/") <> 0 Or InStr(strImage, "\") <> 0 Or _
   InStr(strAlbum, "/") <> 0 Or InStr(strAlbum, "\") <> 0 Then
    Exit Sub
  End If
 
  Dim sWidth = Request("w")
  Dim sHeight = Request("h")
 
  If Not sHeight = String.Empty And Not sWidth = String.Empty Then 
    sWidth = Integer.Parse(sWidth)
    sHeight = Integer.Parse(sHeight)
  Else
    sWidth = 20
    sHeight = 20
  End If
 
  Dim strPath As String = Server.MapPath("photos/" & strAlbum & "/" & strImage)
  Dim fsMain As System.IO.FileStream = New System.IO.FileStream(strPath, _
   System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Read)
 
  'Cache.Remove(strPath & "_" & sWidth & "_" & sHeight)
  Dim bytImage As Byte() = Cache.Get(strPath & "_" & sWidth & "_" & sHeight)
 
  Dim msTempStream As System.IO.MemoryStream
  Dim imgMain As System.Drawing.Image
 
  If bytImage Is Nothing Then
    ReDim bytImage(fsMain.Length)
    fsMain.Read(bytImage, 0, fsMain.Length)
    fsMain.Close()
 
    msTempStream = New System.IO.MemoryStream(bytImage)
    imgMain = System.Drawing.Image.FromStream(msTempStream)
 
    Dim lnRatio As Decimal
    Dim lnNewWidth As Integer = 0
    Dim lnNewHeight As Integer = 0
    If (imgMain.Width > imgMain.Height) Then
      lnRatio = Integer.Parse(sWidth) / imgMain.Width
      lnNewWidth = Integer.Parse(sWidth)
      Dim lnTemp As Decimal = imgMain.Height * lnRatio
      lnNewHeight = lnTemp
    Else 
      lnRatio = Integer.Parse(sHeight) / imgMain.Height
      lnNewHeight = Integer.Parse(sHeight)
      Dim lnTemp As Decimal = imgMain.Width * lnRatio
      lnNewWidth = lnTemp
    End If
 
    Dim imgThumbnail As System.Drawing.Image = New Bitmap(lnNewWidth, lnNewHeight)
    Dim graThumbnail As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(imgThumbnail)
 
    graThumbnail.InterpolationMode = InterpolationMode.HighQualityBicubic
    graThumbnail.SmoothingMode = SmoothingMode.HighQuality
    graThumbnail.PixelOffsetMode = PixelOffsetMode.HighQuality
    graThumbnail.CompositingQuality = CompositingQuality.HighQuality
    graThumbnail.DrawImage(imgMain, 0, 0, lnNewWidth, lnNewHeight)
 
    Dim iciInfo() As ImageCodecInfo = ImageCodecInfo.GetImageEncoders()
    Dim encpMain As EncoderParameters = New EncoderParameters(1)
    encpMain.Param(0) = New EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L)
 
    Dim strOutputFilename As String = String.Empty 
    strOutputFilename = Request.QueryString("OutputFilename") 
 
    If Not strOutputFilename = String.Empty Then 
      Try 
        imgThumbnail.Save(Server.MapPath("photos/" & strAlbum & "/") & strOutputFilename, ImageFormat.Jpeg)
      Catch ex As Exception 
        imgThumbnail.Dispose() 
        Return
      End Try 
    End If
 
    Response.ContentType = "image/jpeg" 
    Dim msSaveStream As System.IO.MemoryStream = New System.IO.MemoryStream
    imgThumbnail.Save(msSaveStream, iciInfo(1), encpMain)
    msSaveStream.WriteTo(Response.OutputStream)
    Dim bytSave(msSaveStream.Length) As Byte
    msSaveStream.Position = 0
    msSaveStream.Read(bytSave, 0, msSaveStream.Length)
    Cache.Insert(strPath & "_" & sWidth & "_" & sHeight, _
     bytSave, Nothing, DateTime.MaxValue, TimeSpan.Zero)
    imgThumbnail.Dispose()
  Else
    msTempStream = New System.IO.MemoryStream(bytImage)
    Response.ContentType = "image/jpeg" 
    msTempStream.WriteTo(Response.OutputStream)
 
    Dim strOutputFilename As String = String.Empty 
    strOutputFilename = Request.QueryString("OutputFilename") 
 
    If Not strOutputFilename = String.Empty Then 
      Try 
        imgMain = System.Drawing.Image.FromStream(msTempStream)
        imgMain.Save(Server.MapPath("photos/" & strAlbum & "/") & strOutputFilename, ImageFormat.Jpeg)
      Catch ex As Exception 
        imgMain.Dispose() 
        Return
      End Try 
      imgMain.Dispose() 
    End If
  End If
End Sub 
</script>

There's a distinct lack of comments, but essentially, instead of caching the Image object, I cache a byte array containing the image.

What do you reckon? Is there going to be a big difference in speed?