Vixed Vixed - 17 days ago 5
ASP.NET (C#) Question

Can't delete or rename original file after resizing

This function return an resized and centered image, and I execute it calling an url

thumb.aspx?image=test.jpg&width=100&height=50
the problem is that after the execution, I can't rename or delete the original file from server.

<%@ Import Namespace="System.Drawing" %>
<script language="C#" runat="server">
void Page_Load(Object sender, EventArgs e) {
try {
Response.Cache.VaryByParams["Image;Width;Height;needToFill"] = true;
Response.ContentType = "image/jpeg";
System.Collections.Hashtable imageOutputFormatsTable = new System.Collections.Hashtable();
imageOutputFormatsTable.Add(System.Drawing.Imaging.ImageFormat.Gif.Guid, System.Drawing.Imaging.ImageFormat.Gif);
imageOutputFormatsTable.Add(System.Drawing.Imaging.ImageFormat.Jpeg.Guid, System.Drawing.Imaging.ImageFormat.Jpeg);
imageOutputFormatsTable.Add(System.Drawing.Imaging.ImageFormat.Bmp.Guid, System.Drawing.Imaging.ImageFormat.Gif);
imageOutputFormatsTable.Add(System.Drawing.Imaging.ImageFormat.Tiff.Guid, System.Drawing.Imaging.ImageFormat.Jpeg);
imageOutputFormatsTable.Add(System.Drawing.Imaging.ImageFormat.Png.Guid, System.Drawing.Imaging.ImageFormat.Jpeg);
string imageLocation = Server.MapPath(Request.QueryString["Image"]);
int Width = Convert.ToInt32(Request.QueryString["Width"]);
int Height = Convert.ToInt32(Request.QueryString["Height"]);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageLocation);
int sourceWidth = image.Width;
int sourceHeight = image.Height;
int sourceX = 0;
int sourceY = 0;
double destX = 0;
double destY = 0;
double nScale = 0;
double nScaleW = 0;
double nScaleH = 0;
bool needToFill=true;
nScaleW = ((double)Width / (double)sourceWidth);
nScaleH = ((double)Height / (double)sourceHeight);

if (Request.QueryString["needToFill"] != null) {
needToFill = Convert.ToBoolean(Request.QueryString["needToFill"]);
}

if (!needToFill) {
nScale = Math.Min(nScaleH, nScaleW);
} else {
nScale = Math.Max(nScaleH, nScaleW);
destY = (Height - sourceHeight * nScale) / 2;
destX = (Width - sourceWidth * nScale) / 2;
}

if (nScale > 1) nScale = 1;

int destWidth = (int)Math.Round(sourceWidth * nScale);
int destHeight = (int)Math.Round(sourceHeight * nScale);

System.Drawing.Bitmap bmPhoto = new System.Drawing.Bitmap(destWidth + (int)Math.Round(2 * destX), destHeight + (int)Math.Round(2 * destY));
bmPhoto.SetResolution(72, 72);
System.Drawing.Imaging.ImageFormat outputFormat = (System.Drawing.Imaging.ImageFormat)imageOutputFormatsTable[image.RawFormat.Guid];
ApplicationException ex= new ApplicationException(string.Format("destWidth:{0}, destX:{1}, destHeight:{2}, desxtY:{3}, Width:{4}, Height:{5}", destWidth, destX, destHeight, destY, Width, Height));
System.Drawing.Graphics grPhoto = System.Drawing.Graphics.FromImage(bmPhoto);
Rectangle to = new System.Drawing.Rectangle((int)Math.Round(destX), (int)Math.Round(destY), destWidth, destHeight);
Rectangle from = new System.Drawing.Rectangle(sourceX, sourceY, sourceWidth, sourceHeight);
grPhoto.DrawImage(image, to, from, System.Drawing.GraphicsUnit.Pixel);

bmPhoto.Save(Response.OutputStream, outputFormat);
bmPhoto.Dispose();
grPhoto.Dispose();
}
catch (Exception ex){
System.IO.StreamWriter sw=null;
try{
sw=new System.IO.StreamWriter(Server.MapPath("error.txt"),true);
sw.WriteLine("Error : " + ex.Message + " processing " + Request.QueryString["Image"]);
}
catch{}
finally{sw.Close();}
Response.Redirect("thumberror.gif");
}
}
</script>

Answer

image doesn't look like it's being disposed. I'd recommend using a using statement to make resource management more clear.

A using statement allows placing something in a scope, and when the scope is left, it gets Dispose called on it. For example:

using(var image = new Bitmap(imageLocation))
{
    //Use image here
} //image will be disposed here
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