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PO
 

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  1. PO
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    <p>This is correct, it will not work. The problem is that you are crossing a managed/unmanaged boundary, I recently encountered the same. Other problems are that the stream is not directly there and the Image.FromStream has no idea how to deal with it.</p> <p>The solution is quite straightforward: read everything from PostedFile into a MemoryStream (just use <code>new MemoryStream()</code>) and use the MemoryStream with the <code>Image.FromStream</code>. This will solve your problem.</p> <p>Make sure to make proper use of <code>using</code> when you work with <code>Image</code>, <code>Graphics</code> and <code>Stream</code>s. All of them implement the IDisposable and in an ASP.NET environment, not using <code>using</code> blocks properly, can and will lead to increased memory usage and other nasty side effect on the long run (and ASP.NET apps do run very long!).</p> <p>The solution should look something like this:</p> <pre><code>using(Stream memstr = new MemoryStream()) { // copy to a memory stream Stream uploadStream = AsyncFileUpload1.PostedFile.InputStream; byte[] all = new byte[uploadStream.Length]; uploadStream.Read(all, 0, uploadStream.Length); memstr.Write(all, 0, uploadStream.Length); memstr.Seek(0, SeekOrigin.Begin); using(Graphics g = Graphics.FromStream(memstr)) { // do your img manipulation, or Save it. } } </code></pre> <p><strong>Update:</strong> the crossing managed boundary issue only occurs in the reverse (using Response stream), it seems, not with Upload streams, but I'm not entirely sure.</p>
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    1. POImage.FromStream(PostedFile.InputStream) Fails. (Parameter is not valid.) (AsyncFileUpload))
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    1. COCould you please provide a example on how to read all the bytes into the memory stream?
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      1. USThomas Sandberg
    2. CONote: it is not guaranteed that the `Read` works. If not, the return value contains the amount of bytes that were actually read. You can make your code more robust by always checking the return value of `Read()`, or loop until all bytes are read.
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    3. COTried this: string imageID; using (var mStream = new MemoryStream()) { var uploadStream = AsyncFileUpload1.PostedFile.InputStream; var all = new byte[uploadStream.Length]; uploadStream.Read(all, 0, (int) uploadStream.Length); mStream.Write(all, 0, (int) uploadStream.Length); mStream.Seek(0, SeekOrigin.Begin); using (var img = Image.FromStream(mStream)) { imageID = ImageCreation.SaveImage(img, true); } } But I get {"Parameter is not valid."}, still on the Image.FromStream. (Now even on local machine)
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      1. USThomas Sandberg
 

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