Error when trying to pull a jpeg out of a stream..

[bull.enteract@rcn.com]

Ok, I start off with a bitmap image. I encode it as a jpeg and send it
across the network and pick it up on the other end. Now I have the
jpeg image on the other end as an arrray of bytes and I want to display
it in a picturebox control. How the heck do I convert this byte[] into
a bitmap?

Here is the pertinent code I use to convert it to a jpeg on the server
and send it to client..

....Bitmap workerBmp = new Bitmap(bmp);
MemoryStream memStream = new MemoryStream();
workerBmp.Save( memStream, ImageFormat.Jpe g);
byte[] byteData = memStream.ToArr ay();
networkStream.W rite(byteData, 0, byteData.Length );

So now I pick up the jpeg data on the client and that's where I am
stuck.. how do I get this data into a form that a picturebox can
understand?
I read the data...

while ((bytesRead = networkStream.R ead(dataBuffer, totalBytesRead,
dataBuffer.Leng th - totalBytesRead) ) < (dataBuffer.Len gth -
totalBytesRead) )
totalBytesRead += bytesRead;

Now what? I tried dropping the buffer into a MemoryStream and just
instantiating a Bitmap from the stream...i.e..
MemoryStream memStream = new MemoryStream(da taBuffer);
Bitmap bmp = new Bitmap(memStrea m);
//Image img = Image.FromStrea m(memStream); Same result if I use this

I get the following Exception..
An unhandled exception of type 'System.Argumen tException' occurred in
system.drawing. dll
Additional information: Invalid parameter used.

A point in the right direction please..

[bull.enteract@rcn.com]

Re: Error when trying to pull a jpeg out of a stream..

Ok, I've narrowed the problem down to the fact that I am converting it
to a jpeg image. If I change it to ImageFormat.Bmp then it works
fine.. sooo, I have this jpeg data that I have sent over the wire.. how
do I work with it on the other end? I thought that Image.FromStrea m
would work with jpeg data but it doesn't seem to... also, if I send the
jpeg image to a file on the server workerBmp.Save( "C:\\pic.jp eg",
ImageFormat.Jpe g) it saves as a valid jpeg image, so I'm pretty sure
the data coming across is valid....I'm pretty confused.. there must be
a way to "decode" the jpeg data on the client...

[Jon Skeet [C# MVP]]

Re: Error when trying to pull a jpeg out of a stream..

<bull.enteract@ rcn.com> wrote:[color=blue]
> Ok, I start off with a bitmap image. I encode it as a jpeg and send it
> across the network and pick it up on the other end. Now I have the
> jpeg image on the other end as an arrray of bytes and I want to display
> it in a picturebox control. How the heck do I convert this byte[] into
> a bitmap?
>
> Here is the pertinent code I use to convert it to a jpeg on the server
> and send it to client..[/color]

<snip>

You haven't shown where you're specifying dataBuffer's length. Is it
the exact size of the data you'll be receiving?

Are the server and the client both PCs, or is one a PocketPC or
similar?

If you try to convert byteData on the server side back into a JPEG,
does that work?

Could you post a short but complete program which demonstrates the
problem?

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Eyal Safran]

Re: Error when trying to pull a jpeg out of a stream..

works great:

private byte[] jpegArray;

public Class1()
{
InitializeCompo nent();
Text = "Form1";
FileStream fs = File.OpenRead(@ "C:\pic.jpg ");
jpegArray = new byte[fs.Length];
fs.Read(jpegArr ay, 0, (int)fs.Length) ;
fs.Close();
}

private void Class1_Load(obj ect sender, System.EventArg s e)
{
MemoryStream ms = new MemoryStream(jp egArray);
Bitmap bmp = (Bitmap)System. Drawing.Bitmap. FromStream(ms);
BackgroundImage = bmp;
}

Eyal.