Re: Deleting a file being loaded in a picturebox - C# Discussion Boards

Re: Deleting a file being loaded in a picturebox

21-Aug-07 20:17

I tried using dispose() on a picturebox to remove the file being held open since I am trying to programmatically delete the file. But, it is giving an exception saying that the file is in use.

I am displaying the image in the following way.
pictureBox.Image = System.Drawing.Image.FromFile(path);

How can I remove it from being held open?

Michael Sync21-Aug-07 20:39

Re: Deleting a file being loaded in a picturebox

21-Aug-07 20:39

Try this code ~

 private void button1_Click(object sender, EventArgs e)<br />
        {<br />
            string p = "C:\\a.bmp";<br />
            Image img = Image.FromFile (p);<br />
            pictureBox1.Image = img;<br />
            MessageBox.Show ("Image added.");<br />
            img.Dispose ();<br />
<br />
            if ( !CheckIfFileIsBeingUsed (p) )<br />
            {<br />
                System.IO.File.Delete (p);<br />
                MessageBox.Show ("Image deleted.");<br />
            }<br />
            <br />
        }<br />
        public bool CheckIfFileIsBeingUsed(string fileName)<br />
        {<br />
             System.IO.FileStream fs;<br />
            try<br />
            {<br />
<br />
                fs = System.IO.File.Open (fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.None);<br />
                fs.Close();<br />
            }<br />
            catch ( Exception exp )<br />
            {<br />
                Console.WriteLine (exp.Message);<br />
                return true;<br />
            }<br />
            return false;<br />
<br />
        }

Note that you should not directly set the image to PictureBox. Instead, use one buffer and dispose it if you don't need anymore.

Ref: This CheckIfFileIsBeingUsed method is from http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=547070&SiteID=1[^]

Hope it helps..

Thanks and Regards,
Michael Sync ( Blog: http://michaelsync.net)

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Hessam Jalali21-Aug-07 20:41

Hessam Jalali

21-Aug-07 20:41

as Christian Graus said before ,you must Dispose the image not the pictureBox

this.pictureBox1.Image.Dispose();
System.IO.File.Delete(path);

Good Luck

Re: Deleting a file being loaded in a picturebox

Luc Pattyn22-Aug-07 1:01

Luc Pattyn

22-Aug-07 1:01

Hi, if you use a FileStream to read your image, you will not have these problems,
since FromStream does not keep the file open.

Smile | :)

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Identifying the type of file

aravinda77721-Aug-07 19:57

21-Aug-07 19:57

hi everybody!

I have a requirement to identify whether the file I am copying is an image, audio, video, office document etc.

What's the best way to do this apart from checking the extensions?

Anyway, i handled identifying non-images. but, when it comes to identifying video, audio and office docs, I don't think checking on extensions would be a wise move.How can I do it effectively?

Regards,
A

Christian Graus21-Aug-07 20:01

21-Aug-07 20:01

aravinda777 wrote:
What's the best way to do this apart from checking the extensions?

Use GDI+ to attempt to load a file and verify if it's an image. Write code that reads the file itself and attempts to identify the file format, which means you need to look for unique markers for each of these file types, and look for them.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Michael Sync21-Aug-07 20:19

21-Aug-07 20:19

Christian Graus wrote:
Use GDI+ to attempt to load a file and verify if it's an image.

Okay. Yeah. but what about other extension (eg: doc)?

Christian Graus wrote:
rite code that reads the file itself and attempts to identify the file format, which means you need to look for unique markers for each of these file types, and look for them.

I'm not clear about that. Could you please explain me again?

unique markers

like ??

aravinda77721-Aug-07 20:32

21-Aug-07 20:32

Something like how to identify those particular markers and stuff?

Christian Graus21-Aug-07 20:45

21-Aug-07 20:45

Michael Sync wrote:
but what about other extension (eg: doc)?

Exactly as I said

Michael Sync wrote:
I'm not clear about that. Could you please explain me again?

You'd have to know that the file format contains the word 'WORD' in the first four bytes, for example, and open the file and examine it for those known markers related to the known file format.

Michael Sync wrote:
like ??

I have no idea, I'm not the one with the issue.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Michael Sync21-Aug-07 21:59

21-Aug-07 21:59

Thanks. Christian..

Christian Graus wrote:
Exactly as I said

Yeah.

Christian Graus wrote:
I have no idea, I'm not the one with the issue.

Okay.

Christian Graus wrote:
You'd have to know that the file format contains the word 'WORD' in the first four bytes, for example, and open the file and examine it for those known markers related to the known file format.

Oh.. I didn't know about that.. I will try to check this one.. thanks.

But i think that checking the extension might be more easier than checking the fist four bytes of each file, isn't it?

Christian Graus22-Aug-07 0:10

22-Aug-07 0:10

Michael Sync wrote:
ut i think that checking the extension might be more easier than checking the fist four bytes of each file, isn't it?

The first four bytes is an example off the top of my head. It's not real, Word doesn't do that. But, it may well do *something* to mark it's files.

And yes, checking the extension is going to work 99% of the time, and is a lot easier to do.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Michael Sync21-Aug-07 20:03

21-Aug-07 20:03

aravinda777 wrote:
i handled identifying non-images

non-images files means "*.txt, *.dll, *.exe"?? How did you handle identifying those file type without checking the extension??

aravinda77721-Aug-07 20:13

21-Aug-07 20:13

In fact i am using the image to be displayed in a picturebox. When I try non-images, it gives an OutOfMemoryException.

This way I can identify non-images. Smile | :)

Luc Pattyn22-Aug-07 1:04

Luc Pattyn

22-Aug-07 1:04

There is no general solution to identifying a file's type; new file types are
created every day.
If you are only interested in whether it is a loadable image, then try to load
the image, and live with the possible exception.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Thomas Krojer23-Aug-07 0:53

Thomas Krojer

23-Aug-07 0:53

Maybe you will find this site useful:

http://www.wotsit.org/

Greetings, Thomas

Help me in Invoking Dll's

Giorgi Dalakishvili21-Aug-07 22:07

Giorgi Dalakishvili

21-Aug-07 22:07

You can check only the extension but it might be incorrect. If you want tighter control then look for magic number[^] in that file Smile | :)

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kandy_soliton21-Aug-07 19:38

kandy_soliton

21-Aug-07 19:38

Hi All,

I facing a problem which i have described briefly in the following paragraph.

Let me tell you a scenario where in the user has to choose any kind of dll he wants, rather be .Net Dll or Native Dll for a connection to his server.
In that he knows the function to Invoke.

I need to write a common user interface to invoke any kind of dll, based on the choice of the user. Is that possible ?. If so help me regarding the stratergy that i have to use or any examples of such accomplishment.

FYI
I know one software which is doing to most of the Dll's.

Thanks in Advance

Re: Help me in Invoking Dll's

Christian Graus21-Aug-07 20:00