Solved

Image.FromFile is locking the file

Posted on 2002-07-27
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Last Modified: 2007-12-19
Hi

Hi have this problem.
I am loading images from Sql2000 to file and from the file to an ImageList.

1. Can I load the images directly to the imageList. (Else)
2. When the data is saved to a Temp file and then load to the ImageList, The temp file stay locked, so, when the next image is ready to be loaded, I am getting an error:
~"File is in use (or locked) by another process".

Help!!!

Amitai

          public bool ImageLoad(int pID)
          {
               SqlCommand          cmd = new SqlCommand("EXEC dbo.spGOPImages_Get " + pID.ToString(), Connection);
               long               Size, Start=0;
               int                    BuffSize=2048;
               int                    ImageData = 4;
               byte[]               Buff = new byte[BuffSize-1];

               if(Connection.State!=System.Data.ConnectionState.Open)
                    Connection.Open();


               SqlDataReader dr = cmd.ExecuteReader();
               try
               {
                    while (dr.Read())
                    {
                         FileStream fs = new FileStream("TMP.ICO", FileMode.OpenOrCreate, FileAccess.Write);

                         Start = 0;
                         if (!dr.IsDBNull(ImageData))
                         {
                              Size = dr.GetBytes(ImageData, Start, Buff, 0, BuffSize);
                              while(Size > 0 && Size < BuffSize)
                              {    
                                   fs.Write(Buff, 1, (int) Size);
                                   fs.Flush();
                                   Start=Start+BuffSize;
                                   Size=dr.GetBytes(ImageData, Start, Buff, 0, BuffSize);
                              }
                         }
                         fs.Close();
                         fs = null;
                         
                         if(lstImages[pID] != null)
                         {
                              imlImages.Images.RemoveAt((int)lstImages[pID]);
                              lstImages.Remove(pID);
                         }
                         imlImages.Images.Add(Image.FromHbitmap(FromFile("TMP.ICO"));
                         lstImages.Add(dr["ImageID"], (int) imlImages.Images.Count);
                    }
               }
               finally
               {
                    dr.Close();
               }

               if(Connection.State!=System.Data.ConnectionState.Closed)
                    Connection.Close();
               
               return(true);
          }
0
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Question by:mAmitai
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9 Comments
 
LVL 23

Expert Comment

by:naveenkohli
ID: 7182079
imlImages.Images.Add(Image.FromHbitmap(FromFile("TMP.ICO"));


The above call locked the file. You need to dispose the image object that is loading this image file.

Image myImage = Image.FromHbitmap(FromFile("TMP.ICO"));
imlImages.Images.Add(myImage);
myImage.Dispose();

The other problem you are going to run into is that since you are using the same file for saving the image, if simultaneous calls are made into this method, the file will be locked for one. You may need to think about synchrnizing the call so that if one thread is using it, other has to wait.
0
 
LVL 1

Author Comment

by:mAmitai
ID: 7182157
I tried it it dosen't work.

P.S.
Sould be:
imlImages.Images.Add(Image.FromFile("TMP.ICO"));
0
 
LVL 1

Author Comment

by:mAmitai
ID: 7182619
Hello navee.
Defenatly dosen't work! I checked again.
When i Dispose the image the image in the ImageList allso distroied. Even image.Clone is not working.

****!!!
0
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LVL 1

Author Comment

by:mAmitai
ID: 7183081
I founs an MS Article about that problem...
Q311754
However it creates problems when I try to use the image
I am getting an error:

pictureBox1.Image=(Image) this.imlImages.Images[1];
-->"A generic error occurred in GDI+"
???????????????????????



Resolution: (Q311754)

To work around this problem, use the FileStream object as follows:
// Make sure that you have added the System.IO namespace.
using System.IO;

// Specify a valid picture file path on your computer.
FileStream fs;
fs = new FileStream("C:\\WINNT\\Web\\Wallpaper\\Fly Away.jpg", FileMode.Open, FileAccess.Read);
pictureBox1.Image = System.Drawing.Image.FromStream(fs);
fs.Close();
0
 
LVL 23

Expert Comment

by:naveenkohli
ID: 7183400
put an exception handler around

pictureBox1.Image=(Image) this.imlImages.Images[1];

and check the call stack and see where it is failing inside framework. And if possible get some more information about the exception.
0
 
LVL 1

Author Comment

by:mAmitai
ID: 7183724
Well it was somthing complitly different
The MS Q311754 Solved it.
Since I can't give the points to myself and you Naveenkoli were the only one who bothered I will give the points to  you. I sugest that you put the resolution:

Resolution: (Q311754)

To work around this problem, use the FileStream object as follows:
// Make sure that you have added the System.IO namespace.
using System.IO;

// Specify a valid picture file path on your computer.
FileStream fs;
fs = new FileStream("C:\\WINNT\\Web\\Wallpaper\\Fly Away.jpg", FileMode.Open, FileAccess.Read);
pictureBox1.Image = System.Drawing.Image.FromStream(fs);
fs.Close();


I will accept it so others can use the answer as well.

  Amitai.
0
 
LVL 23

Accepted Solution

by:
naveenkohli earned 100 total points
ID: 7183818
To work around this problem, use the FileStream object as follows:
// Make sure that you have added the System.IO namespace.
using System.IO;

// Specify a valid picture file path on your computer.
FileStream fs;
fs = new FileStream("C:\\WINNT\\Web\\Wallpaper\\Fly Away.jpg", FileMode.Open, FileAccess.Read);
pictureBox1.Image = System.Drawing.Image.FromStream(fs);
fs.Close();
0
 
LVL 1

Author Comment

by:mAmitai
ID: 7184468
Resolution: (Q311754)(MSKB)
0
 
LVL 23

Expert Comment

by:naveenkohli
ID: 7184885
To avoid this problem, i would suggest that you use Guids to name your temp files and implement a file watcher on tyhat folder that will clean up the files every X number of hours/days/months.
This is the technique we use allthe time and avoid headaches of exclusve file locking.
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