loading bitmap locks file until dispose?

I am loading a bitmap from a file and using it as the background image of my form.

Code:

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string sBitmapFullPath = @"C:\picture.bmp";
Bitmap bm = new Bitmap(sBitmapFullPath);

Color col = bm.GetPixel(1, 1);

this.Width = bm.Width;
this.Height = bm.Height;

this.BackgroundImage = bm;

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At some point later I try to modify the file C:\picture.bmp, but the file is locked. After I call Bitmap.Dispose, I can modify the file. Is there any way that I can modify the file while it is still locked? I tried to use Bitmap.Clone image, but that didn't work either. Any ideas?

Basically, I want to change the image used for my form background, but I want it to use the same file path.

If you load an image, it is still connected to its file and keeps it open. You need to detach it - you have to create a in memory copy of the image. Than you can close the stream.

Quote:

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Originally Posted by boudino

If you load an image, it is still connected to its file and keeps it open. You need to detach it - you have to create a in memory copy of the image. Than you can close the stream.

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I'm not sure how to do this. I tried creating a new Bitmap class instance and then performing a Bitmap.Clone to copy the old bitmap to the new bitmap. But now I get the same error in reference to the new Bitmap instance.

Code:

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Bitmap temp = Image.FromFile(...);

Bitmap bmp = new Bitmap(temp.Width, temp.Height);
using ( Graphics g = Graphics.FromImage(bmp) ) {
    g.DrawImage(temp, ...);
}

temp.Dispose();

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edit: though clone should work (I've done it quite a few times). make sure to dispose of the bmp from file before you try to access the image file itself.

I came up with another way. This also keeps the memory usage to a minimum

Code:

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public void SetBitmap(string sBitmapFullPath)
{
    try
    {
        if (m_bitmap != null)
        {
            //first dispose of the previous instance
            m_bitmap.Dispose();
            m_bitmap = null;
        }

        //create a temp bitmap
        Bitmap bmTemp = new Bitmap(sBitmapFullPath);
       
        //create the member variable from the temp
        m_bitmap = new Bitmap(bmTemp);
       
        //dispose the temp bitmap
        bmTemp.Dispose();
        bmTemp = null;

        //set the background image to the member bitmap
        this.BackgroundImage = m_bitmap;

    }
    catch (Exception e)
    {
        AddMasterString(e.Message,true);
    }
   
}

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