Releasing Bitmap from system memory to delete it C#

Question

I'm trying to compare two images and delete the second one if they are the same image. When my program goes to delete a file, it throws an error: The process cannot access the file "C:\Temp\Image.jpg" because it is being used by another process

It seems to be an issue with this method not closing the bitmap file, but I have yet to find out a way to release the bitmap from system memory in order to delete it

    public static bool ImageCompareString(Bitmap firstImage, Bitmap secondImage)
    {
        MemoryStream ms = new MemoryStream();
        firstImage.Save(ms, ImageFormat.Png);
        string firstBitmap = Convert.ToBase64String(ms.ToArray());
        ms.Position = 0;

        secondImage.Save(ms, ImageFormat.Png);
        string secondBitmap = Convert.ToBase64String(ms.ToArray());

        if (firstBitmap.Equals(secondBitmap))
        {
            ms.Close();
            return true;
        }
        else 
        {
            ms.Close();
            return false;
        }
    }

Possible duplicate of [Free file locked by new Bitmap(filePath)](https://stackoverflow.com/questions/4803935/free-file-locked-by-new-bitmapfilepath) — user247702, Nov 14 '18 at 14:40
You should also familiarise yourself with `IDisposable`, take a look at [What are the uses of “using” in C#](https://stackoverflow.com/questions/75401/what-are-the-uses-of-using-in-c-sharp) for an introduction. — user247702, Nov 14 '18 at 14:44
The code you should change is out of this scope. Show us how this is called (with the code that loads the bitmaps) — Jeroen van Langen, Nov 14 '18 at 14:47
J. van Langen is correct; the shown code isn't the one where the problem occurs. That would be the code opening and deleting the images. As side note, why would you compare them as strings? Just use the byte arrays themselves and use `.SequenceEquals()`. Using string operations for stuff like that is usually a dirty programmer shortcut that is quite expensive on a processing level. — Nyerguds, Nov 26 '18 at 15:22

score 0 · Answer 1 · answered Nov 14 '18 at 15:06

0

Dispose the bitmap object of second image before deleting the actual file. So something like 'secondImage.Dispose()'

answered Nov 14 '18 at 15:06

pull420

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Or, the more sane way: use the images in `using` blocks so the objects get disposed automatically at the exact moment their scope ends. It has the added advantage of automatic cleanup in case any kind of exception occurs. – Nyerguds Nov 26 '18 at 15:24

score 0 · Answer 2 · answered Nov 14 '18 at 15:12

I would reccommend to use try cach, and run dispose, to free the resources in finnaly section. This will dispose the object even if exception was thrown:

    public static bool ImageCompareString(Bitmap firstImage, Bitmap secondImage)
{
    try
    {
        MemoryStream ms = new MemoryStream();
        firstImage.Save(ms, ImageFormat.Png);
        string firstBitmap = Convert.ToBase64String(ms.ToArray());
        ms.Position = 0;

        secondImage.Save(ms, ImageFormat.Png);
        string secondBitmap = Convert.ToBase64String(ms.ToArray());

        if (firstBitmap.Equals(secondBitmap))
        {
            return true;
        }
        else 
        {           
            return false;
        }
    } 
    catch(Exception ex)
    {
        //log it, display or whatever
    } 
    finnaly 
    {
        ms.Close();
        ms.Dispose();
    }

}

Irrelevant; the deleting code it crashes on _isn't even in the shown code._ — Nyerguds, Nov 26 '18 at 15:22

Releasing Bitmap from system memory to delete it C#

2 Answers2