How to Unlock a File Locked by Bitmap Initialization in C#?

Solving C# File Locking Problems During Bitmap Loading

The error message "The process cannot access the file because it is being used by another process" typically arises when a Bitmap object holds a lock on the image file after initialization (e.g., pbAvatar.Image = new Bitmap(filePath)). This prevents subsequent attempts to access or modify the file.

The solution lies in releasing this lock. A highly effective method involves loading the image directly from a stream, bypassing the Bitmap constructor's file locking mechanism:

public static Image LoadImageFromStream(string path)
{
    byte[] imageBytes = File.ReadAllBytes(path);
    using (MemoryStream ms = new MemoryStream(imageBytes))
    {
        Image img = Image.FromStream(ms);
        return img;
    }
}

This function reads the image file into a byte array, then uses a MemoryStream to load the Image object, avoiding the file lock. This loaded image can then be assigned to your PictureBox (e.g., pbAvatar.Image = LoadImageFromStream(filePath);).

Performance Considerations

If a Bitmap object is strictly necessary, you can efficiently convert the loaded Image:

return (Bitmap)Image.FromStream(ms);

Benchmarking reveals that loading directly from the byte array is considerably faster (approximately 0.26 ms per image) than creating a Bitmap from an existing Bitmap (around 0.50 ms per image). This performance gain stems from avoiding an unnecessary image copy.

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