Bitmap Graphics CreateBitmapSourceFromHBitmap memory leak

Question

I want to display a Bitmap in an Image container with WPF.

private void updateImagePreview()
{
    Bitmap bmp = new Bitmap(Screen.PrimaryScreen.WorkingArea.Width,
                            Screen.PrimaryScreen.WorkingArea.Height);
    Graphics gr = Graphics.FromImage(bmp);
    Image Image_Preview;

    while (true)
    {
        gr.CopyFromScreen(0, 0, 0, 0, new System.Drawing.Size(bmp.Width, bmp.Height));
        Image_Preview.Source = loadBitmap(bmp);
    }
}

[DllImport("gdi32")]
static extern int DeleteObject(IntPtr o);
public BitmapSource loadBitmap(System.Drawing.Bitmap source)
{
    IntPtr ip = source.GetHbitmap();
    BitmapSource bs = null;
    try
    {
        bs = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                 ip, IntPtr.Zero, Int32Rect.Empty,
                 System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
    }
    finally
    {
        DeleteObject(ip);
    }

    return bs;
}

The problem is, that this creates a huge memory leak. The leak occurs on the CreateBitmapSourceFromHBitmap call and fills memory while looping till the limit is exceeded. If I don't use that call, then the leak disappears. Any idea why it happens?

What do you mean with "memory leak"? It keeps references in memory after it should've been destroyed? Or does a single call fill up your memory? — almulo, Jul 24 '15 at 09:43
It keeps references. A single call would work, but the memory leak would be still there. — Flupp, Jul 24 '15 at 09:45
Did you see [this exact same question](http://stackoverflow.com/q/28952654/1136211)? It has a lot of links, but yet no answer. — Clemens, Jul 24 '15 at 10:01
Try an alternative approach: save the bitmap to a MemoryStream and decode a BitmapImage or BitmapFrame from that stream (as shown in multiple posts on StackOverflow) — Clemens, Jul 24 '15 at 10:04
I tried the approach [here](http://code.logos.com/blog/2008/04/memory_leak_with_bitmapimage_and_memorystream.html), including the wrapper class and it's also leaking memory. — Flupp, Jul 24 '15 at 10:28
How about [`BitmapFrame.Create`](https://msdn.microsoft.com/en-us/library/ms615998(v=vs.110).aspx) with `OnLoad` set? — Clemens, Jul 24 '15 at 10:33

score 1 · Answer 1 · answered Jul 24 '15 at 09:50

Try calling Freeze() on your BitmapSource before returning it. It seems to help release some references to the image bytes.

[DllImport("gdi32")]
static extern int DeleteObject(IntPtr o);
public BitmapSource loadBitmap(System.Drawing.Bitmap source)
{
    IntPtr ip = source.GetHbitmap();
    BitmapSource bs = null;
    try
    {
        bs = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                 ip, IntPtr.Zero, Int32Rect.Empty,
                 System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
    }
    finally
    {
        DeleteObject(ip);
    }

    bs.Freeze();
    return bs;
}

CharithJ · Answer 2 · 2015-07-26T00:49:18.923

If you have a memory leak, the first thing that you should check is, if there are any Disposable objects that are not disposed.

I can see that you don't dispose both Image and Graphics instances, that could cause memory leaks.

Make sure you dispose them at the end of their usage.

Eg: In updateImagePreview method

using (Graphics gr = Graphics.FromImage(bmp))
{
   ....
}

Eg: In loadBitmap method

public BitmapSource loadBitmap(System.Drawing.Bitmap source)
{
    ....

    finally
    {
        DeleteObject(ip);
        source.Dispose();
    }

    return bs;
}

score 0 · Accepted Answer · answered Aug 03 '15 at 08:54

I solved it somehow, but I don't exactly know how I got rid of that leak. I assume that calling the code that causes the memory leak in a thread somehow fixes that problem. I highly recommend to use the stream wrapper mentioned in the comments, because using only a MemoryStream causes also a memory leak. Anyways, the following is the code that doesn't lead to the mentioned memory leak and works like a charm for me.

Timer takeScreen;

// This is a button to start the screen capturing
private void Button_Play_Click(object sender, RoutedEventArgs e)
    {
        int fps = 30;
        takeScreen = new Timer(o => addNewImage(), null, 0, 1000 / fps);
    }

private void addNewImage()
    {
        using (Bitmap bmp = new Bitmap(System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width, System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height))
        {
            using (Graphics gr = Graphics.FromImage(bmp))
            {
                gr.CopyFromScreen(0, 0, 0, 0, new System.Drawing.Size(bmp.Width, bmp.Height));
                Image_Preview.Dispatcher.Invoke(new Action(() => Image_Preview.Source = loadBitmap(bmp)));
            }
        }
    }

public BitmapSource loadBitmap(System.Drawing.Bitmap source)
    {
        BitmapSource bmpf = null;

        using (MemoryStream ms = new MemoryStream())
        {
            using (WrappingStream ws = new WrappingStream(ms))
            {
                source.Save(ws, System.Drawing.Imaging.ImageFormat.Bmp);
                bmpf = BitmapFrame.Create(ws, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
            }
        }

        return bmpf;
    }

Bitmap Graphics CreateBitmapSourceFromHBitmap memory leak

3 Answers3