位图图形 CreateBitmapSourceFromHBitmap 内存泄漏

Question

我想用 WPF 在 Image 容器中显示 Bitmap。

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;
}

问题是，这会造成巨大的内存泄漏。泄漏发生在 CreateBitmapSourceFromHBitmap 调用上，并在循环时填充内存，直到超过限制。如果我不使用那个电话，那么泄漏就会消失。知道为什么会这样吗？

Answer 1

尝试在 BitmapSource 上调用 Freeze()，然后再返回。好像可以帮助释放一些对图片字节的引用。

[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;
}

Answer 2

如果发生内存泄漏，首先要检查的是是否有任何未处理的 Disposable 对象。

我看到您没有处理两个 Image and Graphics 实例，这可能会导致内存泄漏。

确保在使用结束时将它们丢弃。

例如：在updateImagePreview方法中

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

例如：在loadBitmap方法中

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

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

    return bs;
}

Answer 3

我以某种方式解决了它，但我不完全知道我是如何摆脱泄漏的。我假设调用导致线程中内存泄漏的代码以某种方式解决了该问题。我强烈建议使用评论中提到的 stream wrapper，因为仅使用 MemoryStream 也会导致内存泄漏。无论如何，以下是不会导致上述内存泄漏的代码，并且对我来说很有魅力。

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;
    }

位图图形 CreateBitmapSourceFromHBitmap 内存泄漏

Bitmap Graphics CreateBitmapSourceFromHBitmap memory leak

.net

c#

wpf

memory-leaks

memory-management