InvalidOperationException异常 - 对象是目前在其他地方使用 - 红叉 [英] InvalidOperationException - object is currently in use elsewhere - red cross

问题描述

我有一个C＃桌面应用程序中，我创建continously一个线程从源（它实际上是一台数码相机）获得的图像，并把它在GUI面板（panel.Image = IMG）上（必须是另一个线程，因为它是一个控制的code-落后。

I have a C# desktop application in which one thread that I create continously gets an image from a source(it's a digital camera actually) and puts it on a panel(panel.Image = img) in the GUI(which must be another thread as it is the code-behind of a control.

应用程序的工作，但在某些机器上，我得到以下错误随机时间间隔（UN predictable）

The application works but on some machines I get the following error at random time intervals(unpredictable)

************** Exception Text **************
System.InvalidOperationException: The object is currently in use elsewhere. 

然后在面板变成了红叉，红色的X - 我认为这是无效的图片图标是从属性编辑。该应用程序保持工作，但面板永远不会更新。

Then the panel turns into a red cross, red X - i think this is the invalid picture icon that is editable from the properties. The application keeps working but the panel is never updated.

这是我可以告诉这个错误来自控件的OnPaint事件，我画上的画面别的东西。

From what I can tell this error comes from the control's onpaint event where I draw something else on the picture.

我试图用一个锁存在，但没有运气：（

I tried using a lock there but no luck :(

我调用把面板上的图像的功能的方法是如下：

The way I call the function that puts the image on the panel is as follows:

if (this.ReceivedFrame != null)
{
    Delegate[] clients = this.ReceivedFrame.GetInvocationList();
    foreach (Delegate del in clients)
    {
        try
        {
            del.DynamicInvoke(new object[] { this, 
                new StreamEventArgs(frame)} );
        }
        catch { }
    }
}

这是委托：

public delegate void ReceivedFrameEventHandler(object sender, StreamEventArgs e);
    public event ReceivedFrameEventHandler ReceivedFrame;

这是怎么里面的功能控制code-背后注册到它：

and this is how the function inside the control code-behind registers to it:

Camera.ReceivedFrame += 
    new Camera.ReceivedFrameEventHandler(camera_ReceivedFrame);

我也试过

del.Method.Invoke(del.Target, new object[] { this, new StreamEventArgs(b) });

而不是

del.DynamicInvoke(new object[] { this, new StreamEventArgs(frame) });

但没有运气

有谁知道我怎么能解决这个错误，或者至少以某种方式捕获错误，使线程把图像面板上再次？

Does anyone know how I could fix this error or at least catch the error somehow and make the thread put the images on the panel once again?

推荐答案

这是因为GDI +图片类不是线程安全的。 Hovewer您可以通过每次使用锁避免出现InvalidOperationException当你需要访问的图像，例如绘画或获取图像大小：

This is because Gdi+ Image class is not thread safe. Hovewer you can avoid InvalidOperationException by using lock every time when you need to Image access, for example for painting or getting image size:

Image DummyImage;

// Paint
lock (DummyImage)
    e.Graphics.DrawImage(DummyImage, 10, 10);

// Access Image properties
Size ImageSize;
lock (DummyImage)
    ImageSize = DummyImage.Size;

BTW，不需要调用，如果你将使用上面的图案。

BTW, invocation is not needed, if you will use the above pattern.

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