#21 Fix for calls to ImageRenderer::OnTimer (Invoke or BeginInvoke cannot be called on a control until the window handle has been...)

[Soeren Sproessig]

Hi,
with been encountering repeated exceptions like "Invoke or BeginInvoke cannot be called on a control until the window handle has been..." with ObjectListView and ImageRenderer's async events (OnTimer) in an ImageListView that was used in a conditional dialog - and whose Win32 handle was therefore not yet created or already disposed. A sample stack would look like this (pasted to help others searching for it)

at System.Windows.Forms.Control.WaitForWaitHandle(WaitHandle waitHandle)
at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
at System.Windows.Forms.Control.Invoke(Delegate method)
at BrightIdeasSoftware.ImageRenderer.OnTimer(Object state)
at System.Threading._TimerCallback.TimerCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading._TimerCallback.PerformTimerCallback(Object state)

We patched ObjectListView as follows:

    Index: Renderers.cs
    ===================================================================
    --- Renderers.cs    (revision 762)
    +++ Renderers.cs    (working copy)
    @@ -2379,6 +2379,12 @@
                 if (this.ListView == null || this.Paused) 
                     return;

    +            if (this.ListView.Disposing || this.ListView.IsDisposed)
    +                return;
    +
    +            if (!this.ListView.IsHandleCreated)
    +                return;
    +
                 if (this.ListView.InvokeRequired)
                     this.ListView.Invoke((MethodInvoker)delegate { this.OnTimer(state); });
                 else

Maybe you can merge this into trunk tree?

Regards,
Sören

[Soeren Sproessig]

here the diff against trunk:

[Phillip Piper]

Thank you for this fix.

I will implement a similar fix for the next release.

[Soeren Sproessig]

Hi Phillip,
I'm still getting some crashes for the same problem, but not as often as before (still the object is disposed when Invoke is called).

Perhaps the code needs a private object like disposeLock and some lock(disposeLock) {...} sections, as the timer might always trigger un-synchronized to the disposing.

So - pretty sure my suggestion is not yet complete.

btw: I prevented my code from crashing by just calling Pause() on the ImageRenderer, as I'm only showing .png anyway..

Sören