WriteableBitmap.Lock() throws AccessViolationException

Asked Apr 17 '14 at 13:40

Active Apr 17 '14 at 13:46

Viewed 386 times

Ok so I have an application that makes heavy use of WriteableBitmap via the WriteableBitmapEx open source library. Sometimes, rarely (and not sure the exact conditions to cause), calling WriteableBitmap.Lock() throws an AccessViolationException.

The calling code to .Lock() only ever locks the bitmap if it has not already been locked. Many locks/unlocks can be called in quick succession but never in the pattern lock-lock-unlock, only ever lock-unlock-lock-unlock. I can confirm the

Any ideas what is causing this? There seems to be nothing on MSDN to suggest that WriteableBitmap.Lock() should throw an AccessViolationException!

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edited Apr 17 '14 at 13:46

asked Apr 17 '14 at 13:40

Dr. Andrew Burnett-Thompson

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do you lock on the UI thread or a background thread? – thumbmunkeys Apr 17 '14 at 13:45
Ooo good point, will check. UI I believe – Dr. Andrew Burnett-Thompson Apr 17 '14 at 13:46
try it, the documentation is not specific about it, but I think it needs the UI thread – thumbmunkeys Apr 17 '14 at 13:48
Nope sadly it is UI Thread but the call comes from a Dispatcher.BeginInvoke() called inside .Dispose() called from a Finalizer – Dr. Andrew Burnett-Thompson Apr 17 '14 at 14:05
I'm guessing but it could be ... that the Image the WriteableBitmap is attached to has been removed from the Visual Tree after its parent is disposed? – Dr. Andrew Burnett-Thompson Apr 17 '14 at 14:08

WriteableBitmap.Lock() throws AccessViolationException

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